hush: do not allow sh -c '{ echo boo }'

[oweals/busybox.git] / shell / ash.c

/* vi: set sw=4 ts=4: */
/*
 * ash shell port for busybox
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Original BSD copyright notice is retained at the end of this file.
 *
 * Copyright (c) 1989, 1991, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
 * was re-ported from NetBSD and debianized.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

/*
 * The following should be set to reflect the type of system you have:
 *      JOBS -> 1 if you have Berkeley job control, 0 otherwise.
 *      define SYSV if you are running under System V.
 *      define DEBUG=1 to compile in debugging ('set -o debug' to turn on)
 *      define DEBUG=2 to compile in and turn on debugging.
 *
 * When debugging is on (DEBUG is 1 and "set -o debug" was executed),
 * debugging info will be written to ./trace and a quit signal
 * will generate a core dump.
 */
#define DEBUG 0
/* Tweak debug output verbosity here */
#define DEBUG_TIME 0
#define DEBUG_PID 1
#define DEBUG_SIG 1
#define DEBUG_INTONOFF 0

#define PROFILE 0

#define JOBS ENABLE_ASH_JOB_CONTROL

#include <setjmp.h>
#include <fnmatch.h>
#include <sys/times.h>
#include <sys/utsname.h> /* for setting $HOSTNAME */

#include "busybox.h" /* for applet_names */

#if defined(__ANDROID_API__) && __ANDROID_API__ <= 24
/* Bionic at least up to version 24 has no glob() */
# undef  ENABLE_ASH_INTERNAL_GLOB
# define ENABLE_ASH_INTERNAL_GLOB 1
#endif

#if !ENABLE_ASH_INTERNAL_GLOB
# include <glob.h>
#endif

#include "unicode.h"
#include "shell_common.h"
#if ENABLE_SH_MATH_SUPPORT
# include "math.h"
#endif
#if ENABLE_ASH_RANDOM_SUPPORT
# include "random.h"
#else
# define CLEAR_RANDOM_T(rnd) ((void)0)
#endif

#include "NUM_APPLETS.h"
#if NUM_APPLETS == 1
/* STANDALONE does not make sense, and won't compile */
# undef CONFIG_FEATURE_SH_STANDALONE
# undef ENABLE_FEATURE_SH_STANDALONE
# undef IF_FEATURE_SH_STANDALONE
# undef IF_NOT_FEATURE_SH_STANDALONE
# define ENABLE_FEATURE_SH_STANDALONE 0
# define IF_FEATURE_SH_STANDALONE(...)
# define IF_NOT_FEATURE_SH_STANDALONE(...) __VA_ARGS__
#endif

#ifndef PIPE_BUF
# define PIPE_BUF 4096           /* amount of buffering in a pipe */
#endif

#if !BB_MMU
# error "Do not even bother, ash will not run on NOMMU machine"
#endif

//config:config ASH
//config:       bool "ash"
//config:       default y
//config:       depends on !NOMMU
//config:       help
//config:         Tha 'ash' shell adds about 60k in the default configuration and is
//config:         the most complete and most pedantically correct shell included with
//config:         busybox. This shell is actually a derivative of the Debian 'dash'
//config:         shell (by Herbert Xu), which was created by porting the 'ash' shell
//config:         (written by Kenneth Almquist) from NetBSD.
//config:
//config:config ASH_OPTIMIZE_FOR_SIZE
//config:       bool "Optimize for size instead of speed"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Compile ash for reduced size at the price of speed.
//config:
//config:config ASH_INTERNAL_GLOB
//config:       bool "Use internal glob() implementation"
//config:       default n
//config:       depends on ASH
//config:       help
//config:         Do not use glob() function from libc, use internal implementation.
//config:         Use this if you are getting "glob.h: No such file or directory"
//config:         or similar build errors.
//config:
//config:config ASH_RANDOM_SUPPORT
//config:       bool "Pseudorandom generator and $RANDOM variable"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable pseudorandom generator and dynamic variable "$RANDOM".
//config:         Each read of "$RANDOM" will generate a new pseudorandom value.
//config:         You can reset the generator by using a specified start value.
//config:         After "unset RANDOM" the generator will switch off and this
//config:         variable will no longer have special treatment.
//config:
//config:config ASH_EXPAND_PRMT
//config:       bool "Expand prompt string"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         "PS#" may contain volatile content, such as backquote commands.
//config:         This option recreates the prompt string from the environment
//config:         variable each time it is displayed.
//config:
//config:config ASH_BASH_COMPAT
//config:       bool "bash-compatible extensions"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable bash-compatible extensions.
//config:
//config:config ASH_IDLE_TIMEOUT
//config:       bool "Idle timeout variable"
//config:       default n
//config:       depends on ASH
//config:       help
//config:         Enables bash-like auto-logout after $TMOUT seconds of idle time.
//config:
//config:config ASH_JOB_CONTROL
//config:       bool "Job control"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable job control in the ash shell.
//config:
//config:config ASH_ALIAS
//config:       bool "Alias support"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable alias support in the ash shell.
//config:
//config:config ASH_GETOPTS
//config:       bool "Builtin getopt to parse positional parameters"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable support for getopts builtin in ash.
//config:
//config:config ASH_BUILTIN_ECHO
//config:       bool "Builtin version of 'echo'"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable support for echo builtin in ash.
//config:
//config:config ASH_BUILTIN_PRINTF
//config:       bool "Builtin version of 'printf'"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable support for printf builtin in ash.
//config:
//config:config ASH_BUILTIN_TEST
//config:       bool "Builtin version of 'test'"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable support for test builtin in ash.
//config:
//config:config ASH_HELP
//config:       bool "help builtin"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable help builtin in ash.
//config:
//config:config ASH_CMDCMD
//config:       bool "'command' command to override shell builtins"
//config:       default y
//config:       depends on ASH
//config:       help
//config:         Enable support for the ash 'command' builtin, which allows
//config:         you to run the specified command with the specified arguments,
//config:         even when there is an ash builtin command with the same name.
//config:
//config:config ASH_MAIL
//config:       bool "Check for new mail on interactive shells"
//config:       default n
//config:       depends on ASH
//config:       help
//config:         Enable "check for new mail" function in the ash shell.
//config:

//applet:IF_ASH(APPLET(ash, BB_DIR_BIN, BB_SUID_DROP))
//applet:IF_FEATURE_SH_IS_ASH(APPLET_ODDNAME(sh, ash, BB_DIR_BIN, BB_SUID_DROP, sh))
//applet:IF_FEATURE_BASH_IS_ASH(APPLET_ODDNAME(bash, ash, BB_DIR_BIN, BB_SUID_DROP, bash))

//kbuild:lib-$(CONFIG_ASH) += ash.o ash_ptr_hack.o shell_common.o
//kbuild:lib-$(CONFIG_ASH_RANDOM_SUPPORT) += random.o


/* ============ Hash table sizes. Configurable. */

#define VTABSIZE 39
#define ATABSIZE 39
#define CMDTABLESIZE 31         /* should be prime */


/* ============ Shell options */

static const char *const optletters_optnames[] = {
        "e"   "errexit",
        "f"   "noglob",
        "I"   "ignoreeof",
        "i"   "interactive",
        "m"   "monitor",
        "n"   "noexec",
        "s"   "stdin",
        "x"   "xtrace",
        "v"   "verbose",
        "C"   "noclobber",
        "a"   "allexport",
        "b"   "notify",
        "u"   "nounset",
        "\0"  "vi"
#if ENABLE_ASH_BASH_COMPAT
        ,"\0"  "pipefail"
#endif
#if DEBUG
        ,"\0"  "nolog"
        ,"\0"  "debug"
#endif
};

#define optletters(n)  optletters_optnames[n][0]
#define optnames(n)   (optletters_optnames[n] + 1)

enum { NOPTS = ARRAY_SIZE(optletters_optnames) };


/* ============ Misc data */

#define msg_illnum "Illegal number: %s"

/*
 * We enclose jmp_buf in a structure so that we can declare pointers to
 * jump locations.  The global variable handler contains the location to
 * jump to when an exception occurs, and the global variable exception_type
 * contains a code identifying the exception.  To implement nested
 * exception handlers, the user should save the value of handler on entry
 * to an inner scope, set handler to point to a jmploc structure for the
 * inner scope, and restore handler on exit from the scope.
 */
struct jmploc {
        jmp_buf loc;
};

struct globals_misc {
        uint8_t exitstatus;     /* exit status of last command */
        uint8_t back_exitstatus;/* exit status of backquoted command */
        smallint job_warning;   /* user was warned about stopped jobs (can be 2, 1 or 0). */
        int rootpid;            /* pid of main shell */
        /* shell level: 0 for the main shell, 1 for its children, and so on */
        int shlvl;
#define rootshell (!shlvl)
        char *minusc;  /* argument to -c option */

        char *curdir; // = nullstr;     /* current working directory */
        char *physdir; // = nullstr;    /* physical working directory */

        char *arg0; /* value of $0 */

        struct jmploc *exception_handler;

        volatile int suppress_int; /* counter */
        volatile /*sig_atomic_t*/ smallint pending_int; /* 1 = got SIGINT */
        volatile /*sig_atomic_t*/ smallint got_sigchld; /* 1 = got SIGCHLD */
        volatile /*sig_atomic_t*/ smallint pending_sig; /* last pending signal */
        smallint exception_type; /* kind of exception (0..5) */
        /* exceptions */
#define EXINT 0         /* SIGINT received */
#define EXERROR 1       /* a generic error */
#define EXEXIT 4        /* exit the shell */

        smallint isloginsh;
        char nullstr[1];        /* zero length string */

        char optlist[NOPTS];
#define eflag optlist[0]
#define fflag optlist[1]
#define Iflag optlist[2]
#define iflag optlist[3]
#define mflag optlist[4]
#define nflag optlist[5]
#define sflag optlist[6]
#define xflag optlist[7]
#define vflag optlist[8]
#define Cflag optlist[9]
#define aflag optlist[10]
#define bflag optlist[11]
#define uflag optlist[12]
#define viflag optlist[13]
#if ENABLE_ASH_BASH_COMPAT
# define pipefail optlist[14]
#else
# define pipefail 0
#endif
#if DEBUG
# define nolog optlist[14 + ENABLE_ASH_BASH_COMPAT]
# define debug optlist[15 + ENABLE_ASH_BASH_COMPAT]
#endif

        /* trap handler commands */
        /*
         * Sigmode records the current value of the signal handlers for the various
         * modes.  A value of zero means that the current handler is not known.
         * S_HARD_IGN indicates that the signal was ignored on entry to the shell.
         */
        char sigmode[NSIG - 1];
#define S_DFL      1            /* default signal handling (SIG_DFL) */
#define S_CATCH    2            /* signal is caught */
#define S_IGN      3            /* signal is ignored (SIG_IGN) */
#define S_HARD_IGN 4            /* signal is ignored permanently */

        /* indicates specified signal received */
        uint8_t gotsig[NSIG - 1]; /* offset by 1: "signal" 0 is meaningless */
        uint8_t may_have_traps; /* 0: definitely no traps are set, 1: some traps may be set */
        char *trap[NSIG];
        char **trap_ptr;        /* used only by "trap hack" */

        /* Rarely referenced stuff */
#if ENABLE_ASH_RANDOM_SUPPORT
        random_t random_gen;
#endif
        pid_t backgndpid;        /* pid of last background process */
};
extern struct globals_misc *const ash_ptr_to_globals_misc;
#define G_misc (*ash_ptr_to_globals_misc)
#define exitstatus        (G_misc.exitstatus )
#define back_exitstatus   (G_misc.back_exitstatus )
#define job_warning       (G_misc.job_warning)
#define rootpid     (G_misc.rootpid    )
#define shlvl       (G_misc.shlvl      )
#define minusc      (G_misc.minusc     )
#define curdir      (G_misc.curdir     )
#define physdir     (G_misc.physdir    )
#define arg0        (G_misc.arg0       )
#define exception_handler (G_misc.exception_handler)
#define exception_type    (G_misc.exception_type   )
#define suppress_int      (G_misc.suppress_int     )
#define pending_int       (G_misc.pending_int      )
#define got_sigchld       (G_misc.got_sigchld      )
#define pending_sig       (G_misc.pending_sig      )
#define isloginsh   (G_misc.isloginsh  )
#define nullstr     (G_misc.nullstr    )
#define optlist     (G_misc.optlist    )
#define sigmode     (G_misc.sigmode    )
#define gotsig      (G_misc.gotsig     )
#define may_have_traps    (G_misc.may_have_traps   )
#define trap        (G_misc.trap       )
#define trap_ptr    (G_misc.trap_ptr   )
#define random_gen  (G_misc.random_gen )
#define backgndpid  (G_misc.backgndpid )
#define INIT_G_misc() do { \
        (*(struct globals_misc**)&ash_ptr_to_globals_misc) = xzalloc(sizeof(G_misc)); \
        barrier(); \
        curdir = nullstr; \
        physdir = nullstr; \
        trap_ptr = trap; \
} while (0)


/* ============ DEBUG */
#if DEBUG
static void trace_printf(const char *fmt, ...);
static void trace_vprintf(const char *fmt, va_list va);
# define TRACE(param)    trace_printf param
# define TRACEV(param)   trace_vprintf param
# define close(fd) do { \
        int dfd = (fd); \
        if (close(dfd) < 0) \
                bb_error_msg("bug on %d: closing %d(0x%x)", \
                        __LINE__, dfd, dfd); \
} while (0)
#else
# define TRACE(param)
# define TRACEV(param)
#endif


/* ============ Utility functions */
#define is_name(c)      ((c) == '_' || isalpha((unsigned char)(c)))
#define is_in_name(c)   ((c) == '_' || isalnum((unsigned char)(c)))

static int
isdigit_str9(const char *str)
{
        int maxlen = 9 + 1; /* max 9 digits: 999999999 */
        while (--maxlen && isdigit(*str))
                str++;
        return (*str == '\0');
}

static const char *
var_end(const char *var)
{
        while (*var)
                if (*var++ == '=')
                        break;
        return var;
}


/* ============ Interrupts / exceptions */

static void exitshell(void) NORETURN;

/*
 * These macros allow the user to suspend the handling of interrupt signals
 * over a period of time.  This is similar to SIGHOLD or to sigblock, but
 * much more efficient and portable.  (But hacking the kernel is so much
 * more fun than worrying about efficiency and portability. :-))
 */
#if DEBUG_INTONOFF
# define INT_OFF do { \
        TRACE(("%s:%d INT_OFF(%d)\n", __func__, __LINE__, suppress_int)); \
        suppress_int++; \
        barrier(); \
} while (0)
#else
# define INT_OFF do { \
        suppress_int++; \
        barrier(); \
} while (0)
#endif

/*
 * Called to raise an exception.  Since C doesn't include exceptions, we
 * just do a longjmp to the exception handler.  The type of exception is
 * stored in the global variable "exception_type".
 */
static void raise_exception(int) NORETURN;
static void
raise_exception(int e)
{
#if DEBUG
        if (exception_handler == NULL)
                abort();
#endif
        INT_OFF;
        exception_type = e;
        longjmp(exception_handler->loc, 1);
}
#if DEBUG
#define raise_exception(e) do { \
        TRACE(("raising exception %d on line %d\n", (e), __LINE__)); \
        raise_exception(e); \
} while (0)
#endif

/*
 * Called when a SIGINT is received.  (If the user specifies
 * that SIGINT is to be trapped or ignored using the trap builtin, then
 * this routine is not called.)  Suppressint is nonzero when interrupts
 * are held using the INT_OFF macro.  (The test for iflag is just
 * defensive programming.)
 */
static void raise_interrupt(void) NORETURN;
static void
raise_interrupt(void)
{
        pending_int = 0;
        /* Signal is not automatically unmasked after it is raised,
         * do it ourself - unmask all signals */
        sigprocmask_allsigs(SIG_UNBLOCK);
        /* pending_sig = 0; - now done in signal_handler() */

        if (!(rootshell && iflag)) {
                /* Kill ourself with SIGINT */
                signal(SIGINT, SIG_DFL);
                raise(SIGINT);
        }
        /* bash: ^C even on empty command line sets $? */
        exitstatus = SIGINT + 128;
        raise_exception(EXINT);
        /* NOTREACHED */
}
#if DEBUG
#define raise_interrupt() do { \
        TRACE(("raising interrupt on line %d\n", __LINE__)); \
        raise_interrupt(); \
} while (0)
#endif

static IF_ASH_OPTIMIZE_FOR_SIZE(inline) void
int_on(void)
{
        barrier();
        if (--suppress_int == 0 && pending_int) {
                raise_interrupt();
        }
}
#if DEBUG_INTONOFF
# define INT_ON do { \
        TRACE(("%s:%d INT_ON(%d)\n", __func__, __LINE__, suppress_int-1)); \
        int_on(); \
} while (0)
#else
# define INT_ON int_on()
#endif
static IF_ASH_OPTIMIZE_FOR_SIZE(inline) void
force_int_on(void)
{
        barrier();
        suppress_int = 0;
        if (pending_int)
                raise_interrupt();
}
#define FORCE_INT_ON force_int_on()

#define SAVE_INT(v) ((v) = suppress_int)

#define RESTORE_INT(v) do { \
        barrier(); \
        suppress_int = (v); \
        if (suppress_int == 0 && pending_int) \
                raise_interrupt(); \
} while (0)


/* ============ Stdout/stderr output */

static void
outstr(const char *p, FILE *file)
{
        INT_OFF;
        fputs(p, file);
        INT_ON;
}

static void
flush_stdout_stderr(void)
{
        INT_OFF;
        fflush_all();
        INT_ON;
}

/* Was called outcslow(c,FILE*), but c was always '\n' */
static void
newline_and_flush(FILE *dest)
{
        INT_OFF;
        putc('\n', dest);
        fflush(dest);
        INT_ON;
}

static int out1fmt(const char *, ...) __attribute__((__format__(__printf__,1,2)));
static int
out1fmt(const char *fmt, ...)
{
        va_list ap;
        int r;

        INT_OFF;
        va_start(ap, fmt);
        r = vprintf(fmt, ap);
        va_end(ap);
        INT_ON;
        return r;
}

static int fmtstr(char *, size_t, const char *, ...) __attribute__((__format__(__printf__,3,4)));
static int
fmtstr(char *outbuf, size_t length, const char *fmt, ...)
{
        va_list ap;
        int ret;

        va_start(ap, fmt);
        INT_OFF;
        ret = vsnprintf(outbuf, length, fmt, ap);
        va_end(ap);
        INT_ON;
        return ret;
}

static void
out1str(const char *p)
{
        outstr(p, stdout);
}

static void
out2str(const char *p)
{
        outstr(p, stderr);
        flush_stdout_stderr();
}


/* ============ Parser structures */

/* control characters in argument strings */
#define CTL_FIRST CTLESC
#define CTLESC       ((unsigned char)'\201')    /* escape next character */
#define CTLVAR       ((unsigned char)'\202')    /* variable defn */
#define CTLENDVAR    ((unsigned char)'\203')
#define CTLBACKQ     ((unsigned char)'\204')
#define CTLARI       ((unsigned char)'\206')    /* arithmetic expression */
#define CTLENDARI    ((unsigned char)'\207')
#define CTLQUOTEMARK ((unsigned char)'\210')
#define CTL_LAST CTLQUOTEMARK

/* variable substitution byte (follows CTLVAR) */
#define VSTYPE  0x0f            /* type of variable substitution */
#define VSNUL   0x10            /* colon--treat the empty string as unset */

/* values of VSTYPE field */
#define VSNORMAL        0x1     /* normal variable:  $var or ${var} */
#define VSMINUS         0x2     /* ${var-text} */
#define VSPLUS          0x3     /* ${var+text} */
#define VSQUESTION      0x4     /* ${var?message} */
#define VSASSIGN        0x5     /* ${var=text} */
#define VSTRIMRIGHT     0x6     /* ${var%pattern} */
#define VSTRIMRIGHTMAX  0x7     /* ${var%%pattern} */
#define VSTRIMLEFT      0x8     /* ${var#pattern} */
#define VSTRIMLEFTMAX   0x9     /* ${var##pattern} */
#define VSLENGTH        0xa     /* ${#var} */
#if ENABLE_ASH_BASH_COMPAT
#define VSSUBSTR        0xc     /* ${var:position:length} */
#define VSREPLACE       0xd     /* ${var/pattern/replacement} */
#define VSREPLACEALL    0xe     /* ${var//pattern/replacement} */
#endif

static const char dolatstr[] ALIGN1 = {
        CTLQUOTEMARK, CTLVAR, VSNORMAL, '@', '=', CTLQUOTEMARK, '\0'
};
#define DOLATSTRLEN 6

#define NCMD      0
#define NPIPE     1
#define NREDIR    2
#define NBACKGND  3
#define NSUBSHELL 4
#define NAND      5
#define NOR       6
#define NSEMI     7
#define NIF       8
#define NWHILE    9
#define NUNTIL   10
#define NFOR     11
#define NCASE    12
#define NCLIST   13
#define NDEFUN   14
#define NARG     15
#define NTO      16
#if ENABLE_ASH_BASH_COMPAT
#define NTO2     17
#endif
#define NCLOBBER 18
#define NFROM    19
#define NFROMTO  20
#define NAPPEND  21
#define NTOFD    22
#define NFROMFD  23
#define NHERE    24
#define NXHERE   25
#define NNOT     26
#define N_NUMBER 27

union node;

struct ncmd {
        smallint type; /* Nxxxx */
        union node *assign;
        union node *args;
        union node *redirect;
};

struct npipe {
        smallint type;
        smallint pipe_backgnd;
        struct nodelist *cmdlist;
};

struct nredir {
        smallint type;
        union node *n;
        union node *redirect;
};

struct nbinary {
        smallint type;
        union node *ch1;
        union node *ch2;
};

struct nif {
        smallint type;
        union node *test;
        union node *ifpart;
        union node *elsepart;
};

struct nfor {
        smallint type;
        union node *args;
        union node *body;
        char *var;
};

struct ncase {
        smallint type;
        union node *expr;
        union node *cases;
};

struct nclist {
        smallint type;
        union node *next;
        union node *pattern;
        union node *body;
};

struct narg {
        smallint type;
        union node *next;
        char *text;
        struct nodelist *backquote;
};

/* nfile and ndup layout must match!
 * NTOFD (>&fdnum) uses ndup structure, but we may discover mid-flight
 * that it is actually NTO2 (>&file), and change its type.
 */
struct nfile {
        smallint type;
        union node *next;
        int fd;
        int _unused_dupfd;
        union node *fname;
        char *expfname;
};

struct ndup {
        smallint type;
        union node *next;
        int fd;
        int dupfd;
        union node *vname;
        char *_unused_expfname;
};

struct nhere {
        smallint type;
        union node *next;
        int fd;
        union node *doc;
};

struct nnot {
        smallint type;
        union node *com;
};

union node {
        smallint type;
        struct ncmd ncmd;
        struct npipe npipe;
        struct nredir nredir;
        struct nbinary nbinary;
        struct nif nif;
        struct nfor nfor;
        struct ncase ncase;
        struct nclist nclist;
        struct narg narg;
        struct nfile nfile;
        struct ndup ndup;
        struct nhere nhere;
        struct nnot nnot;
};

/*
 * NODE_EOF is returned by parsecmd when it encounters an end of file.
 * It must be distinct from NULL.
 */
#define NODE_EOF ((union node *) -1L)

struct nodelist {
        struct nodelist *next;
        union node *n;
};

struct funcnode {
        int count;
        union node n;
};

/*
 * Free a parse tree.
 */
static void
freefunc(struct funcnode *f)
{
        if (f && --f->count < 0)
                free(f);
}


/* ============ Debugging output */

#if DEBUG

static FILE *tracefile;

static void
trace_printf(const char *fmt, ...)
{
        va_list va;

        if (debug != 1)
                return;
        if (DEBUG_TIME)
                fprintf(tracefile, "%u ", (int) time(NULL));
        if (DEBUG_PID)
                fprintf(tracefile, "[%u] ", (int) getpid());
        if (DEBUG_SIG)
                fprintf(tracefile, "pending s:%d i:%d(supp:%d) ", pending_sig, pending_int, suppress_int);
        va_start(va, fmt);
        vfprintf(tracefile, fmt, va);
        va_end(va);
}

static void
trace_vprintf(const char *fmt, va_list va)
{
        if (debug != 1)
                return;
        vfprintf(tracefile, fmt, va);
        fprintf(tracefile, "\n");
}

static void
trace_puts(const char *s)
{
        if (debug != 1)
                return;
        fputs(s, tracefile);
}

static void
trace_puts_quoted(char *s)
{
        char *p;
        char c;

        if (debug != 1)
                return;
        putc('"', tracefile);
        for (p = s; *p; p++) {
                switch ((unsigned char)*p) {
                case '\n': c = 'n'; goto backslash;
                case '\t': c = 't'; goto backslash;
                case '\r': c = 'r'; goto backslash;
                case '\"': c = '\"'; goto backslash;
                case '\\': c = '\\'; goto backslash;
                case CTLESC: c = 'e'; goto backslash;
                case CTLVAR: c = 'v'; goto backslash;
                case CTLBACKQ: c = 'q'; goto backslash;
 backslash:
                        putc('\\', tracefile);
                        putc(c, tracefile);
                        break;
                default:
                        if (*p >= ' ' && *p <= '~')
                                putc(*p, tracefile);
                        else {
                                putc('\\', tracefile);
                                putc((*p >> 6) & 03, tracefile);
                                putc((*p >> 3) & 07, tracefile);
                                putc(*p & 07, tracefile);
                        }
                        break;
                }
        }
        putc('"', tracefile);
}

static void
trace_puts_args(char **ap)
{
        if (debug != 1)
                return;
        if (!*ap)
                return;
        while (1) {
                trace_puts_quoted(*ap);
                if (!*++ap) {
                        putc('\n', tracefile);
                        break;
                }
                putc(' ', tracefile);
        }
}

static void
opentrace(void)
{
        char s[100];
#ifdef O_APPEND
        int flags;
#endif

        if (debug != 1) {
                if (tracefile)
                        fflush(tracefile);
                /* leave open because libedit might be using it */
                return;
        }
        strcpy(s, "./trace");
        if (tracefile) {
                if (!freopen(s, "a", tracefile)) {
                        fprintf(stderr, "Can't re-open %s\n", s);
                        debug = 0;
                        return;
                }
        } else {
                tracefile = fopen(s, "a");
                if (tracefile == NULL) {
                        fprintf(stderr, "Can't open %s\n", s);
                        debug = 0;
                        return;
                }
        }
#ifdef O_APPEND
        flags = fcntl(fileno(tracefile), F_GETFL);
        if (flags >= 0)
                fcntl(fileno(tracefile), F_SETFL, flags | O_APPEND);
#endif
        setlinebuf(tracefile);
        fputs("\nTracing started.\n", tracefile);
}

static void
indent(int amount, char *pfx, FILE *fp)
{
        int i;

        for (i = 0; i < amount; i++) {
                if (pfx && i == amount - 1)
                        fputs(pfx, fp);
                putc('\t', fp);
        }
}

/* little circular references here... */
static void shtree(union node *n, int ind, char *pfx, FILE *fp);

static void
sharg(union node *arg, FILE *fp)
{
        char *p;
        struct nodelist *bqlist;
        unsigned char subtype;

        if (arg->type != NARG) {
                out1fmt("<node type %d>\n", arg->type);
                abort();
        }
        bqlist = arg->narg.backquote;
        for (p = arg->narg.text; *p; p++) {
                switch ((unsigned char)*p) {
                case CTLESC:
                        p++;
                        putc(*p, fp);
                        break;
                case CTLVAR:
                        putc('$', fp);
                        putc('{', fp);
                        subtype = *++p;
                        if (subtype == VSLENGTH)
                                putc('#', fp);

                        while (*p != '=') {
                                putc(*p, fp);
                                p++;
                        }

                        if (subtype & VSNUL)
                                putc(':', fp);

                        switch (subtype & VSTYPE) {
                        case VSNORMAL:
                                putc('}', fp);
                                break;
                        case VSMINUS:
                                putc('-', fp);
                                break;
                        case VSPLUS:
                                putc('+', fp);
                                break;
                        case VSQUESTION:
                                putc('?', fp);
                                break;
                        case VSASSIGN:
                                putc('=', fp);
                                break;
                        case VSTRIMLEFT:
                                putc('#', fp);
                                break;
                        case VSTRIMLEFTMAX:
                                putc('#', fp);
                                putc('#', fp);
                                break;
                        case VSTRIMRIGHT:
                                putc('%', fp);
                                break;
                        case VSTRIMRIGHTMAX:
                                putc('%', fp);
                                putc('%', fp);
                                break;
                        case VSLENGTH:
                                break;
                        default:
                                out1fmt("<subtype %d>", subtype);
                        }
                        break;
                case CTLENDVAR:
                        putc('}', fp);
                        break;
                case CTLBACKQ:
                        putc('$', fp);
                        putc('(', fp);
                        shtree(bqlist->n, -1, NULL, fp);
                        putc(')', fp);
                        break;
                default:
                        putc(*p, fp);
                        break;
                }
        }
}

static void
shcmd(union node *cmd, FILE *fp)
{
        union node *np;
        int first;
        const char *s;
        int dftfd;

        first = 1;
        for (np = cmd->ncmd.args; np; np = np->narg.next) {
                if (!first)
                        putc(' ', fp);
                sharg(np, fp);
                first = 0;
        }
        for (np = cmd->ncmd.redirect; np; np = np->nfile.next) {
                if (!first)
                        putc(' ', fp);
                dftfd = 0;
                switch (np->nfile.type) {
                case NTO:      s = ">>"+1; dftfd = 1; break;
                case NCLOBBER: s = ">|"; dftfd = 1; break;
                case NAPPEND:  s = ">>"; dftfd = 1; break;
#if ENABLE_ASH_BASH_COMPAT
                case NTO2:
#endif
                case NTOFD:    s = ">&"; dftfd = 1; break;
                case NFROM:    s = "<"; break;
                case NFROMFD:  s = "<&"; break;
                case NFROMTO:  s = "<>"; break;
                default:       s = "*error*"; break;
                }
                if (np->nfile.fd != dftfd)
                        fprintf(fp, "%d", np->nfile.fd);
                fputs(s, fp);
                if (np->nfile.type == NTOFD || np->nfile.type == NFROMFD) {
                        fprintf(fp, "%d", np->ndup.dupfd);
                } else {
                        sharg(np->nfile.fname, fp);
                }
                first = 0;
        }
}

static void
shtree(union node *n, int ind, char *pfx, FILE *fp)
{
        struct nodelist *lp;
        const char *s;

        if (n == NULL)
                return;

        indent(ind, pfx, fp);

        if (n == NODE_EOF) {
                fputs("<EOF>", fp);
                return;
        }

        switch (n->type) {
        case NSEMI:
                s = "; ";
                goto binop;
        case NAND:
                s = " && ";
                goto binop;
        case NOR:
                s = " || ";
 binop:
                shtree(n->nbinary.ch1, ind, NULL, fp);
                /* if (ind < 0) */
                        fputs(s, fp);
                shtree(n->nbinary.ch2, ind, NULL, fp);
                break;
        case NCMD:
                shcmd(n, fp);
                if (ind >= 0)
                        putc('\n', fp);
                break;
        case NPIPE:
                for (lp = n->npipe.cmdlist; lp; lp = lp->next) {
                        shtree(lp->n, 0, NULL, fp);
                        if (lp->next)
                                fputs(" | ", fp);
                }
                if (n->npipe.pipe_backgnd)
                        fputs(" &", fp);
                if (ind >= 0)
                        putc('\n', fp);
                break;
        default:
                fprintf(fp, "<node type %d>", n->type);
                if (ind >= 0)
                        putc('\n', fp);
                break;
        }
}

static void
showtree(union node *n)
{
        trace_puts("showtree called\n");
        shtree(n, 1, NULL, stderr);
}

#endif /* DEBUG */


/* ============ Parser data */

/*
 * ash_vmsg() needs parsefile->fd, hence parsefile definition is moved up.
 */
struct strlist {
        struct strlist *next;
        char *text;
};

struct alias;

struct strpush {
        struct strpush *prev;   /* preceding string on stack */
        char *prev_string;
        int prev_left_in_line;
#if ENABLE_ASH_ALIAS
        struct alias *ap;       /* if push was associated with an alias */
#endif
        char *string;           /* remember the string since it may change */

        /* Remember last two characters for pungetc. */
        int lastc[2];

        /* Number of outstanding calls to pungetc. */
        int unget;
};

struct parsefile {
        struct parsefile *prev; /* preceding file on stack */
        int linno;              /* current line */
        int pf_fd;              /* file descriptor (or -1 if string) */
        int left_in_line;       /* number of chars left in this line */
        int left_in_buffer;     /* number of chars left in this buffer past the line */
        char *next_to_pgetc;    /* next char in buffer */
        char *buf;              /* input buffer */
        struct strpush *strpush; /* for pushing strings at this level */
        struct strpush basestrpush; /* so pushing one is fast */

        /* Remember last two characters for pungetc. */
        int lastc[2];

        /* Number of outstanding calls to pungetc. */
        int unget;
};

static struct parsefile basepf;        /* top level input file */
static struct parsefile *g_parsefile = &basepf;  /* current input file */
static int startlinno;                 /* line # where last token started */
static char *commandname;              /* currently executing command */
static struct strlist *cmdenviron;     /* environment for builtin command */


/* ============ Message printing */

static void
ash_vmsg(const char *msg, va_list ap)
{
        fprintf(stderr, "%s: ", arg0);
        if (commandname) {
                if (strcmp(arg0, commandname))
                        fprintf(stderr, "%s: ", commandname);
                if (!iflag || g_parsefile->pf_fd > 0)
                        fprintf(stderr, "line %d: ", startlinno);
        }
        vfprintf(stderr, msg, ap);
        newline_and_flush(stderr);
}

/*
 * Exverror is called to raise the error exception.  If the second argument
 * is not NULL then error prints an error message using printf style
 * formatting.  It then raises the error exception.
 */
static void ash_vmsg_and_raise(int, const char *, va_list) NORETURN;
static void
ash_vmsg_and_raise(int cond, const char *msg, va_list ap)
{
#if DEBUG
        if (msg) {
                TRACE(("ash_vmsg_and_raise(%d):", cond));
                TRACEV((msg, ap));
        } else
                TRACE(("ash_vmsg_and_raise(%d):NULL\n", cond));
        if (msg)
#endif
                ash_vmsg(msg, ap);

        flush_stdout_stderr();
        raise_exception(cond);
        /* NOTREACHED */
}

static void ash_msg_and_raise_error(const char *, ...) NORETURN;
static void
ash_msg_and_raise_error(const char *msg, ...)
{
        va_list ap;

        va_start(ap, msg);
        ash_vmsg_and_raise(EXERROR, msg, ap);
        /* NOTREACHED */
        va_end(ap);
}

static void raise_error_syntax(const char *) NORETURN;
static void
raise_error_syntax(const char *msg)
{
        ash_msg_and_raise_error("syntax error: %s", msg);
        /* NOTREACHED */
}

static void ash_msg_and_raise(int, const char *, ...) NORETURN;
static void
ash_msg_and_raise(int cond, const char *msg, ...)
{
        va_list ap;

        va_start(ap, msg);
        ash_vmsg_and_raise(cond, msg, ap);
        /* NOTREACHED */
        va_end(ap);
}

/*
 * error/warning routines for external builtins
 */
static void
ash_msg(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        ash_vmsg(fmt, ap);
        va_end(ap);
}

/*
 * Return a string describing an error.  The returned string may be a
 * pointer to a static buffer that will be overwritten on the next call.
 * Action describes the operation that got the error.
 */
static const char *
errmsg(int e, const char *em)
{
        if (e == ENOENT || e == ENOTDIR) {
                return em;
        }
        return strerror(e);
}


/* ============ Memory allocation */

#if 0
/* I consider these wrappers nearly useless:
 * ok, they return you to nearest exception handler, but
 * how much memory do you leak in the process, making
 * memory starvation worse?
 */
static void *
ckrealloc(void * p, size_t nbytes)
{
        p = realloc(p, nbytes);
        if (!p)
                ash_msg_and_raise_error(bb_msg_memory_exhausted);
        return p;
}

static void *
ckmalloc(size_t nbytes)
{
        return ckrealloc(NULL, nbytes);
}

static void *
ckzalloc(size_t nbytes)
{
        return memset(ckmalloc(nbytes), 0, nbytes);
}

static char *
ckstrdup(const char *s)
{
        char *p = strdup(s);
        if (!p)
                ash_msg_and_raise_error(bb_msg_memory_exhausted);
        return p;
}
#else
/* Using bbox equivalents. They exit if out of memory */
# define ckrealloc xrealloc
# define ckmalloc  xmalloc
# define ckzalloc  xzalloc
# define ckstrdup  xstrdup
#endif

/*
 * It appears that grabstackstr() will barf with such alignments
 * because stalloc() will return a string allocated in a new stackblock.
 */
#define SHELL_ALIGN(nbytes) (((nbytes) + SHELL_SIZE) & ~SHELL_SIZE)
enum {
        /* Most machines require the value returned from malloc to be aligned
         * in some way.  The following macro will get this right
         * on many machines.  */
        SHELL_SIZE = sizeof(union { int i; char *cp; double d; }) - 1,
        /* Minimum size of a block */
        MINSIZE = SHELL_ALIGN(504),
};

struct stack_block {
        struct stack_block *prev;
        char space[MINSIZE];
};

struct stackmark {
        struct stack_block *stackp;
        char *stacknxt;
        size_t stacknleft;
};


struct globals_memstack {
        struct stack_block *g_stackp; // = &stackbase;
        char *g_stacknxt; // = stackbase.space;
        char *sstrend; // = stackbase.space + MINSIZE;
        size_t g_stacknleft; // = MINSIZE;
        struct stack_block stackbase;
};
extern struct globals_memstack *const ash_ptr_to_globals_memstack;
#define G_memstack (*ash_ptr_to_globals_memstack)
#define g_stackp     (G_memstack.g_stackp    )
#define g_stacknxt   (G_memstack.g_stacknxt  )
#define sstrend      (G_memstack.sstrend     )
#define g_stacknleft (G_memstack.g_stacknleft)
#define stackbase    (G_memstack.stackbase   )
#define INIT_G_memstack() do { \
        (*(struct globals_memstack**)&ash_ptr_to_globals_memstack) = xzalloc(sizeof(G_memstack)); \
        barrier(); \
        g_stackp = &stackbase; \
        g_stacknxt = stackbase.space; \
        g_stacknleft = MINSIZE; \
        sstrend = stackbase.space + MINSIZE; \
} while (0)


#define stackblock()     ((void *)g_stacknxt)
#define stackblocksize() g_stacknleft

/*
 * Parse trees for commands are allocated in lifo order, so we use a stack
 * to make this more efficient, and also to avoid all sorts of exception
 * handling code to handle interrupts in the middle of a parse.
 *
 * The size 504 was chosen because the Ultrix malloc handles that size
 * well.
 */
static void *
stalloc(size_t nbytes)
{
        char *p;
        size_t aligned;

        aligned = SHELL_ALIGN(nbytes);
        if (aligned > g_stacknleft) {
                size_t len;
                size_t blocksize;
                struct stack_block *sp;

                blocksize = aligned;
                if (blocksize < MINSIZE)
                        blocksize = MINSIZE;
                len = sizeof(struct stack_block) - MINSIZE + blocksize;
                if (len < blocksize)
                        ash_msg_and_raise_error(bb_msg_memory_exhausted);
                INT_OFF;
                sp = ckmalloc(len);
                sp->prev = g_stackp;
                g_stacknxt = sp->space;
                g_stacknleft = blocksize;
                sstrend = g_stacknxt + blocksize;
                g_stackp = sp;
                INT_ON;
        }
        p = g_stacknxt;
        g_stacknxt += aligned;
        g_stacknleft -= aligned;
        return p;
}

static void *
stzalloc(size_t nbytes)
{
        return memset(stalloc(nbytes), 0, nbytes);
}

static void
stunalloc(void *p)
{
#if DEBUG
        if (!p || (g_stacknxt < (char *)p) || ((char *)p < g_stackp->space)) {
                write(STDERR_FILENO, "stunalloc\n", 10);
                abort();
        }
#endif
        g_stacknleft += g_stacknxt - (char *)p;
        g_stacknxt = p;
}

/*
 * Like strdup but works with the ash stack.
 */
static char *
sstrdup(const char *p)
{
        size_t len = strlen(p) + 1;
        return memcpy(stalloc(len), p, len);
}

static inline void
grabstackblock(size_t len)
{
        stalloc(len);
}

static void
pushstackmark(struct stackmark *mark, size_t len)
{
        mark->stackp = g_stackp;
        mark->stacknxt = g_stacknxt;
        mark->stacknleft = g_stacknleft;
        grabstackblock(len);
}

static void
setstackmark(struct stackmark *mark)
{
        pushstackmark(mark, g_stacknxt == g_stackp->space && g_stackp != &stackbase);
}

static void
popstackmark(struct stackmark *mark)
{
        struct stack_block *sp;

        if (!mark->stackp)
                return;

        INT_OFF;
        while (g_stackp != mark->stackp) {
                sp = g_stackp;
                g_stackp = sp->prev;
                free(sp);
        }
        g_stacknxt = mark->stacknxt;
        g_stacknleft = mark->stacknleft;
        sstrend = mark->stacknxt + mark->stacknleft;
        INT_ON;
}

/*
 * When the parser reads in a string, it wants to stick the string on the
 * stack and only adjust the stack pointer when it knows how big the
 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 * of space on top of the stack and stackblocklen returns the length of
 * this block.  Growstackblock will grow this space by at least one byte,
 * possibly moving it (like realloc).  Grabstackblock actually allocates the
 * part of the block that has been used.
 */
static void
growstackblock(void)
{
        size_t newlen;

        newlen = g_stacknleft * 2;
        if (newlen < g_stacknleft)
                ash_msg_and_raise_error(bb_msg_memory_exhausted);
        if (newlen < 128)
                newlen += 128;

        if (g_stacknxt == g_stackp->space && g_stackp != &stackbase) {
                struct stack_block *sp;
                struct stack_block *prevstackp;
                size_t grosslen;

                INT_OFF;
                sp = g_stackp;
                prevstackp = sp->prev;
                grosslen = newlen + sizeof(struct stack_block) - MINSIZE;
                sp = ckrealloc(sp, grosslen);
                sp->prev = prevstackp;
                g_stackp = sp;
                g_stacknxt = sp->space;
                g_stacknleft = newlen;
                sstrend = sp->space + newlen;
                INT_ON;
        } else {
                char *oldspace = g_stacknxt;
                size_t oldlen = g_stacknleft;
                char *p = stalloc(newlen);

                /* free the space we just allocated */
                g_stacknxt = memcpy(p, oldspace, oldlen);
                g_stacknleft += newlen;
        }
}

/*
 * The following routines are somewhat easier to use than the above.
 * The user declares a variable of type STACKSTR, which may be declared
 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 * the user uses the macro STPUTC to add characters to the string.  In
 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 * grown as necessary.  When the user is done, she can just leave the
 * string there and refer to it using stackblock().  Or she can allocate
 * the space for it using grabstackstr().  If it is necessary to allow
 * someone else to use the stack temporarily and then continue to grow
 * the string, the user should use grabstack to allocate the space, and
 * then call ungrabstr(p) to return to the previous mode of operation.
 *
 * USTPUTC is like STPUTC except that it doesn't check for overflow.
 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 * is space for at least one character.
 */
static void *
growstackstr(void)
{
        size_t len = stackblocksize();
        growstackblock();
        return (char *)stackblock() + len;
}

/*
 * Called from CHECKSTRSPACE.
 */
static char *
makestrspace(size_t newlen, char *p)
{
        size_t len = p - g_stacknxt;
        size_t size;

        for (;;) {
                size_t nleft;

                size = stackblocksize();
                nleft = size - len;
                if (nleft >= newlen)
                        break;
                growstackblock();
        }
        return (char *)stackblock() + len;
}

static char *
stack_nputstr(const char *s, size_t n, char *p)
{
        p = makestrspace(n, p);
        p = (char *)memcpy(p, s, n) + n;
        return p;
}

static char *
stack_putstr(const char *s, char *p)
{
        return stack_nputstr(s, strlen(s), p);
}

static char *
_STPUTC(int c, char *p)
{
        if (p == sstrend)
                p = growstackstr();
        *p++ = c;
        return p;
}

#define STARTSTACKSTR(p)        ((p) = stackblock())
#define STPUTC(c, p)            ((p) = _STPUTC((c), (p)))
#define CHECKSTRSPACE(n, p) do { \
        char *q = (p); \
        size_t l = (n); \
        size_t m = sstrend - q; \
        if (l > m) \
                (p) = makestrspace(l, q); \
} while (0)
#define USTPUTC(c, p)           (*(p)++ = (c))
#define STACKSTRNUL(p) do { \
        if ((p) == sstrend) \
                (p) = growstackstr(); \
        *(p) = '\0'; \
} while (0)
#define STUNPUTC(p)             (--(p))
#define STTOPC(p)               ((p)[-1])
#define STADJUST(amount, p)     ((p) += (amount))

#define grabstackstr(p)         stalloc((char *)(p) - (char *)stackblock())
#define ungrabstackstr(s, p)    stunalloc(s)
#define stackstrend()           ((void *)sstrend)


/* ============ String helpers */

/*
 * prefix -- see if pfx is a prefix of string.
 */
static char *
prefix(const char *string, const char *pfx)
{
        while (*pfx) {
                if (*pfx++ != *string++)
                        return NULL;
        }
        return (char *) string;
}

/*
 * Check for a valid number.  This should be elsewhere.
 */
static int
is_number(const char *p)
{
        do {
                if (!isdigit(*p))
                        return 0;
        } while (*++p != '\0');
        return 1;
}

/*
 * Convert a string of digits to an integer, printing an error message on
 * failure.
 */
static int
number(const char *s)
{
        if (!is_number(s))
                ash_msg_and_raise_error(msg_illnum, s);
        return atoi(s);
}

/*
 * Produce a possibly single quoted string suitable as input to the shell.
 * The return string is allocated on the stack.
 */
static char *
single_quote(const char *s)
{
        char *p;

        STARTSTACKSTR(p);

        do {
                char *q;
                size_t len;

                len = strchrnul(s, '\'') - s;

                q = p = makestrspace(len + 3, p);

                *q++ = '\'';
                q = (char *)memcpy(q, s, len) + len;
                *q++ = '\'';
                s += len;

                STADJUST(q - p, p);

                if (*s != '\'')
                        break;
                len = 0;
                do len++; while (*++s == '\'');

                q = p = makestrspace(len + 3, p);

                *q++ = '"';
                q = (char *)memcpy(q, s - len, len) + len;
                *q++ = '"';

                STADJUST(q - p, p);
        } while (*s);

        USTPUTC('\0', p);

        return stackblock();
}


/* ============ nextopt */

static char **argptr;                  /* argument list for builtin commands */
static char *optionarg;                /* set by nextopt (like getopt) */
static char *optptr;                   /* used by nextopt */

/*
 * XXX - should get rid of. Have all builtins use getopt(3).
 * The library getopt must have the BSD extension static variable
 * "optreset", otherwise it can't be used within the shell safely.
 *
 * Standard option processing (a la getopt) for builtin routines.
 * The only argument that is passed to nextopt is the option string;
 * the other arguments are unnecessary. It returns the character,
 * or '\0' on end of input.
 */
static int
nextopt(const char *optstring)
{
        char *p;
        const char *q;
        char c;

        p = optptr;
        if (p == NULL || *p == '\0') {
                /* We ate entire "-param", take next one */
                p = *argptr;
                if (p == NULL)
                        return '\0';
                if (*p != '-')
                        return '\0';
                if (*++p == '\0') /* just "-" ? */
                        return '\0';
                argptr++;
                if (LONE_DASH(p)) /* "--" ? */
                        return '\0';
                /* p => next "-param" */
        }
        /* p => some option char in the middle of a "-param" */
        c = *p++;
        for (q = optstring; *q != c;) {
                if (*q == '\0')
                        ash_msg_and_raise_error("illegal option -%c", c);
                if (*++q == ':')
                        q++;
        }
        if (*++q == ':') {
                if (*p == '\0') {
                        p = *argptr++;
                        if (p == NULL)
                                ash_msg_and_raise_error("no arg for -%c option", c);
                }
                optionarg = p;
                p = NULL;
        }
        optptr = p;
        return c;
}


/* ============ Shell variables */

/*
 * The parsefile structure pointed to by the global variable parsefile
 * contains information about the current file being read.
 */
struct shparam {
        int nparam;             /* # of positional parameters (without $0) */
#if ENABLE_ASH_GETOPTS
        int optind;             /* next parameter to be processed by getopts */
        int optoff;             /* used by getopts */
#endif
        unsigned char malloced; /* if parameter list dynamically allocated */
        char **p;               /* parameter list */
};

/*
 * Free the list of positional parameters.
 */
static void
freeparam(volatile struct shparam *param)
{
        if (param->malloced) {
                char **ap, **ap1;
                ap = ap1 = param->p;
                while (*ap)
                        free(*ap++);
                free(ap1);
        }
}

#if ENABLE_ASH_GETOPTS
static void FAST_FUNC getoptsreset(const char *value);
#endif

struct var {
        struct var *next;               /* next entry in hash list */
        int flags;                      /* flags are defined above */
        const char *var_text;           /* name=value */
        void (*var_func)(const char *) FAST_FUNC; /* function to be called when  */
                                        /* the variable gets set/unset */
};

struct localvar {
        struct localvar *next;          /* next local variable in list */
        struct var *vp;                 /* the variable that was made local */
        int flags;                      /* saved flags */
        const char *text;               /* saved text */
};

/* flags */
#define VEXPORT         0x01    /* variable is exported */
#define VREADONLY       0x02    /* variable cannot be modified */
#define VSTRFIXED       0x04    /* variable struct is statically allocated */
#define VTEXTFIXED      0x08    /* text is statically allocated */
#define VSTACK          0x10    /* text is allocated on the stack */
#define VUNSET          0x20    /* the variable is not set */
#define VNOFUNC         0x40    /* don't call the callback function */
#define VNOSET          0x80    /* do not set variable - just readonly test */
#define VNOSAVE         0x100   /* when text is on the heap before setvareq */
#if ENABLE_ASH_RANDOM_SUPPORT
# define VDYNAMIC       0x200   /* dynamic variable */
#else
# define VDYNAMIC       0
#endif


/* Need to be before varinit_data[] */
#if ENABLE_LOCALE_SUPPORT
static void FAST_FUNC
change_lc_all(const char *value)
{
        if (value && *value != '\0')
                setlocale(LC_ALL, value);
}
static void FAST_FUNC
change_lc_ctype(const char *value)
{
        if (value && *value != '\0')
                setlocale(LC_CTYPE, value);
}
#endif
#if ENABLE_ASH_MAIL
static void chkmail(void);
static void changemail(const char *var_value) FAST_FUNC;
#else
# define chkmail()  ((void)0)
#endif
static void changepath(const char *) FAST_FUNC;
#if ENABLE_ASH_RANDOM_SUPPORT
static void change_random(const char *) FAST_FUNC;
#endif

static const struct {
        int flags;
        const char *var_text;
        void (*var_func)(const char *) FAST_FUNC;
} varinit_data[] = {
        /*
         * Note: VEXPORT would not work correctly here for NOFORK applets:
         * some environment strings may be constant.
         */
        { VSTRFIXED|VTEXTFIXED       , defifsvar   , NULL            },
#if ENABLE_ASH_MAIL
        { VSTRFIXED|VTEXTFIXED|VUNSET, "MAIL"      , changemail      },
        { VSTRFIXED|VTEXTFIXED|VUNSET, "MAILPATH"  , changemail      },
#endif
        { VSTRFIXED|VTEXTFIXED       , bb_PATH_root_path, changepath },
        { VSTRFIXED|VTEXTFIXED       , "PS1=$ "    , NULL            },
        { VSTRFIXED|VTEXTFIXED       , "PS2=> "    , NULL            },
        { VSTRFIXED|VTEXTFIXED       , "PS4=+ "    , NULL            },
#if ENABLE_ASH_GETOPTS
        { VSTRFIXED|VTEXTFIXED       , defoptindvar, getoptsreset    },
#endif
#if ENABLE_ASH_RANDOM_SUPPORT
        { VSTRFIXED|VTEXTFIXED|VUNSET|VDYNAMIC, "RANDOM", change_random },
#endif
#if ENABLE_LOCALE_SUPPORT
        { VSTRFIXED|VTEXTFIXED|VUNSET, "LC_ALL"    , change_lc_all   },
        { VSTRFIXED|VTEXTFIXED|VUNSET, "LC_CTYPE"  , change_lc_ctype },
#endif
#if ENABLE_FEATURE_EDITING_SAVEHISTORY
        { VSTRFIXED|VTEXTFIXED|VUNSET, "HISTFILE"  , NULL            },
#endif
};

struct redirtab;

struct globals_var {
        struct shparam shellparam;      /* $@ current positional parameters */
        struct redirtab *redirlist;
        int preverrout_fd;   /* save fd2 before print debug if xflag is set. */
        struct var *vartab[VTABSIZE];
        struct var varinit[ARRAY_SIZE(varinit_data)];
};
extern struct globals_var *const ash_ptr_to_globals_var;
#define G_var (*ash_ptr_to_globals_var)
#define shellparam    (G_var.shellparam   )
//#define redirlist     (G_var.redirlist    )
#define preverrout_fd (G_var.preverrout_fd)
#define vartab        (G_var.vartab       )
#define varinit       (G_var.varinit      )
#define INIT_G_var() do { \
        unsigned i; \
        (*(struct globals_var**)&ash_ptr_to_globals_var) = xzalloc(sizeof(G_var)); \
        barrier(); \
        for (i = 0; i < ARRAY_SIZE(varinit_data); i++) { \
                varinit[i].flags    = varinit_data[i].flags; \
                varinit[i].var_text = varinit_data[i].var_text; \
                varinit[i].var_func = varinit_data[i].var_func; \
        } \
} while (0)

#define vifs      varinit[0]
#if ENABLE_ASH_MAIL
# define vmail    (&vifs)[1]
# define vmpath   (&vmail)[1]
# define vpath    (&vmpath)[1]
#else
# define vpath    (&vifs)[1]
#endif
#define vps1      (&vpath)[1]
#define vps2      (&vps1)[1]
#define vps4      (&vps2)[1]
#if ENABLE_ASH_GETOPTS
# define voptind  (&vps4)[1]
# if ENABLE_ASH_RANDOM_SUPPORT
#  define vrandom (&voptind)[1]
# endif
#else
# if ENABLE_ASH_RANDOM_SUPPORT
#  define vrandom (&vps4)[1]
# endif
#endif

/*
 * The following macros access the values of the above variables.
 * They have to skip over the name.  They return the null string
 * for unset variables.
 */
#define ifsval()        (vifs.var_text + 4)
#define ifsset()        ((vifs.flags & VUNSET) == 0)
#if ENABLE_ASH_MAIL
# define mailval()      (vmail.var_text + 5)
# define mpathval()     (vmpath.var_text + 9)
# define mpathset()     ((vmpath.flags & VUNSET) == 0)
#endif
#define pathval()       (vpath.var_text + 5)
#define ps1val()        (vps1.var_text + 4)
#define ps2val()        (vps2.var_text + 4)
#define ps4val()        (vps4.var_text + 4)
#if ENABLE_ASH_GETOPTS
# define optindval()    (voptind.var_text + 7)
#endif

#if ENABLE_ASH_GETOPTS
static void FAST_FUNC
getoptsreset(const char *value)
{
        shellparam.optind = number(value) ?: 1;
        shellparam.optoff = -1;
}
#endif

/*
 * Compares two strings up to the first = or '\0'.  The first
 * string must be terminated by '='; the second may be terminated by
 * either '=' or '\0'.
 */
static int
varcmp(const char *p, const char *q)
{
        int c, d;

        while ((c = *p) == (d = *q)) {
                if (c == '\0' || c == '=')
                        goto out;
                p++;
                q++;
        }
        if (c == '=')
                c = '\0';
        if (d == '=')
                d = '\0';
 out:
        return c - d;
}

/*
 * Find the appropriate entry in the hash table from the name.
 */
static struct var **
hashvar(const char *p)
{
        unsigned hashval;

        hashval = ((unsigned char) *p) << 4;
        while (*p && *p != '=')
                hashval += (unsigned char) *p++;
        return &vartab[hashval % VTABSIZE];
}

static int
vpcmp(const void *a, const void *b)
{
        return varcmp(*(const char **)a, *(const char **)b);
}

/*
 * This routine initializes the builtin variables.
 */
static void
initvar(void)
{
        struct var *vp;
        struct var *end;
        struct var **vpp;

        /*
         * PS1 depends on uid
         */
#if ENABLE_FEATURE_EDITING && ENABLE_FEATURE_EDITING_FANCY_PROMPT
        vps1.var_text = "PS1=\\w \\$ ";
#else
        if (!geteuid())
                vps1.var_text = "PS1=# ";
#endif
        vp = varinit;
        end = vp + ARRAY_SIZE(varinit);
        do {
                vpp = hashvar(vp->var_text);
                vp->next = *vpp;
                *vpp = vp;
        } while (++vp < end);
}

static struct var **
findvar(struct var **vpp, const char *name)
{
        for (; *vpp; vpp = &(*vpp)->next) {
                if (varcmp((*vpp)->var_text, name) == 0) {
                        break;
                }
        }
        return vpp;
}

/*
 * Find the value of a variable.  Returns NULL if not set.
 */
static const char* FAST_FUNC
lookupvar(const char *name)
{
        struct var *v;

        v = *findvar(hashvar(name), name);
        if (v) {
#if ENABLE_ASH_RANDOM_SUPPORT
        /*
         * Dynamic variables are implemented roughly the same way they are
         * in bash. Namely, they're "special" so long as they aren't unset.
         * As soon as they're unset, they're no longer dynamic, and dynamic
         * lookup will no longer happen at that point. -- PFM.
         */
                if (v->flags & VDYNAMIC)
                        v->var_func(NULL);
#endif
                if (!(v->flags & VUNSET))
                        return var_end(v->var_text);
        }
        return NULL;
}

static void
reinit_unicode_for_ash(void)
{
        /* Unicode support should be activated even if LANG is set
         * _during_ shell execution, not only if it was set when
         * shell was started. Therefore, re-check LANG every time:
         */
        if (ENABLE_FEATURE_CHECK_UNICODE_IN_ENV
         || ENABLE_UNICODE_USING_LOCALE
        ) {
                const char *s = lookupvar("LC_ALL");
                if (!s) s = lookupvar("LC_CTYPE");
                if (!s) s = lookupvar("LANG");
                reinit_unicode(s);
        }
}

/*
 * Search the environment of a builtin command.
 */
static const char *
bltinlookup(const char *name)
{
        struct strlist *sp;

        for (sp = cmdenviron; sp; sp = sp->next) {
                if (varcmp(sp->text, name) == 0)
                        return var_end(sp->text);
        }
        return lookupvar(name);
}

/*
 * Same as setvar except that the variable and value are passed in
 * the first argument as name=value.  Since the first argument will
 * be actually stored in the table, it should not be a string that
 * will go away.
 * Called with interrupts off.
 */
static void
setvareq(char *s, int flags)
{
        struct var *vp, **vpp;

        vpp = hashvar(s);
        flags |= (VEXPORT & (((unsigned) (1 - aflag)) - 1));
        vp = *findvar(vpp, s);
        if (vp) {
                if ((vp->flags & (VREADONLY|VDYNAMIC)) == VREADONLY) {
                        const char *n;

                        if (flags & VNOSAVE)
                                free(s);
                        n = vp->var_text;
                        exitstatus = 1;
                        ash_msg_and_raise_error("%.*s: is read only", strchrnul(n, '=') - n, n);
                }

                if (flags & VNOSET)
                        return;

                if (vp->var_func && !(flags & VNOFUNC))
                        vp->var_func(var_end(s));

                if (!(vp->flags & (VTEXTFIXED|VSTACK)))
                        free((char*)vp->var_text);

                flags |= vp->flags & ~(VTEXTFIXED|VSTACK|VNOSAVE|VUNSET);
        } else {
                /* variable s is not found */
                if (flags & VNOSET)
                        return;
                vp = ckzalloc(sizeof(*vp));
                vp->next = *vpp;
                /*vp->func = NULL; - ckzalloc did it */
                *vpp = vp;
        }
        if (!(flags & (VTEXTFIXED|VSTACK|VNOSAVE)))
                s = ckstrdup(s);
        vp->var_text = s;
        vp->flags = flags;
}

/*
 * Set the value of a variable.  The flags argument is ored with the
 * flags of the variable.  If val is NULL, the variable is unset.
 */
static void
setvar(const char *name, const char *val, int flags)
{
        const char *q;
        char *p;
        char *nameeq;
        size_t namelen;
        size_t vallen;

        q = endofname(name);
        p = strchrnul(q, '=');
        namelen = p - name;
        if (!namelen || p != q)
                ash_msg_and_raise_error("%.*s: bad variable name", namelen, name);
        vallen = 0;
        if (val == NULL) {
                flags |= VUNSET;
        } else {
                vallen = strlen(val);
        }

        INT_OFF;
        nameeq = ckmalloc(namelen + vallen + 2);
        p = memcpy(nameeq, name, namelen) + namelen;
        if (val) {
                *p++ = '=';
                p = memcpy(p, val, vallen) + vallen;
        }
        *p = '\0';
        setvareq(nameeq, flags | VNOSAVE);
        INT_ON;
}

static void FAST_FUNC
setvar0(const char *name, const char *val)
{
        setvar(name, val, 0);
}

/*
 * Unset the specified variable.
 */
static int
unsetvar(const char *s)
{
        struct var **vpp;
        struct var *vp;
        int retval;

        vpp = findvar(hashvar(s), s);
        vp = *vpp;
        retval = 2;
        if (vp) {
                int flags = vp->flags;

                retval = 1;
                if (flags & VREADONLY)
                        goto out;
#if ENABLE_ASH_RANDOM_SUPPORT
                vp->flags &= ~VDYNAMIC;
#endif
                if (flags & VUNSET)
                        goto ok;
                if ((flags & VSTRFIXED) == 0) {
                        INT_OFF;
                        if ((flags & (VTEXTFIXED|VSTACK)) == 0)
                                free((char*)vp->var_text);
                        *vpp = vp->next;
                        free(vp);
                        INT_ON;
                } else {
                        setvar0(s, NULL);
                        vp->flags &= ~VEXPORT;
                }
 ok:
                retval = 0;
        }
 out:
        return retval;
}

/*
 * Process a linked list of variable assignments.
 */
static void
listsetvar(struct strlist *list_set_var, int flags)
{
        struct strlist *lp = list_set_var;

        if (!lp)
                return;
        INT_OFF;
        do {
                setvareq(lp->text, flags);
                lp = lp->next;
        } while (lp);
        INT_ON;
}

/*
 * Generate a list of variables satisfying the given conditions.
 */
static char **
listvars(int on, int off, char ***end)
{
        struct var **vpp;
        struct var *vp;
        char **ep;
        int mask;

        STARTSTACKSTR(ep);
        vpp = vartab;
        mask = on | off;
        do {
                for (vp = *vpp; vp; vp = vp->next) {
                        if ((vp->flags & mask) == on) {
                                if (ep == stackstrend())
                                        ep = growstackstr();
                                *ep++ = (char*)vp->var_text;
                        }
                }
        } while (++vpp < vartab + VTABSIZE);
        if (ep == stackstrend())
                ep = growstackstr();
        if (end)
                *end = ep;
        *ep++ = NULL;
        return grabstackstr(ep);
}


/* ============ Path search helper
 *
 * The variable path (passed by reference) should be set to the start
 * of the path before the first call; path_advance will update
 * this value as it proceeds.  Successive calls to path_advance will return
 * the possible path expansions in sequence.  If an option (indicated by
 * a percent sign) appears in the path entry then the global variable
 * pathopt will be set to point to it; otherwise pathopt will be set to
 * NULL.
 */
static const char *pathopt;     /* set by path_advance */

static char *
path_advance(const char **path, const char *name)
{
        const char *p;
        char *q;
        const char *start;
        size_t len;

        if (*path == NULL)
                return NULL;
        start = *path;
        for (p = start; *p && *p != ':' && *p != '%'; p++)
                continue;
        len = p - start + strlen(name) + 2;     /* "2" is for '/' and '\0' */
        while (stackblocksize() < len)
                growstackblock();
        q = stackblock();
        if (p != start) {
                memcpy(q, start, p - start);
                q += p - start;
                *q++ = '/';
        }
        strcpy(q, name);
        pathopt = NULL;
        if (*p == '%') {
                pathopt = ++p;
                while (*p && *p != ':')
                        p++;
        }
        if (*p == ':')
                *path = p + 1;
        else
                *path = NULL;
        return stalloc(len);
}


/* ============ Prompt */

static smallint doprompt;                   /* if set, prompt the user */
static smallint needprompt;                 /* true if interactive and at start of line */

#if ENABLE_FEATURE_EDITING
static line_input_t *line_input_state;
static const char *cmdedit_prompt;
static void
putprompt(const char *s)
{
        if (ENABLE_ASH_EXPAND_PRMT) {
                free((char*)cmdedit_prompt);
                cmdedit_prompt = ckstrdup(s);
                return;
        }
        cmdedit_prompt = s;
}
#else
static void
putprompt(const char *s)
{
        out2str(s);
}
#endif

#if ENABLE_ASH_EXPAND_PRMT
/* expandstr() needs parsing machinery, so it is far away ahead... */
static const char *expandstr(const char *ps);
#else
#define expandstr(s) s
#endif

static void
setprompt_if(smallint do_set, int whichprompt)
{
        const char *prompt;
        IF_ASH_EXPAND_PRMT(struct stackmark smark;)

        if (!do_set)
                return;

        needprompt = 0;

        switch (whichprompt) {
        case 1:
                prompt = ps1val();
                break;
        case 2:
                prompt = ps2val();
                break;
        default:                        /* 0 */
                prompt = nullstr;
        }
#if ENABLE_ASH_EXPAND_PRMT
        pushstackmark(&smark, stackblocksize());
#endif
        putprompt(expandstr(prompt));
#if ENABLE_ASH_EXPAND_PRMT
        popstackmark(&smark);
#endif
}


/* ============ The cd and pwd commands */

#define CD_PHYSICAL 1
#define CD_PRINT 2

static int
cdopt(void)
{
        int flags = 0;
        int i, j;

        j = 'L';
        while ((i = nextopt("LP")) != '\0') {
                if (i != j) {
                        flags ^= CD_PHYSICAL;
                        j = i;
                }
        }

        return flags;
}

/*
 * Update curdir (the name of the current directory) in response to a
 * cd command.
 */
static const char *
updatepwd(const char *dir)
{
        char *new;
        char *p;
        char *cdcomppath;
        const char *lim;

        cdcomppath = sstrdup(dir);
        STARTSTACKSTR(new);
        if (*dir != '/') {
                if (curdir == nullstr)
                        return 0;
                new = stack_putstr(curdir, new);
        }
        new = makestrspace(strlen(dir) + 2, new);
        lim = (char *)stackblock() + 1;
        if (*dir != '/') {
                if (new[-1] != '/')
                        USTPUTC('/', new);
                if (new > lim && *lim == '/')
                        lim++;
        } else {
                USTPUTC('/', new);
                cdcomppath++;
                if (dir[1] == '/' && dir[2] != '/') {
                        USTPUTC('/', new);
                        cdcomppath++;
                        lim++;
                }
        }
        p = strtok(cdcomppath, "/");
        while (p) {
                switch (*p) {
                case '.':
                        if (p[1] == '.' && p[2] == '\0') {
                                while (new > lim) {
                                        STUNPUTC(new);
                                        if (new[-1] == '/')
                                                break;
                                }
                                break;
                        }
                        if (p[1] == '\0')
                                break;
                        /* fall through */
                default:
                        new = stack_putstr(p, new);
                        USTPUTC('/', new);
                }
                p = strtok(NULL, "/");
        }
        if (new > lim)
                STUNPUTC(new);
        *new = 0;
        return stackblock();
}

/*
 * Find out what the current directory is. If we already know the current
 * directory, this routine returns immediately.
 */
static char *
getpwd(void)
{
        char *dir = getcwd(NULL, 0); /* huh, using glibc extension? */
        return dir ? dir : nullstr;
}

static void
setpwd(const char *val, int setold)
{
        char *oldcur, *dir;

        oldcur = dir = curdir;

        if (setold) {
                setvar("OLDPWD", oldcur, VEXPORT);
        }
        INT_OFF;
        if (physdir != nullstr) {
                if (physdir != oldcur)
                        free(physdir);
                physdir = nullstr;
        }
        if (oldcur == val || !val) {
                char *s = getpwd();
                physdir = s;
                if (!val)
                        dir = s;
        } else
                dir = ckstrdup(val);
        if (oldcur != dir && oldcur != nullstr) {
                free(oldcur);
        }
        curdir = dir;
        INT_ON;
        setvar("PWD", dir, VEXPORT);
}

static void hashcd(void);

/*
 * Actually do the chdir.  We also call hashcd to let other routines
 * know that the current directory has changed.
 */
static int
docd(const char *dest, int flags)
{
        const char *dir = NULL;
        int err;

        TRACE(("docd(\"%s\", %d) called\n", dest, flags));

        INT_OFF;
        if (!(flags & CD_PHYSICAL)) {
                dir = updatepwd(dest);
                if (dir)
                        dest = dir;
        }
        err = chdir(dest);
        if (err)
                goto out;
        setpwd(dir, 1);
        hashcd();
 out:
        INT_ON;
        return err;
}

static int FAST_FUNC
cdcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        const char *dest;
        const char *path;
        const char *p;
        char c;
        struct stat statb;
        int flags;

        flags = cdopt();
        dest = *argptr;
        if (!dest)
                dest = bltinlookup("HOME");
        else if (LONE_DASH(dest)) {
                dest = bltinlookup("OLDPWD");
                flags |= CD_PRINT;
        }
        if (!dest)
                dest = nullstr;
        if (*dest == '/')
                goto step6;
        if (*dest == '.') {
                c = dest[1];
 dotdot:
                switch (c) {
                case '\0':
                case '/':
                        goto step6;
                case '.':
                        c = dest[2];
                        if (c != '.')
                                goto dotdot;
                }
        }
        if (!*dest)
                dest = ".";
        path = bltinlookup("CDPATH");
        while (path) {
                c = *path;
                p = path_advance(&path, dest);
                if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
                        if (c && c != ':')
                                flags |= CD_PRINT;
 docd:
                        if (!docd(p, flags))
                                goto out;
                        goto err;
                }
        }

 step6:
        p = dest;
        goto docd;

 err:
        ash_msg_and_raise_error("can't cd to %s", dest);
        /* NOTREACHED */
 out:
        if (flags & CD_PRINT)
                out1fmt("%s\n", curdir);
        return 0;
}

static int FAST_FUNC
pwdcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        int flags;
        const char *dir = curdir;

        flags = cdopt();
        if (flags) {
                if (physdir == nullstr)
                        setpwd(dir, 0);
                dir = physdir;
        }
        out1fmt("%s\n", dir);
        return 0;
}


/* ============ ... */


#define IBUFSIZ (ENABLE_FEATURE_EDITING ? CONFIG_FEATURE_EDITING_MAX_LEN : 1024)

/* Syntax classes */
#define CWORD     0             /* character is nothing special */
#define CNL       1             /* newline character */
#define CBACK     2             /* a backslash character */
#define CSQUOTE   3             /* single quote */
#define CDQUOTE   4             /* double quote */
#define CENDQUOTE 5             /* a terminating quote */
#define CBQUOTE   6             /* backwards single quote */
#define CVAR      7             /* a dollar sign */
#define CENDVAR   8             /* a '}' character */
#define CLP       9             /* a left paren in arithmetic */
#define CRP      10             /* a right paren in arithmetic */
#define CENDFILE 11             /* end of file */
#define CCTL     12             /* like CWORD, except it must be escaped */
#define CSPCL    13             /* these terminate a word */
#define CIGN     14             /* character should be ignored */

#define PEOF     256
#if ENABLE_ASH_ALIAS
# define PEOA    257
#endif

#define USE_SIT_FUNCTION ENABLE_ASH_OPTIMIZE_FOR_SIZE

#if ENABLE_SH_MATH_SUPPORT
# define SIT_ITEM(a,b,c,d) (a | (b << 4) | (c << 8) | (d << 12))
#else
# define SIT_ITEM(a,b,c,d) (a | (b << 4) | (c << 8))
#endif
static const uint16_t S_I_T[] ALIGN2 = {
#if ENABLE_ASH_ALIAS
        SIT_ITEM(CSPCL   , CIGN     , CIGN , CIGN   ),    /* 0, PEOA */
#endif
        SIT_ITEM(CSPCL   , CWORD    , CWORD, CWORD  ),    /* 1, ' ' */
        SIT_ITEM(CNL     , CNL      , CNL  , CNL    ),    /* 2, \n */
        SIT_ITEM(CWORD   , CCTL     , CCTL , CWORD  ),    /* 3, !*-/:=?[]~ */
        SIT_ITEM(CDQUOTE , CENDQUOTE, CWORD, CWORD  ),    /* 4, '"' */
        SIT_ITEM(CVAR    , CVAR     , CWORD, CVAR   ),    /* 5, $ */
        SIT_ITEM(CSQUOTE , CWORD    , CENDQUOTE, CWORD),  /* 6, "'" */
        SIT_ITEM(CSPCL   , CWORD    , CWORD, CLP    ),    /* 7, ( */
        SIT_ITEM(CSPCL   , CWORD    , CWORD, CRP    ),    /* 8, ) */
        SIT_ITEM(CBACK   , CBACK    , CCTL , CBACK  ),    /* 9, \ */
        SIT_ITEM(CBQUOTE , CBQUOTE  , CWORD, CBQUOTE),    /* 10, ` */
        SIT_ITEM(CENDVAR , CENDVAR  , CWORD, CENDVAR),    /* 11, } */
#if !USE_SIT_FUNCTION
        SIT_ITEM(CENDFILE, CENDFILE , CENDFILE, CENDFILE),/* 12, PEOF */
        SIT_ITEM(CWORD   , CWORD    , CWORD, CWORD  ),    /* 13, 0-9A-Za-z */
        SIT_ITEM(CCTL    , CCTL     , CCTL , CCTL   )     /* 14, CTLESC ... */
#endif
#undef SIT_ITEM
};
/* Constants below must match table above */
enum {
#if ENABLE_ASH_ALIAS
        CSPCL_CIGN_CIGN_CIGN               , /*  0 */
#endif
        CSPCL_CWORD_CWORD_CWORD            , /*  1 */
        CNL_CNL_CNL_CNL                    , /*  2 */
        CWORD_CCTL_CCTL_CWORD              , /*  3 */
        CDQUOTE_CENDQUOTE_CWORD_CWORD      , /*  4 */
        CVAR_CVAR_CWORD_CVAR               , /*  5 */
        CSQUOTE_CWORD_CENDQUOTE_CWORD      , /*  6 */
        CSPCL_CWORD_CWORD_CLP              , /*  7 */
        CSPCL_CWORD_CWORD_CRP              , /*  8 */
        CBACK_CBACK_CCTL_CBACK             , /*  9 */
        CBQUOTE_CBQUOTE_CWORD_CBQUOTE      , /* 10 */
        CENDVAR_CENDVAR_CWORD_CENDVAR      , /* 11 */
        CENDFILE_CENDFILE_CENDFILE_CENDFILE, /* 12 */
        CWORD_CWORD_CWORD_CWORD            , /* 13 */
        CCTL_CCTL_CCTL_CCTL                , /* 14 */
};

/* c in SIT(c, syntax) must be an *unsigned char* or PEOA or PEOF,
 * caller must ensure proper cast on it if c is *char_ptr!
 */
/* Values for syntax param */
#define BASESYNTAX 0    /* not in quotes */
#define DQSYNTAX   1    /* in double quotes */
#define SQSYNTAX   2    /* in single quotes */
#define ARISYNTAX  3    /* in arithmetic */
#define PSSYNTAX   4    /* prompt. never passed to SIT() */

#if USE_SIT_FUNCTION

static int
SIT(int c, int syntax)
{
        /* Used to also have '/' in this string: "\t\n !\"$&'()*-/:;<=>?[\\]`|}~" */
        static const char spec_symbls[] ALIGN1 = "\t\n !\"$&'()*-:;<=>?[\\]`|}~";
        /*
         * This causes '/' to be prepended with CTLESC in dquoted string,
         * making "./file"* treated incorrectly because we feed
         * ".\/file*" string to glob(), confusing it (see expandmeta func).
         * The "homegrown" glob implementation is okay with that,
         * but glibc one isn't. With '/' always treated as CWORD,
         * both work fine.
         */
# if ENABLE_ASH_ALIAS
        static const uint8_t syntax_index_table[] ALIGN1 = {
                1, 2, 1, 3, 4, 5, 1, 6,         /* "\t\n !\"$&'" */
                7, 8, 3, 3,/*3,*/3, 1, 1,       /* "()*-/:;<" */
                3, 1, 3, 3, 9, 3, 10, 1,        /* "=>?[\\]`|" */
                11, 3                           /* "}~" */
        };
# else
        static const uint8_t syntax_index_table[] ALIGN1 = {
                0, 1, 0, 2, 3, 4, 0, 5,         /* "\t\n !\"$&'" */
                6, 7, 2, 2,/*2,*/2, 0, 0,       /* "()*-/:;<" */
                2, 0, 2, 2, 8, 2, 9, 0,         /* "=>?[\\]`|" */
                10, 2                           /* "}~" */
        };
# endif
        const char *s;
        int indx;

        if (c == PEOF)
                return CENDFILE;
# if ENABLE_ASH_ALIAS
        if (c == PEOA)
                indx = 0;
        else
# endif
        {
                /* Cast is purely for paranoia here,
                 * just in case someone passed signed char to us */
                if ((unsigned char)c >= CTL_FIRST
                 && (unsigned char)c <= CTL_LAST
                ) {
                        return CCTL;
                }
                s = strchrnul(spec_symbls, c);
                if (*s == '\0')
                        return CWORD;
                indx = syntax_index_table[s - spec_symbls];
        }
        return (S_I_T[indx] >> (syntax*4)) & 0xf;
}

#else   /* !USE_SIT_FUNCTION */

static const uint8_t syntax_index_table[] ALIGN1 = {
        /* BASESYNTAX_DQSYNTAX_SQSYNTAX_ARISYNTAX */
        /*   0      */ CWORD_CWORD_CWORD_CWORD,
        /*   1      */ CWORD_CWORD_CWORD_CWORD,
        /*   2      */ CWORD_CWORD_CWORD_CWORD,
        /*   3      */ CWORD_CWORD_CWORD_CWORD,
        /*   4      */ CWORD_CWORD_CWORD_CWORD,
        /*   5      */ CWORD_CWORD_CWORD_CWORD,
        /*   6      */ CWORD_CWORD_CWORD_CWORD,
        /*   7      */ CWORD_CWORD_CWORD_CWORD,
        /*   8      */ CWORD_CWORD_CWORD_CWORD,
        /*   9 "\t" */ CSPCL_CWORD_CWORD_CWORD,
        /*  10 "\n" */ CNL_CNL_CNL_CNL,
        /*  11      */ CWORD_CWORD_CWORD_CWORD,
        /*  12      */ CWORD_CWORD_CWORD_CWORD,
        /*  13      */ CWORD_CWORD_CWORD_CWORD,
        /*  14      */ CWORD_CWORD_CWORD_CWORD,
        /*  15      */ CWORD_CWORD_CWORD_CWORD,
        /*  16      */ CWORD_CWORD_CWORD_CWORD,
        /*  17      */ CWORD_CWORD_CWORD_CWORD,
        /*  18      */ CWORD_CWORD_CWORD_CWORD,
        /*  19      */ CWORD_CWORD_CWORD_CWORD,
        /*  20      */ CWORD_CWORD_CWORD_CWORD,
        /*  21      */ CWORD_CWORD_CWORD_CWORD,
        /*  22      */ CWORD_CWORD_CWORD_CWORD,
        /*  23      */ CWORD_CWORD_CWORD_CWORD,
        /*  24      */ CWORD_CWORD_CWORD_CWORD,
        /*  25      */ CWORD_CWORD_CWORD_CWORD,
        /*  26      */ CWORD_CWORD_CWORD_CWORD,
        /*  27      */ CWORD_CWORD_CWORD_CWORD,
        /*  28      */ CWORD_CWORD_CWORD_CWORD,
        /*  29      */ CWORD_CWORD_CWORD_CWORD,
        /*  30      */ CWORD_CWORD_CWORD_CWORD,
        /*  31      */ CWORD_CWORD_CWORD_CWORD,
        /*  32  " " */ CSPCL_CWORD_CWORD_CWORD,
        /*  33  "!" */ CWORD_CCTL_CCTL_CWORD,
        /*  34  """ */ CDQUOTE_CENDQUOTE_CWORD_CWORD,
        /*  35  "#" */ CWORD_CWORD_CWORD_CWORD,
        /*  36  "$" */ CVAR_CVAR_CWORD_CVAR,
        /*  37  "%" */ CWORD_CWORD_CWORD_CWORD,
        /*  38  "&" */ CSPCL_CWORD_CWORD_CWORD,
        /*  39  "'" */ CSQUOTE_CWORD_CENDQUOTE_CWORD,
        /*  40  "(" */ CSPCL_CWORD_CWORD_CLP,
        /*  41  ")" */ CSPCL_CWORD_CWORD_CRP,
        /*  42  "*" */ CWORD_CCTL_CCTL_CWORD,
        /*  43  "+" */ CWORD_CWORD_CWORD_CWORD,
        /*  44  "," */ CWORD_CWORD_CWORD_CWORD,
        /*  45  "-" */ CWORD_CCTL_CCTL_CWORD,
        /*  46  "." */ CWORD_CWORD_CWORD_CWORD,
/* "/" was CWORD_CCTL_CCTL_CWORD, see comment in SIT() function why this is changed: */
        /*  47  "/" */ CWORD_CWORD_CWORD_CWORD,
        /*  48  "0" */ CWORD_CWORD_CWORD_CWORD,
        /*  49  "1" */ CWORD_CWORD_CWORD_CWORD,
        /*  50  "2" */ CWORD_CWORD_CWORD_CWORD,
        /*  51  "3" */ CWORD_CWORD_CWORD_CWORD,
        /*  52  "4" */ CWORD_CWORD_CWORD_CWORD,
        /*  53  "5" */ CWORD_CWORD_CWORD_CWORD,
        /*  54  "6" */ CWORD_CWORD_CWORD_CWORD,
        /*  55  "7" */ CWORD_CWORD_CWORD_CWORD,
        /*  56  "8" */ CWORD_CWORD_CWORD_CWORD,
        /*  57  "9" */ CWORD_CWORD_CWORD_CWORD,
        /*  58  ":" */ CWORD_CCTL_CCTL_CWORD,
        /*  59  ";" */ CSPCL_CWORD_CWORD_CWORD,
        /*  60  "<" */ CSPCL_CWORD_CWORD_CWORD,
        /*  61  "=" */ CWORD_CCTL_CCTL_CWORD,
        /*  62  ">" */ CSPCL_CWORD_CWORD_CWORD,
        /*  63  "?" */ CWORD_CCTL_CCTL_CWORD,
        /*  64  "@" */ CWORD_CWORD_CWORD_CWORD,
        /*  65  "A" */ CWORD_CWORD_CWORD_CWORD,
        /*  66  "B" */ CWORD_CWORD_CWORD_CWORD,
        /*  67  "C" */ CWORD_CWORD_CWORD_CWORD,
        /*  68  "D" */ CWORD_CWORD_CWORD_CWORD,
        /*  69  "E" */ CWORD_CWORD_CWORD_CWORD,
        /*  70  "F" */ CWORD_CWORD_CWORD_CWORD,
        /*  71  "G" */ CWORD_CWORD_CWORD_CWORD,
        /*  72  "H" */ CWORD_CWORD_CWORD_CWORD,
        /*  73  "I" */ CWORD_CWORD_CWORD_CWORD,
        /*  74  "J" */ CWORD_CWORD_CWORD_CWORD,
        /*  75  "K" */ CWORD_CWORD_CWORD_CWORD,
        /*  76  "L" */ CWORD_CWORD_CWORD_CWORD,
        /*  77  "M" */ CWORD_CWORD_CWORD_CWORD,
        /*  78  "N" */ CWORD_CWORD_CWORD_CWORD,
        /*  79  "O" */ CWORD_CWORD_CWORD_CWORD,
        /*  80  "P" */ CWORD_CWORD_CWORD_CWORD,
        /*  81  "Q" */ CWORD_CWORD_CWORD_CWORD,
        /*  82  "R" */ CWORD_CWORD_CWORD_CWORD,
        /*  83  "S" */ CWORD_CWORD_CWORD_CWORD,
        /*  84  "T" */ CWORD_CWORD_CWORD_CWORD,
        /*  85  "U" */ CWORD_CWORD_CWORD_CWORD,
        /*  86  "V" */ CWORD_CWORD_CWORD_CWORD,
        /*  87  "W" */ CWORD_CWORD_CWORD_CWORD,
        /*  88  "X" */ CWORD_CWORD_CWORD_CWORD,
        /*  89  "Y" */ CWORD_CWORD_CWORD_CWORD,
        /*  90  "Z" */ CWORD_CWORD_CWORD_CWORD,
        /*  91  "[" */ CWORD_CCTL_CCTL_CWORD,
        /*  92  "\" */ CBACK_CBACK_CCTL_CBACK,
        /*  93  "]" */ CWORD_CCTL_CCTL_CWORD,
        /*  94  "^" */ CWORD_CWORD_CWORD_CWORD,
        /*  95  "_" */ CWORD_CWORD_CWORD_CWORD,
        /*  96  "`" */ CBQUOTE_CBQUOTE_CWORD_CBQUOTE,
        /*  97  "a" */ CWORD_CWORD_CWORD_CWORD,
        /*  98  "b" */ CWORD_CWORD_CWORD_CWORD,
        /*  99  "c" */ CWORD_CWORD_CWORD_CWORD,
        /* 100  "d" */ CWORD_CWORD_CWORD_CWORD,
        /* 101  "e" */ CWORD_CWORD_CWORD_CWORD,
        /* 102  "f" */ CWORD_CWORD_CWORD_CWORD,
        /* 103  "g" */ CWORD_CWORD_CWORD_CWORD,
        /* 104  "h" */ CWORD_CWORD_CWORD_CWORD,
        /* 105  "i" */ CWORD_CWORD_CWORD_CWORD,
        /* 106  "j" */ CWORD_CWORD_CWORD_CWORD,
        /* 107  "k" */ CWORD_CWORD_CWORD_CWORD,
        /* 108  "l" */ CWORD_CWORD_CWORD_CWORD,
        /* 109  "m" */ CWORD_CWORD_CWORD_CWORD,
        /* 110  "n" */ CWORD_CWORD_CWORD_CWORD,
        /* 111  "o" */ CWORD_CWORD_CWORD_CWORD,
        /* 112  "p" */ CWORD_CWORD_CWORD_CWORD,
        /* 113  "q" */ CWORD_CWORD_CWORD_CWORD,
        /* 114  "r" */ CWORD_CWORD_CWORD_CWORD,
        /* 115  "s" */ CWORD_CWORD_CWORD_CWORD,
        /* 116  "t" */ CWORD_CWORD_CWORD_CWORD,
        /* 117  "u" */ CWORD_CWORD_CWORD_CWORD,
        /* 118  "v" */ CWORD_CWORD_CWORD_CWORD,
        /* 119  "w" */ CWORD_CWORD_CWORD_CWORD,
        /* 120  "x" */ CWORD_CWORD_CWORD_CWORD,
        /* 121  "y" */ CWORD_CWORD_CWORD_CWORD,
        /* 122  "z" */ CWORD_CWORD_CWORD_CWORD,
        /* 123  "{" */ CWORD_CWORD_CWORD_CWORD,
        /* 124  "|" */ CSPCL_CWORD_CWORD_CWORD,
        /* 125  "}" */ CENDVAR_CENDVAR_CWORD_CENDVAR,
        /* 126  "~" */ CWORD_CCTL_CCTL_CWORD,
        /* 127  del */ CWORD_CWORD_CWORD_CWORD,
        /* 128 0x80 */ CWORD_CWORD_CWORD_CWORD,
        /* 129 CTLESC       */ CCTL_CCTL_CCTL_CCTL,
        /* 130 CTLVAR       */ CCTL_CCTL_CCTL_CCTL,
        /* 131 CTLENDVAR    */ CCTL_CCTL_CCTL_CCTL,
        /* 132 CTLBACKQ     */ CCTL_CCTL_CCTL_CCTL,
        /* 133 CTLQUOTE     */ CCTL_CCTL_CCTL_CCTL,
        /* 134 CTLARI       */ CCTL_CCTL_CCTL_CCTL,
        /* 135 CTLENDARI    */ CCTL_CCTL_CCTL_CCTL,
        /* 136 CTLQUOTEMARK */ CCTL_CCTL_CCTL_CCTL,
        /* 137      */ CWORD_CWORD_CWORD_CWORD,
        /* 138      */ CWORD_CWORD_CWORD_CWORD,
        /* 139      */ CWORD_CWORD_CWORD_CWORD,
        /* 140      */ CWORD_CWORD_CWORD_CWORD,
        /* 141      */ CWORD_CWORD_CWORD_CWORD,
        /* 142      */ CWORD_CWORD_CWORD_CWORD,
        /* 143      */ CWORD_CWORD_CWORD_CWORD,
        /* 144      */ CWORD_CWORD_CWORD_CWORD,
        /* 145      */ CWORD_CWORD_CWORD_CWORD,
        /* 146      */ CWORD_CWORD_CWORD_CWORD,
        /* 147      */ CWORD_CWORD_CWORD_CWORD,
        /* 148      */ CWORD_CWORD_CWORD_CWORD,
        /* 149      */ CWORD_CWORD_CWORD_CWORD,
        /* 150      */ CWORD_CWORD_CWORD_CWORD,
        /* 151      */ CWORD_CWORD_CWORD_CWORD,
        /* 152      */ CWORD_CWORD_CWORD_CWORD,
        /* 153      */ CWORD_CWORD_CWORD_CWORD,
        /* 154      */ CWORD_CWORD_CWORD_CWORD,
        /* 155      */ CWORD_CWORD_CWORD_CWORD,
        /* 156      */ CWORD_CWORD_CWORD_CWORD,
        /* 157      */ CWORD_CWORD_CWORD_CWORD,
        /* 158      */ CWORD_CWORD_CWORD_CWORD,
        /* 159      */ CWORD_CWORD_CWORD_CWORD,
        /* 160      */ CWORD_CWORD_CWORD_CWORD,
        /* 161      */ CWORD_CWORD_CWORD_CWORD,
        /* 162      */ CWORD_CWORD_CWORD_CWORD,
        /* 163      */ CWORD_CWORD_CWORD_CWORD,
        /* 164      */ CWORD_CWORD_CWORD_CWORD,
        /* 165      */ CWORD_CWORD_CWORD_CWORD,
        /* 166      */ CWORD_CWORD_CWORD_CWORD,
        /* 167      */ CWORD_CWORD_CWORD_CWORD,
        /* 168      */ CWORD_CWORD_CWORD_CWORD,
        /* 169      */ CWORD_CWORD_CWORD_CWORD,
        /* 170      */ CWORD_CWORD_CWORD_CWORD,
        /* 171      */ CWORD_CWORD_CWORD_CWORD,
        /* 172      */ CWORD_CWORD_CWORD_CWORD,
        /* 173      */ CWORD_CWORD_CWORD_CWORD,
        /* 174      */ CWORD_CWORD_CWORD_CWORD,
        /* 175      */ CWORD_CWORD_CWORD_CWORD,
        /* 176      */ CWORD_CWORD_CWORD_CWORD,
        /* 177      */ CWORD_CWORD_CWORD_CWORD,
        /* 178      */ CWORD_CWORD_CWORD_CWORD,
        /* 179      */ CWORD_CWORD_CWORD_CWORD,
        /* 180      */ CWORD_CWORD_CWORD_CWORD,
        /* 181      */ CWORD_CWORD_CWORD_CWORD,
        /* 182      */ CWORD_CWORD_CWORD_CWORD,
        /* 183      */ CWORD_CWORD_CWORD_CWORD,
        /* 184      */ CWORD_CWORD_CWORD_CWORD,
        /* 185      */ CWORD_CWORD_CWORD_CWORD,
        /* 186      */ CWORD_CWORD_CWORD_CWORD,
        /* 187      */ CWORD_CWORD_CWORD_CWORD,
        /* 188      */ CWORD_CWORD_CWORD_CWORD,
        /* 189      */ CWORD_CWORD_CWORD_CWORD,
        /* 190      */ CWORD_CWORD_CWORD_CWORD,
        /* 191      */ CWORD_CWORD_CWORD_CWORD,
        /* 192      */ CWORD_CWORD_CWORD_CWORD,
        /* 193      */ CWORD_CWORD_CWORD_CWORD,
        /* 194      */ CWORD_CWORD_CWORD_CWORD,
        /* 195      */ CWORD_CWORD_CWORD_CWORD,
        /* 196      */ CWORD_CWORD_CWORD_CWORD,
        /* 197      */ CWORD_CWORD_CWORD_CWORD,
        /* 198      */ CWORD_CWORD_CWORD_CWORD,
        /* 199      */ CWORD_CWORD_CWORD_CWORD,
        /* 200      */ CWORD_CWORD_CWORD_CWORD,
        /* 201      */ CWORD_CWORD_CWORD_CWORD,
        /* 202      */ CWORD_CWORD_CWORD_CWORD,
        /* 203      */ CWORD_CWORD_CWORD_CWORD,
        /* 204      */ CWORD_CWORD_CWORD_CWORD,
        /* 205      */ CWORD_CWORD_CWORD_CWORD,
        /* 206      */ CWORD_CWORD_CWORD_CWORD,
        /* 207      */ CWORD_CWORD_CWORD_CWORD,
        /* 208      */ CWORD_CWORD_CWORD_CWORD,
        /* 209      */ CWORD_CWORD_CWORD_CWORD,
        /* 210      */ CWORD_CWORD_CWORD_CWORD,
        /* 211      */ CWORD_CWORD_CWORD_CWORD,
        /* 212      */ CWORD_CWORD_CWORD_CWORD,
        /* 213      */ CWORD_CWORD_CWORD_CWORD,
        /* 214      */ CWORD_CWORD_CWORD_CWORD,
        /* 215      */ CWORD_CWORD_CWORD_CWORD,
        /* 216      */ CWORD_CWORD_CWORD_CWORD,
        /* 217      */ CWORD_CWORD_CWORD_CWORD,
        /* 218      */ CWORD_CWORD_CWORD_CWORD,
        /* 219      */ CWORD_CWORD_CWORD_CWORD,
        /* 220      */ CWORD_CWORD_CWORD_CWORD,
        /* 221      */ CWORD_CWORD_CWORD_CWORD,
        /* 222      */ CWORD_CWORD_CWORD_CWORD,
        /* 223      */ CWORD_CWORD_CWORD_CWORD,
        /* 224      */ CWORD_CWORD_CWORD_CWORD,
        /* 225      */ CWORD_CWORD_CWORD_CWORD,
        /* 226      */ CWORD_CWORD_CWORD_CWORD,
        /* 227      */ CWORD_CWORD_CWORD_CWORD,
        /* 228      */ CWORD_CWORD_CWORD_CWORD,
        /* 229      */ CWORD_CWORD_CWORD_CWORD,
        /* 230      */ CWORD_CWORD_CWORD_CWORD,
        /* 231      */ CWORD_CWORD_CWORD_CWORD,
        /* 232      */ CWORD_CWORD_CWORD_CWORD,
        /* 233      */ CWORD_CWORD_CWORD_CWORD,
        /* 234      */ CWORD_CWORD_CWORD_CWORD,
        /* 235      */ CWORD_CWORD_CWORD_CWORD,
        /* 236      */ CWORD_CWORD_CWORD_CWORD,
        /* 237      */ CWORD_CWORD_CWORD_CWORD,
        /* 238      */ CWORD_CWORD_CWORD_CWORD,
        /* 239      */ CWORD_CWORD_CWORD_CWORD,
        /* 230      */ CWORD_CWORD_CWORD_CWORD,
        /* 241      */ CWORD_CWORD_CWORD_CWORD,
        /* 242      */ CWORD_CWORD_CWORD_CWORD,
        /* 243      */ CWORD_CWORD_CWORD_CWORD,
        /* 244      */ CWORD_CWORD_CWORD_CWORD,
        /* 245      */ CWORD_CWORD_CWORD_CWORD,
        /* 246      */ CWORD_CWORD_CWORD_CWORD,
        /* 247      */ CWORD_CWORD_CWORD_CWORD,
        /* 248      */ CWORD_CWORD_CWORD_CWORD,
        /* 249      */ CWORD_CWORD_CWORD_CWORD,
        /* 250      */ CWORD_CWORD_CWORD_CWORD,
        /* 251      */ CWORD_CWORD_CWORD_CWORD,
        /* 252      */ CWORD_CWORD_CWORD_CWORD,
        /* 253      */ CWORD_CWORD_CWORD_CWORD,
        /* 254      */ CWORD_CWORD_CWORD_CWORD,
        /* 255      */ CWORD_CWORD_CWORD_CWORD,
        /* PEOF */     CENDFILE_CENDFILE_CENDFILE_CENDFILE,
# if ENABLE_ASH_ALIAS
        /* PEOA */     CSPCL_CIGN_CIGN_CIGN,
# endif
};

# define SIT(c, syntax) ((S_I_T[syntax_index_table[c]] >> ((syntax)*4)) & 0xf)

#endif  /* !USE_SIT_FUNCTION */


/* ============ Alias handling */

#if ENABLE_ASH_ALIAS

#define ALIASINUSE 1
#define ALIASDEAD  2

struct alias {
        struct alias *next;
        char *name;
        char *val;
        int flag;
};


static struct alias **atab; // [ATABSIZE];
#define INIT_G_alias() do { \
        atab = xzalloc(ATABSIZE * sizeof(atab[0])); \
} while (0)


static struct alias **
__lookupalias(const char *name)
{
        unsigned int hashval;
        struct alias **app;
        const char *p;
        unsigned int ch;

        p = name;

        ch = (unsigned char)*p;
        hashval = ch << 4;
        while (ch) {
                hashval += ch;
                ch = (unsigned char)*++p;
        }
        app = &atab[hashval % ATABSIZE];

        for (; *app; app = &(*app)->next) {
                if (strcmp(name, (*app)->name) == 0) {
                        break;
                }
        }

        return app;
}

static struct alias *
lookupalias(const char *name, int check)
{
        struct alias *ap = *__lookupalias(name);

        if (check && ap && (ap->flag & ALIASINUSE))
                return NULL;
        return ap;
}

static struct alias *
freealias(struct alias *ap)
{
        struct alias *next;

        if (ap->flag & ALIASINUSE) {
                ap->flag |= ALIASDEAD;
                return ap;
        }

        next = ap->next;
        free(ap->name);
        free(ap->val);
        free(ap);
        return next;
}

static void
setalias(const char *name, const char *val)
{
        struct alias *ap, **app;

        app = __lookupalias(name);
        ap = *app;
        INT_OFF;
        if (ap) {
                if (!(ap->flag & ALIASINUSE)) {
                        free(ap->val);
                }
                ap->val = ckstrdup(val);
                ap->flag &= ~ALIASDEAD;
        } else {
                /* not found */
                ap = ckzalloc(sizeof(struct alias));
                ap->name = ckstrdup(name);
                ap->val = ckstrdup(val);
                /*ap->flag = 0; - ckzalloc did it */
                /*ap->next = NULL;*/
                *app = ap;
        }
        INT_ON;
}

static int
unalias(const char *name)
{
        struct alias **app;

        app = __lookupalias(name);

        if (*app) {
                INT_OFF;
                *app = freealias(*app);
                INT_ON;
                return 0;
        }

        return 1;
}

static void
rmaliases(void)
{
        struct alias *ap, **app;
        int i;

        INT_OFF;
        for (i = 0; i < ATABSIZE; i++) {
                app = &atab[i];
                for (ap = *app; ap; ap = *app) {
                        *app = freealias(*app);
                        if (ap == *app) {
                                app = &ap->next;
                        }
                }
        }
        INT_ON;
}

static void
printalias(const struct alias *ap)
{
        out1fmt("%s=%s\n", ap->name, single_quote(ap->val));
}

/*
 * TODO - sort output
 */
static int FAST_FUNC
aliascmd(int argc UNUSED_PARAM, char **argv)
{
        char *n, *v;
        int ret = 0;
        struct alias *ap;

        if (!argv[1]) {
                int i;

                for (i = 0; i < ATABSIZE; i++) {
                        for (ap = atab[i]; ap; ap = ap->next) {
                                printalias(ap);
                        }
                }
                return 0;
        }
        while ((n = *++argv) != NULL) {
                v = strchr(n+1, '=');
                if (v == NULL) { /* n+1: funny ksh stuff */
                        ap = *__lookupalias(n);
                        if (ap == NULL) {
                                fprintf(stderr, "%s: %s not found\n", "alias", n);
                                ret = 1;
                        } else
                                printalias(ap);
                } else {
                        *v++ = '\0';
                        setalias(n, v);
                }
        }

        return ret;
}

static int FAST_FUNC
unaliascmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        int i;

        while ((i = nextopt("a")) != '\0') {
                if (i == 'a') {
                        rmaliases();
                        return 0;
                }
        }
        for (i = 0; *argptr; argptr++) {
                if (unalias(*argptr)) {
                        fprintf(stderr, "%s: %s not found\n", "unalias", *argptr);
                        i = 1;
                }
        }

        return i;
}

#endif /* ASH_ALIAS */


/* Mode argument to forkshell.  Don't change FORK_FG or FORK_BG. */
#define FORK_FG    0
#define FORK_BG    1
#define FORK_NOJOB 2

/* mode flags for showjob(s) */
#define SHOW_ONLY_PGID  0x01    /* show only pgid (jobs -p) */
#define SHOW_PIDS       0x02    /* show individual pids, not just one line per job */
#define SHOW_CHANGED    0x04    /* only jobs whose state has changed */
#define SHOW_STDERR     0x08    /* print to stderr (else stdout) */

/*
 * A job structure contains information about a job.  A job is either a
 * single process or a set of processes contained in a pipeline.  In the
 * latter case, pidlist will be non-NULL, and will point to a -1 terminated
 * array of pids.
 */
struct procstat {
        pid_t   ps_pid;         /* process id */
        int     ps_status;      /* last process status from wait() */
        char    *ps_cmd;        /* text of command being run */
};

struct job {
        struct procstat ps0;    /* status of process */
        struct procstat *ps;    /* status or processes when more than one */
#if JOBS
        int stopstatus;         /* status of a stopped job */
#endif
        uint32_t
                nprocs: 16,     /* number of processes */
                state: 8,
#define JOBRUNNING      0       /* at least one proc running */
#define JOBSTOPPED      1       /* all procs are stopped */
#define JOBDONE         2       /* all procs are completed */
#if JOBS
                sigint: 1,      /* job was killed by SIGINT */
                jobctl: 1,      /* job running under job control */
#endif
                waited: 1,      /* true if this entry has been waited for */
                used: 1,        /* true if this entry is in used */
                changed: 1;     /* true if status has changed */
        struct job *prev_job;   /* previous job */
};

static struct job *makejob(/*union node *,*/ int);
static int forkshell(struct job *, union node *, int);
static int waitforjob(struct job *);

#if !JOBS
enum { doing_jobctl = 0 };
#define setjobctl(on) do {} while (0)
#else
static smallint doing_jobctl; //references:8
static void setjobctl(int);
#endif

/*
 * Ignore a signal.
 */
static void
ignoresig(int signo)
{
        /* Avoid unnecessary system calls. Is it already SIG_IGNed? */
        if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
                /* No, need to do it */
                signal(signo, SIG_IGN);
        }
        sigmode[signo - 1] = S_HARD_IGN;
}

/*
 * Only one usage site - in setsignal()
 */
static void
signal_handler(int signo)
{
        if (signo == SIGCHLD) {
                got_sigchld = 1;
                if (!trap[SIGCHLD])
                        return;
        }

        gotsig[signo - 1] = 1;
        pending_sig = signo;

        if (signo == SIGINT && !trap[SIGINT]) {
                if (!suppress_int) {
                        pending_sig = 0;
                        raise_interrupt(); /* does not return */
                }
                pending_int = 1;
        }
}

/*
 * Set the signal handler for the specified signal.  The routine figures
 * out what it should be set to.
 */
static void
setsignal(int signo)
{
        char *t;
        char cur_act, new_act;
        struct sigaction act;

        t = trap[signo];
        new_act = S_DFL;
        if (t != NULL) { /* trap for this sig is set */
                new_act = S_CATCH;
                if (t[0] == '\0') /* trap is "": ignore this sig */
                        new_act = S_IGN;
        }

        if (rootshell && new_act == S_DFL) {
                switch (signo) {
                case SIGINT:
                        if (iflag || minusc || sflag == 0)
                                new_act = S_CATCH;
                        break;
                case SIGQUIT:
#if DEBUG
                        if (debug)
                                break;
#endif
                        /* man bash:
                         * "In all cases, bash ignores SIGQUIT. Non-builtin
                         * commands run by bash have signal handlers
                         * set to the values inherited by the shell
                         * from its parent". */
                        new_act = S_IGN;
                        break;
                case SIGTERM:
                        if (iflag)
                                new_act = S_IGN;
                        break;
#if JOBS
                case SIGTSTP:
                case SIGTTOU:
                        if (mflag)
                                new_act = S_IGN;
                        break;
#endif
                }
        }
//TODO: if !rootshell, we reset SIGQUIT to DFL,
//whereas we have to restore it to what shell got on entry
//from the parent. See comment above

        if (signo == SIGCHLD)
                new_act = S_CATCH;

        t = &sigmode[signo - 1];
        cur_act = *t;
        if (cur_act == 0) {
                /* current setting is not yet known */
                if (sigaction(signo, NULL, &act)) {
                        /* pretend it worked; maybe we should give a warning,
                         * but other shells don't. We don't alter sigmode,
                         * so we retry every time.
                         * btw, in Linux it never fails. --vda */
                        return;
                }
                if (act.sa_handler == SIG_IGN) {
                        cur_act = S_HARD_IGN;
                        if (mflag
                         && (signo == SIGTSTP || signo == SIGTTIN || signo == SIGTTOU)
                        ) {
                                cur_act = S_IGN;   /* don't hard ignore these */
                        }
                }
        }
        if (cur_act == S_HARD_IGN || cur_act == new_act)
                return;

        act.sa_handler = SIG_DFL;
        switch (new_act) {
        case S_CATCH:
                act.sa_handler = signal_handler;
                break;
        case S_IGN:
                act.sa_handler = SIG_IGN;
                break;
        }

        /* flags and mask matter only if !DFL and !IGN, but we do it
         * for all cases for more deterministic behavior:
         */
        act.sa_flags = 0;
        sigfillset(&act.sa_mask);

        sigaction_set(signo, &act);

        *t = new_act;
}

/* mode flags for set_curjob */
#define CUR_DELETE 2
#define CUR_RUNNING 1
#define CUR_STOPPED 0

#if JOBS
/* pgrp of shell on invocation */
static int initialpgrp; //references:2
static int ttyfd = -1; //5
#endif
/* array of jobs */
static struct job *jobtab; //5
/* size of array */
static unsigned njobs; //4
/* current job */
static struct job *curjob; //lots
/* number of presumed living untracked jobs */
static int jobless; //4

static void
set_curjob(struct job *jp, unsigned mode)
{
        struct job *jp1;
        struct job **jpp, **curp;

        /* first remove from list */
        jpp = curp = &curjob;
        while (1) {
                jp1 = *jpp;
                if (jp1 == jp)
                        break;
                jpp = &jp1->prev_job;
        }
        *jpp = jp1->prev_job;

        /* Then re-insert in correct position */
        jpp = curp;
        switch (mode) {
        default:
#if DEBUG
                abort();
#endif
        case CUR_DELETE:
                /* job being deleted */
                break;
        case CUR_RUNNING:
                /* newly created job or backgrounded job,
                 * put after all stopped jobs.
                 */
                while (1) {
                        jp1 = *jpp;
#if JOBS
                        if (!jp1 || jp1->state != JOBSTOPPED)
#endif
                                break;
                        jpp = &jp1->prev_job;
                }
                /* FALLTHROUGH */
#if JOBS
        case CUR_STOPPED:
#endif
                /* newly stopped job - becomes curjob */
                jp->prev_job = *jpp;
                *jpp = jp;
                break;
        }
}

#if JOBS || DEBUG
static int
jobno(const struct job *jp)
{
        return jp - jobtab + 1;
}
#endif

/*
 * Convert a job name to a job structure.
 */
#if !JOBS
#define getjob(name, getctl) getjob(name)
#endif
static struct job *
getjob(const char *name, int getctl)
{
        struct job *jp;
        struct job *found;
        const char *err_msg = "%s: no such job";
        unsigned num;
        int c;
        const char *p;
        char *(*match)(const char *, const char *);

        jp = curjob;
        p = name;
        if (!p)
                goto currentjob;

        if (*p != '%')
                goto err;

        c = *++p;
        if (!c)
                goto currentjob;

        if (!p[1]) {
                if (c == '+' || c == '%') {
 currentjob:
                        err_msg = "No current job";
                        goto check;
                }
                if (c == '-') {
                        if (jp)
                                jp = jp->prev_job;
                        err_msg = "No previous job";
 check:
                        if (!jp)
                                goto err;
                        goto gotit;
                }
        }

        if (is_number(p)) {
                num = atoi(p);
                if (num > 0 && num <= njobs) {
                        jp = jobtab + num - 1;
                        if (jp->used)
                                goto gotit;
                        goto err;
                }
        }

        match = prefix;
        if (*p == '?') {
                match = strstr;
                p++;
        }

        found = NULL;
        while (jp) {
                if (match(jp->ps[0].ps_cmd, p)) {
                        if (found)
                                goto err;
                        found = jp;
                        err_msg = "%s: ambiguous";
                }
                jp = jp->prev_job;
        }
        if (!found)
                goto err;
        jp = found;

 gotit:
#if JOBS
        err_msg = "job %s not created under job control";
        if (getctl && jp->jobctl == 0)
                goto err;
#endif
        return jp;
 err:
        ash_msg_and_raise_error(err_msg, name);
}

/*
 * Mark a job structure as unused.
 */
static void
freejob(struct job *jp)
{
        struct procstat *ps;
        int i;

        INT_OFF;
        for (i = jp->nprocs, ps = jp->ps; --i >= 0; ps++) {
                if (ps->ps_cmd != nullstr)
                        free(ps->ps_cmd);
        }
        if (jp->ps != &jp->ps0)
                free(jp->ps);
        jp->used = 0;
        set_curjob(jp, CUR_DELETE);
        INT_ON;
}

#if JOBS
static void
xtcsetpgrp(int fd, pid_t pgrp)
{
        if (tcsetpgrp(fd, pgrp))
                ash_msg_and_raise_error("can't set tty process group (%m)");
}

/*
 * Turn job control on and off.
 *
 * Note:  This code assumes that the third arg to ioctl is a character
 * pointer, which is true on Berkeley systems but not System V.  Since
 * System V doesn't have job control yet, this isn't a problem now.
 *
 * Called with interrupts off.
 */
static void
setjobctl(int on)
{
        int fd;
        int pgrp;

        if (on == doing_jobctl || rootshell == 0)
                return;
        if (on) {
                int ofd;
                ofd = fd = open(_PATH_TTY, O_RDWR);
                if (fd < 0) {
        /* BTW, bash will try to open(ttyname(0)) if open("/dev/tty") fails.
         * That sometimes helps to acquire controlling tty.
         * Obviously, a workaround for bugs when someone
         * failed to provide a controlling tty to bash! :) */
                        fd = 2;
                        while (!isatty(fd))
                                if (--fd < 0)
                                        goto out;
                }
                /* fd is a tty at this point */
                fd = fcntl(fd, F_DUPFD, 10);
                if (ofd >= 0) /* if it is "/dev/tty", close. If 0/1/2, dont */
                        close(ofd);
                if (fd < 0)
                        goto out; /* F_DUPFD failed */
                close_on_exec_on(fd);
                while (1) { /* while we are in the background */
                        pgrp = tcgetpgrp(fd);
                        if (pgrp < 0) {
 out:
                                ash_msg("can't access tty; job control turned off");
                                mflag = on = 0;
                                goto close;
                        }
                        if (pgrp == getpgrp())
                                break;
                        killpg(0, SIGTTIN);
                }
                initialpgrp = pgrp;

                setsignal(SIGTSTP);
                setsignal(SIGTTOU);
                setsignal(SIGTTIN);
                pgrp = rootpid;
                setpgid(0, pgrp);
                xtcsetpgrp(fd, pgrp);
        } else {
                /* turning job control off */
                fd = ttyfd;
                pgrp = initialpgrp;
                /* was xtcsetpgrp, but this can make exiting ash
                 * loop forever if pty is already deleted */
                tcsetpgrp(fd, pgrp);
                setpgid(0, pgrp);
                setsignal(SIGTSTP);
                setsignal(SIGTTOU);
                setsignal(SIGTTIN);
 close:
                if (fd >= 0)
                        close(fd);
                fd = -1;
        }
        ttyfd = fd;
        doing_jobctl = on;
}

static int FAST_FUNC
killcmd(int argc, char **argv)
{
        if (argv[1] && strcmp(argv[1], "-l") != 0) {
                int i = 1;
                do {
                        if (argv[i][0] == '%') {
                                /*
                                 * "kill %N" - job kill
                                 * Converting to pgrp / pid kill
                                 */
                                struct job *jp;
                                char *dst;
                                int j, n;

                                jp = getjob(argv[i], 0);
                                /*
                                 * In jobs started under job control, we signal
                                 * entire process group by kill -PGRP_ID.
                                 * This happens, f.e., in interactive shell.
                                 *
                                 * Otherwise, we signal each child via
                                 * kill PID1 PID2 PID3.
                                 * Testcases:
                                 * sh -c 'sleep 1|sleep 1 & kill %1'
                                 * sh -c 'true|sleep 2 & sleep 1; kill %1'
                                 * sh -c 'true|sleep 1 & sleep 2; kill %1'
                                 */
                                n = jp->nprocs; /* can't be 0 (I hope) */
                                if (jp->jobctl)
                                        n = 1;
                                dst = alloca(n * sizeof(int)*4);
                                argv[i] = dst;
                                for (j = 0; j < n; j++) {
                                        struct procstat *ps = &jp->ps[j];
                                        /* Skip non-running and not-stopped members
                                         * (i.e. dead members) of the job
                                         */
                                        if (ps->ps_status != -1 && !WIFSTOPPED(ps->ps_status))
                                                continue;
                                        /*
                                         * kill_main has matching code to expect
                                         * leading space. Needed to not confuse
                                         * negative pids with "kill -SIGNAL_NO" syntax
                                         */
                                        dst += sprintf(dst, jp->jobctl ? " -%u" : " %u", (int)ps->ps_pid);
                                }
                                *dst = '\0';
                        }
                } while (argv[++i]);
        }
        return kill_main(argc, argv);
}

static void
showpipe(struct job *jp /*, FILE *out*/)
{
        struct procstat *ps;
        struct procstat *psend;

        psend = jp->ps + jp->nprocs;
        for (ps = jp->ps + 1; ps < psend; ps++)
                printf(" | %s", ps->ps_cmd);
        newline_and_flush(stdout);
        flush_stdout_stderr();
}


static int
restartjob(struct job *jp, int mode)
{
        struct procstat *ps;
        int i;
        int status;
        pid_t pgid;

        INT_OFF;
        if (jp->state == JOBDONE)
                goto out;
        jp->state = JOBRUNNING;
        pgid = jp->ps[0].ps_pid;
        if (mode == FORK_FG)
                xtcsetpgrp(ttyfd, pgid);
        killpg(pgid, SIGCONT);
        ps = jp->ps;
        i = jp->nprocs;
        do {
                if (WIFSTOPPED(ps->ps_status)) {
                        ps->ps_status = -1;
                }
                ps++;
        } while (--i);
 out:
        status = (mode == FORK_FG) ? waitforjob(jp) : 0;
        INT_ON;
        return status;
}

static int FAST_FUNC
fg_bgcmd(int argc UNUSED_PARAM, char **argv)
{
        struct job *jp;
        int mode;
        int retval;

        mode = (**argv == 'f') ? FORK_FG : FORK_BG;
        nextopt(nullstr);
        argv = argptr;
        do {
                jp = getjob(*argv, 1);
                if (mode == FORK_BG) {
                        set_curjob(jp, CUR_RUNNING);
                        printf("[%d] ", jobno(jp));
                }
                out1str(jp->ps[0].ps_cmd);
                showpipe(jp /*, stdout*/);
                retval = restartjob(jp, mode);
        } while (*argv && *++argv);
        return retval;
}
#endif

static int
sprint_status48(char *s, int status, int sigonly)
{
        int col;
        int st;

        col = 0;
        if (!WIFEXITED(status)) {
                if (JOBS && WIFSTOPPED(status))
                        st = WSTOPSIG(status);
                else
                        st = WTERMSIG(status);
                if (sigonly) {
                        if (st == SIGINT || st == SIGPIPE)
                                goto out;
                        if (JOBS && WIFSTOPPED(status))
                                goto out;
                }
                st &= 0x7f;
//TODO: use bbox's get_signame? strsignal adds ~600 bytes to text+rodata
                col = fmtstr(s, 32, strsignal(st));
                if (WCOREDUMP(status)) {
                        strcpy(s + col, " (core dumped)");
                        col += sizeof(" (core dumped)")-1;
                }
        } else if (!sigonly) {
                st = WEXITSTATUS(status);
                col = fmtstr(s, 16, (st ? "Done(%d)" : "Done"), st);
        }
 out:
        return col;
}

static int
wait_block_or_sig(int *status)
{
        int pid;

        do {
                sigset_t mask;

                /* Poll all children for changes in their state */
                got_sigchld = 0;
                /* if job control is active, accept stopped processes too */
                pid = waitpid(-1, status, doing_jobctl ? (WNOHANG|WUNTRACED) : WNOHANG);
                if (pid != 0)
                        break; /* Error (e.g. EINTR, ECHILD) or pid */

                /* Children exist, but none are ready. Sleep until interesting signal */
#if 1
                sigfillset(&mask);
                sigprocmask(SIG_SETMASK, &mask, &mask);
                while (!got_sigchld && !pending_sig)
                        sigsuspend(&mask);
                sigprocmask(SIG_SETMASK, &mask, NULL);
#else /* unsafe: a signal can set pending_sig after check, but before pause() */
                while (!got_sigchld && !pending_sig)
                        pause();
#endif

                /* If it was SIGCHLD, poll children again */
        } while (got_sigchld);

        return pid;
}

#define DOWAIT_NONBLOCK 0
#define DOWAIT_BLOCK    1
#define DOWAIT_BLOCK_OR_SIG 2

static int
dowait(int block, struct job *job)
{
        int pid;
        int status;
        struct job *jp;
        struct job *thisjob = NULL;

        TRACE(("dowait(0x%x) called\n", block));

        /* It's wrong to call waitpid() outside of INT_OFF region:
         * signal can arrive just after syscall return and handler can
         * longjmp away, losing stop/exit notification processing.
         * Thus, for "jobs" builtin, and for waiting for a fg job,
         * we call waitpid() (blocking or non-blocking) inside INT_OFF.
         *
         * However, for "wait" builtin it is wrong to simply call waitpid()
         * in INT_OFF region: "wait" needs to wait for any running job
         * to change state, but should exit on any trap too.
         * In INT_OFF region, a signal just before syscall entry can set
         * pending_sig variables, but we can't check them, and we would
         * either enter a sleeping waitpid() (BUG), or need to busy-loop.
         *
         * Because of this, we run inside INT_OFF, but use a special routine
         * which combines waitpid() and sigsuspend().
         * This is the reason why we need to have a handler for SIGCHLD:
         * SIG_DFL handler does not wake sigsuspend().
         */
        INT_OFF;
        if (block == DOWAIT_BLOCK_OR_SIG) {
                pid = wait_block_or_sig(&status);
        } else {
                int wait_flags = 0;
                if (block == DOWAIT_NONBLOCK)
                        wait_flags = WNOHANG;
                /* if job control is active, accept stopped processes too */
                if (doing_jobctl)
                        wait_flags |= WUNTRACED;
                /* NB: _not_ safe_waitpid, we need to detect EINTR */
                pid = waitpid(-1, &status, wait_flags);
        }
        TRACE(("wait returns pid=%d, status=0x%x, errno=%d(%s)\n",
                                pid, status, errno, strerror(errno)));
        if (pid <= 0)
                goto out;

        thisjob = NULL;
        for (jp = curjob; jp; jp = jp->prev_job) {
                int jobstate;
                struct procstat *ps;
                struct procstat *psend;
                if (jp->state == JOBDONE)
                        continue;
                jobstate = JOBDONE;
                ps = jp->ps;
                psend = ps + jp->nprocs;
                do {
                        if (ps->ps_pid == pid) {
                                TRACE(("Job %d: changing status of proc %d "
                                        "from 0x%x to 0x%x\n",
                                        jobno(jp), pid, ps->ps_status, status));
                                ps->ps_status = status;
                                thisjob = jp;
                        }
                        if (ps->ps_status == -1)
                                jobstate = JOBRUNNING;
#if JOBS
                        if (jobstate == JOBRUNNING)
                                continue;
                        if (WIFSTOPPED(ps->ps_status)) {
                                jp->stopstatus = ps->ps_status;
                                jobstate = JOBSTOPPED;
                        }
#endif
                } while (++ps < psend);
                if (!thisjob)
                        continue;

                /* Found the job where one of its processes changed its state.
                 * Is there at least one live and running process in this job? */
                if (jobstate != JOBRUNNING) {
                        /* No. All live processes in the job are stopped
                         * (JOBSTOPPED) or there are no live processes (JOBDONE)
                         */
                        thisjob->changed = 1;
                        if (thisjob->state != jobstate) {
                                TRACE(("Job %d: changing state from %d to %d\n",
                                        jobno(thisjob), thisjob->state, jobstate));
                                thisjob->state = jobstate;
#if JOBS
                                if (jobstate == JOBSTOPPED)
                                        set_curjob(thisjob, CUR_STOPPED);
#endif
                        }
                }
                goto out;
        }
        /* The process wasn't found in job list */
        if (JOBS && !WIFSTOPPED(status))
                jobless--;
 out:
        INT_ON;

        if (thisjob && thisjob == job) {
                char s[48 + 1];
                int len;

                len = sprint_status48(s, status, 1);
                if (len) {
                        s[len] = '\n';
                        s[len + 1] = '\0';
                        out2str(s);
                }
        }
        return pid;
}

#if JOBS
static void
showjob(struct job *jp, int mode)
{
        struct procstat *ps;
        struct procstat *psend;
        int col;
        int indent_col;
        char s[16 + 16 + 48];
        FILE *out = (mode & SHOW_STDERR ? stderr : stdout);

        ps = jp->ps;

        if (mode & SHOW_ONLY_PGID) { /* jobs -p */
                /* just output process (group) id of pipeline */
                fprintf(out, "%d\n", ps->ps_pid);
                return;
        }

        col = fmtstr(s, 16, "[%d]   ", jobno(jp));
        indent_col = col;

        if (jp == curjob)
                s[col - 3] = '+';
        else if (curjob && jp == curjob->prev_job)
                s[col - 3] = '-';

        if (mode & SHOW_PIDS)
                col += fmtstr(s + col, 16, "%d ", ps->ps_pid);

        psend = ps + jp->nprocs;

        if (jp->state == JOBRUNNING) {
                strcpy(s + col, "Running");
                col += sizeof("Running") - 1;
        } else {
                int status = psend[-1].ps_status;
                if (jp->state == JOBSTOPPED)
                        status = jp->stopstatus;
                col += sprint_status48(s + col, status, 0);
        }
        /* By now, "[JOBID]*  [maybe PID] STATUS" is printed */

        /* This loop either prints "<cmd1> | <cmd2> | <cmd3>" line
         * or prints several "PID             | <cmdN>" lines,
         * depending on SHOW_PIDS bit.
         * We do not print status of individual processes
         * between PID and <cmdN>. bash does it, but not very well:
         * first line shows overall job status, not process status,
         * making it impossible to know 1st process status.
         */
        goto start;
        do {
                /* for each process */
                s[0] = '\0';
                col = 33;
                if (mode & SHOW_PIDS)
                        col = fmtstr(s, 48, "\n%*c%d ", indent_col, ' ', ps->ps_pid) - 1;
 start:
                fprintf(out, "%s%*c%s%s",
                                s,
                                33 - col >= 0 ? 33 - col : 0, ' ',
                                ps == jp->ps ? "" : "| ",
                                ps->ps_cmd
                );
        } while (++ps != psend);
        newline_and_flush(out);

        jp->changed = 0;

        if (jp->state == JOBDONE) {
                TRACE(("showjob: freeing job %d\n", jobno(jp)));
                freejob(jp);
        }
}

/*
 * Print a list of jobs.  If "change" is nonzero, only print jobs whose
 * statuses have changed since the last call to showjobs.
 */
static void
showjobs(int mode)
{
        struct job *jp;

        TRACE(("showjobs(0x%x) called\n", mode));

        /* Handle all finished jobs */
        while (dowait(DOWAIT_NONBLOCK, NULL) > 0)
                continue;

        for (jp = curjob; jp; jp = jp->prev_job) {
                if (!(mode & SHOW_CHANGED) || jp->changed) {
                        showjob(jp, mode);
                }
        }
}

static int FAST_FUNC
jobscmd(int argc UNUSED_PARAM, char **argv)
{
        int mode, m;

        mode = 0;
        while ((m = nextopt("lp")) != '\0') {
                if (m == 'l')
                        mode |= SHOW_PIDS;
                else
                        mode |= SHOW_ONLY_PGID;
        }

        argv = argptr;
        if (*argv) {
                do
                        showjob(getjob(*argv, 0), mode);
                while (*++argv);
        } else {
                showjobs(mode);
        }

        return 0;
}
#endif /* JOBS */

/* Called only on finished or stopped jobs (no members are running) */
static int
getstatus(struct job *job)
{
        int status;
        int retval;
        struct procstat *ps;

        /* Fetch last member's status */
        ps = job->ps + job->nprocs - 1;
        status = ps->ps_status;
        if (pipefail) {
                /* "set -o pipefail" mode: use last _nonzero_ status */
                while (status == 0 && --ps >= job->ps)
                        status = ps->ps_status;
        }

        retval = WEXITSTATUS(status);
        if (!WIFEXITED(status)) {
#if JOBS
                retval = WSTOPSIG(status);
                if (!WIFSTOPPED(status))
#endif
                {
                        /* XXX: limits number of signals */
                        retval = WTERMSIG(status);
#if JOBS
                        if (retval == SIGINT)
                                job->sigint = 1;
#endif
                }
                retval += 128;
        }
        TRACE(("getstatus: job %d, nproc %d, status 0x%x, retval 0x%x\n",
                jobno(job), job->nprocs, status, retval));
        return retval;
}

static int FAST_FUNC
waitcmd(int argc UNUSED_PARAM, char **argv)
{
        struct job *job;
        int retval;
        struct job *jp;

        nextopt(nullstr);
        retval = 0;

        argv = argptr;
        if (!*argv) {
                /* wait for all jobs */
                for (;;) {
                        jp = curjob;
                        while (1) {
                                if (!jp) /* no running procs */
                                        goto ret;
                                if (jp->state == JOBRUNNING)
                                        break;
                                jp->waited = 1;
                                jp = jp->prev_job;
                        }
        /* man bash:
         * "When bash is waiting for an asynchronous command via
         * the wait builtin, the reception of a signal for which a trap
         * has been set will cause the wait builtin to return immediately
         * with an exit status greater than 128, immediately after which
         * the trap is executed."
         */
                        dowait(DOWAIT_BLOCK_OR_SIG, NULL);
        /* if child sends us a signal *and immediately exits*,
         * dowait() returns pid > 0. Check this case,
         * not "if (dowait() < 0)"!
         */
                        if (pending_sig)
                                goto sigout;
                }
        }

        retval = 127;
        do {
                if (**argv != '%') {
                        pid_t pid = number(*argv);
                        job = curjob;
                        while (1) {
                                if (!job)
                                        goto repeat;
                                if (job->ps[job->nprocs - 1].ps_pid == pid)
                                        break;
                                job = job->prev_job;
                        }
                } else {
                        job = getjob(*argv, 0);
                }
                /* loop until process terminated or stopped */
                while (job->state == JOBRUNNING) {
                        dowait(DOWAIT_BLOCK_OR_SIG, NULL);
                        if (pending_sig)
                                goto sigout;
                }
                job->waited = 1;
                retval = getstatus(job);
 repeat: ;
        } while (*++argv);

 ret:
        return retval;
 sigout:
        retval = 128 + pending_sig;
        return retval;
}

static struct job *
growjobtab(void)
{
        size_t len;
        ptrdiff_t offset;
        struct job *jp, *jq;

        len = njobs * sizeof(*jp);
        jq = jobtab;
        jp = ckrealloc(jq, len + 4 * sizeof(*jp));

        offset = (char *)jp - (char *)jq;
        if (offset) {
                /* Relocate pointers */
                size_t l = len;

                jq = (struct job *)((char *)jq + l);
                while (l) {
                        l -= sizeof(*jp);
                        jq--;
#define joff(p) ((struct job *)((char *)(p) + l))
#define jmove(p) (p) = (void *)((char *)(p) + offset)
                        if (joff(jp)->ps == &jq->ps0)
                                jmove(joff(jp)->ps);
                        if (joff(jp)->prev_job)
                                jmove(joff(jp)->prev_job);
                }
                if (curjob)
                        jmove(curjob);
#undef joff
#undef jmove
        }

        njobs += 4;
        jobtab = jp;
        jp = (struct job *)((char *)jp + len);
        jq = jp + 3;
        do {
                jq->used = 0;
        } while (--jq >= jp);
        return jp;
}

/*
 * Return a new job structure.
 * Called with interrupts off.
 */
static struct job *
makejob(/*union node *node,*/ int nprocs)
{
        int i;
        struct job *jp;

        for (i = njobs, jp = jobtab; ; jp++) {
                if (--i < 0) {
                        jp = growjobtab();
                        break;
                }
                if (jp->used == 0)
                        break;
                if (jp->state != JOBDONE || !jp->waited)
                        continue;
#if JOBS
                if (doing_jobctl)
                        continue;
#endif
                freejob(jp);
                break;
        }
        memset(jp, 0, sizeof(*jp));
#if JOBS
        /* jp->jobctl is a bitfield.
         * "jp->jobctl |= jobctl" likely to give awful code */
        if (doing_jobctl)
                jp->jobctl = 1;
#endif
        jp->prev_job = curjob;
        curjob = jp;
        jp->used = 1;
        jp->ps = &jp->ps0;
        if (nprocs > 1) {
                jp->ps = ckmalloc(nprocs * sizeof(struct procstat));
        }
        TRACE(("makejob(%d) returns %%%d\n", nprocs,
                                jobno(jp)));
        return jp;
}

#if JOBS
/*
 * Return a string identifying a command (to be printed by the
 * jobs command).
 */
static char *cmdnextc;

static void
cmdputs(const char *s)
{
        static const char vstype[VSTYPE + 1][3] = {
                "", "}", "-", "+", "?", "=",
                "%", "%%", "#", "##"
                IF_ASH_BASH_COMPAT(, ":", "/", "//")
        };

        const char *p, *str;
        char cc[2];
        char *nextc;
        unsigned char c;
        unsigned char subtype = 0;
        int quoted = 0;

        cc[1] = '\0';
        nextc = makestrspace((strlen(s) + 1) * 8, cmdnextc);
        p = s;
        while ((c = *p++) != '\0') {
                str = NULL;
                switch (c) {
                case CTLESC:
                        c = *p++;
                        break;
                case CTLVAR:
                        subtype = *p++;
                        if ((subtype & VSTYPE) == VSLENGTH)
                                str = "${#";
                        else
                                str = "${";
                        goto dostr;
                case CTLENDVAR:
                        str = "\"}" + !(quoted & 1);
                        quoted >>= 1;
                        subtype = 0;
                        goto dostr;
                case CTLBACKQ:
                        str = "$(...)";
                        goto dostr;
#if ENABLE_SH_MATH_SUPPORT
                case CTLARI:
                        str = "$((";
                        goto dostr;
                case CTLENDARI:
                        str = "))";
                        goto dostr;
#endif
                case CTLQUOTEMARK:
                        quoted ^= 1;
                        c = '"';
                        break;
                case '=':
                        if (subtype == 0)
                                break;
                        if ((subtype & VSTYPE) != VSNORMAL)
                                quoted <<= 1;
                        str = vstype[subtype & VSTYPE];
                        if (subtype & VSNUL)
                                c = ':';
                        else
                                goto checkstr;
                        break;
                case '\'':
                case '\\':
                case '"':
                case '$':
                        /* These can only happen inside quotes */
                        cc[0] = c;
                        str = cc;
                        c = '\\';
                        break;
                default:
                        break;
                }
                USTPUTC(c, nextc);
 checkstr:
                if (!str)
                        continue;
 dostr:
                while ((c = *str++) != '\0') {
                        USTPUTC(c, nextc);
                }
        } /* while *p++ not NUL */

        if (quoted & 1) {
                USTPUTC('"', nextc);
        }
        *nextc = 0;
        cmdnextc = nextc;
}

/* cmdtxt() and cmdlist() call each other */
static void cmdtxt(union node *n);

static void
cmdlist(union node *np, int sep)
{
        for (; np; np = np->narg.next) {
                if (!sep)
                        cmdputs(" ");
                cmdtxt(np);
                if (sep && np->narg.next)
                        cmdputs(" ");
        }
}

static void
cmdtxt(union node *n)
{
        union node *np;
        struct nodelist *lp;
        const char *p;

        if (!n)
                return;
        switch (n->type) {
        default:
#if DEBUG
                abort();
#endif
        case NPIPE:
                lp = n->npipe.cmdlist;
                for (;;) {
                        cmdtxt(lp->n);
                        lp = lp->next;
                        if (!lp)
                                break;
                        cmdputs(" | ");
                }
                break;
        case NSEMI:
                p = "; ";
                goto binop;
        case NAND:
                p = " && ";
                goto binop;
        case NOR:
                p = " || ";
 binop:
                cmdtxt(n->nbinary.ch1);
                cmdputs(p);
                n = n->nbinary.ch2;
                goto donode;
        case NREDIR:
        case NBACKGND:
                n = n->nredir.n;
                goto donode;
        case NNOT:
                cmdputs("!");
                n = n->nnot.com;
 donode:
                cmdtxt(n);
                break;
        case NIF:
                cmdputs("if ");
                cmdtxt(n->nif.test);
                cmdputs("; then ");
                if (n->nif.elsepart) {
                        cmdtxt(n->nif.ifpart);
                        cmdputs("; else ");
                        n = n->nif.elsepart;
                } else {
                        n = n->nif.ifpart;
                }
                p = "; fi";
                goto dotail;
        case NSUBSHELL:
                cmdputs("(");
                n = n->nredir.n;
                p = ")";
                goto dotail;
        case NWHILE:
                p = "while ";
                goto until;
        case NUNTIL:
                p = "until ";
 until:
                cmdputs(p);
                cmdtxt(n->nbinary.ch1);
                n = n->nbinary.ch2;
                p = "; done";
 dodo:
                cmdputs("; do ");
 dotail:
                cmdtxt(n);
                goto dotail2;
        case NFOR:
                cmdputs("for ");
                cmdputs(n->nfor.var);
                cmdputs(" in ");
                cmdlist(n->nfor.args, 1);
                n = n->nfor.body;
                p = "; done";
                goto dodo;
        case NDEFUN:
                cmdputs(n->narg.text);
                p = "() { ... }";
                goto dotail2;
        case NCMD:
                cmdlist(n->ncmd.args, 1);
                cmdlist(n->ncmd.redirect, 0);
                break;
        case NARG:
                p = n->narg.text;
 dotail2:
                cmdputs(p);
                break;
        case NHERE:
        case NXHERE:
                p = "<<...";
                goto dotail2;
        case NCASE:
                cmdputs("case ");
                cmdputs(n->ncase.expr->narg.text);
                cmdputs(" in ");
                for (np = n->ncase.cases; np; np = np->nclist.next) {
                        cmdtxt(np->nclist.pattern);
                        cmdputs(") ");
                        cmdtxt(np->nclist.body);
                        cmdputs(";; ");
                }
                p = "esac";
                goto dotail2;
        case NTO:
                p = ">";
                goto redir;
        case NCLOBBER:
                p = ">|";
                goto redir;
        case NAPPEND:
                p = ">>";
                goto redir;
#if ENABLE_ASH_BASH_COMPAT
        case NTO2:
#endif
        case NTOFD:
                p = ">&";
                goto redir;
        case NFROM:
                p = "<";
                goto redir;
        case NFROMFD:
                p = "<&";
                goto redir;
        case NFROMTO:
                p = "<>";
 redir:
                cmdputs(utoa(n->nfile.fd));
                cmdputs(p);
                if (n->type == NTOFD || n->type == NFROMFD) {
                        cmdputs(utoa(n->ndup.dupfd));
                        break;
                }
                n = n->nfile.fname;
                goto donode;
        }
}

static char *
commandtext(union node *n)
{
        char *name;

        STARTSTACKSTR(cmdnextc);
        cmdtxt(n);
        name = stackblock();
        TRACE(("commandtext: name %p, end %p\n", name, cmdnextc));
        return ckstrdup(name);
}
#endif /* JOBS */

/*
 * Fork off a subshell.  If we are doing job control, give the subshell its
 * own process group.  Jp is a job structure that the job is to be added to.
 * N is the command that will be evaluated by the child.  Both jp and n may
 * be NULL.  The mode parameter can be one of the following:
 *      FORK_FG - Fork off a foreground process.
 *      FORK_BG - Fork off a background process.
 *      FORK_NOJOB - Like FORK_FG, but don't give the process its own
 *                   process group even if job control is on.
 *
 * When job control is turned off, background processes have their standard
 * input redirected to /dev/null (except for the second and later processes
 * in a pipeline).
 *
 * Called with interrupts off.
 */
/*
 * Clear traps on a fork.
 */
static void
clear_traps(void)
{
        char **tp;

        INT_OFF;
        for (tp = trap; tp < &trap[NSIG]; tp++) {
                if (*tp && **tp) {      /* trap not NULL or "" (SIG_IGN) */
                        if (trap_ptr == trap)
                                free(*tp);
                        /* else: it "belongs" to trap_ptr vector, don't free */
                        *tp = NULL;
                        if ((tp - trap) != 0)
                                setsignal(tp - trap);
                }
        }
        may_have_traps = 0;
        INT_ON;
}

/* Lives far away from here, needed for forkchild */
static void closescript(void);

/* Called after fork(), in child */
/* jp and n are NULL when called by openhere() for heredoc support */
static NOINLINE void
forkchild(struct job *jp, union node *n, int mode)
{
        int oldlvl;

        TRACE(("Child shell %d\n", getpid()));
        oldlvl = shlvl;
        shlvl++;

        /* man bash: "Non-builtin commands run by bash have signal handlers
         * set to the values inherited by the shell from its parent".
         * Do we do it correctly? */

        closescript();

        if (mode == FORK_NOJOB          /* is it `xxx` ? */
         && n && n->type == NCMD        /* is it single cmd? */
        /* && n->ncmd.args->type == NARG - always true? */
         && n->ncmd.args && strcmp(n->ncmd.args->narg.text, "trap") == 0
         && n->ncmd.args->narg.next == NULL /* "trap" with no arguments */
        /* && n->ncmd.args->narg.backquote == NULL - do we need to check this? */
        ) {
                TRACE(("Trap hack\n"));
                /* Awful hack for `trap` or $(trap).
                 *
                 * http://www.opengroup.org/onlinepubs/009695399/utilities/trap.html
                 * contains an example where "trap" is executed in a subshell:
                 *
                 * save_traps=$(trap)
                 * ...
                 * eval "$save_traps"
                 *
                 * Standard does not say that "trap" in subshell shall print
                 * parent shell's traps. It only says that its output
                 * must have suitable form, but then, in the above example
                 * (which is not supposed to be normative), it implies that.
                 *
                 * bash (and probably other shell) does implement it
                 * (traps are reset to defaults, but "trap" still shows them),
                 * but as a result, "trap" logic is hopelessly messed up:
                 *
                 * # trap
                 * trap -- 'echo Ho' SIGWINCH  <--- we have a handler
                 * # (trap)        <--- trap is in subshell - no output (correct, traps are reset)
                 * # true | trap   <--- trap is in subshell - no output (ditto)
                 * # echo `true | trap`    <--- in subshell - output (but traps are reset!)
                 * trap -- 'echo Ho' SIGWINCH
                 * # echo `(trap)`         <--- in subshell in subshell - output
                 * trap -- 'echo Ho' SIGWINCH
                 * # echo `true | (trap)`  <--- in subshell in subshell in subshell - output!
                 * trap -- 'echo Ho' SIGWINCH
                 *
                 * The rules when to forget and when to not forget traps
                 * get really complex and nonsensical.
                 *
                 * Our solution: ONLY bare $(trap) or `trap` is special.
                 */
                /* Save trap handler strings for trap builtin to print */
                trap_ptr = xmemdup(trap, sizeof(trap));
                /* Fall through into clearing traps */
        }
        clear_traps();
#if JOBS
        /* do job control only in root shell */
        doing_jobctl = 0;
        if (mode != FORK_NOJOB && jp->jobctl && oldlvl == 0) {
                pid_t pgrp;

                if (jp->nprocs == 0)
                        pgrp = getpid();
                else
                        pgrp = jp->ps[0].ps_pid;
                /* this can fail because we are doing it in the parent also */
                setpgid(0, pgrp);
                if (mode == FORK_FG)
                        xtcsetpgrp(ttyfd, pgrp);
                setsignal(SIGTSTP);
                setsignal(SIGTTOU);
        } else
#endif
        if (mode == FORK_BG) {
                /* man bash: "When job control is not in effect,
                 * asynchronous commands ignore SIGINT and SIGQUIT" */
                ignoresig(SIGINT);
                ignoresig(SIGQUIT);
                if (jp->nprocs == 0) {
                        close(0);
                        if (open(bb_dev_null, O_RDONLY) != 0)
                                ash_msg_and_raise_error("can't open '%s'", bb_dev_null);
                }
        }
        if (oldlvl == 0) {
                if (iflag) { /* why if iflag only? */
                        setsignal(SIGINT);
                        setsignal(SIGTERM);
                }
                /* man bash:
                 * "In all cases, bash ignores SIGQUIT. Non-builtin
                 * commands run by bash have signal handlers
                 * set to the values inherited by the shell
                 * from its parent".
                 * Take care of the second rule: */
                setsignal(SIGQUIT);
        }
#if JOBS
        if (n && n->type == NCMD
         && n->ncmd.args && strcmp(n->ncmd.args->narg.text, "jobs") == 0
        ) {
                TRACE(("Job hack\n"));
                /* "jobs": we do not want to clear job list for it,
                 * instead we remove only _its_ own_ job from job list.
                 * This makes "jobs .... | cat" more useful.
                 */
                freejob(curjob);
                return;
        }
#endif
        for (jp = curjob; jp; jp = jp->prev_job)
                freejob(jp);
        jobless = 0;
}

/* Called after fork(), in parent */
#if !JOBS
#define forkparent(jp, n, mode, pid) forkparent(jp, mode, pid)
#endif
static void
forkparent(struct job *jp, union node *n, int mode, pid_t pid)
{
        TRACE(("In parent shell: child = %d\n", pid));
        if (!jp) {
                /* jp is NULL when called by openhere() for heredoc support */
                while (jobless && dowait(DOWAIT_NONBLOCK, NULL) > 0)
                        continue;
                jobless++;
                return;
        }
#if JOBS
        if (mode != FORK_NOJOB && jp->jobctl) {
                int pgrp;

                if (jp->nprocs == 0)
                        pgrp = pid;
                else
                        pgrp = jp->ps[0].ps_pid;
                /* This can fail because we are doing it in the child also */
                setpgid(pid, pgrp);
        }
#endif
        if (mode == FORK_BG) {
                backgndpid = pid;               /* set $! */
                set_curjob(jp, CUR_RUNNING);
        }
        if (jp) {
                struct procstat *ps = &jp->ps[jp->nprocs++];
                ps->ps_pid = pid;
                ps->ps_status = -1;
                ps->ps_cmd = nullstr;
#if JOBS
                if (doing_jobctl && n)
                        ps->ps_cmd = commandtext(n);
#endif
        }
}

/* jp and n are NULL when called by openhere() for heredoc support */
static int
forkshell(struct job *jp, union node *n, int mode)
{
        int pid;

        TRACE(("forkshell(%%%d, %p, %d) called\n", jobno(jp), n, mode));
        pid = fork();
        if (pid < 0) {
                TRACE(("Fork failed, errno=%d", errno));
                if (jp)
                        freejob(jp);
                ash_msg_and_raise_error("can't fork");
        }
        if (pid == 0) {
                CLEAR_RANDOM_T(&random_gen); /* or else $RANDOM repeats in child */
                forkchild(jp, n, mode);
        } else {
                forkparent(jp, n, mode, pid);
        }
        return pid;
}

/*
 * Wait for job to finish.
 *
 * Under job control we have the problem that while a child process
 * is running interrupts generated by the user are sent to the child
 * but not to the shell.  This means that an infinite loop started by
 * an interactive user may be hard to kill.  With job control turned off,
 * an interactive user may place an interactive program inside a loop.
 * If the interactive program catches interrupts, the user doesn't want
 * these interrupts to also abort the loop.  The approach we take here
 * is to have the shell ignore interrupt signals while waiting for a
 * foreground process to terminate, and then send itself an interrupt
 * signal if the child process was terminated by an interrupt signal.
 * Unfortunately, some programs want to do a bit of cleanup and then
 * exit on interrupt; unless these processes terminate themselves by
 * sending a signal to themselves (instead of calling exit) they will
 * confuse this approach.
 *
 * Called with interrupts off.
 */
static int
waitforjob(struct job *jp)
{
        int st;

        TRACE(("waitforjob(%%%d) called\n", jobno(jp)));

        INT_OFF;
        while (jp->state == JOBRUNNING) {
                /* In non-interactive shells, we _can_ get
                 * a keyboard signal here and be EINTRed,
                 * but we just loop back, waiting for command to complete.
                 *
                 * man bash:
                 * "If bash is waiting for a command to complete and receives
                 * a signal for which a trap has been set, the trap
                 * will not be executed until the command completes."
                 *
                 * Reality is that even if trap is not set, bash
                 * will not act on the signal until command completes.
                 * Try this. sleep5intoff.c:
                 * #include <signal.h>
                 * #include <unistd.h>
                 * int main() {
                 *         sigset_t set;
                 *         sigemptyset(&set);
                 *         sigaddset(&set, SIGINT);
                 *         sigaddset(&set, SIGQUIT);
                 *         sigprocmask(SIG_BLOCK, &set, NULL);
                 *         sleep(5);
                 *         return 0;
                 * }
                 * $ bash -c './sleep5intoff; echo hi'
                 * ^C^C^C^C <--- pressing ^C once a second
                 * $ _
                 * $ bash -c './sleep5intoff; echo hi'
                 * ^\^\^\^\hi <--- pressing ^\ (SIGQUIT)
                 * $ _
                 */
                dowait(DOWAIT_BLOCK, jp);
        }
        INT_ON;

        st = getstatus(jp);
#if JOBS
        if (jp->jobctl) {
                xtcsetpgrp(ttyfd, rootpid);
                /*
                 * This is truly gross.
                 * If we're doing job control, then we did a TIOCSPGRP which
                 * caused us (the shell) to no longer be in the controlling
                 * session -- so we wouldn't have seen any ^C/SIGINT.  So, we
                 * intuit from the subprocess exit status whether a SIGINT
                 * occurred, and if so interrupt ourselves.  Yuck.  - mycroft
                 */
                if (jp->sigint) /* TODO: do the same with all signals */
                        raise(SIGINT); /* ... by raise(jp->sig) instead? */
        }
        if (jp->state == JOBDONE)
#endif
                freejob(jp);
        return st;
}

/*
 * return 1 if there are stopped jobs, otherwise 0
 */
static int
stoppedjobs(void)
{
        struct job *jp;
        int retval;

        retval = 0;
        if (job_warning)
                goto out;
        jp = curjob;
        if (jp && jp->state == JOBSTOPPED) {
                out2str("You have stopped jobs.\n");
                job_warning = 2;
                retval++;
        }
 out:
        return retval;
}


/*
 * Code for dealing with input/output redirection.
 */

#undef EMPTY
#undef CLOSED
#define EMPTY -2                /* marks an unused slot in redirtab */
#define CLOSED -3               /* marks a slot of previously-closed fd */

/*
 * Open a file in noclobber mode.
 * The code was copied from bash.
 */
static int
noclobberopen(const char *fname)
{
        int r, fd;
        struct stat finfo, finfo2;

        /*
         * If the file exists and is a regular file, return an error
         * immediately.
         */
        r = stat(fname, &finfo);
        if (r == 0 && S_ISREG(finfo.st_mode)) {
                errno = EEXIST;
                return -1;
        }

        /*
         * If the file was not present (r != 0), make sure we open it
         * exclusively so that if it is created before we open it, our open
         * will fail.  Make sure that we do not truncate an existing file.
         * Note that we don't turn on O_EXCL unless the stat failed -- if the
         * file was not a regular file, we leave O_EXCL off.
         */
        if (r != 0)
                return open(fname, O_WRONLY|O_CREAT|O_EXCL, 0666);
        fd = open(fname, O_WRONLY|O_CREAT, 0666);

        /* If the open failed, return the file descriptor right away. */
        if (fd < 0)
                return fd;

        /*
         * OK, the open succeeded, but the file may have been changed from a
         * non-regular file to a regular file between the stat and the open.
         * We are assuming that the O_EXCL open handles the case where FILENAME
         * did not exist and is symlinked to an existing file between the stat
         * and open.
         */

        /*
         * If we can open it and fstat the file descriptor, and neither check
         * revealed that it was a regular file, and the file has not been
         * replaced, return the file descriptor.
         */
        if (fstat(fd, &finfo2) == 0
         && !S_ISREG(finfo2.st_mode)
         && finfo.st_dev == finfo2.st_dev
         && finfo.st_ino == finfo2.st_ino
        ) {
                return fd;
        }

        /* The file has been replaced.  badness. */
        close(fd);
        errno = EEXIST;
        return -1;
}

/*
 * Handle here documents.  Normally we fork off a process to write the
 * data to a pipe.  If the document is short, we can stuff the data in
 * the pipe without forking.
 */
/* openhere needs this forward reference */
static void expandhere(union node *arg, int fd);
static int
openhere(union node *redir)
{
        int pip[2];
        size_t len = 0;

        if (pipe(pip) < 0)
                ash_msg_and_raise_error("pipe call failed");
        if (redir->type == NHERE) {
                len = strlen(redir->nhere.doc->narg.text);
                if (len <= PIPE_BUF) {
                        full_write(pip[1], redir->nhere.doc->narg.text, len);
                        goto out;
                }
        }
        if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
                /* child */
                close(pip[0]);
                ignoresig(SIGINT);  //signal(SIGINT, SIG_IGN);
                ignoresig(SIGQUIT); //signal(SIGQUIT, SIG_IGN);
                ignoresig(SIGHUP);  //signal(SIGHUP, SIG_IGN);
                ignoresig(SIGTSTP); //signal(SIGTSTP, SIG_IGN);
                signal(SIGPIPE, SIG_DFL);
                if (redir->type == NHERE)
                        full_write(pip[1], redir->nhere.doc->narg.text, len);
                else /* NXHERE */
                        expandhere(redir->nhere.doc, pip[1]);
                _exit(EXIT_SUCCESS);
        }
 out:
        close(pip[1]);
        return pip[0];
}

static int
openredirect(union node *redir)
{
        char *fname;
        int f;

        switch (redir->nfile.type) {
/* Can't happen, our single caller does this itself */
//      case NTOFD:
//      case NFROMFD:
//              return -1;
        case NHERE:
        case NXHERE:
                return openhere(redir);
        }

        /* For N[X]HERE, reading redir->nfile.expfname would touch beyond
         * allocated space. Do it only when we know it is safe.
         */
        fname = redir->nfile.expfname;

        switch (redir->nfile.type) {
        default:
#if DEBUG
                abort();
#endif
        case NFROM:
                f = open(fname, O_RDONLY);
                if (f < 0)
                        goto eopen;
                break;
        case NFROMTO:
                f = open(fname, O_RDWR|O_CREAT, 0666);
                if (f < 0)
                        goto ecreate;
                break;
        case NTO:
#if ENABLE_ASH_BASH_COMPAT
        case NTO2:
#endif
                /* Take care of noclobber mode. */
                if (Cflag) {
                        f = noclobberopen(fname);
                        if (f < 0)
                                goto ecreate;
                        break;
                }
                /* FALLTHROUGH */
        case NCLOBBER:
                f = open(fname, O_WRONLY|O_CREAT|O_TRUNC, 0666);
                if (f < 0)
                        goto ecreate;
                break;
        case NAPPEND:
                f = open(fname, O_WRONLY|O_CREAT|O_APPEND, 0666);
                if (f < 0)
                        goto ecreate;
                break;
        }

        return f;
 ecreate:
        ash_msg_and_raise_error("can't create %s: %s", fname, errmsg(errno, "nonexistent directory"));
 eopen:
        ash_msg_and_raise_error("can't open %s: %s", fname, errmsg(errno, "no such file"));
}

/*
 * Copy a file descriptor to be >= 10. Throws exception on error.
 */
static int
savefd(int from)
{
        int newfd;
        int err;

        newfd = fcntl(from, F_DUPFD, 10);
        err = newfd < 0 ? errno : 0;
        if (err != EBADF) {
                if (err)
                        ash_msg_and_raise_error("%d: %m", from);
                close(from);
                fcntl(newfd, F_SETFD, FD_CLOEXEC);
        }

        return newfd;
}
static int
dup2_or_raise(int from, int to)
{
        int newfd;

        newfd = (from != to) ? dup2(from, to) : to;
        if (newfd < 0) {
                /* Happens when source fd is not open: try "echo >&99" */
                ash_msg_and_raise_error("%d: %m", from);
        }
        return newfd;
}

/* Struct def and variable are moved down to the first usage site */
struct two_fd_t {
        int orig, copy;
};
struct redirtab {
        struct redirtab *next;
        int pair_count;
        struct two_fd_t two_fd[];
};
#define redirlist (G_var.redirlist)
enum {
        COPYFD_RESTORE = (int)~(INT_MAX),
};

static int
need_to_remember(struct redirtab *rp, int fd)
{
        int i;

        if (!rp) /* remembering was not requested */
                return 0;

        for (i = 0; i < rp->pair_count; i++) {
                if (rp->two_fd[i].orig == fd) {
                        /* already remembered */
                        return 0;
                }
        }
        return 1;
}

/* "hidden" fd is a fd used to read scripts, or a copy of such */
static int
is_hidden_fd(struct redirtab *rp, int fd)
{
        int i;
        struct parsefile *pf;

        if (fd == -1)
                return 0;
        /* Check open scripts' fds */
        pf = g_parsefile;
        while (pf) {
                /* We skip pf_fd == 0 case because of the following case:
                 * $ ash  # running ash interactively
                 * $ . ./script.sh
                 * and in script.sh: "exec 9>&0".
                 * Even though top-level pf_fd _is_ 0,
                 * it's still ok to use it: "read" builtin uses it,
                 * why should we cripple "exec" builtin?
                 */
                if (pf->pf_fd > 0 && fd == pf->pf_fd) {
                        return 1;
                }
                pf = pf->prev;
        }

        if (!rp)
                return 0;
        /* Check saved fds of redirects */
        fd |= COPYFD_RESTORE;
        for (i = 0; i < rp->pair_count; i++) {
                if (rp->two_fd[i].copy == fd) {
                        return 1;
                }
        }
        return 0;
}

/*
 * Process a list of redirection commands.  If the REDIR_PUSH flag is set,
 * old file descriptors are stashed away so that the redirection can be
 * undone by calling popredir.
 */
/* flags passed to redirect */
#define REDIR_PUSH    01        /* save previous values of file descriptors */
#define REDIR_SAVEFD2 03        /* set preverrout */
static void
redirect(union node *redir, int flags)
{
        struct redirtab *sv;
        int sv_pos;
        int i;
        int fd;
        int newfd;
        int copied_fd2 = -1;

        if (!redir) {
                return;
        }

        sv = NULL;
        sv_pos = 0;
        INT_OFF;
        if (flags & REDIR_PUSH) {
                union node *tmp = redir;
                do {
                        sv_pos++;
#if ENABLE_ASH_BASH_COMPAT
                        if (tmp->nfile.type == NTO2)
                                sv_pos++;
#endif
                        tmp = tmp->nfile.next;
                } while (tmp);
                sv = ckmalloc(sizeof(*sv) + sv_pos * sizeof(sv->two_fd[0]));
                sv->next = redirlist;
                sv->pair_count = sv_pos;
                redirlist = sv;
                while (sv_pos > 0) {
                        sv_pos--;
                        sv->two_fd[sv_pos].orig = sv->two_fd[sv_pos].copy = EMPTY;
                }
        }

        do {
                int right_fd = -1;
                fd = redir->nfile.fd;
                if (redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) {
                        right_fd = redir->ndup.dupfd;
                        //bb_error_msg("doing %d > %d", fd, right_fd);
                        /* redirect from/to same file descriptor? */
                        if (right_fd == fd)
                                continue;
                        /* "echo >&10" and 10 is a fd opened to a sh script? */
                        if (is_hidden_fd(sv, right_fd)) {
                                errno = EBADF; /* as if it is closed */
                                ash_msg_and_raise_error("%d: %m", right_fd);
                        }
                        newfd = -1;
                } else {
                        newfd = openredirect(redir); /* always >= 0 */
                        if (fd == newfd) {
                                /* Descriptor wasn't open before redirect.
                                 * Mark it for close in the future */
                                if (need_to_remember(sv, fd)) {
                                        goto remember_to_close;
                                }
                                continue;
                        }
                }
#if ENABLE_ASH_BASH_COMPAT
 redirect_more:
#endif
                if (need_to_remember(sv, fd)) {
                        /* Copy old descriptor */
                        /* Careful to not accidentally "save"
                         * to the same fd as right side fd in N>&M */
                        int minfd = right_fd < 10 ? 10 : right_fd + 1;
                        i = fcntl(fd, F_DUPFD, minfd);
/* You'd expect copy to be CLOEXECed. Currently these extra "saved" fds
 * are closed in popredir() in the child, preventing them from leaking
 * into child. (popredir() also cleans up the mess in case of failures)
 */
                        if (i == -1) {
                                i = errno;
                                if (i != EBADF) {
                                        /* Strange error (e.g. "too many files" EMFILE?) */
                                        if (newfd >= 0)
                                                close(newfd);
                                        errno = i;
                                        ash_msg_and_raise_error("%d: %m", fd);
                                        /* NOTREACHED */
                                }
                                /* EBADF: it is not open - good, remember to close it */
 remember_to_close:
                                i = CLOSED;
                        } else { /* fd is open, save its copy */
                                /* "exec fd>&-" should not close fds
                                 * which point to script file(s).
                                 * Force them to be restored afterwards */
                                if (is_hidden_fd(sv, fd))
                                        i |= COPYFD_RESTORE;
                        }
                        if (fd == 2)
                                copied_fd2 = i;
                        sv->two_fd[sv_pos].orig = fd;
                        sv->two_fd[sv_pos].copy = i;
                        sv_pos++;
                }
                if (newfd < 0) {
                        /* NTOFD/NFROMFD: copy redir->ndup.dupfd to fd */
                        if (redir->ndup.dupfd < 0) { /* "fd>&-" */
                                /* Don't want to trigger debugging */
                                if (fd != -1)
                                        close(fd);
                        } else {
                                dup2_or_raise(redir->ndup.dupfd, fd);
                        }
                } else if (fd != newfd) { /* move newfd to fd */
                        dup2_or_raise(newfd, fd);
#if ENABLE_ASH_BASH_COMPAT
                        if (!(redir->nfile.type == NTO2 && fd == 2))
#endif
                                close(newfd);
                }
#if ENABLE_ASH_BASH_COMPAT
                if (redir->nfile.type == NTO2 && fd == 1) {
                        /* We already redirected it to fd 1, now copy it to 2 */
                        newfd = 1;
                        fd = 2;
                        goto redirect_more;
                }
#endif
        } while ((redir = redir->nfile.next) != NULL);

        INT_ON;
        if ((flags & REDIR_SAVEFD2) && copied_fd2 >= 0)
                preverrout_fd = copied_fd2;
}

/*
 * Undo the effects of the last redirection.
 */
static void
popredir(int drop, int restore)
{
        struct redirtab *rp;
        int i;

        if (redirlist == NULL)
                return;
        INT_OFF;
        rp = redirlist;
        for (i = 0; i < rp->pair_count; i++) {
                int fd = rp->two_fd[i].orig;
                int copy = rp->two_fd[i].copy;
                if (copy == CLOSED) {
                        if (!drop)
                                close(fd);
                        continue;
                }
                if (copy != EMPTY) {
                        if (!drop || (restore && (copy & COPYFD_RESTORE))) {
                                copy &= ~COPYFD_RESTORE;
                                /*close(fd);*/
                                dup2_or_raise(copy, fd);
                        }
                        close(copy & ~COPYFD_RESTORE);
                }
        }
        redirlist = rp->next;
        free(rp);
        INT_ON;
}

/*
 * Undo all redirections.  Called on error or interrupt.
 */

static int
redirectsafe(union node *redir, int flags)
{
        int err;
        volatile int saveint;
        struct jmploc *volatile savehandler = exception_handler;
        struct jmploc jmploc;

        SAVE_INT(saveint);
        /* "echo 9>/dev/null; echo >&9; echo result: $?" - result should be 1, not 2! */
        err = setjmp(jmploc.loc); // huh?? was = setjmp(jmploc.loc) * 2;
        if (!err) {
                exception_handler = &jmploc;
                redirect(redir, flags);
        }
        exception_handler = savehandler;
        if (err && exception_type != EXERROR)
                longjmp(exception_handler->loc, 1);
        RESTORE_INT(saveint);
        return err;
}


/* ============ Routines to expand arguments to commands
 *
 * We have to deal with backquotes, shell variables, and file metacharacters.
 */

#if ENABLE_SH_MATH_SUPPORT
static arith_t
ash_arith(const char *s)
{
        arith_state_t math_state;
        arith_t result;

        math_state.lookupvar = lookupvar;
        math_state.setvar    = setvar0;
        //math_state.endofname = endofname;

        INT_OFF;
        result = arith(&math_state, s);
        if (math_state.errmsg)
                ash_msg_and_raise_error(math_state.errmsg);
        INT_ON;

        return result;
}
#endif

/*
 * expandarg flags
 */
#define EXP_FULL        0x1     /* perform word splitting & file globbing */
#define EXP_TILDE       0x2     /* do normal tilde expansion */
#define EXP_VARTILDE    0x4     /* expand tildes in an assignment */
#define EXP_REDIR       0x8     /* file glob for a redirection (1 match only) */
/* ^^^^^^^^^^^^^^ this is meant to support constructs such as "cmd >file*.txt"
 * POSIX says for this case:
 *  Pathname expansion shall not be performed on the word by a
 *  non-interactive shell; an interactive shell may perform it, but shall
 *  do so only when the expansion would result in one word.
 * Currently, our code complies to the above rule by never globbing
 * redirection filenames.
 * Bash performs globbing, unless it is non-interactive and in POSIX mode.
 * (this means that on a typical Linux distro, bash almost always
 * performs globbing, and thus diverges from what we do).
 */
#define EXP_CASE        0x10    /* keeps quotes around for CASE pattern */
#define EXP_QPAT        0x20    /* pattern in quoted parameter expansion */
#define EXP_VARTILDE2   0x40    /* expand tildes after colons only */
#define EXP_WORD        0x80    /* expand word in parameter expansion */
#define EXP_QUOTED      0x100   /* expand word in double quotes */
/*
 * rmescape() flags
 */
#define RMESCAPE_ALLOC  0x1     /* Allocate a new string */
#define RMESCAPE_GLOB   0x2     /* Add backslashes for glob */
#define RMESCAPE_GROW   0x8     /* Grow strings instead of stalloc */
#define RMESCAPE_HEAP   0x10    /* Malloc strings instead of stalloc */
#define RMESCAPE_SLASH  0x20    /* Stop globbing after slash */

/* Add CTLESC when necessary. */
#define QUOTES_ESC     (EXP_FULL | EXP_CASE | EXP_QPAT | EXP_REDIR)
/* Do not skip NUL characters. */
#define QUOTES_KEEPNUL EXP_TILDE

/*
 * Structure specifying which parts of the string should be searched
 * for IFS characters.
 */
struct ifsregion {
        struct ifsregion *next; /* next region in list */
        int begoff;             /* offset of start of region */
        int endoff;             /* offset of end of region */
        int nulonly;            /* search for nul bytes only */
};

struct arglist {
        struct strlist *list;
        struct strlist **lastp;
};

/* output of current string */
static char *expdest;
/* list of back quote expressions */
static struct nodelist *argbackq;
/* first struct in list of ifs regions */
static struct ifsregion ifsfirst;
/* last struct in list */
static struct ifsregion *ifslastp;
/* holds expanded arg list */
static struct arglist exparg;

/*
 * Our own itoa().
 */
#if !ENABLE_SH_MATH_SUPPORT
/* cvtnum() is used even if math support is off (to prepare $? values and such) */
typedef long arith_t;
# define ARITH_FMT "%ld"
#endif
static int
cvtnum(arith_t num)
{
        int len;

        expdest = makestrspace(sizeof(arith_t)*3 + 2, expdest);
        len = fmtstr(expdest, sizeof(arith_t)*3 + 2, ARITH_FMT, num);
        STADJUST(len, expdest);
        return len;
}

/*
 * Break the argument string into pieces based upon IFS and add the
 * strings to the argument list.  The regions of the string to be
 * searched for IFS characters have been stored by recordregion.
 */
static void
ifsbreakup(char *string, struct arglist *arglist)
{
        struct ifsregion *ifsp;
        struct strlist *sp;
        char *start;
        char *p;
        char *q;
        const char *ifs, *realifs;
        int ifsspc;
        int nulonly;

        start = string;
        if (ifslastp != NULL) {
                ifsspc = 0;
                nulonly = 0;
                realifs = ifsset() ? ifsval() : defifs;
                ifsp = &ifsfirst;
                do {
                        p = string + ifsp->begoff;
                        nulonly = ifsp->nulonly;
                        ifs = nulonly ? nullstr : realifs;
                        ifsspc = 0;
                        while (p < string + ifsp->endoff) {
                                q = p;
                                if ((unsigned char)*p == CTLESC)
                                        p++;
                                if (!strchr(ifs, *p)) {
                                        p++;
                                        continue;
                                }
                                if (!nulonly)
                                        ifsspc = (strchr(defifs, *p) != NULL);
                                /* Ignore IFS whitespace at start */
                                if (q == start && ifsspc) {
                                        p++;
                                        start = p;
                                        continue;
                                }
                                *q = '\0';
                                sp = stzalloc(sizeof(*sp));
                                sp->text = start;
                                *arglist->lastp = sp;
                                arglist->lastp = &sp->next;
                                p++;
                                if (!nulonly) {
                                        for (;;) {
                                                if (p >= string + ifsp->endoff) {
                                                        break;
                                                }
                                                q = p;
                                                if ((unsigned char)*p == CTLESC)
                                                        p++;
                                                if (strchr(ifs, *p) == NULL) {
                                                        p = q;
                                                        break;
                                                }
                                                if (strchr(defifs, *p) == NULL) {
                                                        if (ifsspc) {
                                                                p++;
                                                                ifsspc = 0;
                                                        } else {
                                                                p = q;
                                                                break;
                                                        }
                                                } else
                                                        p++;
                                        }
                                }
                                start = p;
                        } /* while */
                        ifsp = ifsp->next;
                } while (ifsp != NULL);
                if (nulonly)
                        goto add;
        }

        if (!*start)
                return;

 add:
        sp = stzalloc(sizeof(*sp));
        sp->text = start;
        *arglist->lastp = sp;
        arglist->lastp = &sp->next;
}

static void
ifsfree(void)
{
        struct ifsregion *p = ifsfirst.next;

        if (!p)
                goto out;

        INT_OFF;
        do {
                struct ifsregion *ifsp;
                ifsp = p->next;
                free(p);
                p = ifsp;
        } while (p);
        ifsfirst.next = NULL;
        INT_ON;
 out:
        ifslastp = NULL;
}

static size_t
esclen(const char *start, const char *p)
{
        size_t esc = 0;

        while (p > start && (unsigned char)*--p == CTLESC) {
                esc++;
        }
        return esc;
}

/*
 * Remove any CTLESC characters from a string.
 */
static char *
rmescapes(char *str, int flag)
{
        static const char qchars[] ALIGN1 = {
                IF_ASH_BASH_COMPAT('/',) CTLESC, CTLQUOTEMARK, '\0' };

        char *p, *q, *r;
        unsigned inquotes;
        unsigned protect_against_glob;
        unsigned globbing;
        IF_ASH_BASH_COMPAT(unsigned slash = flag & RMESCAPE_SLASH;)

        p = strpbrk(str, qchars IF_ASH_BASH_COMPAT(+ !slash));
        if (!p)
                return str;

        q = p;
        r = str;
        if (flag & RMESCAPE_ALLOC) {
                size_t len = p - str;
                size_t fulllen = len + strlen(p) + 1;

                if (flag & RMESCAPE_GROW) {
                        int strloc = str - (char *)stackblock();
                        r = makestrspace(fulllen, expdest);
                        /* p and str may be invalidated by makestrspace */
                        str = (char *)stackblock() + strloc;
                        p = str + len;
                } else if (flag & RMESCAPE_HEAP) {
                        r = ckmalloc(fulllen);
                } else {
                        r = stalloc(fulllen);
                }
                q = r;
                if (len > 0) {
                        q = (char *)memcpy(q, str, len) + len;
                }
        }

        inquotes = 0;
        globbing = flag & RMESCAPE_GLOB;
        protect_against_glob = globbing;
        while (*p) {
                if ((unsigned char)*p == CTLQUOTEMARK) {
// Note: both inquotes and protect_against_glob only affect whether
                        inquotes = ~inquotes;
                        p++;
                        protect_against_glob = globbing;
                        continue;
                }
                if ((unsigned char)*p == CTLESC) {
                        p++;
#if DEBUG
                        if (*p == '\0')
                                ash_msg_and_raise_error("CTLESC at EOL (shouldn't happen)");
#endif
                        if (protect_against_glob) {
                                *q++ = '\\';
                        }
                } else if (*p == '\\' && !inquotes) {
                        /* naked back slash */
                        protect_against_glob = 0;
                        goto copy;
                }
#if ENABLE_ASH_BASH_COMPAT
                else if (*p == '/' && slash) {
                        /* stop handling globbing and mark location of slash */
                        globbing = slash = 0;
                        *p = CTLESC;
                }
#endif
                protect_against_glob = globbing;
 copy:
                *q++ = *p++;
        }
        *q = '\0';
        if (flag & RMESCAPE_GROW) {
                expdest = r;
                STADJUST(q - r + 1, expdest);
        }
        return r;
}
#define pmatch(a, b) !fnmatch((a), (b), 0)

/*
 * Prepare a pattern for a expmeta (internal glob(3)) call.
 *
 * Returns an stalloced string.
 */
static char *
preglob(const char *pattern, int flag)
{
        return rmescapes((char *)pattern, flag | RMESCAPE_GLOB);
}

/*
 * Put a string on the stack.
 */
static void
memtodest(const char *p, size_t len, int syntax, int quotes)
{
        char *q;

        if (!len)
                return;

        q = makestrspace((quotes & QUOTES_ESC) ? len * 2 : len, expdest);

        do {
                unsigned char c = *p++;
                if (c) {
                        int n = SIT(c, syntax);
                        if ((quotes & QUOTES_ESC)
                         && ((n == CCTL)
                            ||  (((quotes & EXP_FULL) || syntax != BASESYNTAX)
                                && n == CBACK)
                                )
                        ) {
                                USTPUTC(CTLESC, q);
                        }
                } else if (!(quotes & QUOTES_KEEPNUL))
                        continue;
                USTPUTC(c, q);
        } while (--len);

        expdest = q;
}

static size_t
strtodest(const char *p, int syntax, int quotes)
{
        size_t len = strlen(p);
        memtodest(p, len, syntax, quotes);
        return len;
}

/*
 * Record the fact that we have to scan this region of the
 * string for IFS characters.
 */
static void
recordregion(int start, int end, int nulonly)
{
        struct ifsregion *ifsp;

        if (ifslastp == NULL) {
                ifsp = &ifsfirst;
        } else {
                INT_OFF;
                ifsp = ckzalloc(sizeof(*ifsp));
                /*ifsp->next = NULL; - ckzalloc did it */
                ifslastp->next = ifsp;
                INT_ON;
        }
        ifslastp = ifsp;
        ifslastp->begoff = start;
        ifslastp->endoff = end;
        ifslastp->nulonly = nulonly;
}

static void
removerecordregions(int endoff)
{
        if (ifslastp == NULL)
                return;

        if (ifsfirst.endoff > endoff) {
                while (ifsfirst.next) {
                        struct ifsregion *ifsp;
                        INT_OFF;
                        ifsp = ifsfirst.next->next;
                        free(ifsfirst.next);
                        ifsfirst.next = ifsp;
                        INT_ON;
                }
                if (ifsfirst.begoff > endoff) {
                        ifslastp = NULL;
                } else {
                        ifslastp = &ifsfirst;
                        ifsfirst.endoff = endoff;
                }
                return;
        }

        ifslastp = &ifsfirst;
        while (ifslastp->next && ifslastp->next->begoff < endoff)
                ifslastp = ifslastp->next;
        while (ifslastp->next) {
                struct ifsregion *ifsp;
                INT_OFF;
                ifsp = ifslastp->next->next;
                free(ifslastp->next);
                ifslastp->next = ifsp;
                INT_ON;
        }
        if (ifslastp->endoff > endoff)
                ifslastp->endoff = endoff;
}

static char *
exptilde(char *startp, char *p, int flags)
{
        unsigned char c;
        char *name;
        struct passwd *pw;
        const char *home;
        int quotes = flags & QUOTES_ESC;

        name = p + 1;

        while ((c = *++p) != '\0') {
                switch (c) {
                case CTLESC:
                        return startp;
                case CTLQUOTEMARK:
                        return startp;
                case ':':
                        if (flags & EXP_VARTILDE)
                                goto done;
                        break;
                case '/':
                case CTLENDVAR:
                        goto done;
                }
        }
 done:
        *p = '\0';
        if (*name == '\0') {
                home = lookupvar("HOME");
        } else {
                pw = getpwnam(name);
                if (pw == NULL)
                        goto lose;
                home = pw->pw_dir;
        }
        if (!home || !*home)
                goto lose;
        *p = c;
        strtodest(home, SQSYNTAX, quotes);
        return p;
 lose:
        *p = c;
        return startp;
}

/*
 * Execute a command inside back quotes.  If it's a builtin command, we
 * want to save its output in a block obtained from malloc.  Otherwise
 * we fork off a subprocess and get the output of the command via a pipe.
 * Should be called with interrupts off.
 */
struct backcmd {                /* result of evalbackcmd */
        int fd;                 /* file descriptor to read from */
        int nleft;              /* number of chars in buffer */
        char *buf;              /* buffer */
        struct job *jp;         /* job structure for command */
};

/* These forward decls are needed to use "eval" code for backticks handling: */
#define EV_EXIT 01              /* exit after evaluating tree */
static int evaltree(union node *, int);

static void FAST_FUNC
evalbackcmd(union node *n, struct backcmd *result)
{
        int pip[2];
        struct job *jp;

        result->fd = -1;
        result->buf = NULL;
        result->nleft = 0;
        result->jp = NULL;
        if (n == NULL) {
                goto out;
        }

        if (pipe(pip) < 0)
                ash_msg_and_raise_error("pipe call failed");
        jp = makejob(/*n,*/ 1);
        if (forkshell(jp, n, FORK_NOJOB) == 0) {
                /* child */
                FORCE_INT_ON;
                close(pip[0]);
                if (pip[1] != 1) {
                        /*close(1);*/
                        dup2_or_raise(pip[1], 1);
                        close(pip[1]);
                }
/* TODO: eflag clearing makes the following not abort:
 *  ash -c 'set -e; z=$(false;echo foo); echo $z'
 * which is what bash does (unless it is in POSIX mode).
 * dash deleted "eflag = 0" line in the commit
 *  Date: Mon, 28 Jun 2010 17:11:58 +1000
 *  [EVAL] Don't clear eflag in evalbackcmd
 * For now, preserve bash-like behavior, it seems to be somewhat more useful:
 */
                eflag = 0;
                ifsfree();
                evaltree(n, EV_EXIT); /* actually evaltreenr... */
                /* NOTREACHED */
        }
        /* parent */
        close(pip[1]);
        result->fd = pip[0];
        result->jp = jp;

 out:
        TRACE(("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
                result->fd, result->buf, result->nleft, result->jp));
}

/*
 * Expand stuff in backwards quotes.
 */
static void
expbackq(union node *cmd, int flag)
{
        struct backcmd in;
        int i;
        char buf[128];
        char *p;
        char *dest;
        int startloc;
        int syntax = flag & EXP_QUOTED ? DQSYNTAX : BASESYNTAX;
        struct stackmark smark;

        INT_OFF;
        startloc = expdest - (char *)stackblock();
        pushstackmark(&smark, startloc);
        evalbackcmd(cmd, &in);
        popstackmark(&smark);

        p = in.buf;
        i = in.nleft;
        if (i == 0)
                goto read;
        for (;;) {
                memtodest(p, i, syntax, flag & QUOTES_ESC);
 read:
                if (in.fd < 0)
                        break;
                i = nonblock_immune_read(in.fd, buf, sizeof(buf));
                TRACE(("expbackq: read returns %d\n", i));
                if (i <= 0)
                        break;
                p = buf;
        }

        free(in.buf);
        if (in.fd >= 0) {
                close(in.fd);
                back_exitstatus = waitforjob(in.jp);
        }
        INT_ON;

        /* Eat all trailing newlines */
        dest = expdest;
        for (; dest > (char *)stackblock() && dest[-1] == '\n';)
                STUNPUTC(dest);
        expdest = dest;

        if (!(flag & EXP_QUOTED))
                recordregion(startloc, dest - (char *)stackblock(), 0);
        TRACE(("evalbackq: size:%d:'%.*s'\n",
                (int)((dest - (char *)stackblock()) - startloc),
                (int)((dest - (char *)stackblock()) - startloc),
                stackblock() + startloc));
}

#if ENABLE_SH_MATH_SUPPORT
/*
 * Expand arithmetic expression.  Backup to start of expression,
 * evaluate, place result in (backed up) result, adjust string position.
 */
static void
expari(int flag)
{
        char *p, *start;
        int begoff;
        int len;

        /* ifsfree(); */

        /*
         * This routine is slightly over-complicated for
         * efficiency.  Next we scan backwards looking for the
         * start of arithmetic.
         */
        start = stackblock();
        p = expdest - 1;
        *p = '\0';
        p--;
        while (1) {
                int esc;

                while ((unsigned char)*p != CTLARI) {
                        p--;
#if DEBUG
                        if (p < start) {
                                ash_msg_and_raise_error("missing CTLARI (shouldn't happen)");
                        }
#endif
                }

                esc = esclen(start, p);
                if (!(esc % 2)) {
                        break;
                }

                p -= esc + 1;
        }

        begoff = p - start;

        removerecordregions(begoff);

        expdest = p;

        if (flag & QUOTES_ESC)
                rmescapes(p + 1, 0);

        len = cvtnum(ash_arith(p + 1));

        if (!(flag & EXP_QUOTED))
                recordregion(begoff, begoff + len, 0);
}
#endif

/* argstr needs it */
static char *evalvar(char *p, int flags, struct strlist *var_str_list);

/*
 * Perform variable and command substitution.  If EXP_FULL is set, output CTLESC
 * characters to allow for further processing.  Otherwise treat
 * $@ like $* since no splitting will be performed.
 *
 * var_str_list (can be NULL) is a list of "VAR=val" strings which take precedence
 * over shell varables. Needed for "A=a B=$A; echo $B" case - we use it
 * for correct expansion of "B=$A" word.
 */
static void
argstr(char *p, int flags, struct strlist *var_str_list)
{
        static const char spclchars[] ALIGN1 = {
                '=',
                ':',
                CTLQUOTEMARK,
                CTLENDVAR,
                CTLESC,
                CTLVAR,
                CTLBACKQ,
#if ENABLE_SH_MATH_SUPPORT
                CTLENDARI,
#endif
                '\0'
        };
        const char *reject = spclchars;
        int breakall = (flags & (EXP_WORD | EXP_QUOTED)) == EXP_WORD;
        int inquotes;
        size_t length;
        int startloc;

        if (!(flags & EXP_VARTILDE)) {
                reject += 2;
        } else if (flags & EXP_VARTILDE2) {
                reject++;
        }
        inquotes = 0;
        length = 0;
        if (flags & EXP_TILDE) {
                char *q;

                flags &= ~EXP_TILDE;
 tilde:
                q = p;
                if (*q == '~')
                        p = exptilde(p, q, flags);
        }
 start:
        startloc = expdest - (char *)stackblock();
        for (;;) {
                unsigned char c;

                length += strcspn(p + length, reject);
                c = p[length];
                if (c) {
                        if (!(c & 0x80)
                        IF_SH_MATH_SUPPORT(|| c == CTLENDARI)
                        ) {
                                /* c == '=' || c == ':' || c == CTLENDARI */
                                length++;
                        }
                }
                if (length > 0) {
                        int newloc;
                        expdest = stack_nputstr(p, length, expdest);
                        newloc = expdest - (char *)stackblock();
                        if (breakall && !inquotes && newloc > startloc) {
                                recordregion(startloc, newloc, 0);
                        }
                        startloc = newloc;
                }
                p += length + 1;
                length = 0;

                switch (c) {
                case '\0':
                        goto breakloop;
                case '=':
                        if (flags & EXP_VARTILDE2) {
                                p--;
                                continue;
                        }
                        flags |= EXP_VARTILDE2;
                        reject++;
                        /* fall through */
                case ':':
                        /*
                         * sort of a hack - expand tildes in variable
                         * assignments (after the first '=' and after ':'s).
                         */
                        if (*--p == '~') {
                                goto tilde;
                        }
                        continue;
                }

                switch (c) {
                case CTLENDVAR: /* ??? */
                        goto breakloop;
                case CTLQUOTEMARK:
                        inquotes ^= EXP_QUOTED;
                        /* "$@" syntax adherence hack */
                        if (inquotes && !memcmp(p, dolatstr + 1, DOLATSTRLEN - 1)) {
                                p = evalvar(p + 1, flags | inquotes, /* var_str_list: */ NULL) + 1;
                                goto start;
                        }
 addquote:
                        if (flags & QUOTES_ESC) {
                                p--;
                                length++;
                                startloc++;
                        }
                        break;
                case CTLESC:
                        startloc++;
                        length++;

                        /*
                         * Quoted parameter expansion pattern: remove quote
                         * unless inside inner quotes or we have a literal
                         * backslash.
                         */
                        if (((flags | inquotes) & (EXP_QPAT | EXP_QUOTED)) ==
                            EXP_QPAT && *p != '\\')
                                break;

                        goto addquote;
                case CTLVAR:
                        TRACE(("argstr: evalvar('%s')\n", p));
                        p = evalvar(p, flags | inquotes, var_str_list);
                        TRACE(("argstr: evalvar:'%s'\n", (char *)stackblock()));
                        goto start;
                case CTLBACKQ:
                        expbackq(argbackq->n, flags | inquotes);
                        argbackq = argbackq->next;
                        goto start;
#if ENABLE_SH_MATH_SUPPORT
                case CTLENDARI:
                        p--;
                        expari(flags | inquotes);
                        goto start;
#endif
                }
        }
 breakloop: ;
}

static char *
scanleft(char *startp, char *rmesc, char *rmescend UNUSED_PARAM,
                char *pattern, int quotes, int zero)
{
        char *loc, *loc2;
        char c;

        loc = startp;
        loc2 = rmesc;
        do {
                int match;
                const char *s = loc2;

                c = *loc2;
                if (zero) {
                        *loc2 = '\0';
                        s = rmesc;
                }
                match = pmatch(pattern, s);

                *loc2 = c;
                if (match)
                        return loc;
                if (quotes && (unsigned char)*loc == CTLESC)
                        loc++;
                loc++;
                loc2++;
        } while (c);
        return NULL;
}

static char *
scanright(char *startp, char *rmesc, char *rmescend,
                char *pattern, int quotes, int match_at_start)
{
#if !ENABLE_ASH_OPTIMIZE_FOR_SIZE
        int try2optimize = match_at_start;
#endif
        int esc = 0;
        char *loc;
        char *loc2;

        /* If we called by "${v/pattern/repl}" or "${v//pattern/repl}":
         * startp="escaped_value_of_v" rmesc="raw_value_of_v"
         * rmescend=""(ptr to NUL in rmesc) pattern="pattern" quotes=match_at_start=1
         * Logic:
         * loc starts at NUL at the end of startp, loc2 starts at the end of rmesc,
         * and on each iteration they go back two/one char until they reach the beginning.
         * We try to find a match in "raw_value_of_v", "raw_value_of_", "raw_value_of" etc.
         */
        /* TODO: document in what other circumstances we are called. */

        for (loc = pattern - 1, loc2 = rmescend; loc >= startp; loc2--) {
                int match;
                char c = *loc2;
                const char *s = loc2;
                if (match_at_start) {
                        *loc2 = '\0';
                        s = rmesc;
                }
                match = pmatch(pattern, s);
                //bb_error_msg("pmatch(pattern:'%s',s:'%s'):%d", pattern, s, match);
                *loc2 = c;
                if (match)
                        return loc;
#if !ENABLE_ASH_OPTIMIZE_FOR_SIZE
                if (try2optimize) {
                        /* Maybe we can optimize this:
                         * if pattern ends with unescaped *, we can avoid checking
                         * shorter strings: if "foo*" doesnt match "raw_value_of_v",
                         * it wont match truncated "raw_value_of_" strings too.
                         */
                        unsigned plen = strlen(pattern);
                        /* Does it end with "*"? */
                        if (plen != 0 && pattern[--plen] == '*') {
                                /* "xxxx*" is not escaped */
                                /* "xxx\*" is escaped */
                                /* "xx\\*" is not escaped */
                                /* "x\\\*" is escaped */
                                int slashes = 0;
                                while (plen != 0 && pattern[--plen] == '\\')
                                        slashes++;
                                if (!(slashes & 1))
                                        break; /* ends with unescaped "*" */
                        }
                        try2optimize = 0;
                }
#endif
                loc--;
                if (quotes) {
                        if (--esc < 0) {
                                esc = esclen(startp, loc);
                        }
                        if (esc % 2) {
                                esc--;
                                loc--;
                        }
                }
        }
        return NULL;
}

static void varunset(const char *, const char *, const char *, int) NORETURN;
static void
varunset(const char *end, const char *var, const char *umsg, int varflags)
{
        const char *msg;
        const char *tail;

        tail = nullstr;
        msg = "parameter not set";
        if (umsg) {
                if ((unsigned char)*end == CTLENDVAR) {
                        if (varflags & VSNUL)
                                tail = " or null";
                } else {
                        msg = umsg;
                }
        }
        ash_msg_and_raise_error("%.*s: %s%s", (int)(end - var - 1), var, msg, tail);
}

static const char *
subevalvar(char *p, char *varname, int strloc, int subtype,
                int startloc, int varflags, int flag, struct strlist *var_str_list)
{
        struct nodelist *saveargbackq = argbackq;
        int quotes = flag & QUOTES_ESC;
        char *startp;
        char *loc;
        char *rmesc, *rmescend;
        char *str;
        IF_ASH_BASH_COMPAT(char *repl = NULL;)
        IF_ASH_BASH_COMPAT(int pos, len, orig_len;)
        int amount, resetloc;
        IF_ASH_BASH_COMPAT(int workloc;)
        int zero;
        char *(*scan)(char*, char*, char*, char*, int, int);

        //bb_error_msg("subevalvar(p:'%s',varname:'%s',strloc:%d,subtype:%d,startloc:%d,varflags:%x,quotes:%d)",
        //              p, varname, strloc, subtype, startloc, varflags, quotes);

        argstr(p, EXP_TILDE | (subtype != VSASSIGN && subtype != VSQUESTION ?
                        (flag & (EXP_QUOTED | EXP_QPAT) ? EXP_QPAT : EXP_CASE) : 0),
                        var_str_list);
        STPUTC('\0', expdest);
        argbackq = saveargbackq;
        startp = (char *)stackblock() + startloc;

        switch (subtype) {
        case VSASSIGN:
                setvar0(varname, startp);
                amount = startp - expdest;
                STADJUST(amount, expdest);
                return startp;

        case VSQUESTION:
                varunset(p, varname, startp, varflags);
                /* NOTREACHED */

#if ENABLE_ASH_BASH_COMPAT
        case VSSUBSTR:
//TODO: support more general format ${v:EXPR:EXPR},
// where EXPR follows $(()) rules
                loc = str = stackblock() + strloc;
                /* Read POS in ${var:POS:LEN} */
                pos = atoi(loc); /* number(loc) errors out on "1:4" */
                len = str - startp - 1;

                /* *loc != '\0', guaranteed by parser */
                if (quotes) {
                        char *ptr;

                        /* Adjust the length by the number of escapes */
                        for (ptr = startp; ptr < (str - 1); ptr++) {
                                if ((unsigned char)*ptr == CTLESC) {
                                        len--;
                                        ptr++;
                                }
                        }
                }
                orig_len = len;

                if (*loc++ == ':') {
                        /* ${var::LEN} */
                        len = number(loc);
                } else {
                        /* Skip POS in ${var:POS:LEN} */
                        len = orig_len;
                        while (*loc && *loc != ':') {
                                /* TODO?
                                 * bash complains on: var=qwe; echo ${var:1a:123}
                                if (!isdigit(*loc))
                                        ash_msg_and_raise_error(msg_illnum, str);
                                 */
                                loc++;
                        }
                        if (*loc++ == ':') {
                                len = number(loc);
                        }
                }
                if (pos < 0) {
                        /* ${VAR:$((-n)):l} starts n chars from the end */
                        pos = orig_len + pos;
                }
                if ((unsigned)pos >= orig_len) {
                        /* apart from obvious ${VAR:999999:l},
                         * covers ${VAR:$((-9999999)):l} - result is ""
                         * (bash-compat)
                         */
                        pos = 0;
                        len = 0;
                }
                if (len > (orig_len - pos))
                        len = orig_len - pos;

                for (str = startp; pos; str++, pos--) {
                        if (quotes && (unsigned char)*str == CTLESC)
                                str++;
                }
                for (loc = startp; len; len--) {
                        if (quotes && (unsigned char)*str == CTLESC)
                                *loc++ = *str++;
                        *loc++ = *str++;
                }
                *loc = '\0';
                amount = loc - expdest;
                STADJUST(amount, expdest);
                return loc;
#endif
        }

        resetloc = expdest - (char *)stackblock();

        /* We'll comeback here if we grow the stack while handling
         * a VSREPLACE or VSREPLACEALL, since our pointers into the
         * stack will need rebasing, and we'll need to remove our work
         * areas each time
         */
 IF_ASH_BASH_COMPAT(restart:)

        amount = expdest - ((char *)stackblock() + resetloc);
        STADJUST(-amount, expdest);
        startp = (char *)stackblock() + startloc;

        rmesc = startp;
        rmescend = (char *)stackblock() + strloc;
        if (quotes) {
                rmesc = rmescapes(startp, RMESCAPE_ALLOC | RMESCAPE_GROW);
                if (rmesc != startp) {
                        rmescend = expdest;
                        startp = (char *)stackblock() + startloc;
                }
        }
        rmescend--;
        str = (char *)stackblock() + strloc;
        /*
         * Example: v='a\bc'; echo ${v/\\b/_\\_\z_}
         * The result is a_\_z_c (not a\_\_z_c)!
         *
         * The search pattern and replace string treat backslashes differently!
         * RMESCAPE_SLASH causes preglob to work differently on the pattern
         * and string.  It's only used on the first call.
         */
        preglob(str, IF_ASH_BASH_COMPAT(
                (subtype == VSREPLACE || subtype == VSREPLACEALL) && !repl ?
                        RMESCAPE_SLASH :) 0);

#if ENABLE_ASH_BASH_COMPAT
        workloc = expdest - (char *)stackblock();
        if (subtype == VSREPLACE || subtype == VSREPLACEALL) {
                char *idx, *end;

                if (!repl) {
                        repl = strchr(str, CTLESC);
                        if (repl)
                                *repl++ = '\0';
                        else
                                repl = nullstr;
                }
                //bb_error_msg("str:'%s' repl:'%s'", str, repl);

                /* If there's no pattern to match, return the expansion unmolested */
                if (str[0] == '\0')
                        return NULL;

                len = 0;
                idx = startp;
                end = str - 1;
                while (idx < end) {
 try_to_match:
                        loc = scanright(idx, rmesc, rmescend, str, quotes, 1);
                        //bb_error_msg("scanright('%s'):'%s'", str, loc);
                        if (!loc) {
                                /* No match, advance */
                                char *restart_detect = stackblock();
 skip_matching:
                                STPUTC(*idx, expdest);
                                if (quotes && (unsigned char)*idx == CTLESC) {
                                        idx++;
                                        len++;
                                        STPUTC(*idx, expdest);
                                }
                                if (stackblock() != restart_detect)
                                        goto restart;
                                idx++;
                                len++;
                                rmesc++;
                                /* continue; - prone to quadratic behavior, smarter code: */
                                if (idx >= end)
                                        break;
                                if (str[0] == '*') {
                                        /* Pattern is "*foo". If "*foo" does not match "long_string",
                                         * it would never match "ong_string" etc, no point in trying.
                                         */
                                        goto skip_matching;
                                }
                                goto try_to_match;
                        }

                        if (subtype == VSREPLACEALL) {
                                while (idx < loc) {
                                        if (quotes && (unsigned char)*idx == CTLESC)
                                                idx++;
                                        idx++;
                                        rmesc++;
                                }
                        } else {
                                idx = loc;
                        }

                        //bb_error_msg("repl:'%s'", repl);
                        for (loc = (char*)repl; *loc; loc++) {
                                char *restart_detect = stackblock();
                                if (quotes && *loc == '\\') {
                                        STPUTC(CTLESC, expdest);
                                        len++;
                                }
                                STPUTC(*loc, expdest);
                                if (stackblock() != restart_detect)
                                        goto restart;
                                len++;
                        }

                        if (subtype == VSREPLACE) {
                                //bb_error_msg("tail:'%s', quotes:%x", idx, quotes);
                                while (*idx) {
                                        char *restart_detect = stackblock();
                                        STPUTC(*idx, expdest);
                                        if (stackblock() != restart_detect)
                                                goto restart;
                                        len++;
                                        idx++;
                                }
                                break;
                        }
                }

                /* We've put the replaced text into a buffer at workloc, now
                 * move it to the right place and adjust the stack.
                 */
                STPUTC('\0', expdest);
                startp = (char *)stackblock() + startloc;
                memmove(startp, (char *)stackblock() + workloc, len + 1);
                //bb_error_msg("startp:'%s'", startp);
                amount = expdest - (startp + len);
                STADJUST(-amount, expdest);
                return startp;
        }
#endif /* ENABLE_ASH_BASH_COMPAT */

        subtype -= VSTRIMRIGHT;
#if DEBUG
        if (subtype < 0 || subtype > 7)
                abort();
#endif
        /* zero = (subtype == VSTRIMLEFT || subtype == VSTRIMLEFTMAX) */
        zero = subtype >> 1;
        /* VSTRIMLEFT/VSTRIMRIGHTMAX -> scanleft */
        scan = (subtype & 1) ^ zero ? scanleft : scanright;

        loc = scan(startp, rmesc, rmescend, str, quotes, zero);
        if (loc) {
                if (zero) {
                        memmove(startp, loc, str - loc);
                        loc = startp + (str - loc) - 1;
                }
                *loc = '\0';
                amount = loc - expdest;
                STADJUST(amount, expdest);
        }
        return loc;
}

/*
 * Add the value of a specialized variable to the stack string.
 * name parameter (examples):
 * ash -c 'echo $1'      name:'1='
 * ash -c 'echo $qwe'    name:'qwe='
 * ash -c 'echo $$'      name:'$='
 * ash -c 'echo ${$}'    name:'$='
 * ash -c 'echo ${$##q}' name:'$=q'
 * ash -c 'echo ${#$}'   name:'$='
 * note: examples with bad shell syntax:
 * ash -c 'echo ${#$1}'  name:'$=1'
 * ash -c 'echo ${#1#}'  name:'1=#'
 */
static NOINLINE ssize_t
varvalue(char *name, int varflags, int flags, struct strlist *var_str_list, int *quotedp)
{
        const char *p;
        int num;
        int i;
        ssize_t len = 0;
        int sep;
        int quoted = *quotedp;
        int subtype = varflags & VSTYPE;
        int discard = subtype == VSPLUS || subtype == VSLENGTH;
        int quotes = (discard ? 0 : (flags & QUOTES_ESC)) | QUOTES_KEEPNUL;
        int syntax;

        sep = (flags & EXP_FULL) << CHAR_BIT;
        syntax = quoted ? DQSYNTAX : BASESYNTAX;

        switch (*name) {
        case '$':
                num = rootpid;
                goto numvar;
        case '?':
                num = exitstatus;
                goto numvar;
        case '#':
                num = shellparam.nparam;
                goto numvar;
        case '!':
                num = backgndpid;
                if (num == 0)
                        return -1;
 numvar:
                len = cvtnum(num);
                goto check_1char_name;
        case '-':
                expdest = makestrspace(NOPTS, expdest);
                for (i = NOPTS - 1; i >= 0; i--) {
                        if (optlist[i]) {
                                USTPUTC(optletters(i), expdest);
                                len++;
                        }
                }
 check_1char_name:
#if 0
                /* handles cases similar to ${#$1} */
                if (name[2] != '\0')
                        raise_error_syntax("bad substitution");
#endif
                break;
        case '@':
                if (quoted && sep)
                        goto param;
                /* fall through */
        case '*': {
                char **ap;
                char sepc;

                if (quoted)
                        sep = 0;
                sep |= ifsset() ? ifsval()[0] : ' ';
 param:
                sepc = sep;
                *quotedp = !sepc;
                ap = shellparam.p;
                if (!ap)
                        return -1;
                while ((p = *ap++) != NULL) {
                        len += strtodest(p, syntax, quotes);

                        if (*ap && sep) {
                                len++;
                                memtodest(&sepc, 1, syntax, quotes);
                        }
                }
                break;
        } /* case '*' */
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':
                num = atoi(name); /* number(name) fails on ${N#str} etc */
                if (num < 0 || num > shellparam.nparam)
                        return -1;
                p = num ? shellparam.p[num - 1] : arg0;
                goto value;
        default:
                /* NB: name has form "VAR=..." */

                /* "A=a B=$A" case: var_str_list is a list of "A=a" strings
                 * which should be considered before we check variables. */
                if (var_str_list) {
                        unsigned name_len = (strchrnul(name, '=') - name) + 1;
                        p = NULL;
                        do {
                                char *str, *eq;
                                str = var_str_list->text;
                                eq = strchr(str, '=');
                                if (!eq) /* stop at first non-assignment */
                                        break;
                                eq++;
                                if (name_len == (unsigned)(eq - str)
                                 && strncmp(str, name, name_len) == 0
                                ) {
                                        p = eq;
                                        /* goto value; - WRONG! */
                                        /* think "A=1 A=2 B=$A" */
                                }
                                var_str_list = var_str_list->next;
                        } while (var_str_list);
                        if (p)
                                goto value;
                }
                p = lookupvar(name);
 value:
                if (!p)
                        return -1;

                len = strtodest(p, syntax, quotes);
#if ENABLE_UNICODE_SUPPORT
                if (subtype == VSLENGTH && len > 0) {
                        reinit_unicode_for_ash();
                        if (unicode_status == UNICODE_ON) {
                                STADJUST(-len, expdest);
                                discard = 0;
                                len = unicode_strlen(p);
                        }
                }
#endif
                break;
        }

        if (discard)
                STADJUST(-len, expdest);
        return len;
}

/*
 * Expand a variable, and return a pointer to the next character in the
 * input string.
 */
static char *
evalvar(char *p, int flag, struct strlist *var_str_list)
{
        char varflags;
        char subtype;
        int quoted;
        char easy;
        char *var;
        int patloc;
        int startloc;
        ssize_t varlen;

        varflags = (unsigned char) *p++;
        subtype = varflags & VSTYPE;

        if (!subtype)
                raise_error_syntax("bad substitution");

        quoted = flag & EXP_QUOTED;
        var = p;
        easy = (!quoted || (*var == '@' && shellparam.nparam));
        startloc = expdest - (char *)stackblock();
        p = strchr(p, '=') + 1; //TODO: use var_end(p)?

 again:
        varlen = varvalue(var, varflags, flag, var_str_list, &quoted);
        if (varflags & VSNUL)
                varlen--;

        if (subtype == VSPLUS) {
                varlen = -1 - varlen;
                goto vsplus;
        }

        if (subtype == VSMINUS) {
 vsplus:
                if (varlen < 0) {
                        argstr(
                                p,
                                flag | EXP_TILDE | EXP_WORD,
                                var_str_list
                        );
                        goto end;
                }
                goto record;
        }

        if (subtype == VSASSIGN || subtype == VSQUESTION) {
                if (varlen >= 0)
                        goto record;

                subevalvar(p, var, 0, subtype, startloc, varflags,
                           flag & ~QUOTES_ESC, var_str_list);
                varflags &= ~VSNUL;
                /*
                 * Remove any recorded regions beyond
                 * start of variable
                 */
                removerecordregions(startloc);
                goto again;
        }

        if (varlen < 0 && uflag)
                varunset(p, var, 0, 0);

        if (subtype == VSLENGTH) {
                cvtnum(varlen > 0 ? varlen : 0);
                goto record;
        }

        if (subtype == VSNORMAL) {
 record:
                if (!easy)
                        goto end;
                recordregion(startloc, expdest - (char *)stackblock(), quoted);
                goto end;
        }

#if DEBUG
        switch (subtype) {
        case VSTRIMLEFT:
        case VSTRIMLEFTMAX:
        case VSTRIMRIGHT:
        case VSTRIMRIGHTMAX:
#if ENABLE_ASH_BASH_COMPAT
        case VSSUBSTR:
        case VSREPLACE:
        case VSREPLACEALL:
#endif
                break;
        default:
                abort();
        }
#endif

        if (varlen >= 0) {
                /*
                 * Terminate the string and start recording the pattern
                 * right after it
                 */
                STPUTC('\0', expdest);
                patloc = expdest - (char *)stackblock();
                if (NULL == subevalvar(p, /* varname: */ NULL, patloc, subtype,
                                startloc, varflags, flag, var_str_list)) {
                        int amount = expdest - (
                                (char *)stackblock() + patloc - 1
                        );
                        STADJUST(-amount, expdest);
                }
                /* Remove any recorded regions beyond start of variable */
                removerecordregions(startloc);
                goto record;
        }

 end:
        if (subtype != VSNORMAL) {      /* skip to end of alternative */
                int nesting = 1;
                for (;;) {
                        unsigned char c = *p++;
                        if (c == CTLESC)
                                p++;
                        else if (c == CTLBACKQ) {
                                if (varlen >= 0)
                                        argbackq = argbackq->next;
                        } else if (c == CTLVAR) {
                                if ((*p++ & VSTYPE) != VSNORMAL)
                                        nesting++;
                        } else if (c == CTLENDVAR) {
                                if (--nesting == 0)
                                        break;
                        }
                }
        }
        return p;
}

/*
 * Add a file name to the list.
 */
static void
addfname(const char *name)
{
        struct strlist *sp;

        sp = stzalloc(sizeof(*sp));
        sp->text = sstrdup(name);
        *exparg.lastp = sp;
        exparg.lastp = &sp->next;
}

/* If we want to use glob() from libc... */
#if !ENABLE_ASH_INTERNAL_GLOB

/* Add the result of glob() to the list */
static void
addglob(const glob_t *pglob)
{
        char **p = pglob->gl_pathv;

        do {
                addfname(*p);
        } while (*++p);
}
static void
expandmeta(struct strlist *str /*, int flag*/)
{
        /* TODO - EXP_REDIR */

        while (str) {
                char *p;
                glob_t pglob;
                int i;

                if (fflag)
                        goto nometa;

                /* Avoid glob() (and thus, stat() et al) for words like "echo" */
                p = str->text;
                while (*p) {
                        if (*p == '*')
                                goto need_glob;
                        if (*p == '?')
                                goto need_glob;
                        if (*p == '[')
                                goto need_glob;
                        p++;
                }
                goto nometa;

 need_glob:
                INT_OFF;
                p = preglob(str->text, RMESCAPE_ALLOC | RMESCAPE_HEAP);
// GLOB_NOMAGIC (GNU): if no *?[ chars in pattern, return it even if no match
// GLOB_NOCHECK: if no match, return unchanged pattern (sans \* escapes?)
//
// glibc 2.24.90 glob(GLOB_NOMAGIC) does not remove backslashes used for escaping:
// if you pass it "file\?", it returns "file\?", not "file?", if no match.
// Which means you need to unescape the string, right? Not so fast:
// if there _is_ a file named "file\?" (with backslash), it is returned
// as "file\?" too (whichever pattern you used to find it, say, "file*").
// You DONT KNOW by looking at the result whether you need to unescape it.
//
// Worse, globbing of "file\?" in a directory with two files, "file?" and "file\?",
// returns "file\?" - which is WRONG: "file\?" pattern matches "file?" file.
// Without GLOB_NOMAGIC, this works correctly ("file?" is returned as a match).
// With GLOB_NOMAGIC | GLOB_NOCHECK, this also works correctly.
//              i = glob(p, GLOB_NOMAGIC | GLOB_NOCHECK, NULL, &pglob);
//              i = glob(p, GLOB_NOMAGIC, NULL, &pglob);
                i = glob(p, 0, NULL, &pglob);
                //bb_error_msg("glob('%s'):%d '%s'...", p, i, pglob.gl_pathv ? pglob.gl_pathv[0] : "-");
                if (p != str->text)
                        free(p);
                switch (i) {
                case 0:
#if 0 // glibc 2.24.90 bug? Patterns like "*/file", when match, don't set GLOB_MAGCHAR
                        /* GLOB_MAGCHAR is set if *?[ chars were seen (GNU) */
                        if (!(pglob.gl_flags & GLOB_MAGCHAR))
                                goto nometa2;
#endif
                        addglob(&pglob);
                        globfree(&pglob);
                        INT_ON;
                        break;
                case GLOB_NOMATCH:
 //nometa2:
                        globfree(&pglob);
                        INT_ON;
 nometa:
                        *exparg.lastp = str;
                        rmescapes(str->text, 0);
                        exparg.lastp = &str->next;
                        break;
                default:        /* GLOB_NOSPACE */
                        globfree(&pglob);
                        INT_ON;
                        ash_msg_and_raise_error(bb_msg_memory_exhausted);
                }
                str = str->next;
        }
}

#else
/* ENABLE_ASH_INTERNAL_GLOB: Homegrown globbing code. (dash also has both, uses homegrown one.) */

/*
 * Do metacharacter (i.e. *, ?, [...]) expansion.
 */
static void
expmeta(char *expdir, char *enddir, char *name)
{
        char *p;
        const char *cp;
        char *start;
        char *endname;
        int metaflag;
        struct stat statb;
        DIR *dirp;
        struct dirent *dp;
        int atend;
        int matchdot;
        int esc;

        metaflag = 0;
        start = name;
        for (p = name; esc = 0, *p; p += esc + 1) {
                if (*p == '*' || *p == '?')
                        metaflag = 1;
                else if (*p == '[') {
                        char *q = p + 1;
                        if (*q == '!')
                                q++;
                        for (;;) {
                                if (*q == '\\')
                                        q++;
                                if (*q == '/' || *q == '\0')
                                        break;
                                if (*++q == ']') {
                                        metaflag = 1;
                                        break;
                                }
                        }
                } else {
                        if (*p == '\\')
                                esc++;
                        if (p[esc] == '/') {
                                if (metaflag)
                                        break;
                                start = p + esc + 1;
                        }
                }
        }
        if (metaflag == 0) {    /* we've reached the end of the file name */
                if (enddir != expdir)
                        metaflag++;
                p = name;
                do {
                        if (*p == '\\')
                                p++;
                        *enddir++ = *p;
                } while (*p++);
                if (metaflag == 0 || lstat(expdir, &statb) >= 0)
                        addfname(expdir);
                return;
        }
        endname = p;
        if (name < start) {
                p = name;
                do {
                        if (*p == '\\')
                                p++;
                        *enddir++ = *p++;
                } while (p < start);
        }
        if (enddir == expdir) {
                cp = ".";
        } else if (enddir == expdir + 1 && *expdir == '/') {
                cp = "/";
        } else {
                cp = expdir;
                enddir[-1] = '\0';
        }
        dirp = opendir(cp);
        if (dirp == NULL)
                return;
        if (enddir != expdir)
                enddir[-1] = '/';
        if (*endname == 0) {
                atend = 1;
        } else {
                atend = 0;
                *endname = '\0';
                endname += esc + 1;
        }
        matchdot = 0;
        p = start;
        if (*p == '\\')
                p++;
        if (*p == '.')
                matchdot++;
        while (!pending_int && (dp = readdir(dirp)) != NULL) {
                if (dp->d_name[0] == '.' && !matchdot)
                        continue;
                if (pmatch(start, dp->d_name)) {
                        if (atend) {
                                strcpy(enddir, dp->d_name);
                                addfname(expdir);
                        } else {
                                for (p = enddir, cp = dp->d_name; (*p++ = *cp++) != '\0';)
                                        continue;
                                p[-1] = '/';
                                expmeta(expdir, p, endname);
                        }
                }
        }
        closedir(dirp);
        if (!atend)
                endname[-esc - 1] = esc ? '\\' : '/';
}

static struct strlist *
msort(struct strlist *list, int len)
{
        struct strlist *p, *q = NULL;
        struct strlist **lpp;
        int half;
        int n;

        if (len <= 1)
                return list;
        half = len >> 1;
        p = list;
        for (n = half; --n >= 0;) {
                q = p;
                p = p->next;
        }
        q->next = NULL;                 /* terminate first half of list */
        q = msort(list, half);          /* sort first half of list */
        p = msort(p, len - half);               /* sort second half */
        lpp = &list;
        for (;;) {
#if ENABLE_LOCALE_SUPPORT
                if (strcoll(p->text, q->text) < 0)
#else
                if (strcmp(p->text, q->text) < 0)
#endif
                                                {
                        *lpp = p;
                        lpp = &p->next;
                        p = *lpp;
                        if (p == NULL) {
                                *lpp = q;
                                break;
                        }
                } else {
                        *lpp = q;
                        lpp = &q->next;
                        q = *lpp;
                        if (q == NULL) {
                                *lpp = p;
                                break;
                        }
                }
        }
        return list;
}

/*
 * Sort the results of file name expansion.  It calculates the number of
 * strings to sort and then calls msort (short for merge sort) to do the
 * work.
 */
static struct strlist *
expsort(struct strlist *str)
{
        int len;
        struct strlist *sp;

        len = 0;
        for (sp = str; sp; sp = sp->next)
                len++;
        return msort(str, len);
}

static void
expandmeta(struct strlist *str /*, int flag*/)
{
        static const char metachars[] ALIGN1 = {
                '*', '?', '[', 0
        };
        /* TODO - EXP_REDIR */

        while (str) {
                char *expdir;
                struct strlist **savelastp;
                struct strlist *sp;
                char *p;

                if (fflag)
                        goto nometa;
                if (!strpbrk(str->text, metachars))
                        goto nometa;
                savelastp = exparg.lastp;

                INT_OFF;
                p = preglob(str->text, RMESCAPE_ALLOC | RMESCAPE_HEAP);
                {
                        int i = strlen(str->text);
//BUGGY estimation of how long expanded name can be
                        expdir = ckmalloc(i < 2048 ? 2048 : i+1);
                }
                expmeta(expdir, expdir, p);
                free(expdir);
                if (p != str->text)
                        free(p);
                INT_ON;
                if (exparg.lastp == savelastp) {
                        /*
                         * no matches
                         */
 nometa:
                        *exparg.lastp = str;
                        rmescapes(str->text, 0);
                        exparg.lastp = &str->next;
                } else {
                        *exparg.lastp = NULL;
                        *savelastp = sp = expsort(*savelastp);
                        while (sp->next != NULL)
                                sp = sp->next;
                        exparg.lastp = &sp->next;
                }
                str = str->next;
        }
}
#endif /* ENABLE_ASH_INTERNAL_GLOB */

/*
 * Perform variable substitution and command substitution on an argument,
 * placing the resulting list of arguments in arglist.  If EXP_FULL is true,
 * perform splitting and file name expansion.  When arglist is NULL, perform
 * here document expansion.
 */
static void
expandarg(union node *arg, struct arglist *arglist, int flag)
{
        struct strlist *sp;
        char *p;

        argbackq = arg->narg.backquote;
        STARTSTACKSTR(expdest);
        TRACE(("expandarg: argstr('%s',flags:%x)\n", arg->narg.text, flag));
        argstr(arg->narg.text, flag,
                        /* var_str_list: */ arglist ? arglist->list : NULL);
        p = _STPUTC('\0', expdest);
        expdest = p - 1;
        if (arglist == NULL) {
                /* here document expanded */
                goto out;
        }
        p = grabstackstr(p);
        TRACE(("expandarg: p:'%s'\n", p));
        exparg.lastp = &exparg.list;
        /*
         * TODO - EXP_REDIR
         */
        if (flag & EXP_FULL) {
                ifsbreakup(p, &exparg);
                *exparg.lastp = NULL;
                exparg.lastp = &exparg.list;
                expandmeta(exparg.list /*, flag*/);
        } else {
                if (flag & EXP_REDIR) { /*XXX - for now, just remove escapes */
                        rmescapes(p, 0);
                        TRACE(("expandarg: rmescapes:'%s'\n", p));
                }
                sp = stzalloc(sizeof(*sp));
                sp->text = p;
                *exparg.lastp = sp;
                exparg.lastp = &sp->next;
        }
        *exparg.lastp = NULL;
        if (exparg.list) {
                *arglist->lastp = exparg.list;
                arglist->lastp = exparg.lastp;
        }

 out:
        ifsfree();
}

/*
 * Expand shell variables and backquotes inside a here document.
 */
static void
expandhere(union node *arg, int fd)
{
        expandarg(arg, (struct arglist *)NULL, EXP_QUOTED);
        full_write(fd, stackblock(), expdest - (char *)stackblock());
}

/*
 * Returns true if the pattern matches the string.
 */
static int
patmatch(char *pattern, const char *string)
{
        return pmatch(preglob(pattern, 0), string);
}

/*
 * See if a pattern matches in a case statement.
 */
static int
casematch(union node *pattern, char *val)
{
        struct stackmark smark;
        int result;

        setstackmark(&smark);
        argbackq = pattern->narg.backquote;
        STARTSTACKSTR(expdest);
        argstr(pattern->narg.text, EXP_TILDE | EXP_CASE,
                        /* var_str_list: */ NULL);
        STACKSTRNUL(expdest);
        ifsfree();
        result = patmatch(stackblock(), val);
        popstackmark(&smark);
        return result;
}


/* ============ find_command */

struct builtincmd {
        const char *name;
        int (*builtin)(int, char **) FAST_FUNC;
        /* unsigned flags; */
};
#define IS_BUILTIN_SPECIAL(b) ((b)->name[0] & 1)
/* "regular" builtins always take precedence over commands,
 * regardless of PATH=....%builtin... position */
#define IS_BUILTIN_REGULAR(b) ((b)->name[0] & 2)
#define IS_BUILTIN_ASSIGN(b)  ((b)->name[0] & 4)

struct cmdentry {
        smallint cmdtype;       /* CMDxxx */
        union param {
                int index;
                /* index >= 0 for commands without path (slashes) */
                /* (TODO: what exactly does the value mean? PATH position?) */
                /* index == -1 for commands with slashes */
                /* index == (-2 - applet_no) for NOFORK applets */
                const struct builtincmd *cmd;
                struct funcnode *func;
        } u;
};
/* values of cmdtype */
#define CMDUNKNOWN      -1      /* no entry in table for command */
#define CMDNORMAL       0       /* command is an executable program */
#define CMDFUNCTION     1       /* command is a shell function */
#define CMDBUILTIN      2       /* command is a shell builtin */

/* action to find_command() */
#define DO_ERR          0x01    /* prints errors */
#define DO_ABS          0x02    /* checks absolute paths */
#define DO_NOFUNC       0x04    /* don't return shell functions, for command */
#define DO_ALTPATH      0x08    /* using alternate path */
#define DO_ALTBLTIN     0x20    /* %builtin in alt. path */

static void find_command(char *, struct cmdentry *, int, const char *);


/* ============ Hashing commands */

/*
 * When commands are first encountered, they are entered in a hash table.
 * This ensures that a full path search will not have to be done for them
 * on each invocation.
 *
 * We should investigate converting to a linear search, even though that
 * would make the command name "hash" a misnomer.
 */

struct tblentry {
        struct tblentry *next;  /* next entry in hash chain */
        union param param;      /* definition of builtin function */
        smallint cmdtype;       /* CMDxxx */
        char rehash;            /* if set, cd done since entry created */
        char cmdname[1];        /* name of command */
};

static struct tblentry **cmdtable;
#define INIT_G_cmdtable() do { \
        cmdtable = xzalloc(CMDTABLESIZE * sizeof(cmdtable[0])); \
} while (0)

static int builtinloc = -1;     /* index in path of %builtin, or -1 */


static void
tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) char *cmd, char **argv, char **envp)
{
#if ENABLE_FEATURE_SH_STANDALONE
        if (applet_no >= 0) {
                if (APPLET_IS_NOEXEC(applet_no)) {
                        clearenv();
                        while (*envp)
                                putenv(*envp++);
                        run_applet_no_and_exit(applet_no, argv);
                }
                /* re-exec ourselves with the new arguments */
                execve(bb_busybox_exec_path, argv, envp);
                /* If they called chroot or otherwise made the binary no longer
                 * executable, fall through */
        }
#endif

 repeat:
#ifdef SYSV
        do {
                execve(cmd, argv, envp);
        } while (errno == EINTR);
#else
        execve(cmd, argv, envp);
#endif
        if (cmd != (char*) bb_busybox_exec_path && errno == ENOEXEC) {
                /* Run "cmd" as a shell script:
                 * http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
                 * "If the execve() function fails with ENOEXEC, the shell
                 * shall execute a command equivalent to having a shell invoked
                 * with the command name as its first operand,
                 * with any remaining arguments passed to the new shell"
                 *
                 * That is, do not use $SHELL, user's shell, or /bin/sh;
                 * just call ourselves.
                 *
                 * Note that bash reads ~80 chars of the file, and if it sees
                 * a zero byte before it sees newline, it doesn't try to
                 * interpret it, but fails with "cannot execute binary file"
                 * message and exit code 126. For one, this prevents attempts
                 * to interpret foreign ELF binaries as shell scripts.
                 */
                argv[0] = cmd;
                cmd = (char*) bb_busybox_exec_path;
                /* NB: this is only possible because all callers of shellexec()
                 * ensure that the argv[-1] slot exists!
                 */
                argv--;
                argv[0] = (char*) "ash";
                goto repeat;
        }
}

/*
 * Exec a program.  Never returns.  If you change this routine, you may
 * have to change the find_command routine as well.
 * argv[-1] must exist and be writable! See tryexec() for why.
 */
static void shellexec(char **, const char *, int) NORETURN;
static void
shellexec(char **argv, const char *path, int idx)
{
        char *cmdname;
        int e;
        char **envp;
        int exerrno;
        int applet_no = -1; /* used only by FEATURE_SH_STANDALONE */

        envp = listvars(VEXPORT, VUNSET, /*end:*/ NULL);
        if (strchr(argv[0], '/') != NULL
#if ENABLE_FEATURE_SH_STANDALONE
         || (applet_no = find_applet_by_name(argv[0])) >= 0
#endif
        ) {
                tryexec(IF_FEATURE_SH_STANDALONE(applet_no,) argv[0], argv, envp);
                if (applet_no >= 0) {
                        /* We tried execing ourself, but it didn't work.
                         * Maybe /proc/self/exe doesn't exist?
                         * Try $PATH search.
                         */
                        goto try_PATH;
                }
                e = errno;
        } else {
 try_PATH:
                e = ENOENT;
                while ((cmdname = path_advance(&path, argv[0])) != NULL) {
                        if (--idx < 0 && pathopt == NULL) {
                                tryexec(IF_FEATURE_SH_STANDALONE(-1,) cmdname, argv, envp);
                                if (errno != ENOENT && errno != ENOTDIR)
                                        e = errno;
                        }
                        stunalloc(cmdname);
                }
        }

        /* Map to POSIX errors */
        switch (e) {
        case EACCES:
                exerrno = 126;
                break;
        case ENOENT:
                exerrno = 127;
                break;
        default:
                exerrno = 2;
                break;
        }
        exitstatus = exerrno;
        TRACE(("shellexec failed for %s, errno %d, suppress_int %d\n",
                argv[0], e, suppress_int));
        ash_msg_and_raise(EXEXIT, "%s: %s", argv[0], errmsg(e, "not found"));
        /* NOTREACHED */
}

static void
printentry(struct tblentry *cmdp)
{
        int idx;
        const char *path;
        char *name;

        idx = cmdp->param.index;
        path = pathval();
        do {
                name = path_advance(&path, cmdp->cmdname);
                stunalloc(name);
        } while (--idx >= 0);
        out1fmt("%s%s\n", name, (cmdp->rehash ? "*" : nullstr));
}

/*
 * Clear out command entries.  The argument specifies the first entry in
 * PATH which has changed.
 */
static void
clearcmdentry(int firstchange)
{
        struct tblentry **tblp;
        struct tblentry **pp;
        struct tblentry *cmdp;

        INT_OFF;
        for (tblp = cmdtable; tblp < &cmdtable[CMDTABLESIZE]; tblp++) {
                pp = tblp;
                while ((cmdp = *pp) != NULL) {
                        if ((cmdp->cmdtype == CMDNORMAL &&
                             cmdp->param.index >= firstchange)
                         || (cmdp->cmdtype == CMDBUILTIN &&
                             builtinloc >= firstchange)
                        ) {
                                *pp = cmdp->next;
                                free(cmdp);
                        } else {
                                pp = &cmdp->next;
                        }
                }
        }
        INT_ON;
}

/*
 * Locate a command in the command hash table.  If "add" is nonzero,
 * add the command to the table if it is not already present.  The
 * variable "lastcmdentry" is set to point to the address of the link
 * pointing to the entry, so that delete_cmd_entry can delete the
 * entry.
 *
 * Interrupts must be off if called with add != 0.
 */
static struct tblentry **lastcmdentry;

static struct tblentry *
cmdlookup(const char *name, int add)
{
        unsigned int hashval;
        const char *p;
        struct tblentry *cmdp;
        struct tblentry **pp;

        p = name;
        hashval = (unsigned char)*p << 4;
        while (*p)
                hashval += (unsigned char)*p++;
        hashval &= 0x7FFF;
        pp = &cmdtable[hashval % CMDTABLESIZE];
        for (cmdp = *pp; cmdp; cmdp = cmdp->next) {
                if (strcmp(cmdp->cmdname, name) == 0)
                        break;
                pp = &cmdp->next;
        }
        if (add && cmdp == NULL) {
                cmdp = *pp = ckzalloc(sizeof(struct tblentry)
                                + strlen(name)
                                /* + 1 - already done because
                                 * tblentry::cmdname is char[1] */);
                /*cmdp->next = NULL; - ckzalloc did it */
                cmdp->cmdtype = CMDUNKNOWN;
                strcpy(cmdp->cmdname, name);
        }
        lastcmdentry = pp;
        return cmdp;
}

/*
 * Delete the command entry returned on the last lookup.
 */
static void
delete_cmd_entry(void)
{
        struct tblentry *cmdp;

        INT_OFF;
        cmdp = *lastcmdentry;
        *lastcmdentry = cmdp->next;
        if (cmdp->cmdtype == CMDFUNCTION)
                freefunc(cmdp->param.func);
        free(cmdp);
        INT_ON;
}

/*
 * Add a new command entry, replacing any existing command entry for
 * the same name - except special builtins.
 */
static void
addcmdentry(char *name, struct cmdentry *entry)
{
        struct tblentry *cmdp;

        cmdp = cmdlookup(name, 1);
        if (cmdp->cmdtype == CMDFUNCTION) {
                freefunc(cmdp->param.func);
        }
        cmdp->cmdtype = entry->cmdtype;
        cmdp->param = entry->u;
        cmdp->rehash = 0;
}

static int FAST_FUNC
hashcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        struct tblentry **pp;
        struct tblentry *cmdp;
        int c;
        struct cmdentry entry;
        char *name;

        if (nextopt("r") != '\0') {
                clearcmdentry(0);
                return 0;
        }

        if (*argptr == NULL) {
                for (pp = cmdtable; pp < &cmdtable[CMDTABLESIZE]; pp++) {
                        for (cmdp = *pp; cmdp; cmdp = cmdp->next) {
                                if (cmdp->cmdtype == CMDNORMAL)
                                        printentry(cmdp);
                        }
                }
                return 0;
        }

        c = 0;
        while ((name = *argptr) != NULL) {
                cmdp = cmdlookup(name, 0);
                if (cmdp != NULL
                 && (cmdp->cmdtype == CMDNORMAL
                     || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
                ) {
                        delete_cmd_entry();
                }
                find_command(name, &entry, DO_ERR, pathval());
                if (entry.cmdtype == CMDUNKNOWN)
                        c = 1;
                argptr++;
        }
        return c;
}

/*
 * Called when a cd is done.  Marks all commands so the next time they
 * are executed they will be rehashed.
 */
static void
hashcd(void)
{
        struct tblentry **pp;
        struct tblentry *cmdp;

        for (pp = cmdtable; pp < &cmdtable[CMDTABLESIZE]; pp++) {
                for (cmdp = *pp; cmdp; cmdp = cmdp->next) {
                        if (cmdp->cmdtype == CMDNORMAL
                         || (cmdp->cmdtype == CMDBUILTIN
                             && !IS_BUILTIN_REGULAR(cmdp->param.cmd)
                             && builtinloc > 0)
                        ) {
                                cmdp->rehash = 1;
                        }
                }
        }
}

/*
 * Fix command hash table when PATH changed.
 * Called before PATH is changed.  The argument is the new value of PATH;
 * pathval() still returns the old value at this point.
 * Called with interrupts off.
 */
static void FAST_FUNC
changepath(const char *new)
{
        const char *old;
        int firstchange;
        int idx;
        int idx_bltin;

        old = pathval();
        firstchange = 9999;     /* assume no change */
        idx = 0;
        idx_bltin = -1;
        for (;;) {
                if (*old != *new) {
                        firstchange = idx;
                        if ((*old == '\0' && *new == ':')
                         || (*old == ':' && *new == '\0')
                        ) {
                                firstchange++;
                        }
                        old = new;      /* ignore subsequent differences */
                }
                if (*new == '\0')
                        break;
                if (*new == '%' && idx_bltin < 0 && prefix(new + 1, "builtin"))
                        idx_bltin = idx;
                if (*new == ':')
                        idx++;
                new++;
                old++;
        }
        if (builtinloc < 0 && idx_bltin >= 0)
                builtinloc = idx_bltin;             /* zap builtins */
        if (builtinloc >= 0 && idx_bltin < 0)
                firstchange = 0;
        clearcmdentry(firstchange);
        builtinloc = idx_bltin;
}
enum {
        TEOF,
        TNL,
        TREDIR,
        TWORD,
        TSEMI,
        TBACKGND,
        TAND,
        TOR,
        TPIPE,
        TLP,
        TRP,
        TENDCASE,
        TENDBQUOTE,
        TNOT,
        TCASE,
        TDO,
        TDONE,
        TELIF,
        TELSE,
        TESAC,
        TFI,
        TFOR,
#if ENABLE_ASH_BASH_COMPAT
        TFUNCTION,
#endif
        TIF,
        TIN,
        TTHEN,
        TUNTIL,
        TWHILE,
        TBEGIN,
        TEND
};
typedef smallint token_id_t;

/* Nth bit indicates if token marks the end of a list */
enum {
        tokendlist = 0
        /*  0 */ | (1u << TEOF)
        /*  1 */ | (0u << TNL)
        /*  2 */ | (0u << TREDIR)
        /*  3 */ | (0u << TWORD)
        /*  4 */ | (0u << TSEMI)
        /*  5 */ | (0u << TBACKGND)
        /*  6 */ | (0u << TAND)
        /*  7 */ | (0u << TOR)
        /*  8 */ | (0u << TPIPE)
        /*  9 */ | (0u << TLP)
        /* 10 */ | (1u << TRP)
        /* 11 */ | (1u << TENDCASE)
        /* 12 */ | (1u << TENDBQUOTE)
        /* 13 */ | (0u << TNOT)
        /* 14 */ | (0u << TCASE)
        /* 15 */ | (1u << TDO)
        /* 16 */ | (1u << TDONE)
        /* 17 */ | (1u << TELIF)
        /* 18 */ | (1u << TELSE)
        /* 19 */ | (1u << TESAC)
        /* 20 */ | (1u << TFI)
        /* 21 */ | (0u << TFOR)
#if ENABLE_ASH_BASH_COMPAT
        /* 22 */ | (0u << TFUNCTION)
#endif
        /* 23 */ | (0u << TIF)
        /* 24 */ | (0u << TIN)
        /* 25 */ | (1u << TTHEN)
        /* 26 */ | (0u << TUNTIL)
        /* 27 */ | (0u << TWHILE)
        /* 28 */ | (0u << TBEGIN)
        /* 29 */ | (1u << TEND)
        , /* thus far 29 bits used */
};

static const char *const tokname_array[] = {
        "end of file",
        "newline",
        "redirection",
        "word",
        ";",
        "&",
        "&&",
        "||",
        "|",
        "(",
        ")",
        ";;",
        "`",
#define KWDOFFSET 13
        /* the following are keywords */
        "!",
        "case",
        "do",
        "done",
        "elif",
        "else",
        "esac",
        "fi",
        "for",
#if ENABLE_ASH_BASH_COMPAT
        "function",
#endif
        "if",
        "in",
        "then",
        "until",
        "while",
        "{",
        "}",
};

/* Wrapper around strcmp for qsort/bsearch/... */
static int
pstrcmp(const void *a, const void *b)
{
        return strcmp((char*)a, *(char**)b);
}

static const char *const *
findkwd(const char *s)
{
        return bsearch(s, tokname_array + KWDOFFSET,
                        ARRAY_SIZE(tokname_array) - KWDOFFSET,
                        sizeof(tokname_array[0]), pstrcmp);
}

/*
 * Locate and print what a word is...
 */
static int
describe_command(char *command, const char *path, int describe_command_verbose)
{
        struct cmdentry entry;
        struct tblentry *cmdp;
#if ENABLE_ASH_ALIAS
        const struct alias *ap;
#endif

        path = path ? path : pathval();

        if (describe_command_verbose) {
                out1str(command);
        }

        /* First look at the keywords */
        if (findkwd(command)) {
                out1str(describe_command_verbose ? " is a shell keyword" : command);
                goto out;
        }

#if ENABLE_ASH_ALIAS
        /* Then look at the aliases */
        ap = lookupalias(command, 0);
        if (ap != NULL) {
                if (!describe_command_verbose) {
                        out1str("alias ");
                        printalias(ap);
                        return 0;
                }
                out1fmt(" is an alias for %s", ap->val);
                goto out;
        }
#endif
        /* Then check if it is a tracked alias */
        cmdp = cmdlookup(command, 0);
        if (cmdp != NULL) {
                entry.cmdtype = cmdp->cmdtype;
                entry.u = cmdp->param;
        } else {
                /* Finally use brute force */
                find_command(command, &entry, DO_ABS, path);
        }

        switch (entry.cmdtype) {
        case CMDNORMAL: {
                int j = entry.u.index;
                char *p;
                if (j < 0) {
                        p = command;
                } else {
                        do {
                                p = path_advance(&path, command);
                                stunalloc(p);
                        } while (--j >= 0);
                }
                if (describe_command_verbose) {
                        out1fmt(" is%s %s",
                                (cmdp ? " a tracked alias for" : nullstr), p
                        );
                } else {
                        out1str(p);
                }
                break;
        }

        case CMDFUNCTION:
                if (describe_command_verbose) {
                        out1str(" is a shell function");
                } else {
                        out1str(command);
                }
                break;

        case CMDBUILTIN:
                if (describe_command_verbose) {
                        out1fmt(" is a %sshell builtin",
                                IS_BUILTIN_SPECIAL(entry.u.cmd) ?
                                        "special " : nullstr
                        );
                } else {
                        out1str(command);
                }
                break;

        default:
                if (describe_command_verbose) {
                        out1str(": not found\n");
                }
                return 127;
        }
 out:
        out1str("\n");
        return 0;
}

static int FAST_FUNC
typecmd(int argc UNUSED_PARAM, char **argv)
{
        int i = 1;
        int err = 0;
        int verbose = 1;

        /* type -p ... ? (we don't bother checking for 'p') */
        if (argv[1] && argv[1][0] == '-') {
                i++;
                verbose = 0;
        }
        while (argv[i]) {
                err |= describe_command(argv[i++], NULL, verbose);
        }
        return err;
}

#if ENABLE_ASH_CMDCMD
/* Is it "command [-p] PROG ARGS" bltin, no other opts? Return ptr to "PROG" if yes */
static char **
parse_command_args(char **argv, const char **path)
{
        char *cp, c;

        for (;;) {
                cp = *++argv;
                if (!cp)
                        return NULL;
                if (*cp++ != '-')
                        break;
                c = *cp++;
                if (!c)
                        break;
                if (c == '-' && !*cp) {
                        if (!*++argv)
                                return NULL;
                        break;
                }
                do {
                        switch (c) {
                        case 'p':
                                *path = bb_default_path;
                                break;
                        default:
                                /* run 'typecmd' for other options */
                                return NULL;
                        }
                        c = *cp++;
                } while (c);
        }
        return argv;
}

static int FAST_FUNC
commandcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        char *cmd;
        int c;
        enum {
                VERIFY_BRIEF = 1,
                VERIFY_VERBOSE = 2,
        } verify = 0;
        const char *path = NULL;

        /* "command [-p] PROG ARGS" (that is, without -V or -v)
         * never reaches this function.
         */

        while ((c = nextopt("pvV")) != '\0')
                if (c == 'V')
                        verify |= VERIFY_VERBOSE;
                else if (c == 'v')
                        /*verify |= VERIFY_BRIEF*/;
#if DEBUG
                else if (c != 'p')
                        abort();
#endif
                else
                        path = bb_default_path;

        /* Mimic bash: just "command -v" doesn't complain, it's a nop */
        cmd = *argptr;
        if (/*verify && */ cmd)
                return describe_command(cmd, path, verify /* - VERIFY_BRIEF*/);

        return 0;
}
#endif


/*static int funcblocksize;     // size of structures in function */
/*static int funcstringsize;    // size of strings in node */
static void *funcblock;         /* block to allocate function from */
static char *funcstring_end;    /* end of block to allocate strings from */

/* flags in argument to evaltree */
#define EV_EXIT    01           /* exit after evaluating tree */
#define EV_TESTED  02           /* exit status is checked; ignore -e flag */

static const uint8_t nodesize[N_NUMBER] ALIGN1 = {
        [NCMD     ] = SHELL_ALIGN(sizeof(struct ncmd)),
        [NPIPE    ] = SHELL_ALIGN(sizeof(struct npipe)),
        [NREDIR   ] = SHELL_ALIGN(sizeof(struct nredir)),
        [NBACKGND ] = SHELL_ALIGN(sizeof(struct nredir)),
        [NSUBSHELL] = SHELL_ALIGN(sizeof(struct nredir)),
        [NAND     ] = SHELL_ALIGN(sizeof(struct nbinary)),
        [NOR      ] = SHELL_ALIGN(sizeof(struct nbinary)),
        [NSEMI    ] = SHELL_ALIGN(sizeof(struct nbinary)),
        [NIF      ] = SHELL_ALIGN(sizeof(struct nif)),
        [NWHILE   ] = SHELL_ALIGN(sizeof(struct nbinary)),
        [NUNTIL   ] = SHELL_ALIGN(sizeof(struct nbinary)),
        [NFOR     ] = SHELL_ALIGN(sizeof(struct nfor)),
        [NCASE    ] = SHELL_ALIGN(sizeof(struct ncase)),
        [NCLIST   ] = SHELL_ALIGN(sizeof(struct nclist)),
        [NDEFUN   ] = SHELL_ALIGN(sizeof(struct narg)),
        [NARG     ] = SHELL_ALIGN(sizeof(struct narg)),
        [NTO      ] = SHELL_ALIGN(sizeof(struct nfile)),
#if ENABLE_ASH_BASH_COMPAT
        [NTO2     ] = SHELL_ALIGN(sizeof(struct nfile)),
#endif
        [NCLOBBER ] = SHELL_ALIGN(sizeof(struct nfile)),
        [NFROM    ] = SHELL_ALIGN(sizeof(struct nfile)),
        [NFROMTO  ] = SHELL_ALIGN(sizeof(struct nfile)),
        [NAPPEND  ] = SHELL_ALIGN(sizeof(struct nfile)),
        [NTOFD    ] = SHELL_ALIGN(sizeof(struct ndup)),
        [NFROMFD  ] = SHELL_ALIGN(sizeof(struct ndup)),
        [NHERE    ] = SHELL_ALIGN(sizeof(struct nhere)),
        [NXHERE   ] = SHELL_ALIGN(sizeof(struct nhere)),
        [NNOT     ] = SHELL_ALIGN(sizeof(struct nnot)),
};

static int calcsize(int funcblocksize, union node *n);

static int
sizenodelist(int funcblocksize, struct nodelist *lp)
{
        while (lp) {
                funcblocksize += SHELL_ALIGN(sizeof(struct nodelist));
                funcblocksize = calcsize(funcblocksize, lp->n);
                lp = lp->next;
        }
        return funcblocksize;
}

static int
calcsize(int funcblocksize, union node *n)
{
        if (n == NULL)
                return funcblocksize;
        funcblocksize += nodesize[n->type];
        switch (n->type) {
        case NCMD:
                funcblocksize = calcsize(funcblocksize, n->ncmd.redirect);
                funcblocksize = calcsize(funcblocksize, n->ncmd.args);
                funcblocksize = calcsize(funcblocksize, n->ncmd.assign);
                break;
        case NPIPE:
                funcblocksize = sizenodelist(funcblocksize, n->npipe.cmdlist);
                break;
        case NREDIR:
        case NBACKGND:
        case NSUBSHELL:
                funcblocksize = calcsize(funcblocksize, n->nredir.redirect);
                funcblocksize = calcsize(funcblocksize, n->nredir.n);
                break;
        case NAND:
        case NOR:
        case NSEMI:
        case NWHILE:
        case NUNTIL:
                funcblocksize = calcsize(funcblocksize, n->nbinary.ch2);
                funcblocksize = calcsize(funcblocksize, n->nbinary.ch1);
                break;
        case NIF:
                funcblocksize = calcsize(funcblocksize, n->nif.elsepart);
                funcblocksize = calcsize(funcblocksize, n->nif.ifpart);
                funcblocksize = calcsize(funcblocksize, n->nif.test);
                break;
        case NFOR:
                funcblocksize += SHELL_ALIGN(strlen(n->nfor.var) + 1); /* was funcstringsize += ... */
                funcblocksize = calcsize(funcblocksize, n->nfor.body);
                funcblocksize = calcsize(funcblocksize, n->nfor.args);
                break;
        case NCASE:
                funcblocksize = calcsize(funcblocksize, n->ncase.cases);
                funcblocksize = calcsize(funcblocksize, n->ncase.expr);
                break;
        case NCLIST:
                funcblocksize = calcsize(funcblocksize, n->nclist.body);
                funcblocksize = calcsize(funcblocksize, n->nclist.pattern);
                funcblocksize = calcsize(funcblocksize, n->nclist.next);
                break;
        case NDEFUN:
        case NARG:
                funcblocksize = sizenodelist(funcblocksize, n->narg.backquote);
                funcblocksize += SHELL_ALIGN(strlen(n->narg.text) + 1); /* was funcstringsize += ... */
                funcblocksize = calcsize(funcblocksize, n->narg.next);
                break;
        case NTO:
#if ENABLE_ASH_BASH_COMPAT
        case NTO2:
#endif
        case NCLOBBER:
        case NFROM:
        case NFROMTO:
        case NAPPEND:
                funcblocksize = calcsize(funcblocksize, n->nfile.fname);
                funcblocksize = calcsize(funcblocksize, n->nfile.next);
                break;
        case NTOFD:
        case NFROMFD:
                funcblocksize = calcsize(funcblocksize, n->ndup.vname);
                funcblocksize = calcsize(funcblocksize, n->ndup.next);
        break;
        case NHERE:
        case NXHERE:
                funcblocksize = calcsize(funcblocksize, n->nhere.doc);
                funcblocksize = calcsize(funcblocksize, n->nhere.next);
                break;
        case NNOT:
                funcblocksize = calcsize(funcblocksize, n->nnot.com);
                break;
        };
        return funcblocksize;
}

static char *
nodeckstrdup(char *s)
{
        funcstring_end -= SHELL_ALIGN(strlen(s) + 1);
        return strcpy(funcstring_end, s);
}

static union node *copynode(union node *);

static struct nodelist *
copynodelist(struct nodelist *lp)
{
        struct nodelist *start;
        struct nodelist **lpp;

        lpp = &start;
        while (lp) {
                *lpp = funcblock;
                funcblock = (char *) funcblock + SHELL_ALIGN(sizeof(struct nodelist));
                (*lpp)->n = copynode(lp->n);
                lp = lp->next;
                lpp = &(*lpp)->next;
        }
        *lpp = NULL;
        return start;
}

static union node *
copynode(union node *n)
{
        union node *new;

        if (n == NULL)
                return NULL;
        new = funcblock;
        funcblock = (char *) funcblock + nodesize[n->type];

        switch (n->type) {
        case NCMD:
                new->ncmd.redirect = copynode(n->ncmd.redirect);
                new->ncmd.args = copynode(n->ncmd.args);
                new->ncmd.assign = copynode(n->ncmd.assign);
                break;
        case NPIPE:
                new->npipe.cmdlist = copynodelist(n->npipe.cmdlist);
                new->npipe.pipe_backgnd = n->npipe.pipe_backgnd;
                break;
        case NREDIR:
        case NBACKGND:
        case NSUBSHELL:
                new->nredir.redirect = copynode(n->nredir.redirect);
                new->nredir.n = copynode(n->nredir.n);
                break;
        case NAND:
        case NOR:
        case NSEMI:
        case NWHILE:
        case NUNTIL:
                new->nbinary.ch2 = copynode(n->nbinary.ch2);
                new->nbinary.ch1 = copynode(n->nbinary.ch1);
                break;
        case NIF:
                new->nif.elsepart = copynode(n->nif.elsepart);
                new->nif.ifpart = copynode(n->nif.ifpart);
                new->nif.test = copynode(n->nif.test);
                break;
        case NFOR:
                new->nfor.var = nodeckstrdup(n->nfor.var);
                new->nfor.body = copynode(n->nfor.body);
                new->nfor.args = copynode(n->nfor.args);
                break;
        case NCASE:
                new->ncase.cases = copynode(n->ncase.cases);
                new->ncase.expr = copynode(n->ncase.expr);
                break;
        case NCLIST:
                new->nclist.body = copynode(n->nclist.body);
                new->nclist.pattern = copynode(n->nclist.pattern);
                new->nclist.next = copynode(n->nclist.next);
                break;
        case NDEFUN:
        case NARG:
                new->narg.backquote = copynodelist(n->narg.backquote);
                new->narg.text = nodeckstrdup(n->narg.text);
                new->narg.next = copynode(n->narg.next);
                break;
        case NTO:
#if ENABLE_ASH_BASH_COMPAT
        case NTO2:
#endif
        case NCLOBBER:
        case NFROM:
        case NFROMTO:
        case NAPPEND:
                new->nfile.fname = copynode(n->nfile.fname);
                new->nfile.fd = n->nfile.fd;
                new->nfile.next = copynode(n->nfile.next);
                break;
        case NTOFD:
        case NFROMFD:
                new->ndup.vname = copynode(n->ndup.vname);
                new->ndup.dupfd = n->ndup.dupfd;
                new->ndup.fd = n->ndup.fd;
                new->ndup.next = copynode(n->ndup.next);
                break;
        case NHERE:
        case NXHERE:
                new->nhere.doc = copynode(n->nhere.doc);
                new->nhere.fd = n->nhere.fd;
                new->nhere.next = copynode(n->nhere.next);
                break;
        case NNOT:
                new->nnot.com = copynode(n->nnot.com);
                break;
        };
        new->type = n->type;
        return new;
}

/*
 * Make a copy of a parse tree.
 */
static struct funcnode *
copyfunc(union node *n)
{
        struct funcnode *f;
        size_t blocksize;

        /*funcstringsize = 0;*/
        blocksize = offsetof(struct funcnode, n) + calcsize(0, n);
        f = ckzalloc(blocksize /* + funcstringsize */);
        funcblock = (char *) f + offsetof(struct funcnode, n);
        funcstring_end = (char *) f + blocksize;
        copynode(n);
        /* f->count = 0; - ckzalloc did it */
        return f;
}

/*
 * Define a shell function.
 */
static void
defun(union node *func)
{
        struct cmdentry entry;

        INT_OFF;
        entry.cmdtype = CMDFUNCTION;
        entry.u.func = copyfunc(func);
        addcmdentry(func->narg.text, &entry);
        INT_ON;
}

/* Reasons for skipping commands (see comment on breakcmd routine) */
#define SKIPBREAK      (1 << 0)
#define SKIPCONT       (1 << 1)
#define SKIPFUNC       (1 << 2)
static smallint evalskip;       /* set to SKIPxxx if we are skipping commands */
static int skipcount;           /* number of levels to skip */
static int funcnest;            /* depth of function calls */
static int loopnest;            /* current loop nesting level */

/* Forward decl way out to parsing code - dotrap needs it */
static int evalstring(char *s, int flags);

/* Called to execute a trap.
 * Single callsite - at the end of evaltree().
 * If we return non-zero, evaltree raises EXEXIT exception.
 *
 * Perhaps we should avoid entering new trap handlers
 * while we are executing a trap handler. [is it a TODO?]
 */
static void
dotrap(void)
{
        uint8_t *g;
        int sig;
        uint8_t last_status;

        if (!pending_sig)
                return;

        last_status = exitstatus;
        pending_sig = 0;
        barrier();

        TRACE(("dotrap entered\n"));
        for (sig = 1, g = gotsig; sig < NSIG; sig++, g++) {
                char *p;

                if (!*g)
                        continue;

                if (evalskip) {
                        pending_sig = sig;
                        break;
                }

                p = trap[sig];
                /* non-trapped SIGINT is handled separately by raise_interrupt,
                 * don't upset it by resetting gotsig[SIGINT-1] */
                if (sig == SIGINT && !p)
                        continue;

                TRACE(("sig %d is active, will run handler '%s'\n", sig, p));
                *g = 0;
                if (!p)
                        continue;
                evalstring(p, 0);
        }
        exitstatus = last_status;
        TRACE(("dotrap returns\n"));
}

/* forward declarations - evaluation is fairly recursive business... */
static int evalloop(union node *, int);
static int evalfor(union node *, int);
static int evalcase(union node *, int);
static int evalsubshell(union node *, int);
static void expredir(union node *);
static int evalpipe(union node *, int);
static int evalcommand(union node *, int);
static int evalbltin(const struct builtincmd *, int, char **, int);
static void prehash(union node *);

/*
 * Evaluate a parse tree.  The value is left in the global variable
 * exitstatus.
 */
static int
evaltree(union node *n, int flags)
{
        int checkexit = 0;
        int (*evalfn)(union node *, int);
        int status = 0;

        if (n == NULL) {
                TRACE(("evaltree(NULL) called\n"));
                goto out;
        }
        TRACE(("evaltree(%p: %d, %d) called\n", n, n->type, flags));

        dotrap();

        switch (n->type) {
        default:
#if DEBUG
                out1fmt("Node type = %d\n", n->type);
                fflush_all();
                break;
#endif
        case NNOT:
                status = !evaltree(n->nnot.com, EV_TESTED);
                goto setstatus;
        case NREDIR:
                expredir(n->nredir.redirect);
                status = redirectsafe(n->nredir.redirect, REDIR_PUSH);
                if (!status) {
                        status = evaltree(n->nredir.n, flags & EV_TESTED);
                }
                if (n->nredir.redirect)
                        popredir(/*drop:*/ 0, /*restore:*/ 0 /* not sure */);
                goto setstatus;
        case NCMD:
                evalfn = evalcommand;
 checkexit:
                if (eflag && !(flags & EV_TESTED))
                        checkexit = ~0;
                goto calleval;
        case NFOR:
                evalfn = evalfor;
                goto calleval;
        case NWHILE:
        case NUNTIL:
                evalfn = evalloop;
                goto calleval;
        case NSUBSHELL:
        case NBACKGND:
                evalfn = evalsubshell;
                goto checkexit;
        case NPIPE:
                evalfn = evalpipe;
                goto checkexit;
        case NCASE:
                evalfn = evalcase;
                goto calleval;
        case NAND:
        case NOR:
        case NSEMI: {

#if NAND + 1 != NOR
#error NAND + 1 != NOR
#endif
#if NOR + 1 != NSEMI
#error NOR + 1 != NSEMI
#endif
                unsigned is_or = n->type - NAND;
                status = evaltree(
                        n->nbinary.ch1,
                        (flags | ((is_or >> 1) - 1)) & EV_TESTED
                );
                if ((!status) == is_or || evalskip)
                        break;
                n = n->nbinary.ch2;
 evaln:
                evalfn = evaltree;
 calleval:
                status = evalfn(n, flags);
                goto setstatus;
        }
        case NIF:
                status = evaltree(n->nif.test, EV_TESTED);
                if (evalskip)
                        break;
                if (!status) {
                        n = n->nif.ifpart;
                        goto evaln;
                }
                if (n->nif.elsepart) {
                        n = n->nif.elsepart;
                        goto evaln;
                }
                status = 0;
                goto setstatus;
        case NDEFUN:
                defun(n);
                /* Not necessary. To test it:
                 * "false; f() { qwerty; }; echo $?" should print 0.
                 */
                /* status = 0; */
 setstatus:
                exitstatus = status;
                break;
        }
 out:
        /* Order of checks below is important:
         * signal handlers trigger before exit caused by "set -e".
         */
        dotrap();

        if (checkexit & status)
                raise_exception(EXEXIT);
        if (flags & EV_EXIT)
                raise_exception(EXEXIT);

        TRACE(("leaving evaltree (no interrupts)\n"));
        return exitstatus;
}

#if !defined(__alpha__) || (defined(__GNUC__) && __GNUC__ >= 3)
static
#endif
int evaltreenr(union node *, int) __attribute__ ((alias("evaltree"),__noreturn__));

static int
skiploop(void)
{
        int skip = evalskip;

        switch (skip) {
        case 0:
                break;
        case SKIPBREAK:
        case SKIPCONT:
                if (--skipcount <= 0) {
                        evalskip = 0;
                        break;
                }
                skip = SKIPBREAK;
                break;
        }
        return skip;
}

static int
evalloop(union node *n, int flags)
{
        int skip;
        int status;

        loopnest++;
        status = 0;
        flags &= EV_TESTED;
        do {
                int i;

                i = evaltree(n->nbinary.ch1, EV_TESTED);
                skip = skiploop();
                if (skip == SKIPFUNC)
                        status = i;
                if (skip)
                        continue;
                if (n->type != NWHILE)
                        i = !i;
                if (i != 0)
                        break;
                status = evaltree(n->nbinary.ch2, flags);
                skip = skiploop();
        } while (!(skip & ~SKIPCONT));
        loopnest--;

        return status;
}

static int
evalfor(union node *n, int flags)
{
        struct arglist arglist;
        union node *argp;
        struct strlist *sp;
        struct stackmark smark;
        int status = 0;

        setstackmark(&smark);
        arglist.list = NULL;
        arglist.lastp = &arglist.list;
        for (argp = n->nfor.args; argp; argp = argp->narg.next) {
                expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
        }
        *arglist.lastp = NULL;

        loopnest++;
        flags &= EV_TESTED;
        for (sp = arglist.list; sp; sp = sp->next) {
                setvar0(n->nfor.var, sp->text);
                status = evaltree(n->nfor.body, flags);
                if (skiploop() & ~SKIPCONT)
                        break;
        }
        loopnest--;
        popstackmark(&smark);

        return status;
}

static int
evalcase(union node *n, int flags)
{
        union node *cp;
        union node *patp;
        struct arglist arglist;
        struct stackmark smark;
        int status = 0;

        setstackmark(&smark);
        arglist.list = NULL;
        arglist.lastp = &arglist.list;
        expandarg(n->ncase.expr, &arglist, EXP_TILDE);
        for (cp = n->ncase.cases; cp && evalskip == 0; cp = cp->nclist.next) {
                for (patp = cp->nclist.pattern; patp; patp = patp->narg.next) {
                        if (casematch(patp, arglist.list->text)) {
                                /* Ensure body is non-empty as otherwise
                                 * EV_EXIT may prevent us from setting the
                                 * exit status.
                                 */
                                if (evalskip == 0 && cp->nclist.body) {
                                        status = evaltree(cp->nclist.body, flags);
                                }
                                goto out;
                        }
                }
        }
 out:
        popstackmark(&smark);

        return status;
}

/*
 * Kick off a subshell to evaluate a tree.
 */
static int
evalsubshell(union node *n, int flags)
{
        struct job *jp;
        int backgnd = (n->type == NBACKGND);
        int status;

        expredir(n->nredir.redirect);
        if (!backgnd && (flags & EV_EXIT) && !may_have_traps)
                goto nofork;
        INT_OFF;
        jp = makejob(/*n,*/ 1);
        if (forkshell(jp, n, backgnd) == 0) {
                /* child */
                INT_ON;
                flags |= EV_EXIT;
                if (backgnd)
                        flags &= ~EV_TESTED;
 nofork:
                redirect(n->nredir.redirect, 0);
                evaltreenr(n->nredir.n, flags);
                /* never returns */
        }
        /* parent */
        status = 0;
        if (!backgnd)
                status = waitforjob(jp);
        INT_ON;
        return status;
}

/*
 * Compute the names of the files in a redirection list.
 */
static void fixredir(union node *, const char *, int);
static void
expredir(union node *n)
{
        union node *redir;

        for (redir = n; redir; redir = redir->nfile.next) {
                struct arglist fn;

                fn.list = NULL;
                fn.lastp = &fn.list;
                switch (redir->type) {
                case NFROMTO:
                case NFROM:
                case NTO:
#if ENABLE_ASH_BASH_COMPAT
                case NTO2:
#endif
                case NCLOBBER:
                case NAPPEND:
                        expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
                        TRACE(("expredir expanded to '%s'\n", fn.list->text));
#if ENABLE_ASH_BASH_COMPAT
 store_expfname:
#endif
#if 0
// By the design of stack allocator, the loop of this kind:
//      while true; do while true; do break; done </dev/null; done
// will look like a memory leak: ash plans to free expfname's
// of "/dev/null" as soon as it finishes running the loop
// (in this case, never).
// This "fix" is wrong:
                        if (redir->nfile.expfname)
                                stunalloc(redir->nfile.expfname);
// It results in corrupted state of stacked allocations.
#endif
                        redir->nfile.expfname = fn.list->text;
                        break;
                case NFROMFD:
                case NTOFD: /* >& */
                        if (redir->ndup.vname) {
                                expandarg(redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
                                if (fn.list == NULL)
                                        ash_msg_and_raise_error("redir error");
#if ENABLE_ASH_BASH_COMPAT
//FIXME: we used expandarg with different args!
                                if (!isdigit_str9(fn.list->text)) {
                                        /* >&file, not >&fd */
                                        if (redir->nfile.fd != 1) /* 123>&file - BAD */
                                                ash_msg_and_raise_error("redir error");
                                        redir->type = NTO2;
                                        goto store_expfname;
                                }
#endif
                                fixredir(redir, fn.list->text, 1);
                        }
                        break;
                }
        }
}

/*
 * Evaluate a pipeline.  All the processes in the pipeline are children
 * of the process creating the pipeline.  (This differs from some versions
 * of the shell, which make the last process in a pipeline the parent
 * of all the rest.)
 */
static int
evalpipe(union node *n, int flags)
{
        struct job *jp;
        struct nodelist *lp;
        int pipelen;
        int prevfd;
        int pip[2];
        int status = 0;

        TRACE(("evalpipe(0x%lx) called\n", (long)n));
        pipelen = 0;
        for (lp = n->npipe.cmdlist; lp; lp = lp->next)
                pipelen++;
        flags |= EV_EXIT;
        INT_OFF;
        jp = makejob(/*n,*/ pipelen);
        prevfd = -1;
        for (lp = n->npipe.cmdlist; lp; lp = lp->next) {
                prehash(lp->n);
                pip[1] = -1;
                if (lp->next) {
                        if (pipe(pip) < 0) {
                                close(prevfd);
                                ash_msg_and_raise_error("pipe call failed");
                        }
                }
                if (forkshell(jp, lp->n, n->npipe.pipe_backgnd) == 0) {
                        /* child */
                        INT_ON;
                        if (pip[1] >= 0) {
                                close(pip[0]);
                        }
                        if (prevfd > 0) {
                                dup2(prevfd, 0);
                                close(prevfd);
                        }
                        if (pip[1] > 1) {
                                dup2(pip[1], 1);
                                close(pip[1]);
                        }
                        evaltreenr(lp->n, flags);
                        /* never returns */
                }
                /* parent */
                if (prevfd >= 0)
                        close(prevfd);
                prevfd = pip[0];
                /* Don't want to trigger debugging */
                if (pip[1] != -1)
                        close(pip[1]);
        }
        if (n->npipe.pipe_backgnd == 0) {
                status = waitforjob(jp);
                TRACE(("evalpipe:  job done exit status %d\n", status));
        }
        INT_ON;

        return status;
}

/*
 * Controls whether the shell is interactive or not.
 */
static void
setinteractive(int on)
{
        static smallint is_interactive;

        if (++on == is_interactive)
                return;
        is_interactive = on;
        setsignal(SIGINT);
        setsignal(SIGQUIT);
        setsignal(SIGTERM);
#if !ENABLE_FEATURE_SH_EXTRA_QUIET
        if (is_interactive > 1) {
                /* Looks like they want an interactive shell */
                static smallint did_banner;

                if (!did_banner) {
                        /* note: ash and hush share this string */
                        out1fmt("\n\n%s %s\n"
                                IF_ASH_HELP("Enter 'help' for a list of built-in commands.\n")
                                "\n",
                                bb_banner,
                                "built-in shell (ash)"
                        );
                        did_banner = 1;
                }
        }
#endif
}

static void
optschanged(void)
{
#if DEBUG
        opentrace();
#endif
        setinteractive(iflag);
        setjobctl(mflag);
#if ENABLE_FEATURE_EDITING_VI
        if (viflag)
                line_input_state->flags |= VI_MODE;
        else
                line_input_state->flags &= ~VI_MODE;
#else
        viflag = 0; /* forcibly keep the option off */
#endif
}

static struct localvar *localvars;

/*
 * Called after a function returns.
 * Interrupts must be off.
 */
static void
poplocalvars(void)
{
        struct localvar *lvp;
        struct var *vp;

        while ((lvp = localvars) != NULL) {
                localvars = lvp->next;
                vp = lvp->vp;
                TRACE(("poplocalvar %s\n", vp ? vp->var_text : "-"));
                if (vp == NULL) {       /* $- saved */
                        memcpy(optlist, lvp->text, sizeof(optlist));
                        free((char*)lvp->text);
                        optschanged();
                } else if ((lvp->flags & (VUNSET|VSTRFIXED)) == VUNSET) {
                        unsetvar(vp->var_text);
                } else {
                        if (vp->var_func)
                                vp->var_func(var_end(lvp->text));
                        if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
                                free((char*)vp->var_text);
                        vp->flags = lvp->flags;
                        vp->var_text = lvp->text;
                }
                free(lvp);
        }
}

static int
evalfun(struct funcnode *func, int argc, char **argv, int flags)
{
        volatile struct shparam saveparam;
        struct localvar *volatile savelocalvars;
        struct jmploc *volatile savehandler;
        struct jmploc jmploc;
        int e;

        saveparam = shellparam;
        savelocalvars = localvars;
        savehandler = exception_handler;
        e = setjmp(jmploc.loc);
        if (e) {
                goto funcdone;
        }
        INT_OFF;
        exception_handler = &jmploc;
        localvars = NULL;
        shellparam.malloced = 0;
        func->count++;
        funcnest++;
        INT_ON;
        shellparam.nparam = argc - 1;
        shellparam.p = argv + 1;
#if ENABLE_ASH_GETOPTS
        shellparam.optind = 1;
        shellparam.optoff = -1;
#endif
        evaltree(func->n.narg.next, flags & EV_TESTED);
 funcdone:
        INT_OFF;
        funcnest--;
        freefunc(func);
        poplocalvars();
        localvars = savelocalvars;
        freeparam(&shellparam);
        shellparam = saveparam;
        exception_handler = savehandler;
        INT_ON;
        evalskip &= ~SKIPFUNC;
        return e;
}

/*
 * Make a variable a local variable.  When a variable is made local, it's
 * value and flags are saved in a localvar structure.  The saved values
 * will be restored when the shell function returns.  We handle the name
 * "-" as a special case: it makes changes to "set +-options" local
 * (options will be restored on return from the function).
 */
static void
mklocal(char *name)
{
        struct localvar *lvp;
        struct var **vpp;
        struct var *vp;
        char *eq = strchr(name, '=');

        INT_OFF;
        /* Cater for duplicate "local". Examples:
         * x=0; f() { local x=1; echo $x; local x; echo $x; }; f; echo $x
         * x=0; f() { local x=1; echo $x; local x=2; echo $x; }; f; echo $x
         */
        lvp = localvars;
        while (lvp) {
                if (lvp->vp && varcmp(lvp->vp->var_text, name) == 0) {
                        if (eq)
                                setvareq(name, 0);
                        /* else:
                         * it's a duplicate "local VAR" declaration, do nothing
                         */
                        goto ret;
                }
                lvp = lvp->next;
        }

        lvp = ckzalloc(sizeof(*lvp));
        if (LONE_DASH(name)) {
                char *p;
                p = ckmalloc(sizeof(optlist));
                lvp->text = memcpy(p, optlist, sizeof(optlist));
                vp = NULL;
        } else {
                vpp = hashvar(name);
                vp = *findvar(vpp, name);
                if (vp == NULL) {
                        /* variable did not exist yet */
                        if (eq)
                                setvareq(name, VSTRFIXED);
                        else
                                setvar(name, NULL, VSTRFIXED);
                        vp = *vpp;      /* the new variable */
                        lvp->flags = VUNSET;
                } else {
                        lvp->text = vp->var_text;
                        lvp->flags = vp->flags;
                        /* make sure neither "struct var" nor string gets freed
                         * during (un)setting:
                         */
                        vp->flags |= VSTRFIXED|VTEXTFIXED;
                        if (eq)
                                setvareq(name, 0);
                        else
                                /* "local VAR" unsets VAR: */
                                setvar0(name, NULL);
                }
        }
        lvp->vp = vp;
        lvp->next = localvars;
        localvars = lvp;
 ret:
        INT_ON;
}

/*
 * The "local" command.
 */
static int FAST_FUNC
localcmd(int argc UNUSED_PARAM, char **argv)
{
        char *name;

        if (!funcnest)
                ash_msg_and_raise_error("not in a function");

        argv = argptr;
        while ((name = *argv++) != NULL) {
                mklocal(name);
        }
        return 0;
}

static int FAST_FUNC
falsecmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        return 1;
}

static int FAST_FUNC
truecmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        return 0;
}

static int FAST_FUNC
execcmd(int argc UNUSED_PARAM, char **argv)
{
        if (argv[1]) {
                iflag = 0;              /* exit on error */
                mflag = 0;
                optschanged();
                /* We should set up signals for "exec CMD"
                 * the same way as for "CMD" without "exec".
                 * But optschanged->setinteractive->setsignal
                 * still thought we are a root shell. Therefore, for example,
                 * SIGQUIT is still set to IGN. Fix it:
                 */
                shlvl++;
                setsignal(SIGQUIT);
                /*setsignal(SIGTERM); - unnecessary because of iflag=0 */
                /*setsignal(SIGTSTP); - unnecessary because of mflag=0 */
                /*setsignal(SIGTTOU); - unnecessary because of mflag=0 */

                shellexec(argv + 1, pathval(), 0);
                /* NOTREACHED */
        }
        return 0;
}

/*
 * The return command.
 */
static int FAST_FUNC
returncmd(int argc UNUSED_PARAM, char **argv)
{
        /*
         * If called outside a function, do what ksh does;
         * skip the rest of the file.
         */
        evalskip = SKIPFUNC;
        return argv[1] ? number(argv[1]) : exitstatus;
}

/* Forward declarations for builtintab[] */
static int breakcmd(int, char **) FAST_FUNC;
static int dotcmd(int, char **) FAST_FUNC;
static int evalcmd(int, char **, int) FAST_FUNC;
static int exitcmd(int, char **) FAST_FUNC;
static int exportcmd(int, char **) FAST_FUNC;
#if ENABLE_ASH_GETOPTS
static int getoptscmd(int, char **) FAST_FUNC;
#endif
#if ENABLE_ASH_HELP
static int helpcmd(int, char **) FAST_FUNC;
#endif
#if MAX_HISTORY
static int historycmd(int, char **) FAST_FUNC;
#endif
#if ENABLE_SH_MATH_SUPPORT
static int letcmd(int, char **) FAST_FUNC;
#endif
static int readcmd(int, char **) FAST_FUNC;
static int setcmd(int, char **) FAST_FUNC;
static int shiftcmd(int, char **) FAST_FUNC;
static int timescmd(int, char **) FAST_FUNC;
static int trapcmd(int, char **) FAST_FUNC;
static int umaskcmd(int, char **) FAST_FUNC;
static int unsetcmd(int, char **) FAST_FUNC;
static int ulimitcmd(int, char **) FAST_FUNC;

#define BUILTIN_NOSPEC          "0"
#define BUILTIN_SPECIAL         "1"
#define BUILTIN_REGULAR         "2"
#define BUILTIN_SPEC_REG        "3"
#define BUILTIN_ASSIGN          "4"
#define BUILTIN_SPEC_ASSG       "5"
#define BUILTIN_REG_ASSG        "6"
#define BUILTIN_SPEC_REG_ASSG   "7"

/* Stubs for calling non-FAST_FUNC's */
#if ENABLE_ASH_BUILTIN_ECHO
static int FAST_FUNC echocmd(int argc, char **argv)   { return echo_main(argc, argv); }
#endif
#if ENABLE_ASH_BUILTIN_PRINTF
static int FAST_FUNC printfcmd(int argc, char **argv) { return printf_main(argc, argv); }
#endif
#if ENABLE_ASH_BUILTIN_TEST
static int FAST_FUNC testcmd(int argc, char **argv)   { return test_main(argc, argv); }
#endif

/* Keep these in proper order since it is searched via bsearch() */
static const struct builtincmd builtintab[] = {
        { BUILTIN_SPEC_REG      "."       , dotcmd     },
        { BUILTIN_SPEC_REG      ":"       , truecmd    },
#if ENABLE_ASH_BUILTIN_TEST
        { BUILTIN_REGULAR       "["       , testcmd    },
#if ENABLE_ASH_BASH_COMPAT
        { BUILTIN_REGULAR       "[["      , testcmd    },
#endif
#endif
#if ENABLE_ASH_ALIAS
        { BUILTIN_REG_ASSG      "alias"   , aliascmd   },
#endif
#if JOBS
        { BUILTIN_REGULAR       "bg"      , fg_bgcmd   },
#endif
        { BUILTIN_SPEC_REG      "break"   , breakcmd   },
        { BUILTIN_REGULAR       "cd"      , cdcmd      },
        { BUILTIN_NOSPEC        "chdir"   , cdcmd      },
#if ENABLE_ASH_CMDCMD
        { BUILTIN_REGULAR       "command" , commandcmd },
#endif
        { BUILTIN_SPEC_REG      "continue", breakcmd   },
#if ENABLE_ASH_BUILTIN_ECHO
        { BUILTIN_REGULAR       "echo"    , echocmd    },
#endif
        { BUILTIN_SPEC_REG      "eval"    , NULL       }, /*evalcmd() has a differing prototype*/
        { BUILTIN_SPEC_REG      "exec"    , execcmd    },
        { BUILTIN_SPEC_REG      "exit"    , exitcmd    },
        { BUILTIN_SPEC_REG_ASSG "export"  , exportcmd  },
        { BUILTIN_REGULAR       "false"   , falsecmd   },
#if JOBS
        { BUILTIN_REGULAR       "fg"      , fg_bgcmd   },
#endif
#if ENABLE_ASH_GETOPTS
        { BUILTIN_REGULAR       "getopts" , getoptscmd },
#endif
        { BUILTIN_NOSPEC        "hash"    , hashcmd    },
#if ENABLE_ASH_HELP
        { BUILTIN_NOSPEC        "help"    , helpcmd    },
#endif
#if MAX_HISTORY
        { BUILTIN_NOSPEC        "history" , historycmd },
#endif
#if JOBS
        { BUILTIN_REGULAR       "jobs"    , jobscmd    },
        { BUILTIN_REGULAR       "kill"    , killcmd    },
#endif
#if ENABLE_SH_MATH_SUPPORT
        { BUILTIN_NOSPEC        "let"     , letcmd     },
#endif
        { BUILTIN_ASSIGN        "local"   , localcmd   },
#if ENABLE_ASH_BUILTIN_PRINTF
        { BUILTIN_REGULAR       "printf"  , printfcmd  },
#endif
        { BUILTIN_NOSPEC        "pwd"     , pwdcmd     },
        { BUILTIN_REGULAR       "read"    , readcmd    },
        { BUILTIN_SPEC_REG_ASSG "readonly", exportcmd  },
        { BUILTIN_SPEC_REG      "return"  , returncmd  },
        { BUILTIN_SPEC_REG      "set"     , setcmd     },
        { BUILTIN_SPEC_REG      "shift"   , shiftcmd   },
#if ENABLE_ASH_BASH_COMPAT
        { BUILTIN_SPEC_REG      "source"  , dotcmd     },
#endif
#if ENABLE_ASH_BUILTIN_TEST
        { BUILTIN_REGULAR       "test"    , testcmd    },
#endif
        { BUILTIN_SPEC_REG      "times"   , timescmd   },
        { BUILTIN_SPEC_REG      "trap"    , trapcmd    },
        { BUILTIN_REGULAR       "true"    , truecmd    },
        { BUILTIN_NOSPEC        "type"    , typecmd    },
        { BUILTIN_NOSPEC        "ulimit"  , ulimitcmd  },
        { BUILTIN_REGULAR       "umask"   , umaskcmd   },
#if ENABLE_ASH_ALIAS
        { BUILTIN_REGULAR       "unalias" , unaliascmd },
#endif
        { BUILTIN_SPEC_REG      "unset"   , unsetcmd   },
        { BUILTIN_REGULAR       "wait"    , waitcmd    },
};

/* Should match the above table! */
#define COMMANDCMD (builtintab + \
        /* . : */       2 + \
        /* [ */         1 * ENABLE_ASH_BUILTIN_TEST + \
        /* [[ */        1 * ENABLE_ASH_BUILTIN_TEST * ENABLE_ASH_BASH_COMPAT + \
        /* alias */     1 * ENABLE_ASH_ALIAS + \
        /* bg */        1 * ENABLE_ASH_JOB_CONTROL + \
        /* break cd cddir  */   3)
#define EVALCMD (COMMANDCMD + \
        /* command */   1 * ENABLE_ASH_CMDCMD + \
        /* continue */  1 + \
        /* echo */      1 * ENABLE_ASH_BUILTIN_ECHO + \
        0)
#define EXECCMD (EVALCMD + \
        /* eval */      1)

/*
 * Search the table of builtin commands.
 */
static int
pstrcmp1(const void *a, const void *b)
{
        return strcmp((char*)a, *(char**)b + 1);
}
static struct builtincmd *
find_builtin(const char *name)
{
        struct builtincmd *bp;

        bp = bsearch(
                name, builtintab, ARRAY_SIZE(builtintab), sizeof(builtintab[0]),
                pstrcmp1
        );
        return bp;
}

/*
 * Execute a simple command.
 */
static int
isassignment(const char *p)
{
        const char *q = endofname(p);
        if (p == q)
                return 0;
        return *q == '=';
}
static int FAST_FUNC
bltincmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        /* Preserve exitstatus of a previous possible redirection
         * as POSIX mandates */
        return back_exitstatus;
}
static int
evalcommand(union node *cmd, int flags)
{
        static const struct builtincmd null_bltin = {
                "\0\0", bltincmd /* why three NULs? */
        };
        struct stackmark smark;
        union node *argp;
        struct arglist arglist;
        struct arglist varlist;
        char **argv;
        int argc;
        const struct strlist *sp;
        struct cmdentry cmdentry;
        struct job *jp;
        char *lastarg;
        const char *path;
        int spclbltin;
        int status;
        char **nargv;
        struct builtincmd *bcmd;
        smallint cmd_is_exec;
        smallint pseudovarflag = 0;

        /* First expand the arguments. */
        TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
        setstackmark(&smark);
        back_exitstatus = 0;

        cmdentry.cmdtype = CMDBUILTIN;
        cmdentry.u.cmd = &null_bltin;
        varlist.lastp = &varlist.list;
        *varlist.lastp = NULL;
        arglist.lastp = &arglist.list;
        *arglist.lastp = NULL;

        argc = 0;
        if (cmd->ncmd.args) {
                bcmd = find_builtin(cmd->ncmd.args->narg.text);
                pseudovarflag = bcmd && IS_BUILTIN_ASSIGN(bcmd);
        }

        for (argp = cmd->ncmd.args; argp; argp = argp->narg.next) {
                struct strlist **spp;

                spp = arglist.lastp;
                if (pseudovarflag && isassignment(argp->narg.text))
                        expandarg(argp, &arglist, EXP_VARTILDE);
                else
                        expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);

                for (sp = *spp; sp; sp = sp->next)
                        argc++;
        }

        /* Reserve one extra spot at the front for shellexec. */
        nargv = stalloc(sizeof(char *) * (argc + 2));
        argv = ++nargv;
        for (sp = arglist.list; sp; sp = sp->next) {
                TRACE(("evalcommand arg: %s\n", sp->text));
                *nargv++ = sp->text;
        }
        *nargv = NULL;

        lastarg = NULL;
        if (iflag && funcnest == 0 && argc > 0)
                lastarg = nargv[-1];

        preverrout_fd = 2;
        expredir(cmd->ncmd.redirect);
        status = redirectsafe(cmd->ncmd.redirect, REDIR_PUSH | REDIR_SAVEFD2);

        path = vpath.var_text;
        for (argp = cmd->ncmd.assign; argp; argp = argp->narg.next) {
                struct strlist **spp;
                char *p;

                spp = varlist.lastp;
                expandarg(argp, &varlist, EXP_VARTILDE);

                /*
                 * Modify the command lookup path, if a PATH= assignment
                 * is present
                 */
                p = (*spp)->text;
                if (varcmp(p, path) == 0)
                        path = p;
        }

        /* Print the command if xflag is set. */
        if (xflag) {
                int n;
                const char *p = " %s" + 1;

                fdprintf(preverrout_fd, p, expandstr(ps4val()));
                sp = varlist.list;
                for (n = 0; n < 2; n++) {
                        while (sp) {
                                fdprintf(preverrout_fd, p, sp->text);
                                sp = sp->next;
                                p = " %s";
                        }
                        sp = arglist.list;
                }
                safe_write(preverrout_fd, "\n", 1);
        }

        cmd_is_exec = 0;
        spclbltin = -1;

        /* Now locate the command. */
        if (argc) {
                int cmd_flag = DO_ERR;
#if ENABLE_ASH_CMDCMD
                const char *oldpath = path + 5;
#endif
                path += 5;
                for (;;) {
                        find_command(argv[0], &cmdentry, cmd_flag, path);
                        if (cmdentry.cmdtype == CMDUNKNOWN) {
                                flush_stdout_stderr();
                                status = 127;
                                goto bail;
                        }

                        /* implement bltin and command here */
                        if (cmdentry.cmdtype != CMDBUILTIN)
                                break;
                        if (spclbltin < 0)
                                spclbltin = IS_BUILTIN_SPECIAL(cmdentry.u.cmd);
                        if (cmdentry.u.cmd == EXECCMD)
                                cmd_is_exec = 1;
#if ENABLE_ASH_CMDCMD
                        if (cmdentry.u.cmd == COMMANDCMD) {
                                path = oldpath;
                                nargv = parse_command_args(argv, &path);
                                if (!nargv)
                                        break;
                                /* It's "command [-p] PROG ARGS" (that is, no -Vv).
                                 * nargv => "PROG". path is updated if -p.
                                 */
                                argc -= nargv - argv;
                                argv = nargv;
                                cmd_flag |= DO_NOFUNC;
                        } else
#endif
                                break;
                }
        }

        if (status) {
                /* We have a redirection error. */
                if (spclbltin > 0)
                        raise_exception(EXERROR);
 bail:
                exitstatus = status;
                goto out;
        }

        /* Execute the command. */
        switch (cmdentry.cmdtype) {
        default: {

#if ENABLE_FEATURE_SH_NOFORK
/* (1) BUG: if variables are set, we need to fork, or save/restore them
 *     around run_nofork_applet() call.
 * (2) Should this check also be done in forkshell()?
 *     (perhaps it should, so that "VAR=VAL nofork" at least avoids exec...)
 */
                /* find_command() encodes applet_no as (-2 - applet_no) */
                int applet_no = (- cmdentry.u.index - 2);
                if (applet_no >= 0 && APPLET_IS_NOFORK(applet_no)) {
                        listsetvar(varlist.list, VEXPORT|VSTACK);
                        /* run <applet>_main() */
                        status = run_nofork_applet(applet_no, argv);
                        break;
                }
#endif
                /* Can we avoid forking off? For example, very last command
                 * in a script or a subshell does not need forking,
                 * we can just exec it.
                 */
                if (!(flags & EV_EXIT) || may_have_traps) {
                        /* No, forking off a child is necessary */
                        INT_OFF;
                        jp = makejob(/*cmd,*/ 1);
                        if (forkshell(jp, cmd, FORK_FG) != 0) {
                                /* parent */
                                status = waitforjob(jp);
                                INT_ON;
                                TRACE(("forked child exited with %d\n", status));
                                break;
                        }
                        /* child */
                        FORCE_INT_ON;
                        /* fall through to exec'ing external program */
                }
                listsetvar(varlist.list, VEXPORT|VSTACK);
                shellexec(argv, path, cmdentry.u.index);
                /* NOTREACHED */
        } /* default */
        case CMDBUILTIN:
                cmdenviron = varlist.list;
                if (cmdenviron) {
                        struct strlist *list = cmdenviron;
                        int i = VNOSET;
                        if (spclbltin > 0 || argc == 0) {
                                i = 0;
                                if (cmd_is_exec && argc > 1)
                                        i = VEXPORT;
                        }
                        listsetvar(list, i);
                }
                /* Tight loop with builtins only:
                 * "while kill -0 $child; do true; done"
                 * will never exit even if $child died, unless we do this
                 * to reap the zombie and make kill detect that it's gone: */
                dowait(DOWAIT_NONBLOCK, NULL);

                if (evalbltin(cmdentry.u.cmd, argc, argv, flags)) {
                        if (exception_type == EXERROR && spclbltin <= 0) {
                                FORCE_INT_ON;
                                goto readstatus;
                        }
 raise:
                        longjmp(exception_handler->loc, 1);
                }
                goto readstatus;

        case CMDFUNCTION:
                listsetvar(varlist.list, 0);
                /* See above for the rationale */
                dowait(DOWAIT_NONBLOCK, NULL);
                if (evalfun(cmdentry.u.func, argc, argv, flags))
                        goto raise;
 readstatus:
                status = exitstatus;
                break;
        } /* switch */

 out:
        if (cmd->ncmd.redirect)
                popredir(/*drop:*/ cmd_is_exec, /*restore:*/ cmd_is_exec);
        if (lastarg) {
                /* dsl: I think this is intended to be used to support
                 * '_' in 'vi' command mode during line editing...
                 * However I implemented that within libedit itself.
                 */
                setvar0("_", lastarg);
        }
        popstackmark(&smark);

        return status;
}

static int
evalbltin(const struct builtincmd *cmd, int argc, char **argv, int flags)
{
        char *volatile savecmdname;
        struct jmploc *volatile savehandler;
        struct jmploc jmploc;
        int status;
        int i;

        savecmdname = commandname;
        savehandler = exception_handler;
        i = setjmp(jmploc.loc);
        if (i)
                goto cmddone;
        exception_handler = &jmploc;
        commandname = argv[0];
        argptr = argv + 1;
        optptr = NULL;                  /* initialize nextopt */
        if (cmd == EVALCMD)
                status = evalcmd(argc, argv, flags);
        else
                status = (*cmd->builtin)(argc, argv);
        flush_stdout_stderr();
        status |= ferror(stdout);
        exitstatus = status;
 cmddone:
        clearerr(stdout);
        commandname = savecmdname;
        exception_handler = savehandler;

        return i;
}

static int
goodname(const char *p)
{
        return endofname(p)[0] == '\0';
}


/*
 * Search for a command.  This is called before we fork so that the
 * location of the command will be available in the parent as well as
 * the child.  The check for "goodname" is an overly conservative
 * check that the name will not be subject to expansion.
 */
static void
prehash(union node *n)
{
        struct cmdentry entry;

        if (n->type == NCMD && n->ncmd.args && goodname(n->ncmd.args->narg.text))
                find_command(n->ncmd.args->narg.text, &entry, 0, pathval());
}


/* ============ Builtin commands
 *
 * Builtin commands whose functions are closely tied to evaluation
 * are implemented here.
 */

/*
 * Handle break and continue commands.  Break, continue, and return are
 * all handled by setting the evalskip flag.  The evaluation routines
 * above all check this flag, and if it is set they start skipping
 * commands rather than executing them.  The variable skipcount is
 * the number of loops to break/continue, or the number of function
 * levels to return.  (The latter is always 1.)  It should probably
 * be an error to break out of more loops than exist, but it isn't
 * in the standard shell so we don't make it one here.
 */
static int FAST_FUNC
breakcmd(int argc UNUSED_PARAM, char **argv)
{
        int n = argv[1] ? number(argv[1]) : 1;

        if (n <= 0)
                ash_msg_and_raise_error(msg_illnum, argv[1]);
        if (n > loopnest)
                n = loopnest;
        if (n > 0) {
                evalskip = (**argv == 'c') ? SKIPCONT : SKIPBREAK;
                skipcount = n;
        }
        return 0;
}


/*
 * This implements the input routines used by the parser.
 */

enum {
        INPUT_PUSH_FILE = 1,
        INPUT_NOFILE_OK = 2,
};

static smallint checkkwd;
/* values of checkkwd variable */
#define CHKALIAS        0x1
#define CHKKWD          0x2
#define CHKNL           0x4

/*
 * Push a string back onto the input at this current parsefile level.
 * We handle aliases this way.
 */
#if !ENABLE_ASH_ALIAS
#define pushstring(s, ap) pushstring(s)
#endif
static void
pushstring(char *s, struct alias *ap)
{
        struct strpush *sp;
        int len;

        len = strlen(s);
        INT_OFF;
        if (g_parsefile->strpush) {
                sp = ckzalloc(sizeof(*sp));
                sp->prev = g_parsefile->strpush;
        } else {
                sp = &(g_parsefile->basestrpush);
        }
        g_parsefile->strpush = sp;
        sp->prev_string = g_parsefile->next_to_pgetc;
        sp->prev_left_in_line = g_parsefile->left_in_line;
        sp->unget = g_parsefile->unget;
        memcpy(sp->lastc, g_parsefile->lastc, sizeof(sp->lastc));
#if ENABLE_ASH_ALIAS
        sp->ap = ap;
        if (ap) {
                ap->flag |= ALIASINUSE;
                sp->string = s;
        }
#endif
        g_parsefile->next_to_pgetc = s;
        g_parsefile->left_in_line = len;
        g_parsefile->unget = 0;
        INT_ON;
}

static void
popstring(void)
{
        struct strpush *sp = g_parsefile->strpush;

        INT_OFF;
#if ENABLE_ASH_ALIAS
        if (sp->ap) {
                if (g_parsefile->next_to_pgetc[-1] == ' '
                 || g_parsefile->next_to_pgetc[-1] == '\t'
                ) {
                        checkkwd |= CHKALIAS;
                }
                if (sp->string != sp->ap->val) {
                        free(sp->string);
                }
                sp->ap->flag &= ~ALIASINUSE;
                if (sp->ap->flag & ALIASDEAD) {
                        unalias(sp->ap->name);
                }
        }
#endif
        g_parsefile->next_to_pgetc = sp->prev_string;
        g_parsefile->left_in_line = sp->prev_left_in_line;
        g_parsefile->unget = sp->unget;
        memcpy(g_parsefile->lastc, sp->lastc, sizeof(sp->lastc));
        g_parsefile->strpush = sp->prev;
        if (sp != &(g_parsefile->basestrpush))
                free(sp);
        INT_ON;
}

static int
preadfd(void)
{
        int nr;
        char *buf = g_parsefile->buf;

        g_parsefile->next_to_pgetc = buf;
#if ENABLE_FEATURE_EDITING
 retry:
        if (!iflag || g_parsefile->pf_fd != STDIN_FILENO)
                nr = nonblock_immune_read(g_parsefile->pf_fd, buf, IBUFSIZ - 1);
        else {
                int timeout = -1;
# if ENABLE_ASH_IDLE_TIMEOUT
                if (iflag) {
                        const char *tmout_var = lookupvar("TMOUT");
                        if (tmout_var) {
                                timeout = atoi(tmout_var) * 1000;
                                if (timeout <= 0)
                                        timeout = -1;
                        }
                }
# endif
# if ENABLE_FEATURE_TAB_COMPLETION
                line_input_state->path_lookup = pathval();
# endif
                reinit_unicode_for_ash();
                nr = read_line_input(line_input_state, cmdedit_prompt, buf, IBUFSIZ, timeout);
                if (nr == 0) {
                        /* Ctrl+C pressed */
                        if (trap[SIGINT]) {
                                buf[0] = '\n';
                                buf[1] = '\0';
                                raise(SIGINT);
                                return 1;
                        }
                        goto retry;
                }
                if (nr < 0) {
                        if (errno == 0) {
                                /* Ctrl+D pressed */
                                nr = 0;
                        }
# if ENABLE_ASH_IDLE_TIMEOUT
                        else if (errno == EAGAIN && timeout > 0) {
                                puts("\007timed out waiting for input: auto-logout");
                                exitshell();
                        }
# endif
                }
        }
#else
        nr = nonblock_immune_read(g_parsefile->pf_fd, buf, IBUFSIZ - 1);
#endif

#if 0 /* disabled: nonblock_immune_read() handles this problem */
        if (nr < 0) {
                if (parsefile->fd == 0 && errno == EWOULDBLOCK) {
                        int flags = fcntl(0, F_GETFL);
                        if (flags >= 0 && (flags & O_NONBLOCK)) {
                                flags &= ~O_NONBLOCK;
                                if (fcntl(0, F_SETFL, flags) >= 0) {
                                        out2str("sh: turning off NDELAY mode\n");
                                        goto retry;
                                }
                        }
                }
        }
#endif
        return nr;
}

/*
 * Refill the input buffer and return the next input character:
 *
 * 1) If a string was pushed back on the input, pop it;
 * 2) If an EOF was pushed back (g_parsefile->left_in_line < -BIGNUM)
 *    or we are reading from a string so we can't refill the buffer,
 *    return EOF.
 * 3) If there is more stuff in this buffer, use it else call read to fill it.
 * 4) Process input up to the next newline, deleting nul characters.
 */
//#define pgetc_debug(...) bb_error_msg(__VA_ARGS__)
#define pgetc_debug(...) ((void)0)
static int pgetc(void);
static int
preadbuffer(void)
{
        char *q;
        int more;

        if (g_parsefile->strpush) {
#if ENABLE_ASH_ALIAS
                if (g_parsefile->left_in_line == -1
                 && g_parsefile->strpush->ap
                 && g_parsefile->next_to_pgetc[-1] != ' '
                 && g_parsefile->next_to_pgetc[-1] != '\t'
                ) {
                        pgetc_debug("preadbuffer PEOA");
                        return PEOA;
                }
#endif
                popstring();
                return pgetc();
        }
        /* on both branches above g_parsefile->left_in_line < 0.
         * "pgetc" needs refilling.
         */

        /* -90 is our -BIGNUM. Below we use -99 to mark "EOF on read",
         * pungetc() may increment it a few times.
         * Assuming it won't increment it to less than -90.
         */
        if (g_parsefile->left_in_line < -90 || g_parsefile->buf == NULL) {
                pgetc_debug("preadbuffer PEOF1");
                /* even in failure keep left_in_line and next_to_pgetc
                 * in lock step, for correct multi-layer pungetc.
                 * left_in_line was decremented before preadbuffer(),
                 * must inc next_to_pgetc: */
                g_parsefile->next_to_pgetc++;
                return PEOF;
        }

        more = g_parsefile->left_in_buffer;
        if (more <= 0) {
                flush_stdout_stderr();
 again:
                more = preadfd();
                if (more <= 0) {
                        /* don't try reading again */
                        g_parsefile->left_in_line = -99;
                        pgetc_debug("preadbuffer PEOF2");
                        g_parsefile->next_to_pgetc++;
                        return PEOF;
                }
        }

        /* Find out where's the end of line.
         * Set g_parsefile->left_in_line
         * and g_parsefile->left_in_buffer acordingly.
         * NUL chars are deleted.
         */
        q = g_parsefile->next_to_pgetc;
        for (;;) {
                char c;

                more--;

                c = *q;
                if (c == '\0') {
                        memmove(q, q + 1, more);
                } else {
                        q++;
                        if (c == '\n') {
                                g_parsefile->left_in_line = q - g_parsefile->next_to_pgetc - 1;
                                break;
                        }
                }

                if (more <= 0) {
                        g_parsefile->left_in_line = q - g_parsefile->next_to_pgetc - 1;
                        if (g_parsefile->left_in_line < 0)
                                goto again;
                        break;
                }
        }
        g_parsefile->left_in_buffer = more;

        if (vflag) {
                char save = *q;
                *q = '\0';
                out2str(g_parsefile->next_to_pgetc);
                *q = save;
        }

        pgetc_debug("preadbuffer at %d:%p'%s'",
                        g_parsefile->left_in_line,
                        g_parsefile->next_to_pgetc,
                        g_parsefile->next_to_pgetc);
        return (unsigned char)*g_parsefile->next_to_pgetc++;
}

static void
nlprompt(void)
{
        g_parsefile->linno++;
        setprompt_if(doprompt, 2);
}
static void
nlnoprompt(void)
{
        g_parsefile->linno++;
        needprompt = doprompt;
}

static int
pgetc(void)
{
        int c;

        pgetc_debug("pgetc at %d:%p'%s'",
                        g_parsefile->left_in_line,
                        g_parsefile->next_to_pgetc,
                        g_parsefile->next_to_pgetc);
        if (g_parsefile->unget)
                return g_parsefile->lastc[--g_parsefile->unget];

        if (--g_parsefile->left_in_line >= 0)
                c = (signed char)*g_parsefile->next_to_pgetc++;
        else
                c = preadbuffer();

        g_parsefile->lastc[1] = g_parsefile->lastc[0];
        g_parsefile->lastc[0] = c;

        return c;
}

#if ENABLE_ASH_ALIAS
static int
pgetc_without_PEOA(void)
{
        int c;
        do {
                pgetc_debug("pgetc at %d:%p'%s'",
                                g_parsefile->left_in_line,
                                g_parsefile->next_to_pgetc,
                                g_parsefile->next_to_pgetc);
                c = pgetc();
        } while (c == PEOA);
        return c;
}
#else
# define pgetc_without_PEOA() pgetc()
#endif

/*
 * Read a line from the script.
 */
static char *
pfgets(char *line, int len)
{
        char *p = line;
        int nleft = len;
        int c;

        while (--nleft > 0) {
                c = pgetc_without_PEOA();
                if (c == PEOF) {
                        if (p == line)
                                return NULL;
                        break;
                }
                *p++ = c;
                if (c == '\n')
                        break;
        }
        *p = '\0';
        return line;
}

/*
 * Undo a call to pgetc.  Only two characters may be pushed back.
 * PEOF may be pushed back.
 */
static void
pungetc(void)
{
        g_parsefile->unget++;
}

/* This one eats backslash+newline */
static int
pgetc_eatbnl(void)
{
        int c;

        while ((c = pgetc()) == '\\') {
                if (pgetc() != '\n') {
                        pungetc();
                        break;
                }

                nlprompt();
        }

        return c;
}

/*
 * To handle the "." command, a stack of input files is used.  Pushfile
 * adds a new entry to the stack and popfile restores the previous level.
 */
static void
pushfile(void)
{
        struct parsefile *pf;

        pf = ckzalloc(sizeof(*pf));
        pf->prev = g_parsefile;
        pf->pf_fd = -1;
        /*pf->strpush = NULL; - ckzalloc did it */
        /*pf->basestrpush.prev = NULL;*/
        /*pf->unget = 0;*/
        g_parsefile = pf;
}

static void
popfile(void)
{
        struct parsefile *pf = g_parsefile;

        if (pf == &basepf)
                return;

        INT_OFF;
        if (pf->pf_fd >= 0)
                close(pf->pf_fd);
        free(pf->buf);
        while (pf->strpush)
                popstring();
        g_parsefile = pf->prev;
        free(pf);
        INT_ON;
}

/*
 * Return to top level.
 */
static void
popallfiles(void)
{
        while (g_parsefile != &basepf)
                popfile();
}

/*
 * Close the file(s) that the shell is reading commands from.  Called
 * after a fork is done.
 */
static void
closescript(void)
{
        popallfiles();
        if (g_parsefile->pf_fd > 0) {
                close(g_parsefile->pf_fd);
                g_parsefile->pf_fd = 0;
        }
}

/*
 * Like setinputfile, but takes an open file descriptor.  Call this with
 * interrupts off.
 */
static void
setinputfd(int fd, int push)
{
        if (push) {
                pushfile();
                g_parsefile->buf = NULL;
        }
        g_parsefile->pf_fd = fd;
        if (g_parsefile->buf == NULL)
                g_parsefile->buf = ckmalloc(IBUFSIZ);
        g_parsefile->left_in_buffer = 0;
        g_parsefile->left_in_line = 0;
        g_parsefile->linno = 1;
}

/*
 * Set the input to take input from a file.  If push is set, push the
 * old input onto the stack first.
 */
static int
setinputfile(const char *fname, int flags)
{
        int fd;

        INT_OFF;
        fd = open(fname, O_RDONLY);
        if (fd < 0) {
                if (flags & INPUT_NOFILE_OK)
                        goto out;
                exitstatus = 127;
                ash_msg_and_raise_error("can't open '%s'", fname);
        }
        if (fd < 10)
                fd = savefd(fd);
        else
                close_on_exec_on(fd);
        setinputfd(fd, flags & INPUT_PUSH_FILE);
 out:
        INT_ON;
        return fd;
}

/*
 * Like setinputfile, but takes input from a string.
 */
static void
setinputstring(char *string)
{
        INT_OFF;
        pushfile();
        g_parsefile->next_to_pgetc = string;
        g_parsefile->left_in_line = strlen(string);
        g_parsefile->buf = NULL;
        g_parsefile->linno = 1;
        INT_ON;
}


/*
 * Routines to check for mail.
 */

#if ENABLE_ASH_MAIL

/* Hash of mtimes of mailboxes */
static unsigned mailtime_hash;
/* Set if MAIL or MAILPATH is changed. */
static smallint mail_var_path_changed;

/*
 * Print appropriate message(s) if mail has arrived.
 * If mail_var_path_changed is set,
 * then the value of MAIL has mail_var_path_changed,
 * so we just update the values.
 */
static void
chkmail(void)
{
        const char *mpath;
        char *p;
        char *q;
        unsigned new_hash;
        struct stackmark smark;
        struct stat statb;

        setstackmark(&smark);
        mpath = mpathset() ? mpathval() : mailval();
        new_hash = 0;
        for (;;) {
                p = path_advance(&mpath, nullstr);
                if (p == NULL)
                        break;
                if (*p == '\0')
                        continue;
                for (q = p; *q; q++)
                        continue;
#if DEBUG
                if (q[-1] != '/')
                        abort();
#endif
                q[-1] = '\0';                   /* delete trailing '/' */
                if (stat(p, &statb) < 0) {
                        continue;
                }
                /* Very simplistic "hash": just a sum of all mtimes */
                new_hash += (unsigned)statb.st_mtime;
        }
        if (!mail_var_path_changed && mailtime_hash != new_hash) {
                if (mailtime_hash != 0)
                        out2str("you have mail\n");
                mailtime_hash = new_hash;
        }
        mail_var_path_changed = 0;
        popstackmark(&smark);
}

static void FAST_FUNC
changemail(const char *val UNUSED_PARAM)
{
        mail_var_path_changed = 1;
}

#endif /* ASH_MAIL */


/* ============ ??? */

/*
 * Set the shell parameters.
 */
static void
setparam(char **argv)
{
        char **newparam;
        char **ap;
        int nparam;

        for (nparam = 0; argv[nparam]; nparam++)
                continue;
        ap = newparam = ckmalloc((nparam + 1) * sizeof(*ap));
        while (*argv) {
                *ap++ = ckstrdup(*argv++);
        }
        *ap = NULL;
        freeparam(&shellparam);
        shellparam.malloced = 1;
        shellparam.nparam = nparam;
        shellparam.p = newparam;
#if ENABLE_ASH_GETOPTS
        shellparam.optind = 1;
        shellparam.optoff = -1;
#endif
}

/*
 * Process shell options.  The global variable argptr contains a pointer
 * to the argument list; we advance it past the options.
 *
 * SUSv3 section 2.8.1 "Consequences of Shell Errors" says:
 * For a non-interactive shell, an error condition encountered
 * by a special built-in ... shall cause the shell to write a diagnostic message
 * to standard error and exit as shown in the following table:
 * Error                                           Special Built-In
 * ...
 * Utility syntax error (option or operand error)  Shall exit
 * ...
 * However, in bug 1142 (http://busybox.net/bugs/view.php?id=1142)
 * we see that bash does not do that (set "finishes" with error code 1 instead,
 * and shell continues), and people rely on this behavior!
 * Testcase:
 * set -o barfoo 2>/dev/null
 * echo $?
 *
 * Oh well. Let's mimic that.
 */
static int
plus_minus_o(char *name, int val)
{
        int i;

        if (name) {
                for (i = 0; i < NOPTS; i++) {
                        if (strcmp(name, optnames(i)) == 0) {
                                optlist[i] = val;
                                return 0;
                        }
                }
                ash_msg("illegal option %co %s", val ? '-' : '+', name);
                return 1;
        }
        for (i = 0; i < NOPTS; i++) {
                if (val) {
                        out1fmt("%-16s%s\n", optnames(i), optlist[i] ? "on" : "off");
                } else {
                        out1fmt("set %co %s\n", optlist[i] ? '-' : '+', optnames(i));
                }
        }
        return 0;
}
static void
setoption(int flag, int val)
{
        int i;

        for (i = 0; i < NOPTS; i++) {
                if (optletters(i) == flag) {
                        optlist[i] = val;
                        return;
                }
        }
        ash_msg_and_raise_error("illegal option %c%c", val ? '-' : '+', flag);
        /* NOTREACHED */
}
static int
options(int cmdline)
{
        char *p;
        int val;
        int c;

        if (cmdline)
                minusc = NULL;
        while ((p = *argptr) != NULL) {
                c = *p++;
                if (c != '-' && c != '+')
                        break;
                argptr++;
                val = 0; /* val = 0 if c == '+' */
                if (c == '-') {
                        val = 1;
                        if (p[0] == '\0' || LONE_DASH(p)) {
                                if (!cmdline) {
                                        /* "-" means turn off -x and -v */
                                        if (p[0] == '\0')
                                                xflag = vflag = 0;
                                        /* "--" means reset params */
                                        else if (*argptr == NULL)
                                                setparam(argptr);
                                }
                                break;    /* "-" or "--" terminates options */
                        }
                }
                /* first char was + or - */
                while ((c = *p++) != '\0') {
                        /* bash 3.2 indeed handles -c CMD and +c CMD the same */
                        if (c == 'c' && cmdline) {
                                minusc = p;     /* command is after shell args */
                        } else if (c == 'o') {
                                if (plus_minus_o(*argptr, val)) {
                                        /* it already printed err message */
                                        return 1; /* error */
                                }
                                if (*argptr)
                                        argptr++;
                        } else if (cmdline && (c == 'l')) { /* -l or +l == --login */
                                isloginsh = 1;
                        /* bash does not accept +-login, we also won't */
                        } else if (cmdline && val && (c == '-')) { /* long options */
                                if (strcmp(p, "login") == 0)
                                        isloginsh = 1;
                                break;
                        } else {
                                setoption(c, val);
                        }
                }
        }
        return 0;
}

/*
 * The shift builtin command.
 */
static int FAST_FUNC
shiftcmd(int argc UNUSED_PARAM, char **argv)
{
        int n;
        char **ap1, **ap2;

        n = 1;
        if (argv[1])
                n = number(argv[1]);
        if (n > shellparam.nparam)
                n = 0; /* bash compat, was = shellparam.nparam; */
        INT_OFF;
        shellparam.nparam -= n;
        for (ap1 = shellparam.p; --n >= 0; ap1++) {
                if (shellparam.malloced)
                        free(*ap1);
        }
        ap2 = shellparam.p;
        while ((*ap2++ = *ap1++) != NULL)
                continue;
#if ENABLE_ASH_GETOPTS
        shellparam.optind = 1;
        shellparam.optoff = -1;
#endif
        INT_ON;
        return 0;
}

/*
 * POSIX requires that 'set' (but not export or readonly) output the
 * variables in lexicographic order - by the locale's collating order (sigh).
 * Maybe we could keep them in an ordered balanced binary tree
 * instead of hashed lists.
 * For now just roll 'em through qsort for printing...
 */
static int
showvars(const char *sep_prefix, int on, int off)
{
        const char *sep;
        char **ep, **epend;

        ep = listvars(on, off, &epend);
        qsort(ep, epend - ep, sizeof(char *), vpcmp);

        sep = *sep_prefix ? " " : sep_prefix;

        for (; ep < epend; ep++) {
                const char *p;
                const char *q;

                p = strchrnul(*ep, '=');
                q = nullstr;
                if (*p)
                        q = single_quote(++p);
                out1fmt("%s%s%.*s%s\n", sep_prefix, sep, (int)(p - *ep), *ep, q);
        }
        return 0;
}

/*
 * The set command builtin.
 */
static int FAST_FUNC
setcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        int retval;

        if (!argv[1])
                return showvars(nullstr, 0, VUNSET);

        INT_OFF;
        retval = options(/*cmdline:*/ 0);
        if (retval == 0) { /* if no parse error... */
                optschanged();
                if (*argptr != NULL) {
                        setparam(argptr);
                }
        }
        INT_ON;
        return retval;
}

#if ENABLE_ASH_RANDOM_SUPPORT
static void FAST_FUNC
change_random(const char *value)
{
        uint32_t t;

        if (value == NULL) {
                /* "get", generate */
                t = next_random(&random_gen);
                /* set without recursion */
                setvar(vrandom.var_text, utoa(t), VNOFUNC);
                vrandom.flags &= ~VNOFUNC;
        } else {
                /* set/reset */
                t = strtoul(value, NULL, 10);
                INIT_RANDOM_T(&random_gen, (t ? t : 1), t);
        }
}
#endif

#if ENABLE_ASH_GETOPTS
static int
getopts(char *optstr, char *optvar, char **optfirst)
{
        char *p, *q;
        char c = '?';
        int done = 0;
        char sbuf[2];
        char **optnext;
        int ind = shellparam.optind;
        int off = shellparam.optoff;

        sbuf[1] = '\0';

        shellparam.optind = -1;
        optnext = optfirst + ind - 1;

        if (ind <= 1 || off < 0 || (int)strlen(optnext[-1]) < off)
                p = NULL;
        else
                p = optnext[-1] + off;
        if (p == NULL || *p == '\0') {
                /* Current word is done, advance */
                p = *optnext;
                if (p == NULL || *p != '-' || *++p == '\0') {
 atend:
                        p = NULL;
                        done = 1;
                        goto out;
                }
                optnext++;
                if (LONE_DASH(p))        /* check for "--" */
                        goto atend;
        }

        c = *p++;
        for (q = optstr; *q != c;) {
                if (*q == '\0') {
                        if (optstr[0] == ':') {
                                sbuf[0] = c;
                                /*sbuf[1] = '\0'; - already is */
                                setvar0("OPTARG", sbuf);
                        } else {
                                fprintf(stderr, "Illegal option -%c\n", c);
                                unsetvar("OPTARG");
                        }
                        c = '?';
                        goto out;
                }
                if (*++q == ':')
                        q++;
        }

        if (*++q == ':') {
                if (*p == '\0' && (p = *optnext) == NULL) {
                        if (optstr[0] == ':') {
                                sbuf[0] = c;
                                /*sbuf[1] = '\0'; - already is */
                                setvar0("OPTARG", sbuf);
                                c = ':';
                        } else {
                                fprintf(stderr, "No arg for -%c option\n", c);
                                unsetvar("OPTARG");
                                c = '?';
                        }
                        goto out;
                }

                if (p == *optnext)
                        optnext++;
                setvar0("OPTARG", p);
                p = NULL;
        } else
                setvar0("OPTARG", nullstr);
 out:
        ind = optnext - optfirst + 1;
        setvar("OPTIND", itoa(ind), VNOFUNC);
        sbuf[0] = c;
        /*sbuf[1] = '\0'; - already is */
        setvar0(optvar, sbuf);

        shellparam.optoff = p ? p - *(optnext - 1) : -1;
        shellparam.optind = ind;

        return done;
}

/*
 * The getopts builtin.  Shellparam.optnext points to the next argument
 * to be processed.  Shellparam.optptr points to the next character to
 * be processed in the current argument.  If shellparam.optnext is NULL,
 * then it's the first time getopts has been called.
 */
static int FAST_FUNC
getoptscmd(int argc, char **argv)
{
        char **optbase;

        if (argc < 3)
                ash_msg_and_raise_error("usage: getopts optstring var [arg]");
        if (argc == 3) {
                optbase = shellparam.p;
                if ((unsigned)shellparam.optind > shellparam.nparam + 1) {
                        shellparam.optind = 1;
                        shellparam.optoff = -1;
                }
        } else {
                optbase = &argv[3];
                if ((unsigned)shellparam.optind > argc - 2) {
                        shellparam.optind = 1;
                        shellparam.optoff = -1;
                }
        }

        return getopts(argv[1], argv[2], optbase);
}
#endif /* ASH_GETOPTS */


/* ============ Shell parser */

struct heredoc {
        struct heredoc *next;   /* next here document in list */
        union node *here;       /* redirection node */
        char *eofmark;          /* string indicating end of input */
        smallint striptabs;     /* if set, strip leading tabs */
};

static smallint tokpushback;           /* last token pushed back */
static smallint quoteflag;             /* set if (part of) last token was quoted */
static token_id_t lasttoken;           /* last token read (integer id Txxx) */
static struct heredoc *heredoclist;    /* list of here documents to read */
static char *wordtext;                 /* text of last word returned by readtoken */
static struct nodelist *backquotelist;
static union node *redirnode;
static struct heredoc *heredoc;

static const char *
tokname(char *buf, int tok)
{
        if (tok < TSEMI)
                return tokname_array[tok];
        sprintf(buf, "\"%s\"", tokname_array[tok]);
        return buf;
}

/* raise_error_unexpected_syntax:
 * Called when an unexpected token is read during the parse.  The argument
 * is the token that is expected, or -1 if more than one type of token can
 * occur at this point.
 */
static void raise_error_unexpected_syntax(int) NORETURN;
static void
raise_error_unexpected_syntax(int token)
{
        char msg[64];
        char buf[16];
        int l;

        l = sprintf(msg, "unexpected %s", tokname(buf, lasttoken));
        if (token >= 0)
                sprintf(msg + l, " (expecting %s)", tokname(buf, token));
        raise_error_syntax(msg);
        /* NOTREACHED */
}

#define EOFMARKLEN 79

/* parsing is heavily cross-recursive, need these forward decls */
static union node *andor(void);
static union node *pipeline(void);
static union node *parse_command(void);
static void parseheredoc(void);
static int peektoken(void);
static int readtoken(void);

static union node *
list(int nlflag)
{
        union node *n1, *n2, *n3;
        int tok;

        n1 = NULL;
        for (;;) {
                switch (peektoken()) {
                case TNL:
                        if (!(nlflag & 1))
                                break;
                        parseheredoc();
                        return n1;

                case TEOF:
                        if (!n1 && (nlflag & 1))
                                n1 = NODE_EOF;
                        parseheredoc();
                        return n1;
                }

                checkkwd = CHKNL | CHKKWD | CHKALIAS;
                if (nlflag == 2 && ((1 << peektoken()) & tokendlist))
                        return n1;
                nlflag |= 2;

                n2 = andor();
                tok = readtoken();
                if (tok == TBACKGND) {
                        if (n2->type == NPIPE) {
                                n2->npipe.pipe_backgnd = 1;
                        } else {
                                if (n2->type != NREDIR) {
                                        n3 = stzalloc(sizeof(struct nredir));
                                        n3->nredir.n = n2;
                                        /*n3->nredir.redirect = NULL; - stzalloc did it */
                                        n2 = n3;
                                }
                                n2->type = NBACKGND;
                        }
                }
                if (n1 == NULL) {
                        n1 = n2;
                } else {
                        n3 = stzalloc(sizeof(struct nbinary));
                        n3->type = NSEMI;
                        n3->nbinary.ch1 = n1;
                        n3->nbinary.ch2 = n2;
                        n1 = n3;
                }
                switch (tok) {
                case TNL:
                case TEOF:
                        tokpushback = 1;
                        /* fall through */
                case TBACKGND:
                case TSEMI:
                        break;
                default:
                        if ((nlflag & 1))
                                raise_error_unexpected_syntax(-1);
                        tokpushback = 1;
                        return n1;
                }
        }
}

static union node *
andor(void)
{
        union node *n1, *n2, *n3;
        int t;

        n1 = pipeline();
        for (;;) {
                t = readtoken();
                if (t == TAND) {
                        t = NAND;
                } else if (t == TOR) {
                        t = NOR;
                } else {
                        tokpushback = 1;
                        return n1;
                }
                checkkwd = CHKNL | CHKKWD | CHKALIAS;
                n2 = pipeline();
                n3 = stzalloc(sizeof(struct nbinary));
                n3->type = t;
                n3->nbinary.ch1 = n1;
                n3->nbinary.ch2 = n2;
                n1 = n3;
        }
}

static union node *
pipeline(void)
{
        union node *n1, *n2, *pipenode;
        struct nodelist *lp, *prev;
        int negate;

        negate = 0;
        TRACE(("pipeline: entered\n"));
        if (readtoken() == TNOT) {
                negate = !negate;
                checkkwd = CHKKWD | CHKALIAS;
        } else
                tokpushback = 1;
        n1 = parse_command();
        if (readtoken() == TPIPE) {
                pipenode = stzalloc(sizeof(struct npipe));
                pipenode->type = NPIPE;
                /*pipenode->npipe.pipe_backgnd = 0; - stzalloc did it */
                lp = stzalloc(sizeof(struct nodelist));
                pipenode->npipe.cmdlist = lp;
                lp->n = n1;
                do {
                        prev = lp;
                        lp = stzalloc(sizeof(struct nodelist));
                        checkkwd = CHKNL | CHKKWD | CHKALIAS;
                        lp->n = parse_command();
                        prev->next = lp;
                } while (readtoken() == TPIPE);
                lp->next = NULL;
                n1 = pipenode;
        }
        tokpushback = 1;
        if (negate) {
                n2 = stzalloc(sizeof(struct nnot));
                n2->type = NNOT;
                n2->nnot.com = n1;
                return n2;
        }
        return n1;
}

static union node *
makename(void)
{
        union node *n;

        n = stzalloc(sizeof(struct narg));
        n->type = NARG;
        /*n->narg.next = NULL; - stzalloc did it */
        n->narg.text = wordtext;
        n->narg.backquote = backquotelist;
        return n;
}

static void
fixredir(union node *n, const char *text, int err)
{
        int fd;

        TRACE(("Fix redir %s %d\n", text, err));
        if (!err)
                n->ndup.vname = NULL;

        fd = bb_strtou(text, NULL, 10);
        if (!errno && fd >= 0)
                n->ndup.dupfd = fd;
        else if (LONE_DASH(text))
                n->ndup.dupfd = -1;
        else {
                if (err)
                        raise_error_syntax("bad fd number");
                n->ndup.vname = makename();
        }
}

/*
 * Returns true if the text contains nothing to expand (no dollar signs
 * or backquotes).
 */
static int
noexpand(const char *text)
{
        unsigned char c;

        while ((c = *text++) != '\0') {
                if (c == CTLQUOTEMARK)
                        continue;
                if (c == CTLESC)
                        text++;
                else if (SIT(c, BASESYNTAX) == CCTL)
                        return 0;
        }
        return 1;
}

static void
parsefname(void)
{
        union node *n = redirnode;

        if (readtoken() != TWORD)
                raise_error_unexpected_syntax(-1);
        if (n->type == NHERE) {
                struct heredoc *here = heredoc;
                struct heredoc *p;
                int i;

                if (quoteflag == 0)
                        n->type = NXHERE;
                TRACE(("Here document %d\n", n->type));
                if (!noexpand(wordtext) || (i = strlen(wordtext)) == 0 || i > EOFMARKLEN)
                        raise_error_syntax("illegal eof marker for << redirection");
                rmescapes(wordtext, 0);
                here->eofmark = wordtext;
                here->next = NULL;
                if (heredoclist == NULL)
                        heredoclist = here;
                else {
                        for (p = heredoclist; p->next; p = p->next)
                                continue;
                        p->next = here;
                }
        } else if (n->type == NTOFD || n->type == NFROMFD) {
                fixredir(n, wordtext, 0);
        } else {
                n->nfile.fname = makename();
        }
}

static union node *
simplecmd(void)
{
        union node *args, **app;
        union node *n = NULL;
        union node *vars, **vpp;
        union node **rpp, *redir;
        int savecheckkwd;
#if ENABLE_ASH_BASH_COMPAT
        smallint double_brackets_flag = 0;
        smallint function_flag = 0;
#endif

        args = NULL;
        app = &args;
        vars = NULL;
        vpp = &vars;
        redir = NULL;
        rpp = &redir;

        savecheckkwd = CHKALIAS;
        for (;;) {
                int t;
                checkkwd = savecheckkwd;
                t = readtoken();
                switch (t) {
#if ENABLE_ASH_BASH_COMPAT
                case TFUNCTION:
                        if (peektoken() != TWORD)
                                raise_error_unexpected_syntax(TWORD);
                        function_flag = 1;
                        break;
                case TAND: /* "&&" */
                case TOR: /* "||" */
                        if (!double_brackets_flag) {
                                tokpushback = 1;
                                goto out;
                        }
                        wordtext = (char *) (t == TAND ? "-a" : "-o");
#endif
                case TWORD:
                        n = stzalloc(sizeof(struct narg));
                        n->type = NARG;
                        /*n->narg.next = NULL; - stzalloc did it */
                        n->narg.text = wordtext;
#if ENABLE_ASH_BASH_COMPAT
                        if (strcmp("[[", wordtext) == 0)
                                double_brackets_flag = 1;
                        else if (strcmp("]]", wordtext) == 0)
                                double_brackets_flag = 0;
#endif
                        n->narg.backquote = backquotelist;
                        if (savecheckkwd && isassignment(wordtext)) {
                                *vpp = n;
                                vpp = &n->narg.next;
                        } else {
                                *app = n;
                                app = &n->narg.next;
                                savecheckkwd = 0;
                        }
#if ENABLE_ASH_BASH_COMPAT
                        if (function_flag) {
                                checkkwd = CHKNL | CHKKWD;
                                switch (peektoken()) {
                                case TBEGIN:
                                case TIF:
                                case TCASE:
                                case TUNTIL:
                                case TWHILE:
                                case TFOR:
                                        goto do_func;
                                case TLP:
                                        function_flag = 0;
                                        break;
                                case TWORD:
                                        if (strcmp("[[", wordtext) == 0)
                                                goto do_func;
                                        /* fall through */
                                default:
                                        raise_error_unexpected_syntax(-1);
                                }
                        }
#endif
                        break;
                case TREDIR:
                        *rpp = n = redirnode;
                        rpp = &n->nfile.next;
                        parsefname();   /* read name of redirection file */
                        break;
                case TLP:
 IF_ASH_BASH_COMPAT(do_func:)
                        if (args && app == &args->narg.next
                         && !vars && !redir
                        ) {
                                struct builtincmd *bcmd;
                                const char *name;

                                /* We have a function */
                                if (IF_ASH_BASH_COMPAT(!function_flag &&) readtoken() != TRP)
                                        raise_error_unexpected_syntax(TRP);
                                name = n->narg.text;
                                if (!goodname(name)
                                 || ((bcmd = find_builtin(name)) && IS_BUILTIN_SPECIAL(bcmd))
                                ) {
                                        raise_error_syntax("bad function name");
                                }
                                n->type = NDEFUN;
                                checkkwd = CHKNL | CHKKWD | CHKALIAS;
                                n->narg.next = parse_command();
                                return n;
                        }
                        IF_ASH_BASH_COMPAT(function_flag = 0;)
                        /* fall through */
                default:
                        tokpushback = 1;
                        goto out;
                }
        }
 out:
        *app = NULL;
        *vpp = NULL;
        *rpp = NULL;
        n = stzalloc(sizeof(struct ncmd));
        n->type = NCMD;
        n->ncmd.args = args;
        n->ncmd.assign = vars;
        n->ncmd.redirect = redir;
        return n;
}

static union node *
parse_command(void)
{
        union node *n1, *n2;
        union node *ap, **app;
        union node *cp, **cpp;
        union node *redir, **rpp;
        union node **rpp2;
        int t;

        redir = NULL;
        rpp2 = &redir;

        switch (readtoken()) {
        default:
                raise_error_unexpected_syntax(-1);
                /* NOTREACHED */
        case TIF:
                n1 = stzalloc(sizeof(struct nif));
                n1->type = NIF;
                n1->nif.test = list(0);
                if (readtoken() != TTHEN)
                        raise_error_unexpected_syntax(TTHEN);
                n1->nif.ifpart = list(0);
                n2 = n1;
                while (readtoken() == TELIF) {
                        n2->nif.elsepart = stzalloc(sizeof(struct nif));
                        n2 = n2->nif.elsepart;
                        n2->type = NIF;
                        n2->nif.test = list(0);
                        if (readtoken() != TTHEN)
                                raise_error_unexpected_syntax(TTHEN);
                        n2->nif.ifpart = list(0);
                }
                if (lasttoken == TELSE)
                        n2->nif.elsepart = list(0);
                else {
                        n2->nif.elsepart = NULL;
                        tokpushback = 1;
                }
                t = TFI;
                break;
        case TWHILE:
        case TUNTIL: {
                int got;
                n1 = stzalloc(sizeof(struct nbinary));
                n1->type = (lasttoken == TWHILE) ? NWHILE : NUNTIL;
                n1->nbinary.ch1 = list(0);
                got = readtoken();
                if (got != TDO) {
                        TRACE(("expecting DO got '%s' %s\n", tokname_array[got],
                                        got == TWORD ? wordtext : ""));
                        raise_error_unexpected_syntax(TDO);
                }
                n1->nbinary.ch2 = list(0);
                t = TDONE;
                break;
        }
        case TFOR:
                if (readtoken() != TWORD || quoteflag || !goodname(wordtext))
                        raise_error_syntax("bad for loop variable");
                n1 = stzalloc(sizeof(struct nfor));
                n1->type = NFOR;
                n1->nfor.var = wordtext;
                checkkwd = CHKNL | CHKKWD | CHKALIAS;
                if (readtoken() == TIN) {
                        app = &ap;
                        while (readtoken() == TWORD) {
                                n2 = stzalloc(sizeof(struct narg));
                                n2->type = NARG;
                                /*n2->narg.next = NULL; - stzalloc did it */
                                n2->narg.text = wordtext;
                                n2->narg.backquote = backquotelist;
                                *app = n2;
                                app = &n2->narg.next;
                        }
                        *app = NULL;
                        n1->nfor.args = ap;
                        if (lasttoken != TNL && lasttoken != TSEMI)
                                raise_error_unexpected_syntax(-1);
                } else {
                        n2 = stzalloc(sizeof(struct narg));
                        n2->type = NARG;
                        /*n2->narg.next = NULL; - stzalloc did it */
                        n2->narg.text = (char *)dolatstr;
                        /*n2->narg.backquote = NULL;*/
                        n1->nfor.args = n2;
                        /*
                         * Newline or semicolon here is optional (but note
                         * that the original Bourne shell only allowed NL).
                         */
                        if (lasttoken != TSEMI)
                                tokpushback = 1;
                }
                checkkwd = CHKNL | CHKKWD | CHKALIAS;
                if (readtoken() != TDO)
                        raise_error_unexpected_syntax(TDO);
                n1->nfor.body = list(0);
                t = TDONE;
                break;
        case TCASE:
                n1 = stzalloc(sizeof(struct ncase));
                n1->type = NCASE;
                if (readtoken() != TWORD)
                        raise_error_unexpected_syntax(TWORD);
                n1->ncase.expr = n2 = stzalloc(sizeof(struct narg));
                n2->type = NARG;
                /*n2->narg.next = NULL; - stzalloc did it */
                n2->narg.text = wordtext;
                n2->narg.backquote = backquotelist;
                checkkwd = CHKNL | CHKKWD | CHKALIAS;
                if (readtoken() != TIN)
                        raise_error_unexpected_syntax(TIN);
                cpp = &n1->ncase.cases;
 next_case:
                checkkwd = CHKNL | CHKKWD;
                t = readtoken();
                while (t != TESAC) {
                        if (lasttoken == TLP)
                                readtoken();
                        *cpp = cp = stzalloc(sizeof(struct nclist));
                        cp->type = NCLIST;
                        app = &cp->nclist.pattern;
                        for (;;) {
                                *app = ap = stzalloc(sizeof(struct narg));
                                ap->type = NARG;
                                /*ap->narg.next = NULL; - stzalloc did it */
                                ap->narg.text = wordtext;
                                ap->narg.backquote = backquotelist;
                                if (readtoken() != TPIPE)
                                        break;
                                app = &ap->narg.next;
                                readtoken();
                        }
                        //ap->narg.next = NULL;
                        if (lasttoken != TRP)
                                raise_error_unexpected_syntax(TRP);
                        cp->nclist.body = list(2);

                        cpp = &cp->nclist.next;

                        checkkwd = CHKNL | CHKKWD;
                        t = readtoken();
                        if (t != TESAC) {
                                if (t != TENDCASE)
                                        raise_error_unexpected_syntax(TENDCASE);
                                goto next_case;
                        }
                }
                *cpp = NULL;
                goto redir;
        case TLP:
                n1 = stzalloc(sizeof(struct nredir));
                n1->type = NSUBSHELL;
                n1->nredir.n = list(0);
                /*n1->nredir.redirect = NULL; - stzalloc did it */
                t = TRP;
                break;
        case TBEGIN:
                n1 = list(0);
                t = TEND;
                break;
        IF_ASH_BASH_COMPAT(case TFUNCTION:)
        case TWORD:
        case TREDIR:
                tokpushback = 1;
                return simplecmd();
        }

        if (readtoken() != t)
                raise_error_unexpected_syntax(t);

 redir:
        /* Now check for redirection which may follow command */
        checkkwd = CHKKWD | CHKALIAS;
        rpp = rpp2;
        while (readtoken() == TREDIR) {
                *rpp = n2 = redirnode;
                rpp = &n2->nfile.next;
                parsefname();
        }
        tokpushback = 1;
        *rpp = NULL;
        if (redir) {
                if (n1->type != NSUBSHELL) {
                        n2 = stzalloc(sizeof(struct nredir));
                        n2->type = NREDIR;
                        n2->nredir.n = n1;
                        n1 = n2;
                }
                n1->nredir.redirect = redir;
        }
        return n1;
}

#if ENABLE_ASH_BASH_COMPAT
static int
decode_dollar_squote(void)
{
        static const char C_escapes[] ALIGN1 = "nrbtfav""x\\01234567";
        int c, cnt;
        char *p;
        char buf[4];

        c = pgetc();
        p = strchr(C_escapes, c);
        if (p) {
                buf[0] = c;
                p = buf;
                cnt = 3;
                if ((unsigned char)(c - '0') <= 7) { /* \ooo */
                        do {
                                c = pgetc();
                                *++p = c;
                        } while ((unsigned char)(c - '0') <= 7 && --cnt);
                        pungetc();
                } else if (c == 'x') { /* \xHH */
                        do {
                                c = pgetc();
                                *++p = c;
                        } while (isxdigit(c) && --cnt);
                        pungetc();
                        if (cnt == 3) { /* \x but next char is "bad" */
                                c = 'x';
                                goto unrecognized;
                        }
                } else { /* simple seq like \\ or \t */
                        p++;
                }
                *p = '\0';
                p = buf;
                c = bb_process_escape_sequence((void*)&p);
        } else { /* unrecognized "\z": print both chars unless ' or " */
                if (c != '\'' && c != '"') {
 unrecognized:
                        c |= 0x100; /* "please encode \, then me" */
                }
        }
        return c;
}
#endif

/*
 * If eofmark is NULL, read a word or a redirection symbol.  If eofmark
 * is not NULL, read a here document.  In the latter case, eofmark is the
 * word which marks the end of the document and striptabs is true if
 * leading tabs should be stripped from the document.  The argument c
 * is the first character of the input token or document.
 *
 * Because C does not have internal subroutines, I have simulated them
 * using goto's to implement the subroutine linkage.  The following macros
 * will run code that appears at the end of readtoken1.
 */
#define CHECKEND()      {goto checkend; checkend_return:;}
#define PARSEREDIR()    {goto parseredir; parseredir_return:;}
#define PARSESUB()      {goto parsesub; parsesub_return:;}
#define PARSEBACKQOLD() {oldstyle = 1; goto parsebackq; parsebackq_oldreturn:;}
#define PARSEBACKQNEW() {oldstyle = 0; goto parsebackq; parsebackq_newreturn:;}
#define PARSEARITH()    {goto parsearith; parsearith_return:;}
static int
readtoken1(int c, int syntax, char *eofmark, int striptabs)
{
        /* NB: syntax parameter fits into smallint */
        /* c parameter is an unsigned char or PEOF or PEOA */
        char *out;
        size_t len;
        char line[EOFMARKLEN + 1];
        struct nodelist *bqlist;
        smallint quotef;
        smallint dblquote;
        smallint oldstyle;
        smallint prevsyntax; /* syntax before arithmetic */
#if ENABLE_ASH_EXPAND_PRMT
        smallint pssyntax;   /* we are expanding a prompt string */
#endif
        int varnest;         /* levels of variables expansion */
        int arinest;         /* levels of arithmetic expansion */
        int parenlevel;      /* levels of parens in arithmetic */
        int dqvarnest;       /* levels of variables expansion within double quotes */

        IF_ASH_BASH_COMPAT(smallint bash_dollar_squote = 0;)

        startlinno = g_parsefile->linno;
        bqlist = NULL;
        quotef = 0;
        prevsyntax = 0;
#if ENABLE_ASH_EXPAND_PRMT
        pssyntax = (syntax == PSSYNTAX);
        if (pssyntax)
                syntax = DQSYNTAX;
#endif
        dblquote = (syntax == DQSYNTAX);
        varnest = 0;
        arinest = 0;
        parenlevel = 0;
        dqvarnest = 0;

        STARTSTACKSTR(out);
 loop:
        /* For each line, until end of word */
        CHECKEND();     /* set c to PEOF if at end of here document */
        for (;;) {      /* until end of line or end of word */
                CHECKSTRSPACE(4, out);  /* permit 4 calls to USTPUTC */
                switch (SIT(c, syntax)) {
                case CNL:       /* '\n' */
                        if (syntax == BASESYNTAX)
                                goto endword;   /* exit outer loop */
                        USTPUTC(c, out);
                        nlprompt();
                        c = pgetc();
                        goto loop;              /* continue outer loop */
                case CWORD:
                        USTPUTC(c, out);
                        break;
                case CCTL:
#if ENABLE_ASH_BASH_COMPAT
                        if (c == '\\' && bash_dollar_squote) {
                                c = decode_dollar_squote();
                                if (c == '\0') {
                                        /* skip $'\000', $'\x00' (like bash) */
                                        break;
                                }
                                if (c & 0x100) {
                                        /* Unknown escape. Encode as '\z' */
                                        c = (unsigned char)c;
                                        if (eofmark == NULL || dblquote)
                                                USTPUTC(CTLESC, out);
                                        USTPUTC('\\', out);
                                }
                        }
#endif
                        if (eofmark == NULL || dblquote)
                                USTPUTC(CTLESC, out);
                        USTPUTC(c, out);
                        break;
                case CBACK:     /* backslash */
                        c = pgetc_without_PEOA();
                        if (c == PEOF) {
                                USTPUTC(CTLESC, out);
                                USTPUTC('\\', out);
                                pungetc();
                        } else if (c == '\n') {
                                nlprompt();
                        } else {
#if ENABLE_ASH_EXPAND_PRMT
                                if (c == '$' && pssyntax) {
                                        USTPUTC(CTLESC, out);
                                        USTPUTC('\\', out);
                                }
#endif
                                /* Backslash is retained if we are in "str" and next char isn't special */
                                if (dblquote
                                 && c != '\\'
                                 && c != '`'
                                 && c != '$'
                                 && (c != '"' || eofmark != NULL)
                                ) {
                                        USTPUTC('\\', out);
                                }
                                USTPUTC(CTLESC, out);
                                USTPUTC(c, out);
                                quotef = 1;
                        }
                        break;
                case CSQUOTE:
                        syntax = SQSYNTAX;
 quotemark:
                        if (eofmark == NULL) {
                                USTPUTC(CTLQUOTEMARK, out);
                        }
                        break;
                case CDQUOTE:
                        syntax = DQSYNTAX;
                        dblquote = 1;
                        goto quotemark;
                case CENDQUOTE:
                        IF_ASH_BASH_COMPAT(bash_dollar_squote = 0;)
                        if (eofmark != NULL && varnest == 0) {
                                USTPUTC(c, out);
                        } else {
                                if (dqvarnest == 0) {
                                        syntax = BASESYNTAX;
                                        dblquote = 0;
                                }
                                quotef = 1;
                                goto quotemark;
                        }
                        break;
                case CVAR:      /* '$' */
                        PARSESUB();             /* parse substitution */
                        break;
                case CENDVAR:   /* '}' */
                        if (varnest > 0) {
                                varnest--;
                                if (dqvarnest > 0) {
                                        dqvarnest--;
                                }
                                c = CTLENDVAR;
                        }
                        USTPUTC(c, out);
                        break;
#if ENABLE_SH_MATH_SUPPORT
                case CLP:       /* '(' in arithmetic */
                        parenlevel++;
                        USTPUTC(c, out);
                        break;
                case CRP:       /* ')' in arithmetic */
                        if (parenlevel > 0) {
                                parenlevel--;
                        } else {
                                if (pgetc_eatbnl() == ')') {
                                        c = CTLENDARI;
                                        if (--arinest == 0) {
                                                syntax = prevsyntax;
                                        }
                                } else {
                                        /*
                                         * unbalanced parens
                                         * (don't 2nd guess - no error)
                                         */
                                        pungetc();
                                }
                        }
                        USTPUTC(c, out);
                        break;
#endif
                case CBQUOTE:   /* '`' */
                        PARSEBACKQOLD();
                        break;
                case CENDFILE:
                        goto endword;           /* exit outer loop */
                case CIGN:
                        break;
                default:
                        if (varnest == 0) {
#if ENABLE_ASH_BASH_COMPAT
                                if (c == '&') {
//Can't call pgetc_eatbnl() here, this requires three-deep pungetc()
                                        if (pgetc() == '>')
                                                c = 0x100 + '>'; /* flag &> */
                                        pungetc();
                                }
#endif
                                goto endword;   /* exit outer loop */
                        }
                        IF_ASH_ALIAS(if (c != PEOA))
                                USTPUTC(c, out);
                }
                c = pgetc();
        } /* for (;;) */
 endword:

#if ENABLE_SH_MATH_SUPPORT
        if (syntax == ARISYNTAX)
                raise_error_syntax("missing '))'");
#endif
        if (syntax != BASESYNTAX && eofmark == NULL)
                raise_error_syntax("unterminated quoted string");
        if (varnest != 0) {
                startlinno = g_parsefile->linno;
                /* { */
                raise_error_syntax("missing '}'");
        }
        USTPUTC('\0', out);
        len = out - (char *)stackblock();
        out = stackblock();
        if (eofmark == NULL) {
                if ((c == '>' || c == '<' IF_ASH_BASH_COMPAT( || c == 0x100 + '>'))
                 && quotef == 0
                ) {
                        if (isdigit_str9(out)) {
                                PARSEREDIR(); /* passed as params: out, c */
                                lasttoken = TREDIR;
                                return lasttoken;
                        }
                        /* else: non-number X seen, interpret it
                         * as "NNNX>file" = "NNNX >file" */
                }
                pungetc();
        }
        quoteflag = quotef;
        backquotelist = bqlist;
        grabstackblock(len);
        wordtext = out;
        lasttoken = TWORD;
        return lasttoken;
/* end of readtoken routine */

/*
 * Check to see whether we are at the end of the here document.  When this
 * is called, c is set to the first character of the next input line.  If
 * we are at the end of the here document, this routine sets the c to PEOF.
 */
checkend: {
        if (eofmark) {
#if ENABLE_ASH_ALIAS
                if (c == PEOA)
                        c = pgetc_without_PEOA();
#endif
                if (striptabs) {
                        while (c == '\t') {
                                c = pgetc_without_PEOA();
                        }
                }
                if (c == *eofmark) {
                        if (pfgets(line, sizeof(line)) != NULL) {
                                char *p, *q;
                                int cc;

                                p = line;
                                for (q = eofmark + 1;; p++, q++) {
                                        cc = *p;
                                        if (cc == '\n')
                                                cc = 0;
                                        if (!*q || cc != *q)
                                                break;
                                }
                                if (cc == *q) {
                                        c = PEOF;
                                        nlnoprompt();
                                } else {
                                        pushstring(line, NULL);
                                }
                        }
                }
        }
        goto checkend_return;
}

/*
 * Parse a redirection operator.  The variable "out" points to a string
 * specifying the fd to be redirected.  The variable "c" contains the
 * first character of the redirection operator.
 */
parseredir: {
        /* out is already checked to be a valid number or "" */
        int fd = (*out == '\0' ? -1 : atoi(out));
        union node *np;

        np = stzalloc(sizeof(struct nfile));
        if (c == '>') {
                np->nfile.fd = 1;
                c = pgetc();
                if (c == '>')
                        np->type = NAPPEND;
                else if (c == '|')
                        np->type = NCLOBBER;
                else if (c == '&')
                        np->type = NTOFD;
                        /* it also can be NTO2 (>&file), but we can't figure it out yet */
                else {
                        np->type = NTO;
                        pungetc();
                }
        }
#if ENABLE_ASH_BASH_COMPAT
        else if (c == 0x100 + '>') { /* this flags &> redirection */
                np->nfile.fd = 1;
                pgetc(); /* this is '>', no need to check */
                np->type = NTO2;
        }
#endif
        else { /* c == '<' */
                /*np->nfile.fd = 0; - stzalloc did it */
                c = pgetc();
                switch (c) {
                case '<':
                        if (sizeof(struct nfile) != sizeof(struct nhere)) {
                                np = stzalloc(sizeof(struct nhere));
                                /*np->nfile.fd = 0; - stzalloc did it */
                        }
                        np->type = NHERE;
                        heredoc = stzalloc(sizeof(struct heredoc));
                        heredoc->here = np;
                        c = pgetc();
                        if (c == '-') {
                                heredoc->striptabs = 1;
                        } else {
                                /*heredoc->striptabs = 0; - stzalloc did it */
                                pungetc();
                        }
                        break;

                case '&':
                        np->type = NFROMFD;
                        break;

                case '>':
                        np->type = NFROMTO;
                        break;

                default:
                        np->type = NFROM;
                        pungetc();
                        break;
                }
        }
        if (fd >= 0)
                np->nfile.fd = fd;
        redirnode = np;
        goto parseredir_return;
}

/*
 * Parse a substitution.  At this point, we have read the dollar sign
 * and nothing else.
 */

/* is_special(c) evaluates to 1 for c in "!#$*-0123456789?@"; 0 otherwise
 * (assuming ascii char codes, as the original implementation did) */
#define is_special(c) \
        (((unsigned)(c) - 33 < 32) \
                        && ((0xc1ff920dU >> ((unsigned)(c) - 33)) & 1))
parsesub: {
        unsigned char subtype;
        int typeloc;

        c = pgetc_eatbnl();
        if (c > 255 /* PEOA or PEOF */
         || (c != '(' && c != '{' && !is_name(c) && !is_special(c))
        ) {
#if ENABLE_ASH_BASH_COMPAT
                if (syntax != DQSYNTAX && c == '\'')
                        bash_dollar_squote = 1;
                else
#endif
                        USTPUTC('$', out);
                pungetc();
        } else if (c == '(') {
                /* $(command) or $((arith)) */
                if (pgetc_eatbnl() == '(') {
#if ENABLE_SH_MATH_SUPPORT
                        PARSEARITH();
#else
                        raise_error_syntax("you disabled math support for $((arith)) syntax");
#endif
                } else {
                        pungetc();
                        PARSEBACKQNEW();
                }
        } else {
                /* $VAR, $<specialchar>, ${...}, or PEOA/PEOF */
                USTPUTC(CTLVAR, out);
                typeloc = out - (char *)stackblock();
                STADJUST(1, out);
                subtype = VSNORMAL;
                if (c == '{') {
                        c = pgetc_eatbnl();
                        subtype = 0;
                }
 varname:
                if (is_name(c)) {
                        /* $[{[#]]NAME[}] */
                        do {
                                STPUTC(c, out);
                                c = pgetc_eatbnl();
                        } while (is_in_name(c));
                } else if (isdigit(c)) {
                        /* $[{[#]]NUM[}] */
                        do {
                                STPUTC(c, out);
                                c = pgetc_eatbnl();
                        } while (isdigit(c));
                } else if (is_special(c)) {
                        /* $[{[#]]<specialchar>[}] */
                        int cc = c;

                        c = pgetc_eatbnl();
                        if (!subtype && cc == '#') {
                                subtype = VSLENGTH;
                                if (c == '_' || isalnum(c))
                                        goto varname;
                                cc = c;
                                c = pgetc_eatbnl();
                                if (cc == '}' || c != '}') {
                                        pungetc();
                                        subtype = 0;
                                        c = cc;
                                        cc = '#';
                                }
                        }
                        USTPUTC(cc, out);
                } else {
                        goto badsub;
                }
                if (c != '}' && subtype == VSLENGTH) {
                        /* ${#VAR didn't end with } */
                        goto badsub;
                }

                if (subtype == 0) {
                        static const char types[] ALIGN1 = "}-+?=";
                        /* ${VAR...} but not $VAR or ${#VAR} */
                        /* c == first char after VAR */
                        switch (c) {
                        case ':':
                                c = pgetc_eatbnl();
#if ENABLE_ASH_BASH_COMPAT
                                /* This check is only needed to not misinterpret
                                 * ${VAR:-WORD}, ${VAR:+WORD}, ${VAR:=WORD}, ${VAR:?WORD}
                                 * constructs.
                                 */
                                if (!strchr(types, c)) {
                                        subtype = VSSUBSTR;
                                        pungetc();
                                        break; /* "goto badsub" is bigger (!) */
                                }
#endif
                                subtype = VSNUL;
                                /*FALLTHROUGH*/
                        default: {
                                const char *p = strchr(types, c);
                                if (p == NULL)
                                        break;
                                subtype |= p - types + VSNORMAL;
                                break;
                        }
                        case '%':
                        case '#': {
                                int cc = c;
                                subtype = (c == '#' ? VSTRIMLEFT : VSTRIMRIGHT);
                                c = pgetc_eatbnl();
                                if (c != cc)
                                        goto badsub;
                                subtype++;
                                break;
                        }
#if ENABLE_ASH_BASH_COMPAT
                        case '/':
                                /* ${v/[/]pattern/repl} */
//TODO: encode pattern and repl separately.
// Currently ${v/$var_with_slash/repl} is horribly broken
                                subtype = VSREPLACE;
                                c = pgetc_eatbnl();
                                if (c != '/')
                                        goto badsub;
                                subtype++; /* VSREPLACEALL */
                                break;
#endif
                        }
                } else {
 badsub:
                        pungetc();
                }
                ((unsigned char *)stackblock())[typeloc] = subtype;
                if (subtype != VSNORMAL) {
                        varnest++;
                        if (dblquote)
                                dqvarnest++;
                }
                STPUTC('=', out);
        }
        goto parsesub_return;
}

/*
 * Called to parse command substitutions.  Newstyle is set if the command
 * is enclosed inside $(...); nlpp is a pointer to the head of the linked
 * list of commands (passed by reference), and savelen is the number of
 * characters on the top of the stack which must be preserved.
 */
parsebackq: {
        struct nodelist **nlpp;
        union node *n;
        char *str;
        size_t savelen;
        smallint saveprompt = 0;

        str = NULL;
        savelen = out - (char *)stackblock();
        if (savelen > 0) {
                /*
                 * FIXME: this can allocate very large block on stack and SEGV.
                 * Example:
                 * echo "..<100kbytes>..`true` $(true) `true` ..."
                 * allocates 100kb for every command subst. With about
                 * a hundred command substitutions stack overflows.
                 * With larger prepended string, SEGV happens sooner.
                 */
                str = alloca(savelen);
                memcpy(str, stackblock(), savelen);
        }

        if (oldstyle) {
                /* We must read until the closing backquote, giving special
                 * treatment to some slashes, and then push the string and
                 * reread it as input, interpreting it normally.
                 */
                char *pout;
                size_t psavelen;
                char *pstr;

                STARTSTACKSTR(pout);
                for (;;) {
                        int pc;

                        setprompt_if(needprompt, 2);
                        pc = pgetc();
                        switch (pc) {
                        case '`':
                                goto done;

                        case '\\':
                                pc = pgetc();
                                if (pc == '\n') {
                                        nlprompt();
                                        /*
                                         * If eating a newline, avoid putting
                                         * the newline into the new character
                                         * stream (via the STPUTC after the
                                         * switch).
                                         */
                                        continue;
                                }
                                if (pc != '\\' && pc != '`' && pc != '$'
                                 && (!dblquote || pc != '"')
                                ) {
                                        STPUTC('\\', pout);
                                }
                                if (pc <= 255 /* not PEOA or PEOF */) {
                                        break;
                                }
                                /* fall through */

                        case PEOF:
                        IF_ASH_ALIAS(case PEOA:)
                                startlinno = g_parsefile->linno;
                                raise_error_syntax("EOF in backquote substitution");

                        case '\n':
                                nlnoprompt();
                                break;

                        default:
                                break;
                        }
                        STPUTC(pc, pout);
                }
 done:
                STPUTC('\0', pout);
                psavelen = pout - (char *)stackblock();
                if (psavelen > 0) {
                        pstr = grabstackstr(pout);
                        setinputstring(pstr);
                }
        }
        nlpp = &bqlist;
        while (*nlpp)
                nlpp = &(*nlpp)->next;
        *nlpp = stzalloc(sizeof(**nlpp));
        /* (*nlpp)->next = NULL; - stzalloc did it */

        if (oldstyle) {
                saveprompt = doprompt;
                doprompt = 0;
        }

        n = list(2);

        if (oldstyle)
                doprompt = saveprompt;
        else if (readtoken() != TRP)
                raise_error_unexpected_syntax(TRP);

        (*nlpp)->n = n;
        if (oldstyle) {
                /*
                 * Start reading from old file again, ignoring any pushed back
                 * tokens left from the backquote parsing
                 */
                popfile();
                tokpushback = 0;
        }
        while (stackblocksize() <= savelen)
                growstackblock();
        STARTSTACKSTR(out);
        if (str) {
                memcpy(out, str, savelen);
                STADJUST(savelen, out);
        }
        USTPUTC(CTLBACKQ, out);
        if (oldstyle)
                goto parsebackq_oldreturn;
        goto parsebackq_newreturn;
}

#if ENABLE_SH_MATH_SUPPORT
/*
 * Parse an arithmetic expansion (indicate start of one and set state)
 */
parsearith: {
        if (++arinest == 1) {
                prevsyntax = syntax;
                syntax = ARISYNTAX;
        }
        USTPUTC(CTLARI, out);
        goto parsearith_return;
}
#endif
} /* end of readtoken */

/*
 * Read the next input token.
 * If the token is a word, we set backquotelist to the list of cmds in
 *      backquotes.  We set quoteflag to true if any part of the word was
 *      quoted.
 * If the token is TREDIR, then we set redirnode to a structure containing
 *      the redirection.
 * In all cases, the variable startlinno is set to the number of the line
 *      on which the token starts.
 *
 * [Change comment:  here documents and internal procedures]
 * [Readtoken shouldn't have any arguments.  Perhaps we should make the
 *  word parsing code into a separate routine.  In this case, readtoken
 *  doesn't need to have any internal procedures, but parseword does.
 *  We could also make parseoperator in essence the main routine, and
 *  have parseword (readtoken1?) handle both words and redirection.]
 */
#define NEW_xxreadtoken
#ifdef NEW_xxreadtoken
/* singles must be first! */
static const char xxreadtoken_chars[7] ALIGN1 = {
        '\n', '(', ')', /* singles */
        '&', '|', ';',  /* doubles */
        0
};

#define xxreadtoken_singles 3
#define xxreadtoken_doubles 3

static const char xxreadtoken_tokens[] ALIGN1 = {
        TNL, TLP, TRP,          /* only single occurrence allowed */
        TBACKGND, TPIPE, TSEMI, /* if single occurrence */
        TEOF,                   /* corresponds to trailing nul */
        TAND, TOR, TENDCASE     /* if double occurrence */
};

static int
xxreadtoken(void)
{
        int c;

        if (tokpushback) {
                tokpushback = 0;
                return lasttoken;
        }
        setprompt_if(needprompt, 2);
        startlinno = g_parsefile->linno;
        for (;;) {                      /* until token or start of word found */
                c = pgetc();
                if (c == ' ' || c == '\t' IF_ASH_ALIAS( || c == PEOA))
                        continue;

                if (c == '#') {
                        while ((c = pgetc()) != '\n' && c != PEOF)
                                continue;
                        pungetc();
                } else if (c == '\\') {
                        if (pgetc() != '\n') {
                                pungetc();
                                break; /* return readtoken1(...) */
                        }
                        nlprompt();
                } else {
                        const char *p;

                        p = xxreadtoken_chars + sizeof(xxreadtoken_chars) - 1;
                        if (c != PEOF) {
                                if (c == '\n') {
                                        nlnoprompt();
                                }

                                p = strchr(xxreadtoken_chars, c);
                                if (p == NULL)
                                        break; /* return readtoken1(...) */

                                if ((int)(p - xxreadtoken_chars) >= xxreadtoken_singles) {
                                        int cc = pgetc();
                                        if (cc == c) {    /* double occurrence? */
                                                p += xxreadtoken_doubles + 1;
                                        } else {
                                                pungetc();
#if ENABLE_ASH_BASH_COMPAT
                                                if (c == '&' && cc == '>') /* &> */
                                                        break; /* return readtoken1(...) */
#endif
                                        }
                                }
                        }
                        lasttoken = xxreadtoken_tokens[p - xxreadtoken_chars];
                        return lasttoken;
                }
        } /* for (;;) */

        return readtoken1(c, BASESYNTAX, (char *) NULL, 0);
}
#else /* old xxreadtoken */
#define RETURN(token)   return lasttoken = token
static int
xxreadtoken(void)
{
        int c;

        if (tokpushback) {
                tokpushback = 0;
                return lasttoken;
        }
        setprompt_if(needprompt, 2);
        startlinno = g_parsefile->linno;
        for (;;) {      /* until token or start of word found */
                c = pgetc();
                switch (c) {
                case ' ': case '\t':
                IF_ASH_ALIAS(case PEOA:)
                        continue;
                case '#':
                        while ((c = pgetc()) != '\n' && c != PEOF)
                                continue;
                        pungetc();
                        continue;
                case '\\':
                        if (pgetc() == '\n') {
                                nlprompt();
                                continue;
                        }
                        pungetc();
                        goto breakloop;
                case '\n':
                        nlnoprompt();
                        RETURN(TNL);
                case PEOF:
                        RETURN(TEOF);
                case '&':
                        if (pgetc() == '&')
                                RETURN(TAND);
                        pungetc();
                        RETURN(TBACKGND);
                case '|':
                        if (pgetc() == '|')
                                RETURN(TOR);
                        pungetc();
                        RETURN(TPIPE);
                case ';':
                        if (pgetc() == ';')
                                RETURN(TENDCASE);
                        pungetc();
                        RETURN(TSEMI);
                case '(':
                        RETURN(TLP);
                case ')':
                        RETURN(TRP);
                default:
                        goto breakloop;
                }
        }
 breakloop:
        return readtoken1(c, BASESYNTAX, (char *)NULL, 0);
#undef RETURN
}
#endif /* old xxreadtoken */

static int
readtoken(void)
{
        int t;
        int kwd = checkkwd;
#if DEBUG
        smallint alreadyseen = tokpushback;
#endif

#if ENABLE_ASH_ALIAS
 top:
#endif

        t = xxreadtoken();

        /*
         * eat newlines
         */
        if (kwd & CHKNL) {
                while (t == TNL) {
                        parseheredoc();
                        t = xxreadtoken();
                }
        }

        if (t != TWORD || quoteflag) {
                goto out;
        }

        /*
         * check for keywords
         */
        if (kwd & CHKKWD) {
                const char *const *pp;

                pp = findkwd(wordtext);
                if (pp) {
                        lasttoken = t = pp - tokname_array;
                        TRACE(("keyword '%s' recognized\n", tokname_array[t]));
                        goto out;
                }
        }

        if (checkkwd & CHKALIAS) {
#if ENABLE_ASH_ALIAS
                struct alias *ap;
                ap = lookupalias(wordtext, 1);
                if (ap != NULL) {
                        if (*ap->val) {
                                pushstring(ap->val, ap);
                        }
                        goto top;
                }
#endif
        }
 out:
        checkkwd = 0;
#if DEBUG
        if (!alreadyseen)
                TRACE(("token '%s' %s\n", tokname_array[t], t == TWORD ? wordtext : ""));
        else
                TRACE(("reread token '%s' %s\n", tokname_array[t], t == TWORD ? wordtext : ""));
#endif
        return t;
}

static int
peektoken(void)
{
        int t;

        t = readtoken();
        tokpushback = 1;
        return t;
}

/*
 * Read and parse a command.  Returns NODE_EOF on end of file.
 * (NULL is a valid parse tree indicating a blank line.)
 */
static union node *
parsecmd(int interact)
{
        tokpushback = 0;
        checkkwd = 0;
        heredoclist = 0;
        doprompt = interact;
        setprompt_if(doprompt, doprompt);
        needprompt = 0;
        return list(1);
}

/*
 * Input any here documents.
 */
static void
parseheredoc(void)
{
        struct heredoc *here;
        union node *n;

        here = heredoclist;
        heredoclist = NULL;

        while (here) {
                setprompt_if(needprompt, 2);
                readtoken1(pgetc(), here->here->type == NHERE ? SQSYNTAX : DQSYNTAX,
                                here->eofmark, here->striptabs);
                n = stzalloc(sizeof(struct narg));
                n->narg.type = NARG;
                /*n->narg.next = NULL; - stzalloc did it */
                n->narg.text = wordtext;
                n->narg.backquote = backquotelist;
                here->here->nhere.doc = n;
                here = here->next;
        }
}


/*
 * called by editline -- any expansions to the prompt should be added here.
 */
#if ENABLE_ASH_EXPAND_PRMT
static const char *
expandstr(const char *ps)
{
        union node n;
        int saveprompt;

        /* XXX Fix (char *) cast. It _is_ a bug. ps is variable's value,
         * and token processing _can_ alter it (delete NULs etc). */
        setinputstring((char *)ps);

        saveprompt = doprompt;
        doprompt = 0;
        readtoken1(pgetc(), PSSYNTAX, nullstr, 0);
        doprompt = saveprompt;

        popfile();

        n.narg.type = NARG;
        n.narg.next = NULL;
        n.narg.text = wordtext;
        n.narg.backquote = backquotelist;

        expandarg(&n, NULL, EXP_QUOTED);
        return stackblock();
}
#endif

/*
 * Execute a command or commands contained in a string.
 */
static int
evalstring(char *s, int flags)
{
        struct jmploc *volatile savehandler;
        struct jmploc jmploc;
        int ex;

        union node *n;
        struct stackmark smark;
        int status;

        s = sstrdup(s);
        setinputstring(s);
        setstackmark(&smark);

        status = 0;
        /* On exception inside execution loop, we must popfile().
         * Try interactively:
         *      readonly a=a
         *      command eval "a=b"  # throws "is read only" error
         * "command BLTIN" is not supposed to abort (even in non-interactive use).
         * But if we skip popfile(), we hit EOF in eval's string, and exit.
         */
        savehandler = exception_handler;
        ex = setjmp(jmploc.loc);
        if (ex)
                goto out;
        exception_handler = &jmploc;

        while ((n = parsecmd(0)) != NODE_EOF) {
                int i;

                i = evaltree(n, flags);
                if (n)
                        status = i;
                popstackmark(&smark);
                if (evalskip)
                        break;
        }
 out:
        popstackmark(&smark);
        popfile();
        stunalloc(s);

        exception_handler = savehandler;
        if (ex)
                longjmp(exception_handler->loc, ex);

        return status;
}

/*
 * The eval command.
 */
static int FAST_FUNC
evalcmd(int argc UNUSED_PARAM, char **argv, int flags)
{
        char *p;
        char *concat;

        if (argv[1]) {
                p = argv[1];
                argv += 2;
                if (argv[0]) {
                        STARTSTACKSTR(concat);
                        for (;;) {
                                concat = stack_putstr(p, concat);
                                p = *argv++;
                                if (p == NULL)
                                        break;
                                STPUTC(' ', concat);
                        }
                        STPUTC('\0', concat);
                        p = grabstackstr(concat);
                }
                return evalstring(p, flags & EV_TESTED);
        }
        return 0;
}

/*
 * Read and execute commands.
 * "Top" is nonzero for the top level command loop;
 * it turns on prompting if the shell is interactive.
 */
static int
cmdloop(int top)
{
        union node *n;
        struct stackmark smark;
        int inter;
        int status = 0;
        int numeof = 0;

        TRACE(("cmdloop(%d) called\n", top));
        for (;;) {
                int skip;

                setstackmark(&smark);
#if JOBS
                if (doing_jobctl)
                        showjobs(SHOW_CHANGED|SHOW_STDERR);
#endif
                inter = 0;
                if (iflag && top) {
                        inter++;
                        chkmail();
                }
                n = parsecmd(inter);
#if DEBUG
                if (DEBUG > 2 && debug && (n != NODE_EOF))
                        showtree(n);
#endif
                if (n == NODE_EOF) {
                        if (!top || numeof >= 50)
                                break;
                        if (!stoppedjobs()) {
                                if (!Iflag)
                                        break;
                                out2str("\nUse \"exit\" to leave shell.\n");
                        }
                        numeof++;
                } else if (nflag == 0) {
                        int i;

                        /* job_warning can only be 2,1,0. Here 2->1, 1/0->0 */
                        job_warning >>= 1;
                        numeof = 0;
                        i = evaltree(n, 0);
                        if (n)
                                status = i;
                }
                popstackmark(&smark);
                skip = evalskip;

                if (skip) {
                        evalskip &= ~SKIPFUNC;
                        break;
                }
        }
        return status;
}

/*
 * Take commands from a file.  To be compatible we should do a path
 * search for the file, which is necessary to find sub-commands.
 */
static char *
find_dot_file(char *name)
{
        char *fullname;
        const char *path = pathval();
        struct stat statb;

        /* don't try this for absolute or relative paths */
        if (strchr(name, '/'))
                return name;

        /* IIRC standards do not say whether . is to be searched.
         * And it is even smaller this way, making it unconditional for now:
         */
        if (1) { /* ENABLE_ASH_BASH_COMPAT */
                fullname = name;
                goto try_cur_dir;
        }

        while ((fullname = path_advance(&path, name)) != NULL) {
 try_cur_dir:
                if ((stat(fullname, &statb) == 0) && S_ISREG(statb.st_mode)) {
                        /*
                         * Don't bother freeing here, since it will
                         * be freed by the caller.
                         */
                        return fullname;
                }
                if (fullname != name)
                        stunalloc(fullname);
        }

        /* not found in the PATH */
        ash_msg_and_raise_error("%s: not found", name);
        /* NOTREACHED */
}

static int FAST_FUNC
dotcmd(int argc_ UNUSED_PARAM, char **argv_ UNUSED_PARAM)
{
        /* "false; . empty_file; echo $?" should print 0, not 1: */
        int status = 0;
        char *fullname;
        char **argv;
        struct strlist *sp;
        volatile struct shparam saveparam;

        for (sp = cmdenviron; sp; sp = sp->next)
                setvareq(ckstrdup(sp->text), VSTRFIXED | VTEXTFIXED);

        nextopt(nullstr); /* handle possible "--" */
        argv = argptr;

        if (!argv[0]) {
                /* bash says: "bash: .: filename argument required" */
                return 2; /* bash compat */
        }

        /* This aborts if file isn't found, which is POSIXly correct.
         * bash returns exitcode 1 instead.
         */
        fullname = find_dot_file(argv[0]);
        argv++;
        if (argv[0]) { /* . FILE ARGS, ARGS exist */
                int argc;
                saveparam = shellparam;
                shellparam.malloced = 0;
                argc = 1;
                while (argv[argc])
                        argc++;
                shellparam.nparam = argc;
                shellparam.p = argv;
        };

        /* This aborts if file can't be opened, which is POSIXly correct.
         * bash returns exitcode 1 instead.
         */
        setinputfile(fullname, INPUT_PUSH_FILE);
        commandname = fullname;
        status = cmdloop(0);
        popfile();

        if (argv[0]) {
                freeparam(&shellparam);
                shellparam = saveparam;
        };

        return status;
}

static int FAST_FUNC
exitcmd(int argc UNUSED_PARAM, char **argv)
{
        if (stoppedjobs())
                return 0;
        if (argv[1])
                exitstatus = number(argv[1]);
        raise_exception(EXEXIT);
        /* NOTREACHED */
}

/*
 * Read a file containing shell functions.
 */
static void
readcmdfile(char *name)
{
        setinputfile(name, INPUT_PUSH_FILE);
        cmdloop(0);
        popfile();
}


/* ============ find_command inplementation */

/*
 * Resolve a command name.  If you change this routine, you may have to
 * change the shellexec routine as well.
 */
static void
find_command(char *name, struct cmdentry *entry, int act, const char *path)
{
        struct tblentry *cmdp;
        int idx;
        int prev;
        char *fullname;
        struct stat statb;
        int e;
        int updatetbl;
        struct builtincmd *bcmd;

        /* If name contains a slash, don't use PATH or hash table */
        if (strchr(name, '/') != NULL) {
                entry->u.index = -1;
                if (act & DO_ABS) {
                        while (stat(name, &statb) < 0) {
#ifdef SYSV
                                if (errno == EINTR)
                                        continue;
#endif
                                entry->cmdtype = CMDUNKNOWN;
                                return;
                        }
                }
                entry->cmdtype = CMDNORMAL;
                return;
        }

/* #if ENABLE_FEATURE_SH_STANDALONE... moved after builtin check */

        updatetbl = (path == pathval());
        if (!updatetbl) {
                act |= DO_ALTPATH;
                if (strstr(path, "%builtin") != NULL)
                        act |= DO_ALTBLTIN;
        }

        /* If name is in the table, check answer will be ok */
        cmdp = cmdlookup(name, 0);
        if (cmdp != NULL) {
                int bit;

                switch (cmdp->cmdtype) {
                default:
#if DEBUG
                        abort();
#endif
                case CMDNORMAL:
                        bit = DO_ALTPATH;
                        break;
                case CMDFUNCTION:
                        bit = DO_NOFUNC;
                        break;
                case CMDBUILTIN:
                        bit = DO_ALTBLTIN;
                        break;
                }
                if (act & bit) {
                        updatetbl = 0;
                        cmdp = NULL;
                } else if (cmdp->rehash == 0)
                        /* if not invalidated by cd, we're done */
                        goto success;
        }

        /* If %builtin not in path, check for builtin next */
        bcmd = find_builtin(name);
        if (bcmd) {
                if (IS_BUILTIN_REGULAR(bcmd))
                        goto builtin_success;
                if (act & DO_ALTPATH) {
                        if (!(act & DO_ALTBLTIN))
                                goto builtin_success;
                } else if (builtinloc <= 0) {
                        goto builtin_success;
                }
        }

#if ENABLE_FEATURE_SH_STANDALONE
        {
                int applet_no = find_applet_by_name(name);
                if (applet_no >= 0) {
                        entry->cmdtype = CMDNORMAL;
                        entry->u.index = -2 - applet_no;
                        return;
                }
        }
#endif

        /* We have to search path. */
        prev = -1;              /* where to start */
        if (cmdp && cmdp->rehash) {     /* doing a rehash */
                if (cmdp->cmdtype == CMDBUILTIN)
                        prev = builtinloc;
                else
                        prev = cmdp->param.index;
        }

        e = ENOENT;
        idx = -1;
 loop:
        while ((fullname = path_advance(&path, name)) != NULL) {
                stunalloc(fullname);
                /* NB: code below will still use fullname
                 * despite it being "unallocated" */
                idx++;
                if (pathopt) {
                        if (prefix(pathopt, "builtin")) {
                                if (bcmd)
                                        goto builtin_success;
                                continue;
                        }
                        if ((act & DO_NOFUNC)
                         || !prefix(pathopt, "func")
                        ) {     /* ignore unimplemented options */
                                continue;
                        }
                }
                /* if rehash, don't redo absolute path names */
                if (fullname[0] == '/' && idx <= prev) {
                        if (idx < prev)
                                continue;
                        TRACE(("searchexec \"%s\": no change\n", name));
                        goto success;
                }
                while (stat(fullname, &statb) < 0) {
#ifdef SYSV
                        if (errno == EINTR)
                                continue;
#endif
                        if (errno != ENOENT && errno != ENOTDIR)
                                e = errno;
                        goto loop;
                }
                e = EACCES;     /* if we fail, this will be the error */
                if (!S_ISREG(statb.st_mode))
                        continue;
                if (pathopt) {          /* this is a %func directory */
                        stalloc(strlen(fullname) + 1);
                        /* NB: stalloc will return space pointed by fullname
                         * (because we don't have any intervening allocations
                         * between stunalloc above and this stalloc) */
                        readcmdfile(fullname);
                        cmdp = cmdlookup(name, 0);
                        if (cmdp == NULL || cmdp->cmdtype != CMDFUNCTION)
                                ash_msg_and_raise_error("%s not defined in %s", name, fullname);
                        stunalloc(fullname);
                        goto success;
                }
                TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
                if (!updatetbl) {
                        entry->cmdtype = CMDNORMAL;
                        entry->u.index = idx;
                        return;
                }
                INT_OFF;
                cmdp = cmdlookup(name, 1);
                cmdp->cmdtype = CMDNORMAL;
                cmdp->param.index = idx;
                INT_ON;
                goto success;
        }

        /* We failed.  If there was an entry for this command, delete it */
        if (cmdp && updatetbl)
                delete_cmd_entry();
        if (act & DO_ERR)
                ash_msg("%s: %s", name, errmsg(e, "not found"));
        entry->cmdtype = CMDUNKNOWN;
        return;

 builtin_success:
        if (!updatetbl) {
                entry->cmdtype = CMDBUILTIN;
                entry->u.cmd = bcmd;
                return;
        }
        INT_OFF;
        cmdp = cmdlookup(name, 1);
        cmdp->cmdtype = CMDBUILTIN;
        cmdp->param.cmd = bcmd;
        INT_ON;
 success:
        cmdp->rehash = 0;
        entry->cmdtype = cmdp->cmdtype;
        entry->u = cmdp->param;
}


/*
 * The trap builtin.
 */
static int FAST_FUNC
trapcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        char *action;
        char **ap;
        int signo, exitcode;

        nextopt(nullstr);
        ap = argptr;
        if (!*ap) {
                for (signo = 0; signo < NSIG; signo++) {
                        char *tr = trap_ptr[signo];
                        if (tr) {
                                /* note: bash adds "SIG", but only if invoked
                                 * as "bash". If called as "sh", or if set -o posix,
                                 * then it prints short signal names.
                                 * We are printing short names: */
                                out1fmt("trap -- %s %s\n",
                                                single_quote(tr),
                                                get_signame(signo));
                /* trap_ptr != trap only if we are in special-cased `trap` code.
                 * In this case, we will exit very soon, no need to free(). */
                                /* if (trap_ptr != trap && tp[0]) */
                                /*      free(tr); */
                        }
                }
                /*
                if (trap_ptr != trap) {
                        free(trap_ptr);
                        trap_ptr = trap;
                }
                */
                return 0;
        }

        action = NULL;
        if (ap[1])
                action = *ap++;
        exitcode = 0;
        while (*ap) {
                signo = get_signum(*ap);
                if (signo < 0) {
                        /* Mimic bash message exactly */
                        ash_msg("%s: invalid signal specification", *ap);
                        exitcode = 1;
                        goto next;
                }
                INT_OFF;
                if (action) {
                        if (LONE_DASH(action))
                                action = NULL;
                        else {
                                if (action[0]) /* not NULL and not "" and not "-" */
                                        may_have_traps = 1;
                                action = ckstrdup(action);
                        }
                }
                free(trap[signo]);
                trap[signo] = action;
                if (signo != 0)
                        setsignal(signo);
                INT_ON;
 next:
                ap++;
        }
        return exitcode;
}


/* ============ Builtins */

#if ENABLE_ASH_HELP
static int FAST_FUNC
helpcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        unsigned col;
        unsigned i;

        out1fmt(
                "Built-in commands:\n"
                "------------------\n");
        for (col = 0, i = 0; i < ARRAY_SIZE(builtintab); i++) {
                col += out1fmt("%c%s", ((col == 0) ? '\t' : ' '),
                                        builtintab[i].name + 1);
                if (col > 60) {
                        out1fmt("\n");
                        col = 0;
                }
        }
# if ENABLE_FEATURE_SH_STANDALONE
        {
                const char *a = applet_names;
                while (*a) {
                        col += out1fmt("%c%s", ((col == 0) ? '\t' : ' '), a);
                        if (col > 60) {
                                out1fmt("\n");
                                col = 0;
                        }
                        while (*a++ != '\0')
                                continue;
                }
        }
# endif
        newline_and_flush(stdout);
        return EXIT_SUCCESS;
}
#endif

#if MAX_HISTORY
static int FAST_FUNC
historycmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        show_history(line_input_state);
        return EXIT_SUCCESS;
}
#endif

/*
 * The export and readonly commands.
 */
static int FAST_FUNC
exportcmd(int argc UNUSED_PARAM, char **argv)
{
        struct var *vp;
        char *name;
        const char *p;
        char **aptr;
        char opt;
        int flag;
        int flag_off;

        /* "readonly" in bash accepts, but ignores -n.
         * We do the same: it saves a conditional in nextopt's param.
         */
        flag_off = 0;
        while ((opt = nextopt("np")) != '\0') {
                if (opt == 'n')
                        flag_off = VEXPORT;
        }
        flag = VEXPORT;
        if (argv[0][0] == 'r') {
                flag = VREADONLY;
                flag_off = 0; /* readonly ignores -n */
        }
        flag_off = ~flag_off;

        /*if (opt_p_not_specified) - bash doesnt check this. Try "export -p NAME" */
        {
                aptr = argptr;
                name = *aptr;
                if (name) {
                        do {
                                p = strchr(name, '=');
                                if (p != NULL) {
                                        p++;
                                } else {
                                        vp = *findvar(hashvar(name), name);
                                        if (vp) {
                                                vp->flags = ((vp->flags | flag) & flag_off);
                                                continue;
                                        }
                                }
                                setvar(name, p, (flag & flag_off));
                        } while ((name = *++aptr) != NULL);
                        return 0;
                }
        }

        /* No arguments. Show the list of exported or readonly vars.
         * -n is ignored.
         */
        showvars(argv[0], flag, 0);
        return 0;
}

/*
 * Delete a function if it exists.
 */
static void
unsetfunc(const char *name)
{
        struct tblentry *cmdp;

        cmdp = cmdlookup(name, 0);
        if (cmdp != NULL && cmdp->cmdtype == CMDFUNCTION)
                delete_cmd_entry();
}

/*
 * The unset builtin command.  We unset the function before we unset the
 * variable to allow a function to be unset when there is a readonly variable
 * with the same name.
 */
static int FAST_FUNC
unsetcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        char **ap;
        int i;
        int flag = 0;
        int ret = 0;

        while ((i = nextopt("vf")) != 0) {
                flag = i;
        }

        for (ap = argptr; *ap; ap++) {
                if (flag != 'f') {
                        i = unsetvar(*ap);
                        ret |= i;
                        if (!(i & 2))
                                continue;
                }
                if (flag != 'v')
                        unsetfunc(*ap);
        }
        return ret & 1;
}

static const unsigned char timescmd_str[] ALIGN1 = {
        ' ',  offsetof(struct tms, tms_utime),
        '\n', offsetof(struct tms, tms_stime),
        ' ',  offsetof(struct tms, tms_cutime),
        '\n', offsetof(struct tms, tms_cstime),
        0
};
static int FAST_FUNC
timescmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        unsigned long clk_tck, s, t;
        const unsigned char *p;
        struct tms buf;

        clk_tck = bb_clk_tck();
        times(&buf);

        p = timescmd_str;
        do {
                t = *(clock_t *)(((char *) &buf) + p[1]);
                s = t / clk_tck;
                t = t % clk_tck;
                out1fmt("%lum%lu.%03lus%c",
                        s / 60, s % 60,
                        (t * 1000) / clk_tck,
                        p[0]);
                p += 2;
        } while (*p);

        return 0;
}

#if ENABLE_SH_MATH_SUPPORT
/*
 * The let builtin. Partially stolen from GNU Bash, the Bourne Again SHell.
 * Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.
 *
 * Copyright (C) 2003 Vladimir Oleynik <dzo@simtreas.ru>
 */
static int FAST_FUNC
letcmd(int argc UNUSED_PARAM, char **argv)
{
        arith_t i;

        argv++;
        if (!*argv)
                ash_msg_and_raise_error("expression expected");
        do {
                i = ash_arith(*argv);
        } while (*++argv);

        return !i;
}
#endif

/*
 * The read builtin. Options:
 *      -r              Do not interpret '\' specially
 *      -s              Turn off echo (tty only)
 *      -n NCHARS       Read NCHARS max
 *      -p PROMPT       Display PROMPT on stderr (if input is from tty)
 *      -t SECONDS      Timeout after SECONDS (tty or pipe only)
 *      -u FD           Read from given FD instead of fd 0
 * This uses unbuffered input, which may be avoidable in some cases.
 * TODO: bash also has:
 *      -a ARRAY        Read into array[0],[1],etc
 *      -d DELIM        End on DELIM char, not newline
 *      -e              Use line editing (tty only)
 */
static int FAST_FUNC
readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        char *opt_n = NULL;
        char *opt_p = NULL;
        char *opt_t = NULL;
        char *opt_u = NULL;
        int read_flags = 0;
        const char *r;
        int i;

        while ((i = nextopt("p:u:rt:n:s")) != '\0') {
                switch (i) {
                case 'p':
                        opt_p = optionarg;
                        break;
                case 'n':
                        opt_n = optionarg;
                        break;
                case 's':
                        read_flags |= BUILTIN_READ_SILENT;
                        break;
                case 't':
                        opt_t = optionarg;
                        break;
                case 'r':
                        read_flags |= BUILTIN_READ_RAW;
                        break;
                case 'u':
                        opt_u = optionarg;
                        break;
                default:
                        break;
                }
        }

        /* "read -s" needs to save/restore termios, can't allow ^C
         * to jump out of it.
         */
        INT_OFF;
        r = shell_builtin_read(setvar0,
                argptr,
                bltinlookup("IFS"), /* can be NULL */
                read_flags,
                opt_n,
                opt_p,
                opt_t,
                opt_u
        );
        INT_ON;

        if ((uintptr_t)r > 1)
                ash_msg_and_raise_error(r);

        return (uintptr_t)r;
}

static int FAST_FUNC
umaskcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        static const char permuser[3] ALIGN1 = "ogu";

        mode_t mask;
        int symbolic_mode = 0;

        while (nextopt("S") != '\0') {
                symbolic_mode = 1;
        }

        INT_OFF;
        mask = umask(0);
        umask(mask);
        INT_ON;

        if (*argptr == NULL) {
                if (symbolic_mode) {
                        char buf[sizeof(",u=rwx,g=rwx,o=rwx")];
                        char *p = buf;
                        int i;

                        i = 2;
                        for (;;) {
                                *p++ = ',';
                                *p++ = permuser[i];
                                *p++ = '=';
                                /* mask is 0..0uuugggooo. i=2 selects uuu bits */
                                if (!(mask & 0400)) *p++ = 'r';
                                if (!(mask & 0200)) *p++ = 'w';
                                if (!(mask & 0100)) *p++ = 'x';
                                mask <<= 3;
                                if (--i < 0)
                                        break;
                        }
                        *p = '\0';
                        puts(buf + 1);
                } else {
                        out1fmt("%04o\n", mask);
                }
        } else {
                char *modestr = *argptr;
                /* numeric umasks are taken as-is */
                /* symbolic umasks are inverted: "umask a=rx" calls umask(222) */
                if (!isdigit(modestr[0]))
                        mask ^= 0777;
                mask = bb_parse_mode(modestr, mask);
                if ((unsigned)mask > 0777) {
                        ash_msg_and_raise_error("illegal mode: %s", modestr);
                }
                if (!isdigit(modestr[0]))
                        mask ^= 0777;
                umask(mask);
        }
        return 0;
}

static int FAST_FUNC
ulimitcmd(int argc UNUSED_PARAM, char **argv)
{
        return shell_builtin_ulimit(argv);
}

/* ============ main() and helpers */

/*
 * Called to exit the shell.
 */
static void
exitshell(void)
{
        struct jmploc loc;
        char *p;
        int status;

#if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
        save_history(line_input_state);
#endif
        status = exitstatus;
        TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
        if (setjmp(loc.loc)) {
                if (exception_type == EXEXIT)
                        status = exitstatus;
                goto out;
        }
        exception_handler = &loc;
        p = trap[0];
        if (p) {
                trap[0] = NULL;
                evalskip = 0;
                evalstring(p, 0);
                /*free(p); - we'll exit soon */
        }
 out:
        /* dash wraps setjobctl(0) in "if (setjmp(loc.loc) == 0) {...}".
         * our setjobctl(0) does not panic if tcsetpgrp fails inside it.
         */
        setjobctl(0);
        flush_stdout_stderr();
        _exit(status);
        /* NOTREACHED */
}

static void
init(void)
{
        /* we will never free this */
        basepf.next_to_pgetc = basepf.buf = ckmalloc(IBUFSIZ);

        sigmode[SIGCHLD - 1] = S_DFL;
        setsignal(SIGCHLD);

        /* bash re-enables SIGHUP which is SIG_IGNed on entry.
         * Try: "trap '' HUP; bash; echo RET" and type "kill -HUP $$"
         */
        signal(SIGHUP, SIG_DFL);

        {
                char **envp;
                const char *p;
                struct stat st1, st2;

                initvar();
                for (envp = environ; envp && *envp; envp++) {
                        p = endofname(*envp);
                        if (p != *envp && *p == '=') {
                                setvareq(*envp, VEXPORT|VTEXTFIXED);
                        }
                }

                setvareq((char*)defoptindvar, VTEXTFIXED);

                setvar0("PPID", utoa(getppid()));
#if ENABLE_ASH_BASH_COMPAT
                p = lookupvar("SHLVL");
                setvar("SHLVL", utoa((p ? atoi(p) : 0) + 1), VEXPORT);
                if (!lookupvar("HOSTNAME")) {
                        struct utsname uts;
                        uname(&uts);
                        setvar0("HOSTNAME", uts.nodename);
                }
#endif
                p = lookupvar("PWD");
                if (p) {
                        if (p[0] != '/' || stat(p, &st1) || stat(".", &st2)
                         || st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino
                        ) {
                                p = NULL;
                        }
                }
                setpwd(p, 0);
        }
}


//usage:#define ash_trivial_usage
//usage:        "[-/+OPTIONS] [-/+o OPT]... [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]"
//usage:#define ash_full_usage "\n\n"
//usage:        "Unix shell interpreter"

//usage:#if ENABLE_FEATURE_SH_IS_ASH
//usage:# define sh_trivial_usage ash_trivial_usage
//usage:# define sh_full_usage    ash_full_usage
//usage:#endif
//usage:#if ENABLE_FEATURE_BASH_IS_ASH
//usage:# define bash_trivial_usage ash_trivial_usage
//usage:# define bash_full_usage    ash_full_usage
//usage:#endif

/*
 * Process the shell command line arguments.
 */
static void
procargs(char **argv)
{
        int i;
        const char *xminusc;
        char **xargv;

        xargv = argv;
        arg0 = xargv[0];
        /* if (xargv[0]) - mmm, this is always true! */
                xargv++;
        for (i = 0; i < NOPTS; i++)
                optlist[i] = 2;
        argptr = xargv;
        if (options(/*cmdline:*/ 1)) {
                /* it already printed err message */
                raise_exception(EXERROR);
        }
        xargv = argptr;
        xminusc = minusc;
        if (*xargv == NULL) {
                if (xminusc)
                        ash_msg_and_raise_error(bb_msg_requires_arg, "-c");
                sflag = 1;
        }
        if (iflag == 2 && sflag == 1 && isatty(0) && isatty(1))
                iflag = 1;
        if (mflag == 2)
                mflag = iflag;
        for (i = 0; i < NOPTS; i++)
                if (optlist[i] == 2)
                        optlist[i] = 0;
#if DEBUG == 2
        debug = 1;
#endif
        /* POSIX 1003.2: first arg after -c cmd is $0, remainder $1... */
        if (xminusc) {
                minusc = *xargv++;
                if (*xargv)
                        goto setarg0;
        } else if (!sflag) {
                setinputfile(*xargv, 0);
 setarg0:
                arg0 = *xargv++;
                commandname = arg0;
        }

        shellparam.p = xargv;
#if ENABLE_ASH_GETOPTS
        shellparam.optind = 1;
        shellparam.optoff = -1;
#endif
        /* assert(shellparam.malloced == 0 && shellparam.nparam == 0); */
        while (*xargv) {
                shellparam.nparam++;
                xargv++;
        }
        optschanged();
}

/*
 * Read /etc/profile, ~/.profile, $ENV.
 */
static void
read_profile(const char *name)
{
        name = expandstr(name);
        if (setinputfile(name, INPUT_PUSH_FILE | INPUT_NOFILE_OK) < 0)
                return;
        cmdloop(0);
        popfile();
}

/*
 * This routine is called when an error or an interrupt occurs in an
 * interactive shell and control is returned to the main command loop.
 * (In dash, this function is auto-generated by build machinery).
 */
static void
reset(void)
{
        /* from eval.c: */
        evalskip = 0;
        loopnest = 0;

        /* from expand.c: */
        ifsfree();

        /* from input.c: */
        g_parsefile->left_in_buffer = 0;
        g_parsefile->left_in_line = 0;      /* clear input buffer */
        popallfiles();

        /* from redir.c: */
        while (redirlist)
                popredir(/*drop:*/ 0, /*restore:*/ 0);
}

#if PROFILE
static short profile_buf[16384];
extern int etext();
#endif

/*
 * Main routine.  We initialize things, parse the arguments, execute
 * profiles if we're a login shell, and then call cmdloop to execute
 * commands.  The setjmp call sets up the location to jump to when an
 * exception occurs.  When an exception occurs the variable "state"
 * is used to figure out how far we had gotten.
 */
int ash_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int ash_main(int argc UNUSED_PARAM, char **argv)
{
        volatile smallint state;
        struct jmploc jmploc;
        struct stackmark smark;

        /* Initialize global data */
        INIT_G_misc();
        INIT_G_memstack();
        INIT_G_var();
#if ENABLE_ASH_ALIAS
        INIT_G_alias();
#endif
        INIT_G_cmdtable();

#if PROFILE
        monitor(4, etext, profile_buf, sizeof(profile_buf), 50);
#endif

#if ENABLE_FEATURE_EDITING
        line_input_state = new_line_input_t(FOR_SHELL | WITH_PATH_LOOKUP);
#endif
        state = 0;
        if (setjmp(jmploc.loc)) {
                smallint e;
                smallint s;

                reset();

                e = exception_type;
                s = state;
                if (e == EXEXIT || s == 0 || iflag == 0 || shlvl) {
                        exitshell();
                }
                if (e == EXINT) {
                        newline_and_flush(stderr);
                }

                popstackmark(&smark);
                FORCE_INT_ON; /* enable interrupts */
                if (s == 1)
                        goto state1;
                if (s == 2)
                        goto state2;
                if (s == 3)
                        goto state3;
                goto state4;
        }
        exception_handler = &jmploc;
        rootpid = getpid();

        init();
        setstackmark(&smark);
        procargs(argv);
#if DEBUG
        TRACE(("Shell args: "));
        trace_puts_args(argv);
#endif

        if (argv[0] && argv[0][0] == '-')
                isloginsh = 1;
        if (isloginsh) {
                const char *hp;

                state = 1;
                read_profile("/etc/profile");
 state1:
                state = 2;
                hp = lookupvar("HOME");
                if (hp)
                        read_profile("$HOME/.profile");
        }
 state2:
        state = 3;
        if (
#ifndef linux
         getuid() == geteuid() && getgid() == getegid() &&
#endif
         iflag
        ) {
                const char *shinit = lookupvar("ENV");
                if (shinit != NULL && *shinit != '\0')
                        read_profile(shinit);
        }
        popstackmark(&smark);
 state3:
        state = 4;
        if (minusc) {
                /* evalstring pushes parsefile stack.
                 * Ensure we don't falsely claim that 0 (stdin)
                 * is one of stacked source fds.
                 * Testcase: ash -c 'exec 1>&0' must not complain. */
                // if (!sflag) g_parsefile->pf_fd = -1;
                // ^^ not necessary since now we special-case fd 0
                // in is_hidden_fd() to not be considered "hidden fd"
                evalstring(minusc, 0);
        }

        if (sflag || minusc == NULL) {
#if MAX_HISTORY > 0 && ENABLE_FEATURE_EDITING_SAVEHISTORY
                if (iflag) {
                        const char *hp = lookupvar("HISTFILE");
                        if (!hp) {
                                hp = lookupvar("HOME");
                                if (hp) {
                                        hp = concat_path_file(hp, ".ash_history");
                                        setvar0("HISTFILE", hp);
                                        free((char*)hp);
                                        hp = lookupvar("HISTFILE");
                                }
                        }
                        if (hp)
                                line_input_state->hist_file = hp;
# if ENABLE_FEATURE_SH_HISTFILESIZE
                        hp = lookupvar("HISTFILESIZE");
                        line_input_state->max_history = size_from_HISTFILESIZE(hp);
# endif
                }
#endif
 state4: /* XXX ??? - why isn't this before the "if" statement */
                cmdloop(1);
        }
#if PROFILE
        monitor(0);
#endif
#ifdef GPROF
        {
                extern void _mcleanup(void);
                _mcleanup();
        }
#endif
        TRACE(("End of main reached\n"));
        exitshell();
        /* NOTREACHED */
}


/*-
 * Copyright (c) 1989, 1991, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */