hush: fix \<newline> handling
[oweals/busybox.git] / shell / ash.c
index f99c5093326b5bebeb5468aa636c3752a7d79330..b27b2777ea5975e0c2ddd4ba26c9e21f0e4e5ca5 100644 (file)
  */
 
 /*
- * rewrite arith.y to micro stack based cryptic algorithm by
- * Copyright (c) 2001 Aaron Lehmann <aaronl@vitelus.com>
- *
- * Modified by Paul Mundt <lethal@linux-sh.org> (c) 2004 to support
- * dynamic variables.
- *
- * Modified by Vladimir Oleynik <dzo@simtreas.ru> (c) 2001-2005 to be
- * used in busybox and size optimizations,
- * rewrote arith (see notes to this), added locale support,
- * rewrote dynamic variables.
- */
-
-/*
- * The follow should be set to reflect the type of system you have:
+ * 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)
  * 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 PROFILE 0
 
 #define IFS_BROKEN
 #define JOBS ENABLE_ASH_JOB_CONTROL
 
 #if DEBUG
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
+# ifndef _GNU_SOURCE
+#  define _GNU_SOURCE
+# endif
 #endif
 
 #include "busybox.h" /* for applet_names */
+//TODO: pull in some .h and find out do we have SINGLE_APPLET_MAIN?
+//#include "applet_tables.h" doesn't work
 #include <paths.h>
 #include <setjmp.h>
 #include <fnmatch.h>
-#if JOBS || ENABLE_ASH_READ_NCHARS
-#include <termios.h>
+#include "math.h"
+
+#if defined SINGLE_APPLET_MAIN
+/* 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 */
+# define PIPE_BUF 4096           /* amount of buffering in a pipe */
 #endif
 
 #if defined(__uClinux__)
-#error "Do not even bother, ash will not run on uClinux"
+# error "Do not even bother, ash will not run on NOMMU machine"
 #endif
 
 
 #define CMDTABLESIZE 31         /* should be prime */
 
 
-/* ============ Misc helpers */
-
-#define xbarrier() do { __asm__ __volatile__ ("": : :"memory"); } while (0)
-
-/* C99 say: "char" declaration may be signed or unsigned default */
-#define signed_char2int(sc) ((int)((signed char)sc))
-
-
 /* ============ Shell options */
 
 static const char *const optletters_optnames[] = {
@@ -122,7 +117,7 @@ static const char illnum[] ALIGN1 = "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
+ * 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
@@ -152,10 +147,13 @@ struct globals_misc {
 //     /* do we generate EXSIG events */
 //     int exsig; /* counter */
        volatile int suppressint; /* counter */
+// TODO: rename
+// pendingsig -> pending_sig
+// intpending -> pending_int
        volatile /*sig_atomic_t*/ smallint intpending; /* 1 = got SIGINT */
        /* last pending signal */
        volatile /*sig_atomic_t*/ smallint pendingsig;
-       smallint exception; /* kind of exception (0..5) */
+       smallint exception_type; /* kind of exception (0..5) */
        /* exceptions */
 #define EXINT 0         /* SIGINT received */
 #define EXERROR 1       /* a generic error */
@@ -191,17 +189,16 @@ struct globals_misc {
        /*
         * 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,
+        * 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_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 permenantly */
-#define S_RESET 5               /* temporary - to reset a hard ignored sig */
 
        /* indicates specified signal received */
-       char gotsig[NSIG - 1]; /* offset by 1: "signal" 0 is meaningless */
+       uint8_t gotsig[NSIG - 1]; /* offset by 1: "signal" 0 is meaningless */
        char *trap[NSIG];
 
        /* Rarely referenced stuff */
@@ -222,7 +219,7 @@ extern struct globals_misc *const ash_ptr_to_globals_misc;
 #define physdir     (G_misc.physdir    )
 #define arg0        (G_misc.arg0       )
 #define exception_handler (G_misc.exception_handler)
-#define exception         (G_misc.exception        )
+#define exception_type    (G_misc.exception_type   )
 #define suppressint       (G_misc.suppressint      )
 #define intpending        (G_misc.intpending       )
 //#define exsig             (G_misc.exsig            )
@@ -245,7 +242,30 @@ extern struct globals_misc *const ash_ptr_to_globals_misc;
 } 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(%x)", \
+                       __LINE__, dfd, dfd); \
+} while (0)
+#else
+# define TRACE(param)
+# define TRACEV(param)
+#endif
+
+
 /* ============ Utility functions */
+#define xbarrier() do { __asm__ __volatile__ ("": : :"memory"); } while (0)
+
+/* C99 say: "char" declaration may be signed or unsigned by default */
+#define signed_char2int(sc) ((int)(signed char)(sc))
+
 static int isdigit_str9(const char *str)
 {
        int maxlen = 9 + 1; /* max 9 digits: 999999999 */
@@ -270,7 +290,7 @@ static int isdigit_str9(const char *str)
 /*
  * 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".
+ * stored in the global variable "exception_type".
  */
 static void raise_exception(int) NORETURN;
 static void
@@ -281,9 +301,15 @@ raise_exception(int e)
                abort();
 #endif
        INT_OFF;
-       exception = e;
+       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 from trap.c when a SIGINT is received.  (If the user specifies
@@ -296,7 +322,7 @@ static void raise_interrupt(void) NORETURN;
 static void
 raise_interrupt(void)
 {
-       int i;
+       int ex_type;
 
        intpending = 0;
        /* Signal is not automatically unmasked after it is raised,
@@ -304,49 +330,43 @@ raise_interrupt(void)
        sigprocmask_allsigs(SIG_UNBLOCK);
        /* pendingsig = 0; - now done in onsig() */
 
-       i = EXSIG;
+       ex_type = EXSIG;
        if (gotsig[SIGINT - 1] && !trap[SIGINT]) {
                if (!(rootshell && iflag)) {
                        /* Kill ourself with SIGINT */
                        signal(SIGINT, SIG_DFL);
                        raise(SIGINT);
                }
-               i = EXINT;
+               ex_type = EXINT;
        }
-       raise_exception(i);
+       raise_exception(ex_type);
        /* NOTREACHED */
 }
+#if DEBUG
+#define raise_interrupt() do { \
+       TRACE(("raising interrupt on line %d\n", __LINE__)); \
+       raise_interrupt(); \
+} while (0)
+#endif
 
-#if ENABLE_ASH_OPTIMIZE_FOR_SIZE
-static void
+static IF_ASH_OPTIMIZE_FOR_SIZE(inline) void
 int_on(void)
 {
+       xbarrier();
        if (--suppressint == 0 && intpending) {
                raise_interrupt();
        }
 }
 #define INT_ON int_on()
-static void
+static IF_ASH_OPTIMIZE_FOR_SIZE(inline) void
 force_int_on(void)
 {
+       xbarrier();
        suppressint = 0;
        if (intpending)
                raise_interrupt();
 }
 #define FORCE_INT_ON force_int_on()
-#else
-#define INT_ON do { \
-       xbarrier(); \
-       if (--suppressint == 0 && intpending) \
-               raise_interrupt(); \
-} while (0)
-#define FORCE_INT_ON do { \
-       xbarrier(); \
-       suppressint = 0; \
-       if (intpending) \
-               raise_interrupt(); \
-} while (0)
-#endif /* ASH_OPTIMIZE_FOR_SIZE */
 
 #define SAVE_INT(v) ((v) = suppressint)
 
@@ -357,36 +377,6 @@ force_int_on(void)
                raise_interrupt(); \
 } while (0)
 
-/*
- * Ignore a signal. Only one usage site - in forkchild()
- */
-static void
-ignoresig(int signo)
-{
-       if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
-               signal(signo, SIG_IGN);
-       }
-       sigmode[signo - 1] = S_HARD_IGN;
-}
-
-/*
- * Signal handler. Only one usage site - in setsignal()
- */
-static void
-onsig(int signo)
-{
-       gotsig[signo - 1] = 1;
-       pendingsig = signo;
-
-       if (/* exsig || */ (signo == SIGINT && !trap[SIGINT])) {
-               if (!suppressint) {
-                       pendingsig = 0;
-                       raise_interrupt(); /* does not return */
-               }
-               intpending = 1;
-       }
-}
-
 
 /* ============ Stdout/stderr output */
 
@@ -684,6 +674,12 @@ trace_printf(const char *fmt, ...)
 
        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) ", pendingsig, intpending, suppressint);
        va_start(va, fmt);
        vfprintf(tracefile, fmt, va);
        va_end(va);
@@ -694,6 +690,12 @@ trace_vprintf(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) ", pendingsig, intpending, suppressint);
        vfprintf(tracefile, fmt, va);
 }
 
@@ -998,14 +1000,6 @@ showtree(union node *n)
        shtree(n, 1, NULL, stdout);
 }
 
-#define TRACE(param)    trace_printf param
-#define TRACEV(param)   trace_vprintf param
-
-#else
-
-#define TRACE(param)
-#define TRACEV(param)
-
 #endif /* DEBUG */
 
 
@@ -1023,8 +1017,8 @@ struct alias;
 
 struct strpush {
        struct strpush *prev;   /* preceding string on stack */
-       char *prevstring;
-       int prevnleft;
+       char *prev_string;
+       int prev_left_in_line;
 #if ENABLE_ASH_ALIAS
        struct alias *ap;       /* if push was associated with an alias */
 #endif
@@ -1035,9 +1029,9 @@ struct parsefile {
        struct parsefile *prev; /* preceding file on stack */
        int linno;              /* current line */
        int fd;                 /* file descriptor (or -1 if string) */
-       int nleft;              /* number of chars left in this line */
-       int lleft;              /* number of chars left in this buffer */
-       char *nextc;            /* next char in buffer */
+       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 */
@@ -1104,6 +1098,14 @@ ash_msg_and_raise_error(const char *msg, ...)
        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, ...)
@@ -1978,7 +1980,7 @@ findvar(struct var **vpp, const char *name)
 /*
  * Find the value of a variable.  Returns NULL if not set.
  */
-static char *
+static const char *
 lookupvar(const char *name)
 {
        struct var *v;
@@ -2004,7 +2006,7 @@ lookupvar(const char *name)
 /*
  * Search the environment of a builtin command.
  */
-static char *
+static const char *
 bltinlookup(const char *name)
 {
        struct strlist *sp;
@@ -2617,7 +2619,7 @@ pwdcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 #define USE_SIT_FUNCTION
 #endif
 
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
 static const char S_I_T[][4] = {
 #if ENABLE_ASH_ALIAS
        { CSPCL, CIGN, CIGN, CIGN },            /* 0, PEOA */
@@ -2661,7 +2663,7 @@ static const char S_I_T[][3] = {
        { CCTL, CCTL, CCTL }                    /* 14, CTLESC ... */
 #endif
 };
-#endif /* ASH_MATH_SUPPORT */
+#endif /* SH_MATH_SUPPORT */
 
 #ifdef USE_SIT_FUNCTION
 
@@ -2687,22 +2689,24 @@ SIT(int c, int syntax)
        const char *s;
        int indx;
 
-       if (c == PEOF)          /* 2^8+2 */
+       if (c == PEOF) {         /* 2^8+2 */
                return CENDFILE;
+       }
 #if ENABLE_ASH_ALIAS
-       if (c == PEOA)          /* 2^8+1 */
+       if (c == PEOA) {         /* 2^8+1 */
                indx = 0;
-       else
+       else
 #endif
-
-       if ((unsigned char)c >= (unsigned char)(CTLESC)
-        && (unsigned char)c <= (unsigned char)(CTLQUOTEMARK)
-       ) {
-               return CCTL;
-       } else {
+       {
+               if ((unsigned char)c >= (unsigned char)(CTLESC)
+                && (unsigned char)c <= (unsigned char)(CTLQUOTEMARK)
+               ) {
+                       return CCTL;
+               }
                s = strchrnul(spec_symbls, c);
-               if (*s == '\0')
+               if (*s == '\0') {
                        return CWORD;
+               }
                indx = syntax_index_table[s - spec_symbls];
        }
        return S_I_T[indx][syntax];
@@ -3007,7 +3011,7 @@ static const char syntax_index_table[258] = {
        /* 257   127      */ CWORD_CWORD_CWORD_CWORD,
 };
 
-#define SIT(c, syntax) (S_I_T[(int)syntax_index_table[((int)c)+SYNBASE]][syntax])
+#define SIT(c, syntax) (S_I_T[(int)syntax_index_table[(int)(c) + SYNBASE]][syntax])
 
 #endif  /* USE_SIT_FUNCTION */
 
@@ -3278,6 +3282,39 @@ 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;
+}
+
+/*
+ * Signal handler. Only one usage site - in setsignal()
+ */
+static void
+onsig(int signo)
+{
+       gotsig[signo - 1] = 1;
+
+       if (/* exsig || */ (signo == SIGINT && !trap[SIGINT])) {
+               if (!suppressint) {
+                       pendingsig = 0;
+                       raise_interrupt(); /* does not return */
+               }
+               intpending = 1;
+       } else {
+               pendingsig = signo;
+       }
+}
+
 /*
  * Set the signal handler for the specified signal.  The routine figures
  * out what it should be set to.
@@ -3285,81 +3322,90 @@ static void setjobctl(int);
 static void
 setsignal(int signo)
 {
-       int action;
-       char *t, tsig;
+       char *t;
+       char cur_act, new_act;
        struct sigaction act;
 
        t = trap[signo];
-       action = S_IGN;
-       if (t == NULL)
-               action = S_DFL;
-       else if (*t != '\0')
-               action = S_CATCH;
-       if (rootshell && action == S_DFL) {
+       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)
-                               action = S_CATCH;
+                               new_act = S_CATCH;
                        break;
                case SIGQUIT:
 #if DEBUG
                        if (debug)
                                break;
 #endif
-                       /* FALLTHROUGH */
+                       /* 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)
-                               action = S_IGN;
+                               new_act = S_IGN;
                        break;
 #if JOBS
                case SIGTSTP:
                case SIGTTOU:
                        if (mflag)
-                               action = S_IGN;
+                               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
 
        t = &sigmode[signo - 1];
-       tsig = *t;
-       if (tsig == 0) {
-               /*
-                * current setting unknown
-                */
-               if (sigaction(signo, NULL, &act) == -1) {
-                       /*
-                        * Pretend it worked; maybe we should give a warning
-                        * here, but other shells don't. We don't alter
-                        * sigmode, so that we retry every time.
-                        */
+       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;
                }
-               tsig = S_RESET; /* force to be set */
                if (act.sa_handler == SIG_IGN) {
-                       tsig = S_HARD_IGN;
+                       cur_act = S_HARD_IGN;
                        if (mflag
                         && (signo == SIGTSTP || signo == SIGTTIN || signo == SIGTTOU)
                        ) {
-                               tsig = S_IGN;   /* don't hard ignore these */
+                               cur_act = S_IGN;   /* don't hard ignore these */
                        }
                }
        }
-       if (tsig == S_HARD_IGN || tsig == action)
+       if (cur_act == S_HARD_IGN || cur_act == new_act)
                return;
+
        act.sa_handler = SIG_DFL;
-       switch (action) {
+       switch (new_act) {
        case S_CATCH:
                act.sa_handler = onsig;
+               act.sa_flags = 0; /* matters only if !DFL and !IGN */
+               sigfillset(&act.sa_mask); /* ditto */
                break;
        case S_IGN:
                act.sa_handler = SIG_IGN;
                break;
        }
-       *t = action;
-       act.sa_flags = 0;
-       sigfillset(&act.sa_mask);
        sigaction_set(signo, &act);
+
+       *t = new_act;
 }
 
 /* mode flags for set_curjob */
@@ -3779,16 +3825,11 @@ dowait(int wait_flags, struct job *job)
         * NB: _not_ safe_waitpid, we need to detect EINTR */
        pid = waitpid(-1, &status,
                        (doing_jobctl ? (wait_flags | WUNTRACED) : wait_flags));
-       TRACE(("wait returns pid=%d, status=0x%x\n", pid, status));
-
-       if (pid <= 0) {
-               /* If we were doing blocking wait and (probably) got EINTR,
-                * check for pending sigs received while waiting.
-                * (NB: can be moved into callers if needed) */
-               if (wait_flags == DOWAIT_BLOCK && pendingsig)
-                       raise_exception(EXSIG);
+       TRACE(("wait returns pid=%d, status=0x%x, errno=%d(%s)\n",
+                               pid, status, errno, strerror(errno)));
+       if (pid <= 0)
                return pid;
-       }
+
        INT_OFF;
        thisjob = NULL;
        for (jp = curjob; jp; jp = jp->prev_job) {
@@ -3860,6 +3901,15 @@ dowait(int wait_flags, struct job *job)
        return pid;
 }
 
+static int
+blocking_wait_with_raise_on_sig(struct job *job)
+{
+       pid_t pid = dowait(DOWAIT_BLOCK, job);
+       if (pid <= 0 && pendingsig)
+               raise_exception(EXSIG);
+       return pid;
+}
+
 #if JOBS
 static void
 showjob(FILE *out, struct job *jp, int mode)
@@ -3939,7 +3989,7 @@ showjobs(FILE *out, int mode)
 
        TRACE(("showjobs(%x) called\n", mode));
 
-       /* If not even one job changed, there is nothing to do */
+       /* Handle all finished jobs */
        while (dowait(DOWAIT_NONBLOCK, NULL) > 0)
                continue;
 
@@ -4031,7 +4081,14 @@ waitcmd(int argc UNUSED_PARAM, char **argv)
                                jp->waited = 1;
                                jp = jp->prev_job;
                        }
-                       dowait(DOWAIT_BLOCK, NULL);
+       /* 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."
+        * Do we do it that way? */
+                       blocking_wait_with_raise_on_sig(NULL);
                }
        }
 
@@ -4051,11 +4108,10 @@ waitcmd(int argc UNUSED_PARAM, char **argv)
                        job = getjob(*argv, 0);
                /* loop until process terminated or stopped */
                while (job->state == JOBRUNNING)
-                       dowait(DOWAIT_BLOCK, NULL);
+                       blocking_wait_with_raise_on_sig(NULL);
                job->waited = 1;
                retval = getstatus(job);
- repeat:
-               ;
+ repeat: ;
        } while (*++argv);
 
  ret:
@@ -4163,7 +4219,7 @@ cmdputs(const char *s)
        static const char vstype[VSTYPE + 1][3] = {
                "", "}", "-", "+", "?", "=",
                "%", "%%", "#", "##"
-               USE_ASH_BASH_COMPAT(, ":", "/", "//")
+               IF_ASH_BASH_COMPAT(, ":", "/", "//")
        };
 
        const char *p, *str;
@@ -4202,7 +4258,7 @@ cmdputs(const char *s)
                case CTLBACKQ+CTLQUOTE:
                        str = "\"$(...)\"";
                        goto dostr;
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
                case CTLARI:
                        str = "$((";
                        goto dostr;
@@ -4482,6 +4538,10 @@ forkchild(struct job *jp, /*union node *n,*/ int mode)
        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();
        clear_traps();
 #if JOBS
@@ -4494,8 +4554,8 @@ forkchild(struct job *jp, /*union node *n,*/ int mode)
                        pgrp = getpid();
                else
                        pgrp = jp->ps[0].pid;
-               /* This can fail because we are doing it in the parent also */
-               (void)setpgid(0, pgrp);
+               /* this can fail because we are doing it in the parent also */
+               setpgid(0, pgrp);
                if (mode == FORK_FG)
                        xtcsetpgrp(ttyfd, pgrp);
                setsignal(SIGTSTP);
@@ -4503,18 +4563,28 @@ forkchild(struct job *jp, /*union node *n,*/ int mode)
        } 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);
+                               ash_msg_and_raise_error("can't open '%s'", bb_dev_null);
                }
        }
-       if (!oldlvl && iflag) {
-               setsignal(SIGINT);
+       if (!oldlvl) {
+               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);
-               setsignal(SIGTERM);
        }
        for (jp = curjob; jp; jp = jp->prev_job)
                freejob(jp);
@@ -4586,12 +4656,12 @@ forkshell(struct job *jp, union node *n, int mode)
 /*
  * 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 inter-
- * active 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
+ * 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
@@ -4609,9 +4679,43 @@ 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) {
@@ -4747,12 +4851,10 @@ openhere(union node *redir)
        if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
                /* child */
                close(pip[0]);
-               signal(SIGINT, SIG_IGN);
-               signal(SIGQUIT, SIG_IGN);
-               signal(SIGHUP, SIG_IGN);
-#ifdef SIGTSTP
-               signal(SIGTSTP, SIG_IGN);
-#endif
+               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);
@@ -5031,7 +5133,9 @@ redirect(union node *redir, int flags)
                if (newfd < 0) {
                        /* NTOFD/NFROMFD: copy redir->ndup.dupfd to fd */
                        if (redir->ndup.dupfd < 0) { /* "fd>&-" */
-                               close(fd);
+                               /* Don't want to trigger debugging */
+                               if (fd != -1)
+                                       close(fd);
                        } else {
                                copyfd(redir->ndup.dupfd, fd | COPYFD_EXACT);
                        }
@@ -5084,7 +5188,7 @@ popredir(int drop, int restore)
                                /*close(fd);*/
                                copyfd(copy, fd | COPYFD_EXACT);
                        }
-                       close(copy);
+                       close(copy & ~COPYFD_RESTORE);
                }
        }
        redirlist = rp->next;
@@ -5127,7 +5231,7 @@ redirectsafe(union node *redir, int flags)
                redirect(redir, flags);
        }
        exception_handler = savehandler;
-       if (err && exception != EXERROR)
+       if (err && exception_type != EXERROR)
                longjmp(exception_handler->loc, 1);
        RESTORE_INT(saveint);
        return err;
@@ -5139,17 +5243,33 @@ redirectsafe(union node *redir, int flags)
  * We have to deal with backquotes, shell variables, and file metacharacters.
  */
 
-#if ENABLE_ASH_MATH_SUPPORT_64
-typedef int64_t arith_t;
-#define arith_t_type long long
-#else
-typedef long arith_t;
-#define arith_t_type long
-#endif
+#if ENABLE_SH_MATH_SUPPORT
+static arith_t
+ash_arith(const char *s)
+{
+       arith_eval_hooks_t math_hooks;
+       arith_t result;
+       int errcode = 0;
+
+       math_hooks.lookupvar = lookupvar;
+       math_hooks.setvar = setvar;
+       math_hooks.endofname = endofname;
+
+       INT_OFF;
+       result = arith(s, &errcode, &math_hooks);
+       if (errcode < 0) {
+               if (errcode == -3)
+                       ash_msg_and_raise_error("exponent less than 0");
+               if (errcode == -2)
+                       ash_msg_and_raise_error("divide by zero");
+               if (errcode == -5)
+                       ash_msg_and_raise_error("expression recursion loop detected");
+               raise_error_syntax(s);
+       }
+       INT_ON;
 
-#if ENABLE_ASH_MATH_SUPPORT
-static arith_t dash_arith(const char *);
-static arith_t arith(const char *expr, int *perrcode);
+       return result;
+}
 #endif
 
 /*
@@ -5209,11 +5329,7 @@ cvtnum(arith_t num)
        int len;
 
        expdest = makestrspace(32, expdest);
-#if ENABLE_ASH_MATH_SUPPORT_64
-       len = fmtstr(expdest, 32, "%lld", (long long) num);
-#else
-       len = fmtstr(expdest, 32, "%ld", num);
-#endif
+       len = fmtstr(expdest, 32, arith_t_fmt, num);
        STADJUST(len, expdest);
        return len;
 }
@@ -5482,9 +5598,8 @@ evalbackcmd(union node *n, struct backcmd *result)
        result->buf = NULL;
        result->nleft = 0;
        result->jp = NULL;
-       if (n == NULL) {
+       if (n == NULL)
                goto out;
-       }
 
        saveherefd = herefd;
        herefd = -1;
@@ -5578,7 +5693,7 @@ expbackq(union node *cmd, int quoted, int quotes)
                stackblock() + startloc));
 }
 
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
 /*
  * Expand arithmetic expression.  Backup to start of expression,
  * evaluate, place result in (backed up) result, adjust string position.
@@ -5591,7 +5706,7 @@ expari(int quotes)
        int flag;
        int len;
 
-       /*      ifsfree(); */
+       /* ifsfree(); */
 
        /*
         * This routine is slightly over-complicated for
@@ -5633,7 +5748,7 @@ expari(int quotes)
        if (quotes)
                rmescapes(p + 2);
 
-       len = cvtnum(dash_arith(p + 2));
+       len = cvtnum(ash_arith(p + 2));
 
        if (flag != '"')
                recordregion(begoff, begoff + len, 0);
@@ -5664,7 +5779,7 @@ argstr(char *p, int flag, struct strlist *var_str_list)
                CTLVAR,
                CTLBACKQ,
                CTLBACKQ | CTLQUOTE,
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
                CTLENDARI,
 #endif
                0
@@ -5701,7 +5816,7 @@ argstr(char *p, int flag, struct strlist *var_str_list)
                length += strcspn(p + length, reject);
                c = p[length];
                if (c && (!(c & 0x80)
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
                                        || c == CTLENDARI
 #endif
                   )) {
@@ -5779,7 +5894,7 @@ argstr(char *p, int flag, struct strlist *var_str_list)
                        expbackq(argbackq->n, c, quotes);
                        argbackq = argbackq->next;
                        goto start;
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
                case CTLENDARI:
                        p--;
                        expari(quotes);
@@ -5909,8 +6024,9 @@ varunset(const char *end, const char *var, const char *umsg, int varflags)
                if (*end == CTLENDVAR) {
                        if (varflags & VSNUL)
                                tail = " or null";
-               } else
+               } else {
                        msg = umsg;
+               }
        }
        ash_msg_and_raise_error("%.*s: %s%s", end - var - 1, var, msg, tail);
 }
@@ -5953,9 +6069,9 @@ subevalvar(char *p, char *str, int strloc, int subtype,
        char *startp;
        char *loc;
        char *rmesc, *rmescend;
-       USE_ASH_BASH_COMPAT(char *repl = NULL;)
-       USE_ASH_BASH_COMPAT(char null = '\0';)
-       USE_ASH_BASH_COMPAT(int pos, len, orig_len;)
+       IF_ASH_BASH_COMPAT(char *repl = NULL;)
+       IF_ASH_BASH_COMPAT(char null = '\0';)
+       IF_ASH_BASH_COMPAT(int pos, len, orig_len;)
        int saveherefd = herefd;
        int amount, workloc, resetloc;
        int zero;
@@ -6041,7 +6157,7 @@ subevalvar(char *p, char *str, int strloc, int subtype,
         * stack will need rebasing, and we'll need to remove our work
         * areas each time
         */
USE_ASH_BASH_COMPAT(restart:)
IF_ASH_BASH_COMPAT(restart:)
 
        amount = expdest - ((char *)stackblock() + resetloc);
        STADJUST(-amount, expdest);
@@ -6104,8 +6220,9 @@ subevalvar(char *p, char *str, int strloc, int subtype,
                                        idx++;
                                        rmesc++;
                                }
-                       } else
+                       } else {
                                idx = loc;
+                       }
 
                        for (loc = repl; *loc; loc++) {
                                restart_detect = stackblock();
@@ -6171,7 +6288,7 @@ static ssize_t
 varvalue(char *name, int varflags, int flags, struct strlist *var_str_list)
 {
        int num;
-       char *p;
+       const char *p;
        int i;
        int sep = 0;
        int sepq = 0;
@@ -6204,14 +6321,13 @@ varvalue(char *name, int varflags, int flags, struct strlist *var_str_list)
                len = cvtnum(num);
                break;
        case '-':
-               p = makestrspace(NOPTS, expdest);
+               expdest = makestrspace(NOPTS, expdest);
                for (i = NOPTS - 1; i >= 0; i--) {
                        if (optlist[i]) {
-                               USTPUTC(optletters(i), p);
+                               USTPUTC(optletters(i), expdest);
                                len++;
                        }
                }
-               expdest = p;
                break;
        case '@':
                if (sep)
@@ -6967,7 +7083,7 @@ static int builtinloc = -1;     /* index in path of %builtin, or -1 */
 
 
 static void
-tryexec(USE_FEATURE_SH_STANDALONE(int applet_no,) char *cmd, char **argv, char **envp)
+tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) char *cmd, char **argv, char **envp)
 {
        int repeated = 0;
 
@@ -7039,13 +7155,13 @@ shellexec(char **argv, const char *path, int idx)
         || (applet_no = find_applet_by_name(argv[0])) >= 0
 #endif
        ) {
-               tryexec(USE_FEATURE_SH_STANDALONE(applet_no,) argv[0], argv, envp);
+               tryexec(IF_FEATURE_SH_STANDALONE(applet_no,) argv[0], argv, envp);
                e = errno;
        } else {
                e = ENOENT;
                while ((cmdname = padvance(&path, argv[0])) != NULL) {
                        if (--idx < 0 && pathopt == NULL) {
-                               tryexec(USE_FEATURE_SH_STANDALONE(-1,) cmdname, argv, envp);
+                               tryexec(IF_FEATURE_SH_STANDALONE(-1,) cmdname, argv, envp);
                                if (errno != ENOENT && errno != ENOTDIR)
                                        e = errno;
                        }
@@ -7575,7 +7691,9 @@ static const short nodesize[N_NUMBER] = {
        [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)),
@@ -7838,51 +7956,64 @@ defun(char *name, union node *func)
        INT_ON;
 }
 
-static int evalskip;            /* set if we are skipping commands */
-/* reasons for skipping commands (see comment on breakcmd routine) */
+/* Reasons for skipping commands (see comment on breakcmd routine) */
 #define SKIPBREAK      (1 << 0)
 #define SKIPCONT       (1 << 1)
 #define SKIPFUNC       (1 << 2)
 #define SKIPFILE       (1 << 3)
 #define SKIPEVAL       (1 << 4)
+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 */
+/* Forward decl way out to parsing code - dotrap needs it */
 static int evalstring(char *s, int mask);
 
-/*
- * Called to execute a trap.  Perhaps we should avoid entering new trap
- * handlers while we are executing a trap handler.
+/* Called to execute a trap.
+ * Single callsite - at the end of evaltree().
+ * If we return non-zero, exaltree raises EXEXIT exception.
+ *
+ * Perhaps we should avoid entering new trap handlers
+ * while we are executing a trap handler. [is it a TODO?]
  */
 static int
 dotrap(void)
 {
-       char *p;
-       char *q;
-       int i;
-       int savestatus;
-       int skip;
+       uint8_t *g;
+       int sig;
+       uint8_t savestatus;
 
        savestatus = exitstatus;
        pendingsig = 0;
        xbarrier();
 
-       for (i = 1, q = gotsig; i < NSIG; i++, q++) {
-               if (!*q)
+       TRACE(("dotrap entered\n"));
+       for (sig = 1, g = gotsig; sig < NSIG; sig++, g++) {
+               int want_exexit;
+               char *t;
+
+               if (*g == 0)
+                       continue;
+               t = trap[sig];
+               /* non-trapped SIGINT is handled separately by raise_interrupt,
+                * don't upset it by resetting gotsig[SIGINT-1] */
+               if (sig == SIGINT && !t)
                        continue;
-               *q = '\0';
 
-               p = trap[i];
-               if (!p)
+               TRACE(("sig %d is active, will run handler '%s'\n", sig, t));
+               *g = 0;
+               if (!t)
                        continue;
-               skip = evalstring(p, SKIPEVAL);
+               want_exexit = evalstring(t, SKIPEVAL);
                exitstatus = savestatus;
-               if (skip)
-                       return skip;
+               if (want_exexit) {
+                       TRACE(("dotrap returns %d\n", want_exexit));
+                       return want_exexit;
+               }
        }
 
+       TRACE(("dotrap returns 0\n"));
        return 0;
 }
 
@@ -7904,28 +8035,34 @@ static void prehash(union node *);
 static void
 evaltree(union node *n, int flags)
 {
-
        struct jmploc *volatile savehandler = exception_handler;
        struct jmploc jmploc;
        int checkexit = 0;
        void (*evalfn)(union node *, int);
        int status;
+       int int_level;
+
+       SAVE_INT(int_level);
 
        if (n == NULL) {
                TRACE(("evaltree(NULL) called\n"));
                goto out1;
        }
-       TRACE(("pid %d, evaltree(%p: %d, %d) called\n",
-                       getpid(), n, n->type, flags));
+       TRACE(("evaltree(%p: %d, %d) called\n", n, n->type, flags));
 
        exception_handler = &jmploc;
        {
                int err = setjmp(jmploc.loc);
                if (err) {
                        /* if it was a signal, check for trap handlers */
-                       if (exception == EXSIG)
+                       if (exception_type == EXSIG) {
+                               TRACE(("exception %d (EXSIG) in evaltree, err=%d\n",
+                                               exception_type, err));
                                goto out;
+                       }
                        /* continue on the way out */
+                       TRACE(("exception %d in evaltree, propagating err=%d\n",
+                                       exception_type, err));
                        exception_handler = savehandler;
                        longjmp(exception_handler->loc, err);
                }
@@ -8008,7 +8145,8 @@ evaltree(union node *n, int flags)
                if (exitstatus == 0) {
                        n = n->nif.ifpart;
                        goto evaln;
-               } else if (n->nif.elsepart) {
+               }
+               if (n->nif.elsepart) {
                        n = n->nif.elsepart;
                        goto evaln;
                }
@@ -8034,6 +8172,9 @@ evaltree(union node *n, int flags)
  exexit:
                raise_exception(EXEXIT);
        }
+
+       RESTORE_INT(int_level);
+       TRACE(("leaving evaltree (no interrupts)\n"));
 }
 
 #if !defined(__alpha__) || (defined(__GNUC__) && __GNUC__ >= 3)
@@ -8279,7 +8420,9 @@ evalpipe(union node *n, int flags)
                if (prevfd >= 0)
                        close(prevfd);
                prevfd = pip[0];
-               close(pip[1]);
+               /* Don't want to trigger debugging */
+               if (pip[1] != -1)
+                       close(pip[1]);
        }
        if (n->npipe.pipe_backgnd == 0) {
                exitstatus = waitforjob(jp);
@@ -8563,7 +8706,7 @@ static int getoptscmd(int, char **);
 #if !ENABLE_FEATURE_SH_EXTRA_QUIET
 static int helpcmd(int, char **);
 #endif
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
 static int letcmd(int, char **);
 #endif
 static int readcmd(int, char **);
@@ -8645,7 +8788,7 @@ static const struct builtincmd builtintab[] = {
        { BUILTIN_REGULAR       "jobs", jobscmd },
        { BUILTIN_REGULAR       "kill", killcmd },
 #endif
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
        { BUILTIN_NOSPEC        "let", letcmd },
 #endif
        { BUILTIN_ASSIGN        "local", localcmd },
@@ -8911,6 +9054,7 @@ evalcommand(union node *cmd, int flags)
                        if (forkshell(jp, cmd, FORK_FG) != 0) {
                                exitstatus = waitforjob(jp);
                                INT_ON;
+                               TRACE(("forked child exited with %d\n", exitstatus));
                                break;
                        }
                        FORCE_INT_ON;
@@ -8939,7 +9083,7 @@ evalcommand(union node *cmd, int flags)
 
                if (evalbltin(cmdentry.u.cmd, argc, argv)) {
                        int exit_status;
-                       int i = exception;
+                       int i = exception_type;
                        if (i == EXEXIT)
                                goto raise;
                        exit_status = 2;
@@ -9067,26 +9211,53 @@ breakcmd(int argc UNUSED_PARAM, char **argv)
  * This implements the input routines used by the parser.
  */
 
-#define EOF_NLEFT -99           /* value of parsenleft when EOF pushed back */
-
 enum {
        INPUT_PUSH_FILE = 1,
        INPUT_NOFILE_OK = 2,
 };
 
-static int plinno = 1;                  /* input line number */
-/* number of characters left in input buffer */
-static int parsenleft;                  /* copy of parsefile->nleft */
-static int parselleft;                  /* copy of parsefile->lleft */
-/* next character in input buffer */
-static char *parsenextc;                /* copy of parsefile->nextc */
-
 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;
+#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;
+       INT_ON;
+}
+
 static void
 popstring(void)
 {
@@ -9095,7 +9266,9 @@ popstring(void)
        INT_OFF;
 #if ENABLE_ASH_ALIAS
        if (sp->ap) {
-               if (parsenextc[-1] == ' ' || parsenextc[-1] == '\t') {
+               if (g_parsefile->next_to_pgetc[-1] == ' '
+                || g_parsefile->next_to_pgetc[-1] == '\t'
+               ) {
                        checkkwd |= CHKALIAS;
                }
                if (sp->string != sp->ap->val) {
@@ -9107,25 +9280,29 @@ popstring(void)
                }
        }
 #endif
-       parsenextc = sp->prevstring;
-       parsenleft = sp->prevnleft;
-/*dprintf("*** calling popstring: restoring to '%s'\n", parsenextc);*/
+       g_parsefile->next_to_pgetc = sp->prev_string;
+       g_parsefile->left_in_line = sp->prev_left_in_line;
        g_parsefile->strpush = sp->prev;
        if (sp != &(g_parsefile->basestrpush))
                free(sp);
        INT_ON;
 }
 
+//FIXME: BASH_COMPAT with "...&" does TWO pungetc():
+//it peeks whether it is &>, and then pushes back both chars.
+//This function needs to save last *next_to_pgetc to buf[0]
+//to make two pungetc() reliable. Currently,
+// pgetc (out of buf: does preadfd), pgetc, pungetc, pungetc won't work...
 static int
 preadfd(void)
 {
        int nr;
        char *buf = g_parsefile->buf;
-       parsenextc = buf;
 
+       g_parsefile->next_to_pgetc = buf;
 #if ENABLE_FEATURE_EDITING
  retry:
-       if (!iflag || g_parsefile->fd)
+       if (!iflag || g_parsefile->fd != STDIN_FILENO)
                nr = nonblock_safe_read(g_parsefile->fd, buf, BUFSIZ - 1);
        else {
 #if ENABLE_FEATURE_TAB_COMPLETION
@@ -9173,87 +9350,136 @@ preadfd(void)
  * 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 (parsenleft == EOF_NLEFT) or we are reading
- *    from a string so we can't refill the buffer, return EOF.
+ * 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 the 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)
+/*
+ * NB: due to SIT(c) internals (syntax_index_table[] vector),
+ * pgetc() and related functions must return chars SIGN-EXTENDED into ints,
+ * not zero-extended. Seems fragile to me. Affects only !USE_SIT_FUNCTION case,
+ * so we can fix it by ditching !USE_SIT_FUNCTION if Unicode requires that.
+ */
 static int
 preadbuffer(void)
 {
        char *q;
        int more;
-       char savec;
 
        while (g_parsefile->strpush) {
 #if ENABLE_ASH_ALIAS
-               if (parsenleft == -1 && g_parsefile->strpush->ap &&
-                       parsenextc[-1] != ' ' && parsenextc[-1] != '\t') {
+               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();
-               if (--parsenleft >= 0)
-                       return signed_char2int(*parsenextc++);
-       }
-       if (parsenleft == EOF_NLEFT || g_parsefile->buf == NULL)
+               /* try "pgetc" now: */
+               pgetc_debug("preadbuffer internal pgetc at %d:%p'%s'",
+                               g_parsefile->left_in_line,
+                               g_parsefile->next_to_pgetc,
+                               g_parsefile->next_to_pgetc);
+               if (--g_parsefile->left_in_line >= 0)
+                       return (unsigned char)(*g_parsefile->next_to_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;
-       flush_stdout_stderr();
+       }
 
-       more = parselleft;
+       more = g_parsefile->left_in_buffer;
        if (more <= 0) {
+               flush_stdout_stderr();
  again:
                more = preadfd();
                if (more <= 0) {
-                       parselleft = parsenleft = EOF_NLEFT;
+                       /* don't try reading again */
+                       g_parsefile->left_in_line = -99;
+                       pgetc_debug("preadbuffer PEOF2");
+                       g_parsefile->next_to_pgetc++;
                        return PEOF;
                }
        }
 
-       q = parsenextc;
-
-       /* delete nul characters */
+       /* 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 (;;) {
-               int c;
+               char c;
 
                more--;
-               c = *q;
 
-               if (!c)
+               c = *q;
+               if (c == '\0') {
                        memmove(q, q + 1, more);
-               else {
+               else {
                        q++;
                        if (c == '\n') {
-                               parsenleft = q - parsenextc - 1;
+                               g_parsefile->left_in_line = q - g_parsefile->next_to_pgetc - 1;
                                break;
                        }
                }
 
                if (more <= 0) {
-                       parsenleft = q - parsenextc - 1;
-                       if (parsenleft < 0)
+                       g_parsefile->left_in_line = q - g_parsefile->next_to_pgetc - 1;
+                       if (g_parsefile->left_in_line < 0)
                                goto again;
                        break;
                }
        }
-       parselleft = more;
-
-       savec = *q;
-       *q = '\0';
+       g_parsefile->left_in_buffer = more;
 
        if (vflag) {
-               out2str(parsenextc);
+               char save = *q;
+               *q = '\0';
+               out2str(g_parsefile->next_to_pgetc);
+               *q = save;
        }
 
-       *q = savec;
-
-       return signed_char2int(*parsenextc++);
+       pgetc_debug("preadbuffer at %d:%p'%s'",
+                       g_parsefile->left_in_line,
+                       g_parsefile->next_to_pgetc,
+                       g_parsefile->next_to_pgetc);
+       return signed_char2int(*g_parsefile->next_to_pgetc++);
 }
 
-#define pgetc_as_macro() (--parsenleft >= 0 ? signed_char2int(*parsenextc++) : preadbuffer())
+#define pgetc_as_macro() \
+       (--g_parsefile->left_in_line >= 0 \
+       ? signed_char2int(*g_parsefile->next_to_pgetc++) \
+       : preadbuffer() \
+       )
+
 static int
 pgetc(void)
 {
+       pgetc_debug("pgetc_fast at %d:%p'%s'",
+                       g_parsefile->left_in_line,
+                       g_parsefile->next_to_pgetc,
+                       g_parsefile->next_to_pgetc);
        return pgetc_as_macro();
 }
 
@@ -9272,6 +9498,10 @@ pgetc2(void)
 {
        int c;
        do {
+               pgetc_debug("pgetc_fast at %d:%p'%s'",
+                               g_parsefile->left_in_line,
+                               g_parsefile->next_to_pgetc,
+                               g_parsefile->next_to_pgetc);
                c = pgetc_fast();
        } while (c == PEOA);
        return c;
@@ -9312,43 +9542,12 @@ pfgets(char *line, int len)
 static void
 pungetc(void)
 {
-       parsenleft++;
-       parsenextc--;
-}
-
-/*
- * 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;
-       size_t len;
-
-       len = strlen(s);
-       INT_OFF;
-       if (g_parsefile->strpush) {
-               sp = ckzalloc(sizeof(struct strpush));
-               sp->prev = g_parsefile->strpush;
-               g_parsefile->strpush = sp;
-       } else
-               sp = g_parsefile->strpush = &(g_parsefile->basestrpush);
-       sp->prevstring = parsenextc;
-       sp->prevnleft = parsenleft;
-#if ENABLE_ASH_ALIAS
-       sp->ap = ap;
-       if (ap) {
-               ap->flag |= ALIASINUSE;
-               sp->string = s;
-       }
-#endif
-       parsenextc = s;
-       parsenleft = len;
-       INT_ON;
+       g_parsefile->left_in_line++;
+       g_parsefile->next_to_pgetc--;
+       pgetc_debug("pushed back to %d:%p'%s'",
+                       g_parsefile->left_in_line,
+                       g_parsefile->next_to_pgetc,
+                       g_parsefile->next_to_pgetc);
 }
 
 /*
@@ -9360,10 +9559,6 @@ pushfile(void)
 {
        struct parsefile *pf;
 
-       g_parsefile->nleft = parsenleft;
-       g_parsefile->lleft = parselleft;
-       g_parsefile->nextc = parsenextc;
-       g_parsefile->linno = plinno;
        pf = ckzalloc(sizeof(*pf));
        pf->prev = g_parsefile;
        pf->fd = -1;
@@ -9385,10 +9580,6 @@ popfile(void)
                popstring();
        g_parsefile = pf->prev;
        free(pf);
-       parsenleft = g_parsefile->nleft;
-       parselleft = g_parsefile->lleft;
-       parsenextc = g_parsefile->nextc;
-       plinno = g_parsefile->linno;
        INT_ON;
 }
 
@@ -9426,13 +9617,14 @@ setinputfd(int fd, int push)
        close_on_exec_on(fd);
        if (push) {
                pushfile();
-               g_parsefile->buf = 0;
+               g_parsefile->buf = NULL;
        }
        g_parsefile->fd = fd;
        if (g_parsefile->buf == NULL)
                g_parsefile->buf = ckmalloc(IBUFSIZ);
-       parselleft = parsenleft = 0;
-       plinno = 1;
+       g_parsefile->left_in_buffer = 0;
+       g_parsefile->left_in_line = 0;
+       g_parsefile->linno = 1;
 }
 
 /*
@@ -9450,7 +9642,7 @@ setinputfile(const char *fname, int flags)
        if (fd < 0) {
                if (flags & INPUT_NOFILE_OK)
                        goto out;
-               ash_msg_and_raise_error("can't open %s", fname);
+               ash_msg_and_raise_error("can't open '%s'", fname);
        }
        if (fd < 10) {
                fd2 = copyfd(fd, 10);
@@ -9473,10 +9665,10 @@ setinputstring(char *string)
 {
        INT_OFF;
        pushfile();
-       parsenextc = string;
-       parsenleft = strlen(string);
+       g_parsefile->next_to_pgetc = string;
+       g_parsefile->left_in_line = strlen(string);
        g_parsefile->buf = NULL;
-       plinno = 1;
+       g_parsefile->linno = 1;
        INT_ON;
 }
 
@@ -9963,14 +10155,6 @@ static struct heredoc *heredoc;
  */
 #define NEOF ((union node *)&tokpushback)
 
-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 */
-}
-
 /*
  * 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
@@ -9983,7 +10167,7 @@ raise_error_unexpected_syntax(int token)
        char msg[64];
        int l;
 
-       l = sprintf(msg, "%s unexpected", tokname(lasttoken));
+       l = sprintf(msg, "unexpected %s", tokname(lasttoken));
        if (token >= 0)
                sprintf(msg + l, " (expecting %s)", tokname(token));
        raise_error_syntax(msg);
@@ -10175,9 +10359,9 @@ fixredir(union node *n, const char *text, int err)
  * or backquotes).
  */
 static int
-noexpand(char *text)
+noexpand(const char *text)
 {
-       char *p;
+       const char *p;
        char c;
 
        p = text;
@@ -10186,7 +10370,7 @@ noexpand(char *text)
                        continue;
                if (c == CTLESC)
                        p++;
-               else if (SIT(c, BASESYNTAX) == CCTL)
+               else if (SIT((signed char)c, BASESYNTAX) == CCTL)
                        return 0;
        }
        return 1;
@@ -10605,7 +10789,7 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
        int parenlevel;      /* levels of parens in arithmetic */
        int dqvarnest;       /* levels of variables expansion within double quotes */
 
-       USE_ASH_BASH_COMPAT(smallint bash_dollar_squote = 0;)
+       IF_ASH_BASH_COMPAT(smallint bash_dollar_squote = 0;)
 
 #if __GNUC__
        /* Avoid longjmp clobbering */
@@ -10620,7 +10804,7 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
        (void) &prevsyntax;
        (void) &syntax;
 #endif
-       startlinno = plinno;
+       startlinno = g_parsefile->linno;
        bqlist = NULL;
        quotef = 0;
        oldstyle = 0;
@@ -10648,7 +10832,7 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
                                if (syntax == BASESYNTAX)
                                        goto endword;   /* exit outer loop */
                                USTPUTC(c, out);
-                               plinno++;
+                               g_parsefile->linno++;
                                if (doprompt)
                                        setprompt(2);
                                c = pgetc();
@@ -10711,7 +10895,7 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
                                dblquote = 1;
                                goto quotemark;
                        case CENDQUOTE:
-                               USE_ASH_BASH_COMPAT(bash_dollar_squote = 0;)
+                               IF_ASH_BASH_COMPAT(bash_dollar_squote = 0;)
                                if (eofmark != NULL && arinest == 0
                                 && varnest == 0
                                ) {
@@ -10739,7 +10923,7 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
                                        USTPUTC(c, out);
                                }
                                break;
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
                        case CLP:       /* '(' in arithmetic */
                                parenlevel++;
                                USTPUTC(c, out);
@@ -10795,14 +10979,14 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
                } /* for (;;) */
        }
  endword:
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
        if (syntax == ARISYNTAX)
                raise_error_syntax("missing '))'");
 #endif
        if (syntax != BASESYNTAX && !parsebackquote && eofmark == NULL)
                raise_error_syntax("unterminated quoted string");
        if (varnest != 0) {
-               startlinno = plinno;
+               startlinno = g_parsefile->linno;
                /* { */
                raise_error_syntax("missing '}'");
        }
@@ -10810,7 +10994,7 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
        len = out - (char *)stackblock();
        out = stackblock();
        if (eofmark == NULL) {
-               if ((c == '>' || c == '<' USE_ASH_BASH_COMPAT( || c == 0x100 + '>'))
+               if ((c == '>' || c == '<' IF_ASH_BASH_COMPAT( || c == 0x100 + '>'))
                 && quotef == 0
                ) {
                        if (isdigit_str9(out)) {
@@ -10857,7 +11041,7 @@ checkend: {
                                        continue;
                                if (*p == '\n' && *q == '\0') {
                                        c = PEOF;
-                                       plinno++;
+                                       g_parsefile->linno++;
                                        needprompt = doprompt;
                                } else {
                                        pushstring(line, NULL);
@@ -10972,7 +11156,7 @@ parsesub: {
                pungetc();
        } else if (c == '(') {  /* $(command) or $((arith)) */
                if (pgetc() == '(') {
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
                        PARSEARITH();
 #else
                        raise_error_syntax("you disabled math support for $((arith)) syntax");
@@ -11133,7 +11317,7 @@ parsebackq: {
                        case '\\':
                                pc = pgetc();
                                if (pc == '\n') {
-                                       plinno++;
+                                       g_parsefile->linno++;
                                        if (doprompt)
                                                setprompt(2);
                                        /*
@@ -11156,11 +11340,11 @@ parsebackq: {
 #if ENABLE_ASH_ALIAS
                        case PEOA:
 #endif
-                               startlinno = plinno;
+                               startlinno = g_parsefile->linno;
                                raise_error_syntax("EOF in backquote substitution");
 
                        case '\n':
-                               plinno++;
+                               g_parsefile->linno++;
                                needprompt = doprompt;
                                break;
 
@@ -11227,7 +11411,7 @@ parsebackq: {
        goto parsebackq_newreturn;
 }
 
-#if ENABLE_ASH_MATH_SUPPORT
+#if ENABLE_SH_MATH_SUPPORT
 /*
  * Parse an arithmetic expansion (indicate start of one and set state)
  */
@@ -11301,10 +11485,10 @@ xxreadtoken(void)
        if (needprompt) {
                setprompt(2);
        }
-       startlinno = plinno;
+       startlinno = g_parsefile->linno;
        for (;;) {                      /* until token or start of word found */
                c = pgetc_fast();
-               if (c == ' ' || c == '\t' USE_ASH_ALIAS( || c == PEOA))
+               if (c == ' ' || c == '\t' IF_ASH_ALIAS( || c == PEOA))
                        continue;
 
                if (c == '#') {
@@ -11316,7 +11500,7 @@ xxreadtoken(void)
                                pungetc();
                                break; /* return readtoken1(...) */
                        }
-                       startlinno = ++plinno;
+                       startlinno = ++g_parsefile->linno;
                        if (doprompt)
                                setprompt(2);
                } else {
@@ -11325,7 +11509,7 @@ xxreadtoken(void)
                        p = xxreadtoken_chars + sizeof(xxreadtoken_chars) - 1;
                        if (c != PEOF) {
                                if (c == '\n') {
-                                       plinno++;
+                                       g_parsefile->linno++;
                                        needprompt = doprompt;
                                }
 
@@ -11367,7 +11551,7 @@ xxreadtoken(void)
        if (needprompt) {
                setprompt(2);
        }
-       startlinno = plinno;
+       startlinno = g_parsefile->linno;
        for (;;) {      /* until token or start of word found */
                c = pgetc_fast();
                switch (c) {
@@ -11383,7 +11567,7 @@ xxreadtoken(void)
                        continue;
                case '\\':
                        if (pgetc() == '\n') {
-                               startlinno = ++plinno;
+                               startlinno = ++g_parsefile->linno;
                                if (doprompt)
                                        setprompt(2);
                                continue;
@@ -11391,7 +11575,7 @@ xxreadtoken(void)
                        pungetc();
                        goto breakloop;
                case '\n':
-                       plinno++;
+                       g_parsefile->linno++;
                        needprompt = doprompt;
                        RETURN(TNL);
                case PEOF:
@@ -11561,7 +11745,8 @@ expandstr(const char *ps)
 {
        union node n;
 
-       /* XXX Fix (char *) cast. */
+       /* 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);
        readtoken1(pgetc(), PSSYNTAX, nullstr, 0);
        popfile();
@@ -11663,7 +11848,9 @@ cmdloop(int top)
 #endif
                }
                n = parsecmd(inter);
-               /* showtree(n); DEBUG */
+#if DEBUG
+               showtree(n);
+#endif
                if (n == NEOF) {
                        if (!top || numeof >= 50)
                                break;
@@ -11705,7 +11892,16 @@ find_dot_file(char *name)
        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 = padvance(&path, name)) != NULL) {
+ try_cur_dir:
                if ((stat(fullname, &statb) == 0) && S_ISREG(statb.st_mode)) {
                        /*
                         * Don't bother freeing here, since it will
@@ -12036,7 +12232,9 @@ helpcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
        unsigned col;
        unsigned i;
 
-       out1fmt("\nBuilt-in commands:\n-------------------\n");
+       out1fmt("\n"
+               "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);
@@ -12178,34 +12376,12 @@ timescmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
        return 0;
 }
 
-#if ENABLE_ASH_MATH_SUPPORT
-static arith_t
-dash_arith(const char *s)
-{
-       arith_t result;
-       int errcode = 0;
-
-       INT_OFF;
-       result = arith(s, &errcode);
-       if (errcode < 0) {
-               if (errcode == -3)
-                       ash_msg_and_raise_error("exponent less than 0");
-               if (errcode == -2)
-                       ash_msg_and_raise_error("divide by zero");
-               if (errcode == -5)
-                       ash_msg_and_raise_error("expression recursion loop detected");
-               raise_error_syntax(s);
-       }
-       INT_ON;
-
-       return result;
-}
-
+#if ENABLE_SH_MATH_SUPPORT
 /*
- *  The let builtin. partial stolen from GNU Bash, the Bourne Again SHell.
- *  Copyright (C) 1987, 1989, 1991 Free Software Foundation, Inc.
+ * The let builtin. partial 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>
+ * Copyright (C) 2003 Vladimir Oleynik <dzo@simtreas.ru>
  */
 static int
 letcmd(int argc UNUSED_PARAM, char **argv)
@@ -12216,12 +12392,12 @@ letcmd(int argc UNUSED_PARAM, char **argv)
        if (!*argv)
                ash_msg_and_raise_error("expression expected");
        do {
-               i = dash_arith(*argv);
+               i = ash_arith(*argv);
        } while (*++argv);
 
        return !i;
 }
-#endif /* ASH_MATH_SUPPORT */
+#endif /* SH_MATH_SUPPORT */
 
 
 /* ============ miscbltin.c
@@ -12278,8 +12454,8 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
        rflag = 0;
        prompt = NULL;
        while ((i = nextopt("p:u:r"
-               USE_ASH_READ_TIMEOUT("t:")
-               USE_ASH_READ_NCHARS("n:s")
+               IF_ASH_READ_TIMEOUT("t:")
+               IF_ASH_READ_NCHARS("n:s")
        )) != '\0') {
                switch (i) {
                case 'p':
@@ -12368,7 +12544,7 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 #endif
 
        status = 0;
-       startword = 1;
+       startword = 2;
        backslash = 0;
 #if ENABLE_ASH_READ_TIMEOUT
        if (timeout) /* NB: ensuring end_ms is nonzero */
@@ -12376,6 +12552,8 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 #endif
        STARTSTACKSTR(p);
        do {
+               const char *is_ifs;
+
 #if ENABLE_ASH_READ_TIMEOUT
                if (end_ms) {
                        struct pollfd pfd[1];
@@ -12405,25 +12583,36 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
                        continue;
                }
                if (!rflag && c == '\\') {
-                       backslash++;
+                       backslash = 1;
                        continue;
                }
                if (c == '\n')
                        break;
-               if (startword && *ifs == ' ' && strchr(ifs, c)) {
-                       continue;
+               /* $IFS splitting */
+/* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05 */
+               is_ifs = strchr(ifs, c);
+               if (startword && is_ifs) {
+                       if (isspace(c))
+                               continue;
+                       /* it is a non-space ifs char */
+                       startword--;
+                       if (startword == 1) /* first one? */
+                               continue; /* yes, it is not next word yet */
                }
                startword = 0;
-               if (ap[1] != NULL && strchr(ifs, c) != NULL) {
+               if (ap[1] != NULL && is_ifs) {
+                       const char *beg;
                        STACKSTRNUL(p);
-                       setvar(*ap, stackblock(), 0);
+                       beg = stackblock();
+                       setvar(*ap, beg, 0);
                        ap++;
-                       startword = 1;
+                       /* can we skip one non-space ifs char? (2: yes) */
+                       startword = isspace(c) ? 2 : 1;
                        STARTSTACKSTR(p);
-               } else {
- put:
-                       STPUTC(c, p);
+                       continue;
                }
+ put:
+               STPUTC(c, p);
        }
 /* end of do {} while: */
 #if ENABLE_ASH_READ_NCHARS
@@ -12437,8 +12626,8 @@ readcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 #endif
 
        STACKSTRNUL(p);
-       /* Remove trailing blanks */
-       while ((char *)stackblock() <= --p && strchr(ifs, *p) != NULL)
+       /* Remove trailing space ifs chars */
+       while ((char *)stackblock() <= --p && isspace(*p) && strchr(ifs, *p) != NULL)
                *p = '\0';
        setvar(*ap, stackblock(), 0);
        while (*++ap != NULL)
@@ -12457,6 +12646,8 @@ umaskcmd(int argc UNUSED_PARAM, char **argv)
                S_IROTH, S_IWOTH, S_IXOTH
        };
 
+       /* TODO: use bb_parse_mode() instead */
+
        char *ap;
        mode_t mask;
        int i;
@@ -12523,7 +12714,6 @@ umaskcmd(int argc UNUSED_PARAM, char **argv)
  *
  * Public domain.
  */
-
 struct limits {
        uint8_t cmd;          /* RLIMIT_xxx fit into it */
        uint8_t factor_shift; /* shift by to get rlim_{cur,max} values */
@@ -12732,654 +12922,6 @@ ulimitcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
        return 0;
 }
 
-
-/* ============ Math support */
-
-#if ENABLE_ASH_MATH_SUPPORT
-
-/* Copyright (c) 2001 Aaron Lehmann <aaronl@vitelus.com>
-
-   Permission is hereby granted, free of charge, to any person obtaining
-   a copy of this software and associated documentation files (the
-   "Software"), to deal in the Software without restriction, including
-   without limitation the rights to use, copy, modify, merge, publish,
-   distribute, sublicense, and/or sell copies of the Software, and to
-   permit persons to whom the Software is furnished to do so, subject to
-   the following conditions:
-
-   The above copyright notice and this permission notice shall be
-   included in all copies or substantial portions of the Software.
-
-   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-   IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-   CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-   TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-   SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-*/
-
-/* This is my infix parser/evaluator. It is optimized for size, intended
- * as a replacement for yacc-based parsers. However, it may well be faster
- * than a comparable parser written in yacc. The supported operators are
- * listed in #defines below. Parens, order of operations, and error handling
- * are supported. This code is thread safe. The exact expression format should
- * be that which POSIX specifies for shells. */
-
-/* The code uses a simple two-stack algorithm. See
- * http://www.onthenet.com.au/~grahamis/int2008/week02/lect02.html
- * for a detailed explanation of the infix-to-postfix algorithm on which
- * this is based (this code differs in that it applies operators immediately
- * to the stack instead of adding them to a queue to end up with an
- * expression). */
-
-/* To use the routine, call it with an expression string and error return
- * pointer */
-
-/*
- * Aug 24, 2001              Manuel Novoa III
- *
- * Reduced the generated code size by about 30% (i386) and fixed several bugs.
- *
- * 1) In arith_apply():
- *    a) Cached values of *numptr and &(numptr[-1]).
- *    b) Removed redundant test for zero denominator.
- *
- * 2) In arith():
- *    a) Eliminated redundant code for processing operator tokens by moving
- *       to a table-based implementation.  Also folded handling of parens
- *       into the table.
- *    b) Combined all 3 loops which called arith_apply to reduce generated
- *       code size at the cost of speed.
- *
- * 3) The following expressions were treated as valid by the original code:
- *       1()  ,    0!  ,    1 ( *3 )   .
- *    These bugs have been fixed by internally enclosing the expression in
- *    parens and then checking that all binary ops and right parens are
- *    preceded by a valid expression (NUM_TOKEN).
- *
- * Note: It may be desirable to replace Aaron's test for whitespace with
- * ctype's isspace() if it is used by another busybox applet or if additional
- * whitespace chars should be considered.  Look below the "#include"s for a
- * precompiler test.
- */
-
-/*
- * Aug 26, 2001              Manuel Novoa III
- *
- * Return 0 for null expressions.  Pointed out by Vladimir Oleynik.
- *
- * Merge in Aaron's comments previously posted to the busybox list,
- * modified slightly to take account of my changes to the code.
- *
- */
-
-/*
- *  (C) 2003 Vladimir Oleynik <dzo@simtreas.ru>
- *
- * - allow access to variable,
- *   used recursive find value indirection (c=2*2; a="c"; $((a+=2)) produce 6)
- * - realize assign syntax (VAR=expr, +=, *= etc)
- * - realize exponentiation (** operator)
- * - realize comma separated - expr, expr
- * - realise ++expr --expr expr++ expr--
- * - realise expr ? expr : expr (but, second expr calculate always)
- * - allow hexadecimal and octal numbers
- * - was restored loses XOR operator
- * - remove one goto label, added three ;-)
- * - protect $((num num)) as true zero expr (Manuel`s error)
- * - always use special isspace(), see comment from bash ;-)
- */
-
-#define arith_isspace(arithval) \
-       (arithval == ' ' || arithval == '\n' || arithval == '\t')
-
-typedef unsigned char operator;
-
-/* An operator's token id is a bit of a bitfield. The lower 5 bits are the
- * precedence, and 3 high bits are an ID unique across operators of that
- * precedence. The ID portion is so that multiple operators can have the
- * same precedence, ensuring that the leftmost one is evaluated first.
- * Consider * and /. */
-
-#define tok_decl(prec,id) (((id)<<5)|(prec))
-#define PREC(op) ((op) & 0x1F)
-
-#define TOK_LPAREN tok_decl(0,0)
-
-#define TOK_COMMA tok_decl(1,0)
-
-#define TOK_ASSIGN tok_decl(2,0)
-#define TOK_AND_ASSIGN tok_decl(2,1)
-#define TOK_OR_ASSIGN tok_decl(2,2)
-#define TOK_XOR_ASSIGN tok_decl(2,3)
-#define TOK_PLUS_ASSIGN tok_decl(2,4)
-#define TOK_MINUS_ASSIGN tok_decl(2,5)
-#define TOK_LSHIFT_ASSIGN tok_decl(2,6)
-#define TOK_RSHIFT_ASSIGN tok_decl(2,7)
-
-#define TOK_MUL_ASSIGN tok_decl(3,0)
-#define TOK_DIV_ASSIGN tok_decl(3,1)
-#define TOK_REM_ASSIGN tok_decl(3,2)
-
-/* all assign is right associativity and precedence eq, but (7+3)<<5 > 256 */
-#define convert_prec_is_assing(prec) do { if (prec == 3) prec = 2; } while (0)
-
-/* conditional is right associativity too */
-#define TOK_CONDITIONAL tok_decl(4,0)
-#define TOK_CONDITIONAL_SEP tok_decl(4,1)
-
-#define TOK_OR tok_decl(5,0)
-
-#define TOK_AND tok_decl(6,0)
-
-#define TOK_BOR tok_decl(7,0)
-
-#define TOK_BXOR tok_decl(8,0)
-
-#define TOK_BAND tok_decl(9,0)
-
-#define TOK_EQ tok_decl(10,0)
-#define TOK_NE tok_decl(10,1)
-
-#define TOK_LT tok_decl(11,0)
-#define TOK_GT tok_decl(11,1)
-#define TOK_GE tok_decl(11,2)
-#define TOK_LE tok_decl(11,3)
-
-#define TOK_LSHIFT tok_decl(12,0)
-#define TOK_RSHIFT tok_decl(12,1)
-
-#define TOK_ADD tok_decl(13,0)
-#define TOK_SUB tok_decl(13,1)
-
-#define TOK_MUL tok_decl(14,0)
-#define TOK_DIV tok_decl(14,1)
-#define TOK_REM tok_decl(14,2)
-
-/* exponent is right associativity */
-#define TOK_EXPONENT tok_decl(15,1)
-
-/* For now unary operators. */
-#define UNARYPREC 16
-#define TOK_BNOT tok_decl(UNARYPREC,0)
-#define TOK_NOT tok_decl(UNARYPREC,1)
-
-#define TOK_UMINUS tok_decl(UNARYPREC+1,0)
-#define TOK_UPLUS tok_decl(UNARYPREC+1,1)
-
-#define PREC_PRE (UNARYPREC+2)
-
-#define TOK_PRE_INC tok_decl(PREC_PRE, 0)
-#define TOK_PRE_DEC tok_decl(PREC_PRE, 1)
-
-#define PREC_POST (UNARYPREC+3)
-
-#define TOK_POST_INC tok_decl(PREC_POST, 0)
-#define TOK_POST_DEC tok_decl(PREC_POST, 1)
-
-#define SPEC_PREC (UNARYPREC+4)
-
-#define TOK_NUM tok_decl(SPEC_PREC, 0)
-#define TOK_RPAREN tok_decl(SPEC_PREC, 1)
-
-#define NUMPTR (*numstackptr)
-
-static int
-tok_have_assign(operator op)
-{
-       operator prec = PREC(op);
-
-       convert_prec_is_assing(prec);
-       return (prec == PREC(TOK_ASSIGN) ||
-                       prec == PREC_PRE || prec == PREC_POST);
-}
-
-static int
-is_right_associativity(operator prec)
-{
-       return (prec == PREC(TOK_ASSIGN) || prec == PREC(TOK_EXPONENT)
-               || prec == PREC(TOK_CONDITIONAL));
-}
-
-typedef struct {
-       arith_t val;
-       arith_t contidional_second_val;
-       char contidional_second_val_initialized;
-       char *var;      /* if NULL then is regular number,
-                          else is variable name */
-} v_n_t;
-
-typedef struct chk_var_recursive_looped_t {
-       const char *var;
-       struct chk_var_recursive_looped_t *next;
-} chk_var_recursive_looped_t;
-
-static chk_var_recursive_looped_t *prev_chk_var_recursive;
-
-static int
-arith_lookup_val(v_n_t *t)
-{
-       if (t->var) {
-               const char * p = lookupvar(t->var);
-
-               if (p) {
-                       int errcode;
-
-                       /* recursive try as expression */
-                       chk_var_recursive_looped_t *cur;
-                       chk_var_recursive_looped_t cur_save;
-
-                       for (cur = prev_chk_var_recursive; cur; cur = cur->next) {
-                               if (strcmp(cur->var, t->var) == 0) {
-                                       /* expression recursion loop detected */
-                                       return -5;
-                               }
-                       }
-                       /* save current lookuped var name */
-                       cur = prev_chk_var_recursive;
-                       cur_save.var = t->var;
-                       cur_save.next = cur;
-                       prev_chk_var_recursive = &cur_save;
-
-                       t->val = arith (p, &errcode);
-                       /* restore previous ptr after recursiving */
-                       prev_chk_var_recursive = cur;
-                       return errcode;
-               }
-               /* allow undefined var as 0 */
-               t->val = 0;
-       }
-       return 0;
-}
-
-/* "applying" a token means performing it on the top elements on the integer
- * stack. For a unary operator it will only change the top element, but a
- * binary operator will pop two arguments and push a result */
-static int
-arith_apply(operator op, v_n_t *numstack, v_n_t **numstackptr)
-{
-       v_n_t *numptr_m1;
-       arith_t numptr_val, rez;
-       int ret_arith_lookup_val;
-
-       /* There is no operator that can work without arguments */
-       if (NUMPTR == numstack) goto err;
-       numptr_m1 = NUMPTR - 1;
-
-       /* check operand is var with noninteger value */
-       ret_arith_lookup_val = arith_lookup_val(numptr_m1);
-       if (ret_arith_lookup_val)
-               return ret_arith_lookup_val;
-
-       rez = numptr_m1->val;
-       if (op == TOK_UMINUS)
-               rez *= -1;
-       else if (op == TOK_NOT)
-               rez = !rez;
-       else if (op == TOK_BNOT)
-               rez = ~rez;
-       else if (op == TOK_POST_INC || op == TOK_PRE_INC)
-               rez++;
-       else if (op == TOK_POST_DEC || op == TOK_PRE_DEC)
-               rez--;
-       else if (op != TOK_UPLUS) {
-               /* Binary operators */
-
-               /* check and binary operators need two arguments */
-               if (numptr_m1 == numstack) goto err;
-
-               /* ... and they pop one */
-               --NUMPTR;
-               numptr_val = rez;
-               if (op == TOK_CONDITIONAL) {
-                       if (!numptr_m1->contidional_second_val_initialized) {
-                               /* protect $((expr1 ? expr2)) without ": expr" */
-                               goto err;
-                       }
-                       rez = numptr_m1->contidional_second_val;
-               } else if (numptr_m1->contidional_second_val_initialized) {
-                       /* protect $((expr1 : expr2)) without "expr ? " */
-                       goto err;
-               }
-               numptr_m1 = NUMPTR - 1;
-               if (op != TOK_ASSIGN) {
-                       /* check operand is var with noninteger value for not '=' */
-                       ret_arith_lookup_val = arith_lookup_val(numptr_m1);
-                       if (ret_arith_lookup_val)
-                               return ret_arith_lookup_val;
-               }
-               if (op == TOK_CONDITIONAL) {
-                       numptr_m1->contidional_second_val = rez;
-               }
-               rez = numptr_m1->val;
-               if (op == TOK_BOR || op == TOK_OR_ASSIGN)
-                       rez |= numptr_val;
-               else if (op == TOK_OR)
-                       rez = numptr_val || rez;
-               else if (op == TOK_BAND || op == TOK_AND_ASSIGN)
-                       rez &= numptr_val;
-               else if (op == TOK_BXOR || op == TOK_XOR_ASSIGN)
-                       rez ^= numptr_val;
-               else if (op == TOK_AND)
-                       rez = rez && numptr_val;
-               else if (op == TOK_EQ)
-                       rez = (rez == numptr_val);
-               else if (op == TOK_NE)
-                       rez = (rez != numptr_val);
-               else if (op == TOK_GE)
-                       rez = (rez >= numptr_val);
-               else if (op == TOK_RSHIFT || op == TOK_RSHIFT_ASSIGN)
-                       rez >>= numptr_val;
-               else if (op == TOK_LSHIFT || op == TOK_LSHIFT_ASSIGN)
-                       rez <<= numptr_val;
-               else if (op == TOK_GT)
-                       rez = (rez > numptr_val);
-               else if (op == TOK_LT)
-                       rez = (rez < numptr_val);
-               else if (op == TOK_LE)
-                       rez = (rez <= numptr_val);
-               else if (op == TOK_MUL || op == TOK_MUL_ASSIGN)
-                       rez *= numptr_val;
-               else if (op == TOK_ADD || op == TOK_PLUS_ASSIGN)
-                       rez += numptr_val;
-               else if (op == TOK_SUB || op == TOK_MINUS_ASSIGN)
-                       rez -= numptr_val;
-               else if (op == TOK_ASSIGN || op == TOK_COMMA)
-                       rez = numptr_val;
-               else if (op == TOK_CONDITIONAL_SEP) {
-                       if (numptr_m1 == numstack) {
-                               /* protect $((expr : expr)) without "expr ? " */
-                               goto err;
-                       }
-                       numptr_m1->contidional_second_val_initialized = op;
-                       numptr_m1->contidional_second_val = numptr_val;
-               } else if (op == TOK_CONDITIONAL) {
-                       rez = rez ?
-                               numptr_val : numptr_m1->contidional_second_val;
-               } else if (op == TOK_EXPONENT) {
-                       if (numptr_val < 0)
-                               return -3;      /* exponent less than 0 */
-                       else {
-                               arith_t c = 1;
-
-                               if (numptr_val)
-                                       while (numptr_val--)
-                                               c *= rez;
-                               rez = c;
-                       }
-               } else if (numptr_val==0)          /* zero divisor check */
-                       return -2;
-               else if (op == TOK_DIV || op == TOK_DIV_ASSIGN)
-                       rez /= numptr_val;
-               else if (op == TOK_REM || op == TOK_REM_ASSIGN)
-                       rez %= numptr_val;
-       }
-       if (tok_have_assign(op)) {
-               char buf[sizeof(arith_t_type)*3 + 2];
-
-               if (numptr_m1->var == NULL) {
-                       /* Hmm, 1=2 ? */
-                       goto err;
-               }
-               /* save to shell variable */
-#if ENABLE_ASH_MATH_SUPPORT_64
-               snprintf(buf, sizeof(buf), "%lld", (arith_t_type) rez);
-#else
-               snprintf(buf, sizeof(buf), "%ld", (arith_t_type) rez);
-#endif
-               setvar(numptr_m1->var, buf, 0);
-               /* after saving, make previous value for v++ or v-- */
-               if (op == TOK_POST_INC)
-                       rez--;
-               else if (op == TOK_POST_DEC)
-                       rez++;
-       }
-       numptr_m1->val = rez;
-       /* protect geting var value, is number now */
-       numptr_m1->var = NULL;
-       return 0;
- err:
-       return -1;
-}
-
-/* longest must be first */
-static const char op_tokens[] ALIGN1 = {
-       '<','<','=',0, TOK_LSHIFT_ASSIGN,
-       '>','>','=',0, TOK_RSHIFT_ASSIGN,
-       '<','<',    0, TOK_LSHIFT,
-       '>','>',    0, TOK_RSHIFT,
-       '|','|',    0, TOK_OR,
-       '&','&',    0, TOK_AND,
-       '!','=',    0, TOK_NE,
-       '<','=',    0, TOK_LE,
-       '>','=',    0, TOK_GE,
-       '=','=',    0, TOK_EQ,
-       '|','=',    0, TOK_OR_ASSIGN,
-       '&','=',    0, TOK_AND_ASSIGN,
-       '*','=',    0, TOK_MUL_ASSIGN,
-       '/','=',    0, TOK_DIV_ASSIGN,
-       '%','=',    0, TOK_REM_ASSIGN,
-       '+','=',    0, TOK_PLUS_ASSIGN,
-       '-','=',    0, TOK_MINUS_ASSIGN,
-       '-','-',    0, TOK_POST_DEC,
-       '^','=',    0, TOK_XOR_ASSIGN,
-       '+','+',    0, TOK_POST_INC,
-       '*','*',    0, TOK_EXPONENT,
-       '!',        0, TOK_NOT,
-       '<',        0, TOK_LT,
-       '>',        0, TOK_GT,
-       '=',        0, TOK_ASSIGN,
-       '|',        0, TOK_BOR,
-       '&',        0, TOK_BAND,
-       '*',        0, TOK_MUL,
-       '/',        0, TOK_DIV,
-       '%',        0, TOK_REM,
-       '+',        0, TOK_ADD,
-       '-',        0, TOK_SUB,
-       '^',        0, TOK_BXOR,
-       /* uniq */
-       '~',        0, TOK_BNOT,
-       ',',        0, TOK_COMMA,
-       '?',        0, TOK_CONDITIONAL,
-       ':',        0, TOK_CONDITIONAL_SEP,
-       ')',        0, TOK_RPAREN,
-       '(',        0, TOK_LPAREN,
-       0
-};
-/* ptr to ")" */
-#define endexpression (&op_tokens[sizeof(op_tokens)-7])
-
-static arith_t
-arith(const char *expr, int *perrcode)
-{
-       char arithval; /* Current character under analysis */
-       operator lasttok, op;
-       operator prec;
-       operator *stack, *stackptr;
-       const char *p = endexpression;
-       int errcode;
-       v_n_t *numstack, *numstackptr;
-       unsigned datasizes = strlen(expr) + 2;
-
-       /* Stack of integers */
-       /* The proof that there can be no more than strlen(startbuf)/2+1 integers
-        * in any given correct or incorrect expression is left as an exercise to
-        * the reader. */
-       numstackptr = numstack = alloca((datasizes / 2) * sizeof(numstack[0]));
-       /* Stack of operator tokens */
-       stackptr = stack = alloca(datasizes * sizeof(stack[0]));
-
-       *stackptr++ = lasttok = TOK_LPAREN;     /* start off with a left paren */
-       *perrcode = errcode = 0;
-
-       while (1) {
-               arithval = *expr;
-               if (arithval == 0) {
-                       if (p == endexpression) {
-                               /* Null expression. */
-                               return 0;
-                       }
-
-                       /* This is only reached after all tokens have been extracted from the
-                        * input stream. If there are still tokens on the operator stack, they
-                        * are to be applied in order. At the end, there should be a final
-                        * result on the integer stack */
-
-                       if (expr != endexpression + 1) {
-                               /* If we haven't done so already, */
-                               /* append a closing right paren */
-                               expr = endexpression;
-                               /* and let the loop process it. */
-                               continue;
-                       }
-                       /* At this point, we're done with the expression. */
-                       if (numstackptr != numstack+1) {
-                               /* ... but if there isn't, it's bad */
- err:
-                               *perrcode = -1;
-                               return *perrcode;
-                       }
-                       if (numstack->var) {
-                               /* expression is $((var)) only, lookup now */
-                               errcode = arith_lookup_val(numstack);
-                       }
- ret:
-                       *perrcode = errcode;
-                       return numstack->val;
-               }
-
-               /* Continue processing the expression. */
-               if (arith_isspace(arithval)) {
-                       /* Skip whitespace */
-                       goto prologue;
-               }
-               p = endofname(expr);
-               if (p != expr) {
-                       size_t var_name_size = (p-expr) + 1;  /* trailing zero */
-
-                       numstackptr->var = alloca(var_name_size);
-                       safe_strncpy(numstackptr->var, expr, var_name_size);
-                       expr = p;
- num:
-                       numstackptr->contidional_second_val_initialized = 0;
-                       numstackptr++;
-                       lasttok = TOK_NUM;
-                       continue;
-               }
-               if (isdigit(arithval)) {
-                       numstackptr->var = NULL;
-#if ENABLE_ASH_MATH_SUPPORT_64
-                       numstackptr->val = strtoll(expr, (char **) &expr, 0);
-#else
-                       numstackptr->val = strtol(expr, (char **) &expr, 0);
-#endif
-                       goto num;
-               }
-               for (p = op_tokens; ; p++) {
-                       const char *o;
-
-                       if (*p == 0) {
-                               /* strange operator not found */
-                               goto err;
-                       }
-                       for (o = expr; *p && *o == *p; p++)
-                               o++;
-                       if (!*p) {
-                               /* found */
-                               expr = o - 1;
-                               break;
-                       }
-                       /* skip tail uncompared token */
-                       while (*p)
-                               p++;
-                       /* skip zero delim */
-                       p++;
-               }
-               op = p[1];
-
-               /* post grammar: a++ reduce to num */
-               if (lasttok == TOK_POST_INC || lasttok == TOK_POST_DEC)
-                       lasttok = TOK_NUM;
-
-               /* Plus and minus are binary (not unary) _only_ if the last
-                * token was as number, or a right paren (which pretends to be
-                * a number, since it evaluates to one). Think about it.
-                * It makes sense. */
-               if (lasttok != TOK_NUM) {
-                       switch (op) {
-                       case TOK_ADD:
-                               op = TOK_UPLUS;
-                               break;
-                       case TOK_SUB:
-                               op = TOK_UMINUS;
-                               break;
-                       case TOK_POST_INC:
-                               op = TOK_PRE_INC;
-                               break;
-                       case TOK_POST_DEC:
-                               op = TOK_PRE_DEC;
-                               break;
-                       }
-               }
-               /* We don't want a unary operator to cause recursive descent on the
-                * stack, because there can be many in a row and it could cause an
-                * operator to be evaluated before its argument is pushed onto the
-                * integer stack. */
-               /* But for binary operators, "apply" everything on the operator
-                * stack until we find an operator with a lesser priority than the
-                * one we have just extracted. */
-               /* Left paren is given the lowest priority so it will never be
-                * "applied" in this way.
-                * if associativity is right and priority eq, applied also skip
-                */
-               prec = PREC(op);
-               if ((prec > 0 && prec < UNARYPREC) || prec == SPEC_PREC) {
-                       /* not left paren or unary */
-                       if (lasttok != TOK_NUM) {
-                               /* binary op must be preceded by a num */
-                               goto err;
-                       }
-                       while (stackptr != stack) {
-                               if (op == TOK_RPAREN) {
-                                       /* The algorithm employed here is simple: while we don't
-                                        * hit an open paren nor the bottom of the stack, pop
-                                        * tokens and apply them */
-                                       if (stackptr[-1] == TOK_LPAREN) {
-                                               --stackptr;
-                                               /* Any operator directly after a */
-                                               lasttok = TOK_NUM;
-                                               /* close paren should consider itself binary */
-                                               goto prologue;
-                                       }
-                               } else {
-                                       operator prev_prec = PREC(stackptr[-1]);
-
-                                       convert_prec_is_assing(prec);
-                                       convert_prec_is_assing(prev_prec);
-                                       if (prev_prec < prec)
-                                               break;
-                                       /* check right assoc */
-                                       if (prev_prec == prec && is_right_associativity(prec))
-                                               break;
-                               }
-                               errcode = arith_apply(*--stackptr, numstack, &numstackptr);
-                               if (errcode) goto ret;
-                       }
-                       if (op == TOK_RPAREN) {
-                               goto err;
-                       }
-               }
-
-               /* Push this operator to the stack and remember it. */
-               *stackptr++ = lasttok = op;
- prologue:
-               ++expr;
-       } /* while */
-}
-#endif /* ASH_MATH_SUPPORT */
-
-
 /* ============ main() and helpers */
 
 /*
@@ -13396,7 +12938,7 @@ exitshell(void)
        status = exitstatus;
        TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
        if (setjmp(loc.loc)) {
-               if (exception == EXEXIT)
+               if (exception_type == EXEXIT)
 /* dash bug: it just does _exit(exitstatus) here
  * but we have to do setjobctl(0) first!
  * (bug is still not fixed in dash-0.5.3 - if you run dash
@@ -13421,7 +12963,7 @@ static void
 init(void)
 {
        /* from input.c: */
-       basepf.nextc = basepf.buf = basebuf;
+       basepf.next_to_pgetc = basepf.buf = basebuf;
 
        /* from trap.c: */
        signal(SIGCHLD, SIG_DFL);
@@ -13542,7 +13084,8 @@ reset(void)
        evalskip = 0;
        loopnest = 0;
        /* from input.c: */
-       parselleft = parsenleft = 0;      /* clear input buffer */
+       g_parsefile->left_in_buffer = 0;
+       g_parsefile->left_in_line = 0;      /* clear input buffer */
        popallfiles();
        /* from parser.c: */
        tokpushback = 0;
@@ -13566,8 +13109,8 @@ extern int etext();
 int ash_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int ash_main(int argc UNUSED_PARAM, char **argv)
 {
-       char *shinit;
-       volatile int state;
+       const char *shinit;
+       volatile smallint state;
        struct jmploc jmploc;
        struct stackmark smark;
 
@@ -13589,21 +13132,20 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
 #endif
        state = 0;
        if (setjmp(jmploc.loc)) {
-               int e;
-               int s;
+               smallint e;
+               smallint s;
 
                reset();
 
-               e = exception;
+               e = exception_type;
                if (e == EXERROR)
                        exitstatus = 2;
                s = state;
                if (e == EXEXIT || s == 0 || iflag == 0 || shlvl)
                        exitshell();
-
-               if (e == EXINT) {
+               if (e == EXINT)
                        outcslow('\n', stderr);
-               }
+
                popstackmark(&smark);
                FORCE_INT_ON; /* enable interrupts */
                if (s == 1)
@@ -13617,7 +13159,7 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
        exception_handler = &jmploc;
 #if DEBUG
        opentrace();
-       trace_puts("Shell args: ");
+       TRACE(("Shell args: "));
        trace_puts_args(argv);
 #endif
        rootpid = getpid();
@@ -13645,7 +13187,7 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
                }
        }
 #endif
-       if (argv[0] && argv[0][0] == '-')
+       if (/* argv[0] && */ argv[0][0] == '-')
                isloginsh = 1;
        if (isloginsh) {
                state = 1;
@@ -13669,15 +13211,21 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
        }
  state3:
        state = 4;
-       if (minusc)
+       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->fd = -1;
                evalstring(minusc, 0);
+       }
 
        if (sflag || minusc == NULL) {
 #if ENABLE_FEATURE_EDITING_SAVEHISTORY
                if (iflag) {
                        const char *hp = lookupvar("HISTFILE");
-
-                       if (hp != NULL)
+                       if (hp)
                                line_input_state->hist_file = hp;
                }
 #endif
@@ -13697,14 +13245,6 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
        /* NOTREACHED */
 }
 
-#if DEBUG
-const char *applet_name = "debug stuff usage";
-int main(int argc, char **argv)
-{
-       return ash_main(argc, argv);
-}
-#endif
-
 
 /*-
  * Copyright (c) 1989, 1991, 1993, 1994