shell/hush.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * sh.c -- a prototype Bourne shell grammar parser
   4  *      Intended to follow the original Thompson and Ritchie
   5  *      "small and simple is beautiful" philosophy, which
   6  *      incidentally is a good match to today's BusyBox.
   7  *
   8  * Copyright (C) 2000,2001  Larry Doolittle  <larry@doolittle.boa.org>
   9  *
  10  * Credits:
  11  *      The parser routines proper are all original material, first
  12  *      written Dec 2000 and Jan 2001 by Larry Doolittle.  The
  13  *      execution engine, the builtins, and much of the underlying
  14  *      support has been adapted from busybox-0.49pre's lash, which is
  15  *      Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
  16  *      written by Erik Andersen <andersen@codepoet.org>.  That, in turn,
  17  *      is based in part on ladsh.c, by Michael K. Johnson and Erik W.
  18  *      Troan, which they placed in the public domain.  I don't know
  19  *      how much of the Johnson/Troan code has survived the repeated
  20  *      rewrites.
  21  *
  22  * Other credits:
  23  *      simple_itoa() was lifted from boa-0.93.15
  24  *      b_addchr() derived from similar w_addchar function in glibc-2.2
  25  *      setup_redirect(), redirect_opt_num(), and big chunks of main()
  26  *        and many builtins derived from contributions by Erik Andersen
  27  *      miscellaneous bugfixes from Matt Kraai
  28  *
  29  * There are two big (and related) architecture differences between
  30  * this parser and the lash parser.  One is that this version is
  31  * actually designed from the ground up to understand nearly all
  32  * of the Bourne grammar.  The second, consequential change is that
  33  * the parser and input reader have been turned inside out.  Now,
  34  * the parser is in control, and asks for input as needed.  The old
  35  * way had the input reader in control, and it asked for parsing to
  36  * take place as needed.  The new way makes it much easier to properly
  37  * handle the recursion implicit in the various substitutions, especially
  38  * across continuation lines.
  39  *
  40  * Bash grammar not implemented: (how many of these were in original sh?)
  41  *      $@ (those sure look like weird quoting rules)
  42  *      $_
  43  *      ! negation operator for pipes
  44  *      &> and >& redirection of stdout+stderr
  45  *      Brace Expansion
  46  *      Tilde Expansion
  47  *      fancy forms of Parameter Expansion
  48  *      aliases
  49  *      Arithmetic Expansion
  50  *      <(list) and >(list) Process Substitution
  51  *      reserved words: case, esac, select, function
  52  *      Here Documents ( << word )
  53  *      Functions
  54  * Major bugs:
  55  *      job handling woefully incomplete and buggy
  56  *      reserved word execution woefully incomplete and buggy
  57  * to-do:
  58  *      port selected bugfixes from post-0.49 busybox lash - done?
  59  *      finish implementing reserved words: for, while, until, do, done
  60  *      change { and } from special chars to reserved words
  61  *      builtins: break, continue, eval, return, set, trap, ulimit
  62  *      test magic exec
  63  *      handle children going into background
  64  *      clean up recognition of null pipes
  65  *      check setting of global_argc and global_argv
  66  *      control-C handling, probably with longjmp
  67  *      follow IFS rules more precisely, including update semantics
  68  *      figure out what to do with backslash-newline
  69  *      explain why we use signal instead of sigaction
  70  *      propagate syntax errors, die on resource errors?
  71  *      continuation lines, both explicit and implicit - done?
  72  *      memory leak finding and plugging - done?
  73  *      more testing, especially quoting rules and redirection
  74  *      document how quoting rules not precisely followed for variable assignments
  75  *      maybe change map[] to use 2-bit entries
  76  *      (eventually) remove all the printf's
  77  *
  78  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  79  */
  80 #include <ctype.h>     /* isalpha, isdigit */
  81 #include <unistd.h>    /* getpid */
  82 #include <stdlib.h>    /* getenv, atoi */
  83 #include <string.h>    /* strchr */
  84 #include <stdio.h>     /* popen etc. */
  85 #include <glob.h>      /* glob, of course */
  86 #include <stdarg.h>    /* va_list */
  87 #include <errno.h>
  88 #include <fcntl.h>
  89 #include <getopt.h>    /* should be pretty obvious */
  90
  91 #include <sys/stat.h>  /* ulimit */
  92 #include <sys/types.h>
  93 #include <sys/wait.h>
  94 #include <signal.h>
  95
  96 /* #include <dmalloc.h> */
  97 /* #define DEBUG_SHELL */
  98
  99 #if 1
 100 #include "busybox.h"
 101 #include "cmdedit.h"
 102 #else
 103 #define bb_applet_name "hush"
 104 //#include "standalone.h"
 105 #define hush_main main
 106 #undef CONFIG_FEATURE_SH_FANCY_PROMPT
 107 #define BB_BANNER ""
 108 #endif
 109 #define SPECIAL_VAR_SYMBOL 03
 110 #define FLAG_EXIT_FROM_LOOP 1
 111 #define FLAG_PARSE_SEMICOLON (1 << 1)           /* symbol ';' is special for parser */
 112 #define FLAG_REPARSING           (1 << 2)               /* >=2nd pass */
 113
 114 typedef enum {
 115         REDIRECT_INPUT     = 1,
 116         REDIRECT_OVERWRITE = 2,
 117         REDIRECT_APPEND    = 3,
 118         REDIRECT_HEREIS    = 4,
 119         REDIRECT_IO        = 5
 120 } redir_type;
 121
 122 /* The descrip member of this structure is only used to make debugging
 123  * output pretty */
 124 static const struct {int mode; int default_fd; const char *descrip;} redir_table[] = {
 125         { 0,                         0, "()" },
 126         { O_RDONLY,                  0, "<"  },
 127         { O_CREAT|O_TRUNC|O_WRONLY,  1, ">"  },
 128         { O_CREAT|O_APPEND|O_WRONLY, 1, ">>" },
 129         { O_RDONLY,                 -1, "<<" },
 130         { O_RDWR,                    1, "<>" }
 131 };
 132
 133 typedef enum {
 134         PIPE_SEQ = 1,
 135         PIPE_AND = 2,
 136         PIPE_OR  = 3,
 137         PIPE_BG  = 4,
 138 } pipe_style;
 139
 140 /* might eventually control execution */
 141 typedef enum {
 142         RES_NONE  = 0,
 143         RES_IF    = 1,
 144         RES_THEN  = 2,
 145         RES_ELIF  = 3,
 146         RES_ELSE  = 4,
 147         RES_FI    = 5,
 148         RES_FOR   = 6,
 149         RES_WHILE = 7,
 150         RES_UNTIL = 8,
 151         RES_DO    = 9,
 152         RES_DONE  = 10,
 153         RES_XXXX  = 11,
 154         RES_IN    = 12,
 155         RES_SNTX  = 13
 156 } reserved_style;
 157 #define FLAG_END   (1<<RES_NONE)
 158 #define FLAG_IF    (1<<RES_IF)
 159 #define FLAG_THEN  (1<<RES_THEN)
 160 #define FLAG_ELIF  (1<<RES_ELIF)
 161 #define FLAG_ELSE  (1<<RES_ELSE)
 162 #define FLAG_FI    (1<<RES_FI)
 163 #define FLAG_FOR   (1<<RES_FOR)
 164 #define FLAG_WHILE (1<<RES_WHILE)
 165 #define FLAG_UNTIL (1<<RES_UNTIL)
 166 #define FLAG_DO    (1<<RES_DO)
 167 #define FLAG_DONE  (1<<RES_DONE)
 168 #define FLAG_IN    (1<<RES_IN)
 169 #define FLAG_START (1<<RES_XXXX)
 170
 171 /* This holds pointers to the various results of parsing */
 172 struct p_context {
 173         struct child_prog *child;
 174         struct pipe *list_head;
 175         struct pipe *pipe;
 176         struct redir_struct *pending_redirect;
 177         reserved_style w;
 178         int old_flag;                           /* for figuring out valid reserved words */
 179         struct p_context *stack;
 180         int type;                       /* define type of parser : ";$" common or special symbol */
 181         /* How about quoting status? */
 182 };
 183
 184 struct redir_struct {
 185         redir_type type;                        /* type of redirection */
 186         int fd;                                         /* file descriptor being redirected */
 187         int dup;                                        /* -1, or file descriptor being duplicated */
 188         struct redir_struct *next;      /* pointer to the next redirect in the list */
 189         glob_t word;                            /* *word.gl_pathv is the filename */
 190 };
 191
 192 struct child_prog {
 193         pid_t pid;                                      /* 0 if exited */
 194         char **argv;                            /* program name and arguments */
 195         struct pipe *group;                     /* if non-NULL, first in group or subshell */
 196         int subshell;                           /* flag, non-zero if group must be forked */
 197         struct redir_struct *redirects; /* I/O redirections */
 198         glob_t glob_result;                     /* result of parameter globbing */
 199         int is_stopped;                         /* is the program currently running? */
 200         struct pipe *family;            /* pointer back to the child's parent pipe */
 201         int sp;                         /* number of SPECIAL_VAR_SYMBOL */
 202         int type;
 203 };
 204
 205 struct pipe {
 206         int jobid;                                      /* job number */
 207         int num_progs;                          /* total number of programs in job */
 208         int running_progs;                      /* number of programs running */
 209         char *text;                                     /* name of job */
 210         char *cmdbuf;                           /* buffer various argv's point into */
 211         pid_t pgrp;                                     /* process group ID for the job */
 212         struct child_prog *progs;       /* array of commands in pipe */
 213         struct pipe *next;                      /* to track background commands */
 214         int stopped_progs;                      /* number of programs alive, but stopped */
 215         int job_context;                        /* bitmask defining current context */
 216         pipe_style followup;            /* PIPE_BG, PIPE_SEQ, PIPE_OR, PIPE_AND */
 217         reserved_style r_mode;          /* supports if, for, while, until */
 218 };
 219
 220 struct close_me {
 221         int fd;
 222         struct close_me *next;
 223 };
 224
 225 struct variables {
 226         char *name;
 227         char *value;
 228         int flg_export;
 229         int flg_read_only;
 230         struct variables *next;
 231 };
 232
 233 /* globals, connect us to the outside world
 234  * the first three support $?, $#, and $1 */
 235 static char **global_argv;
 236 static int global_argc;
 237 static int last_return_code;
 238 extern char **environ; /* This is in <unistd.h>, but protected with __USE_GNU */
 239
 240 /* "globals" within this file */
 241 static char *ifs;
 242 static unsigned char map[256];
 243 static int fake_mode;
 244 static int interactive;
 245 static struct close_me *close_me_head;
 246 static const char *cwd;
 247 static struct pipe *job_list;
 248 static unsigned int last_bg_pid;
 249 static int last_jobid;
 250 static unsigned int shell_terminal;
 251 static char *PS1;
 252 static char *PS2;
 253 static struct variables shell_ver = { "HUSH_VERSION", "0.01", 1, 1, 0 };
 254 static struct variables *top_vars = &shell_ver;
 255
 256
 257 #define B_CHUNK (100)
 258 #define B_NOSPAC 1
 259
 260 typedef struct {
 261         char *data;
 262         int length;
 263         int maxlen;
 264         int quote;
 265         int nonnull;
 266 } o_string;
 267 #define NULL_O_STRING {NULL,0,0,0,0}
 268 /* used for initialization:
 269         o_string foo = NULL_O_STRING; */
 270
 271 /* I can almost use ordinary FILE *.  Is open_memstream() universally
 272  * available?  Where is it documented? */
 273 struct in_str {
 274         const char *p;
 275         char peek_buf[2];
 276         int __promptme;
 277         int promptmode;
 278         FILE *file;
 279         int (*get) (struct in_str *);
 280         int (*peek) (struct in_str *);
 281 };
 282 #define b_getch(input) ((input)->get(input))
 283 #define b_peek(input) ((input)->peek(input))
 284
 285 #define JOB_STATUS_FORMAT "[%d] %-22s %.40s\n"
 286
 287 struct built_in_command {
 288         const char *cmd;                        /* name */
 289         const char *descr;                      /* description */
 290         int (*function) (struct child_prog *);  /* function ptr */
 291 };
 292
 293 /* belongs in busybox.h */
 294 static inline int max(int a, int b) {
 295         return (a>b)?a:b;
 296 }
 297
 298 /* This should be in utility.c */
 299 #ifdef DEBUG_SHELL
 300 static void debug_printf(const char *format, ...)
 301 {
 302         va_list args;
 303         va_start(args, format);
 304         vfprintf(stderr, format, args);
 305         va_end(args);
 306 }
 307 #else
 308 static inline void debug_printf(const char *format ATTRIBUTE_UNUSED, ...) { }
 309 #endif
 310 #define final_printf debug_printf
 311
 312 static void __syntax(char *file, int line) {
 313         bb_error_msg("syntax error %s:%d", file, line);
 314 }
 315 #define syntax() __syntax(__FILE__, __LINE__)
 316
 317 /* Index of subroutines: */
 318 /*   function prototypes for builtins */
 319 static int builtin_cd(struct child_prog *child);
 320 static int builtin_env(struct child_prog *child);
 321 static int builtin_eval(struct child_prog *child);
 322 static int builtin_exec(struct child_prog *child);
 323 static int builtin_exit(struct child_prog *child);
 324 static int builtin_export(struct child_prog *child);
 325 static int builtin_fg_bg(struct child_prog *child);
 326 static int builtin_help(struct child_prog *child);
 327 static int builtin_jobs(struct child_prog *child);
 328 static int builtin_pwd(struct child_prog *child);
 329 static int builtin_read(struct child_prog *child);
 330 static int builtin_set(struct child_prog *child);
 331 static int builtin_shift(struct child_prog *child);
 332 static int builtin_source(struct child_prog *child);
 333 static int builtin_umask(struct child_prog *child);
 334 static int builtin_unset(struct child_prog *child);
 335 static int builtin_not_written(struct child_prog *child);
 336 /*   o_string manipulation: */
 337 static int b_check_space(o_string *o, int len);
 338 static int b_addchr(o_string *o, int ch);
 339 static void b_reset(o_string *o);
 340 static int b_addqchr(o_string *o, int ch, int quote);
 341 static int b_adduint(o_string *o, unsigned int i);
 342 /*  in_str manipulations: */
 343 static int static_get(struct in_str *i);
 344 static int static_peek(struct in_str *i);
 345 static int file_get(struct in_str *i);
 346 static int file_peek(struct in_str *i);
 347 static void setup_file_in_str(struct in_str *i, FILE *f);
 348 static void setup_string_in_str(struct in_str *i, const char *s);
 349 /*  close_me manipulations: */
 350 static void mark_open(int fd);
 351 static void mark_closed(int fd);
 352 static void close_all(void);
 353 /*  "run" the final data structures: */
 354 static char *indenter(int i);
 355 static int free_pipe_list(struct pipe *head, int indent);
 356 static int free_pipe(struct pipe *pi, int indent);
 357 /*  really run the final data structures: */
 358 static int setup_redirects(struct child_prog *prog, int squirrel[]);
 359 static int run_list_real(struct pipe *pi);
 360 static void pseudo_exec(struct child_prog *child) ATTRIBUTE_NORETURN;
 361 static int run_pipe_real(struct pipe *pi);
 362 /*   extended glob support: */
 363 static int globhack(const char *src, int flags, glob_t *pglob);
 364 static int glob_needed(const char *s);
 365 static int xglob(o_string *dest, int flags, glob_t *pglob);
 366 /*   variable assignment: */
 367 static int is_assignment(const char *s);
 368 /*   data structure manipulation: */
 369 static int setup_redirect(struct p_context *ctx, int fd, redir_type style, struct in_str *input);
 370 static void initialize_context(struct p_context *ctx);
 371 static int done_word(o_string *dest, struct p_context *ctx);
 372 static int done_command(struct p_context *ctx);
 373 static int done_pipe(struct p_context *ctx, pipe_style type);
 374 /*   primary string parsing: */
 375 static int redirect_dup_num(struct in_str *input);
 376 static int redirect_opt_num(o_string *o);
 377 static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end);
 378 static int parse_group(o_string *dest, struct p_context *ctx, struct in_str *input, int ch);
 379 static char *lookup_param(char *src);
 380 static char *make_string(char **inp);
 381 static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input);
 382 static int parse_string(o_string *dest, struct p_context *ctx, const char *src);
 383 static int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input0, int end_trigger);
 384 /*   setup: */
 385 static int parse_stream_outer(struct in_str *inp, int flag);
 386 static int parse_string_outer(const char *s, int flag);
 387 static int parse_file_outer(FILE *f);
 388 /*   job management: */
 389 static int checkjobs(struct pipe* fg_pipe);
 390 static void insert_bg_job(struct pipe *pi);
 391 static void remove_bg_job(struct pipe *pi);
 392 /*     local variable support */
 393 static char **make_list_in(char **inp, char *name);
 394 static char *insert_var_value(char *inp);
 395 static char *get_local_var(const char *var);
 396 static void  unset_local_var(const char *name);
 397 static int set_local_var(const char *s, int flg_export);
 398
 399 /* Table of built-in functions.  They can be forked or not, depending on
 400  * context: within pipes, they fork.  As simple commands, they do not.
 401  * When used in non-forking context, they can change global variables
 402  * in the parent shell process.  If forked, of course they can not.
 403  * For example, 'unset foo | whatever' will parse and run, but foo will
 404  * still be set at the end. */
 405 static const struct built_in_command bltins[] = {
 406         {"bg", "Resume a job in the background", builtin_fg_bg},
 407         {"break", "Exit for, while or until loop", builtin_not_written},
 408         {"cd", "Change working directory", builtin_cd},
 409         {"continue", "Continue for, while or until loop", builtin_not_written},
 410         {"env", "Print all environment variables", builtin_env},
 411         {"eval", "Construct and run shell command", builtin_eval},
 412         {"exec", "Exec command, replacing this shell with the exec'd process",
 413                 builtin_exec},
 414         {"exit", "Exit from shell()", builtin_exit},
 415         {"export", "Set environment variable", builtin_export},
 416         {"fg", "Bring job into the foreground", builtin_fg_bg},
 417         {"jobs", "Lists the active jobs", builtin_jobs},
 418         {"pwd", "Print current directory", builtin_pwd},
 419         {"read", "Input environment variable", builtin_read},
 420         {"return", "Return from a function", builtin_not_written},
 421         {"set", "Set/unset shell local variables", builtin_set},
 422         {"shift", "Shift positional parameters", builtin_shift},
 423         {"trap", "Trap signals", builtin_not_written},
 424         {"ulimit","Controls resource limits", builtin_not_written},
 425         {"umask","Sets file creation mask", builtin_umask},
 426         {"unset", "Unset environment variable", builtin_unset},
 427         {".", "Source-in and run commands in a file", builtin_source},
 428         {"help", "List shell built-in commands", builtin_help},
 429         {NULL, NULL, NULL}
 430 };
 431
 432 static const char *set_cwd(void)
 433 {
 434         if(cwd==bb_msg_unknown)
 435                 cwd = NULL;     /* xgetcwd(arg) called free(arg) */
 436         cwd = xgetcwd((char *)cwd);
 437         if (!cwd)
 438                 cwd = bb_msg_unknown;
 439         return cwd;
 440 }
 441
 442 /* built-in 'eval' handler */
 443 static int builtin_eval(struct child_prog *child)
 444 {
 445         char *str = NULL;
 446         int rcode = EXIT_SUCCESS;
 447
 448         if (child->argv[1]) {
 449                 str = make_string(child->argv + 1);
 450                 parse_string_outer(str, FLAG_EXIT_FROM_LOOP |
 451                                         FLAG_PARSE_SEMICOLON);
 452                 free(str);
 453                 rcode = last_return_code;
 454         }
 455         return rcode;
 456 }
 457
 458 /* built-in 'cd <path>' handler */
 459 static int builtin_cd(struct child_prog *child)
 460 {
 461         char *newdir;
 462         if (child->argv[1] == NULL)
 463                 newdir = getenv("HOME");
 464         else
 465                 newdir = child->argv[1];
 466         if (chdir(newdir)) {
 467                 printf("cd: %s: %s\n", newdir, strerror(errno));
 468                 return EXIT_FAILURE;
 469         }
 470         set_cwd();
 471         return EXIT_SUCCESS;
 472 }
 473
 474 /* built-in 'env' handler */
 475 static int builtin_env(struct child_prog *dummy ATTRIBUTE_UNUSED)
 476 {
 477         char **e = environ;
 478         if (e == NULL) return EXIT_FAILURE;
 479         for (; *e; e++) {
 480                 puts(*e);
 481         }
 482         return EXIT_SUCCESS;
 483 }
 484
 485 /* built-in 'exec' handler */
 486 static int builtin_exec(struct child_prog *child)
 487 {
 488         if (child->argv[1] == NULL)
 489                 return EXIT_SUCCESS;   /* Really? */
 490         child->argv++;
 491         pseudo_exec(child);
 492         /* never returns */
 493 }
 494
 495 /* built-in 'exit' handler */
 496 static int builtin_exit(struct child_prog *child)
 497 {
 498         if (child->argv[1] == NULL)
 499                 exit(last_return_code);
 500         exit (atoi(child->argv[1]));
 501 }
 502
 503 /* built-in 'export VAR=value' handler */
 504 static int builtin_export(struct child_prog *child)
 505 {
 506         int res = 0;
 507         char *name = child->argv[1];
 508
 509         if (name == NULL) {
 510                 return (builtin_env(child));
 511         }
 512
 513         name = strdup(name);
 514
 515         if(name) {
 516                 char *value = strchr(name, '=');
 517
 518                 if (!value) {
 519                         char *tmp;
 520                         /* They are exporting something without an =VALUE */
 521
 522                         value = get_local_var(name);
 523                         if (value) {
 524                                 size_t ln = strlen(name);
 525
 526                                 tmp = realloc(name, ln+strlen(value)+2);
 527                                 if(tmp==NULL)
 528                                         res = -1;
 529                                 else {
 530                                         sprintf(tmp+ln, "=%s", value);
 531                                         name = tmp;
 532                                 }
 533                         } else {
 534                                 /* bash does not return an error when trying to export
 535                                  * an undefined variable.  Do likewise. */
 536                                 res = 1;
 537                         }
 538                 }
 539         }
 540         if (res<0)
 541                 bb_perror_msg("export");
 542         else if(res==0)
 543                 res = set_local_var(name, 1);
 544         else
 545                 res = 0;
 546         free(name);
 547         return res;
 548 }
 549
 550 /* built-in 'fg' and 'bg' handler */
 551 static int builtin_fg_bg(struct child_prog *child)
 552 {
 553         int i, jobnum;
 554         struct pipe *pi=NULL;
 555
 556         if (!interactive)
 557                 return EXIT_FAILURE;
 558         /* If they gave us no args, assume they want the last backgrounded task */
 559         if (!child->argv[1]) {
 560                 for (pi = job_list; pi; pi = pi->next) {
 561                         if (pi->jobid == last_jobid) {
 562                                 break;
 563                         }
 564                 }
 565                 if (!pi) {
 566                         bb_error_msg("%s: no current job", child->argv[0]);
 567                         return EXIT_FAILURE;
 568                 }
 569         } else {
 570                 if (sscanf(child->argv[1], "%%%d", &jobnum) != 1) {
 571                         bb_error_msg("%s: bad argument '%s'", child->argv[0], child->argv[1]);
 572                         return EXIT_FAILURE;
 573                 }
 574                 for (pi = job_list; pi; pi = pi->next) {
 575                         if (pi->jobid == jobnum) {
 576                                 break;
 577                         }
 578                 }
 579                 if (!pi) {
 580                         bb_error_msg("%s: %d: no such job", child->argv[0], jobnum);
 581                         return EXIT_FAILURE;
 582                 }
 583         }
 584
 585         if (*child->argv[0] == 'f') {
 586                 /* Put the job into the foreground.  */
 587                 tcsetpgrp(shell_terminal, pi->pgrp);
 588         }
 589
 590         /* Restart the processes in the job */
 591         for (i = 0; i < pi->num_progs; i++)
 592                 pi->progs[i].is_stopped = 0;
 593
 594         if ( (i=kill(- pi->pgrp, SIGCONT)) < 0) {
 595                 if (i == ESRCH) {
 596                         remove_bg_job(pi);
 597                 } else {
 598                         bb_perror_msg("kill (SIGCONT)");
 599                 }
 600         }
 601
 602         pi->stopped_progs = 0;
 603         return EXIT_SUCCESS;
 604 }
 605
 606 /* built-in 'help' handler */
 607 static int builtin_help(struct child_prog *dummy ATTRIBUTE_UNUSED)
 608 {
 609         const struct built_in_command *x;
 610
 611         printf("\nBuilt-in commands:\n");
 612         printf("-------------------\n");
 613         for (x = bltins; x->cmd; x++) {
 614                 if (x->descr==NULL)
 615                         continue;
 616                 printf("%s\t%s\n", x->cmd, x->descr);
 617         }
 618         printf("\n\n");
 619         return EXIT_SUCCESS;
 620 }
 621
 622 /* built-in 'jobs' handler */
 623 static int builtin_jobs(struct child_prog *child ATTRIBUTE_UNUSED)
 624 {
 625         struct pipe *job;
 626         char *status_string;
 627
 628         for (job = job_list; job; job = job->next) {
 629                 if (job->running_progs == job->stopped_progs)
 630                         status_string = "Stopped";
 631                 else
 632                         status_string = "Running";
 633
 634                 printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->text);
 635         }
 636         return EXIT_SUCCESS;
 637 }
 638
 639
 640 /* built-in 'pwd' handler */
 641 static int builtin_pwd(struct child_prog *dummy ATTRIBUTE_UNUSED)
 642 {
 643         puts(set_cwd());
 644         return EXIT_SUCCESS;
 645 }
 646
 647 /* built-in 'read VAR' handler */
 648 static int builtin_read(struct child_prog *child)
 649 {
 650         int res;
 651
 652         if (child->argv[1]) {
 653                 char string[BUFSIZ];
 654                 char *var = 0;
 655
 656                 string[0] = 0;  /* In case stdin has only EOF */
 657                 /* read string */
 658                 fgets(string, sizeof(string), stdin);
 659                 chomp(string);
 660                 var = malloc(strlen(child->argv[1])+strlen(string)+2);
 661                 if(var) {
 662                         sprintf(var, "%s=%s", child->argv[1], string);
 663                         res = set_local_var(var, 0);
 664                 } else
 665                         res = -1;
 666                 if (res)
 667                         fprintf(stderr, "read: %m\n");
 668                 free(var);      /* So not move up to avoid breaking errno */
 669                 return res;
 670         } else {
 671                 do res=getchar(); while(res!='\n' && res!=EOF);
 672                 return 0;
 673         }
 674 }
 675
 676 /* built-in 'set VAR=value' handler */
 677 static int builtin_set(struct child_prog *child)
 678 {
 679         char *temp = child->argv[1];
 680         struct variables *e;
 681
 682         if (temp == NULL)
 683                 for(e = top_vars; e; e=e->next)
 684                         printf("%s=%s\n", e->name, e->value);
 685         else
 686                 set_local_var(temp, 0);
 687
 688                 return EXIT_SUCCESS;
 689 }
 690
 691
 692 /* Built-in 'shift' handler */
 693 static int builtin_shift(struct child_prog *child)
 694 {
 695         int n=1;
 696         if (child->argv[1]) {
 697                 n=atoi(child->argv[1]);
 698         }
 699         if (n>=0 && n<global_argc) {
 700                 /* XXX This probably breaks $0 */
 701                 global_argc -= n;
 702                 global_argv += n;
 703                 return EXIT_SUCCESS;
 704         } else {
 705                 return EXIT_FAILURE;
 706         }
 707 }
 708
 709 /* Built-in '.' handler (read-in and execute commands from file) */
 710 static int builtin_source(struct child_prog *child)
 711 {
 712         FILE *input;
 713         int status;
 714
 715         if (child->argv[1] == NULL)
 716                 return EXIT_FAILURE;
 717
 718         /* XXX search through $PATH is missing */
 719         input = fopen(child->argv[1], "r");
 720         if (!input) {
 721                 bb_error_msg("Couldn't open file '%s'", child->argv[1]);
 722                 return EXIT_FAILURE;
 723         }
 724
 725         /* Now run the file */
 726         /* XXX argv and argc are broken; need to save old global_argv
 727          * (pointer only is OK!) on this stack frame,
 728          * set global_argv=child->argv+1, recurse, and restore. */
 729         mark_open(fileno(input));
 730         status = parse_file_outer(input);
 731         mark_closed(fileno(input));
 732         fclose(input);
 733         return (status);
 734 }
 735
 736 static int builtin_umask(struct child_prog *child)
 737 {
 738         mode_t new_umask;
 739         const char *arg = child->argv[1];
 740         char *end;
 741         if (arg) {
 742                 new_umask=strtoul(arg, &end, 8);
 743                 if (*end!='\0' || end == arg) {
 744                         return EXIT_FAILURE;
 745                 }
 746         } else {
 747                 printf("%.3o\n", (unsigned int) (new_umask=umask(0)));
 748         }
 749         umask(new_umask);
 750         return EXIT_SUCCESS;
 751 }
 752
 753 /* built-in 'unset VAR' handler */
 754 static int builtin_unset(struct child_prog *child)
 755 {
 756         /* bash returned already true */
 757         unset_local_var(child->argv[1]);
 758         return EXIT_SUCCESS;
 759 }
 760
 761 static int builtin_not_written(struct child_prog *child)
 762 {
 763         printf("builtin_%s not written\n",child->argv[0]);
 764         return EXIT_FAILURE;
 765 }
 766
 767 static int b_check_space(o_string *o, int len)
 768 {
 769         /* It would be easy to drop a more restrictive policy
 770          * in here, such as setting a maximum string length */
 771         if (o->length + len > o->maxlen) {
 772                 char *old_data = o->data;
 773                 /* assert (data == NULL || o->maxlen != 0); */
 774                 o->maxlen += max(2*len, B_CHUNK);
 775                 o->data = realloc(o->data, 1 + o->maxlen);
 776                 if (o->data == NULL) {
 777                         free(old_data);
 778                 }
 779         }
 780         return o->data == NULL;
 781 }
 782
 783 static int b_addchr(o_string *o, int ch)
 784 {
 785         debug_printf("b_addchr: %c %d %p\n", ch, o->length, o);
 786         if (b_check_space(o, 1)) return B_NOSPAC;
 787         o->data[o->length] = ch;
 788         o->length++;
 789         o->data[o->length] = '\0';
 790         return 0;
 791 }
 792
 793 static void b_reset(o_string *o)
 794 {
 795         o->length = 0;
 796         o->nonnull = 0;
 797         if (o->data != NULL) *o->data = '\0';
 798 }
 799
 800 static void b_free(o_string *o)
 801 {
 802         b_reset(o);
 803         free(o->data);
 804         o->data = NULL;
 805         o->maxlen = 0;
 806 }
 807
 808 /* My analysis of quoting semantics tells me that state information
 809  * is associated with a destination, not a source.
 810  */
 811 static int b_addqchr(o_string *o, int ch, int quote)
 812 {
 813         if (quote && strchr("*?[\\",ch)) {
 814                 int rc;
 815                 rc = b_addchr(o, '\\');
 816                 if (rc) return rc;
 817         }
 818         return b_addchr(o, ch);
 819 }
 820
 821 /* belongs in utility.c */
 822 static char *simple_itoa(unsigned int i)
 823 {
 824         /* 21 digits plus null terminator, good for 64-bit or smaller ints */
 825         static char local[22];
 826         char *p = &local[21];
 827         *p-- = '\0';
 828         do {
 829                 *p-- = '0' + i % 10;
 830                 i /= 10;
 831         } while (i > 0);
 832         return p + 1;
 833 }
 834
 835 static int b_adduint(o_string *o, unsigned int i)
 836 {
 837         int r;
 838         char *p = simple_itoa(i);
 839         /* no escape checking necessary */
 840         do r=b_addchr(o, *p++); while (r==0 && *p);
 841         return r;
 842 }
 843
 844 static int static_get(struct in_str *i)
 845 {
 846         int ch=*i->p++;
 847         if (ch=='\0') return EOF;
 848         return ch;
 849 }
 850
 851 static int static_peek(struct in_str *i)
 852 {
 853         return *i->p;
 854 }
 855
 856 static inline void cmdedit_set_initial_prompt(void)
 857 {
 858 #ifndef CONFIG_FEATURE_SH_FANCY_PROMPT
 859         PS1 = NULL;
 860 #else
 861         PS1 = getenv("PS1");
 862         if(PS1==0)
 863                 PS1 = "\\w \\$ ";
 864 #endif
 865 }
 866
 867 static inline void setup_prompt_string(int promptmode, char **prompt_str)
 868 {
 869         debug_printf("setup_prompt_string %d ",promptmode);
 870 #ifndef CONFIG_FEATURE_SH_FANCY_PROMPT
 871         /* Set up the prompt */
 872         if (promptmode == 1) {
 873                 free(PS1);
 874                 PS1=xmalloc(strlen(cwd)+4);
 875                 sprintf(PS1, "%s %s", cwd, ( geteuid() != 0 ) ?  "$ ":"# ");
 876                 *prompt_str = PS1;
 877         } else {
 878                 *prompt_str = PS2;
 879         }
 880 #else
 881         *prompt_str = (promptmode==1)? PS1 : PS2;
 882 #endif
 883         debug_printf("result %s\n",*prompt_str);
 884 }
 885
 886 static void get_user_input(struct in_str *i)
 887 {
 888         char *prompt_str;
 889         static char the_command[BUFSIZ];
 890
 891         setup_prompt_string(i->promptmode, &prompt_str);
 892 #ifdef CONFIG_FEATURE_COMMAND_EDITING
 893         /*
 894          ** enable command line editing only while a command line
 895          ** is actually being read; otherwise, we'll end up bequeathing
 896          ** atexit() handlers and other unwanted stuff to our
 897          ** child processes (rob@sysgo.de)
 898          */
 899         cmdedit_read_input(prompt_str, the_command);
 900 #else
 901         fputs(prompt_str, stdout);
 902         fflush(stdout);
 903         the_command[0]=fgetc(i->file);
 904         the_command[1]='\0';
 905 #endif
 906         fflush(stdout);
 907         i->p = the_command;
 908 }
 909
 910 /* This is the magic location that prints prompts
 911  * and gets data back from the user */
 912 static int file_get(struct in_str *i)
 913 {
 914         int ch;
 915
 916         ch = 0;
 917         /* If there is data waiting, eat it up */
 918         if (i->p && *i->p) {
 919                 ch=*i->p++;
 920         } else {
 921                 /* need to double check i->file because we might be doing something
 922                  * more complicated by now, like sourcing or substituting. */
 923                 if (i->__promptme && interactive && i->file == stdin) {
 924                         while(! i->p || (interactive && strlen(i->p)==0) ) {
 925                                 get_user_input(i);
 926                         }
 927                         i->promptmode=2;
 928                         i->__promptme = 0;
 929                         if (i->p && *i->p) {
 930                                 ch=*i->p++;
 931                         }
 932                 } else {
 933                         ch = fgetc(i->file);
 934                 }
 935
 936                 debug_printf("b_getch: got a %d\n", ch);
 937         }
 938         if (ch == '\n') i->__promptme=1;
 939         return ch;
 940 }
 941
 942 /* All the callers guarantee this routine will never be
 943  * used right after a newline, so prompting is not needed.
 944  */
 945 static int file_peek(struct in_str *i)
 946 {
 947         if (i->p && *i->p) {
 948                 return *i->p;
 949         } else {
 950                 i->peek_buf[0] = fgetc(i->file);
 951                 i->peek_buf[1] = '\0';
 952                 i->p = i->peek_buf;
 953                 debug_printf("b_peek: got a %d\n", *i->p);
 954                 return *i->p;
 955         }
 956 }
 957
 958 static void setup_file_in_str(struct in_str *i, FILE *f)
 959 {
 960         i->peek = file_peek;
 961         i->get = file_get;
 962         i->__promptme=1;
 963         i->promptmode=1;
 964         i->file = f;
 965         i->p = NULL;
 966 }
 967
 968 static void setup_string_in_str(struct in_str *i, const char *s)
 969 {
 970         i->peek = static_peek;
 971         i->get = static_get;
 972         i->__promptme=1;
 973         i->promptmode=1;
 974         i->p = s;
 975 }
 976
 977 static void mark_open(int fd)
 978 {
 979         struct close_me *new = xmalloc(sizeof(struct close_me));
 980         new->fd = fd;
 981         new->next = close_me_head;
 982         close_me_head = new;
 983 }
 984
 985 static void mark_closed(int fd)
 986 {
 987         struct close_me *tmp;
 988         if (close_me_head == NULL || close_me_head->fd != fd)
 989                 bb_error_msg_and_die("corrupt close_me");
 990         tmp = close_me_head;
 991         close_me_head = close_me_head->next;
 992         free(tmp);
 993 }
 994
 995 static void close_all(void)
 996 {
 997         struct close_me *c;
 998         for (c=close_me_head; c; c=c->next) {
 999                 close(c->fd);
1000         }
1001         close_me_head = NULL;
1002 }
1003
1004 /* squirrel != NULL means we squirrel away copies of stdin, stdout,
1005  * and stderr if they are redirected. */
1006 static int setup_redirects(struct child_prog *prog, int squirrel[])
1007 {
1008         int openfd, mode;
1009         struct redir_struct *redir;
1010
1011         for (redir=prog->redirects; redir; redir=redir->next) {
1012                 if (redir->dup == -1 && redir->word.gl_pathv == NULL) {
1013                         /* something went wrong in the parse.  Pretend it didn't happen */
1014                         continue;
1015                 }
1016                 if (redir->dup == -1) {
1017                         mode=redir_table[redir->type].mode;
1018                         openfd = open(redir->word.gl_pathv[0], mode, 0666);
1019                         if (openfd < 0) {
1020                         /* this could get lost if stderr has been redirected, but
1021                            bash and ash both lose it as well (though zsh doesn't!) */
1022                                 bb_perror_msg("error opening %s", redir->word.gl_pathv[0]);
1023                                 return 1;
1024                         }
1025                 } else {
1026                         openfd = redir->dup;
1027                 }
1028
1029                 if (openfd != redir->fd) {
1030                         if (squirrel && redir->fd < 3) {
1031                                 squirrel[redir->fd] = dup(redir->fd);
1032                         }
1033                         if (openfd == -3) {
1034                                 close(openfd);
1035                         } else {
1036                                 dup2(openfd, redir->fd);
1037                                 if (redir->dup == -1)
1038                                         close (openfd);
1039                         }
1040                 }
1041         }
1042         return 0;
1043 }
1044
1045 static void restore_redirects(int squirrel[])
1046 {
1047         int i, fd;
1048         for (i=0; i<3; i++) {
1049                 fd = squirrel[i];
1050                 if (fd != -1) {
1051                         /* No error checking.  I sure wouldn't know what
1052                          * to do with an error if I found one! */
1053                         dup2(fd, i);
1054                         close(fd);
1055                 }
1056         }
1057 }
1058
1059 /* never returns */
1060 /* XXX no exit() here.  If you don't exec, use _exit instead.
1061  * The at_exit handlers apparently confuse the calling process,
1062  * in particular stdin handling.  Not sure why? */
1063 static void pseudo_exec(struct child_prog *child)
1064 {
1065         int i, rcode;
1066         char *p;
1067         const struct built_in_command *x;
1068         if (child->argv) {
1069                 for (i=0; is_assignment(child->argv[i]); i++) {
1070                         debug_printf("pid %d environment modification: %s\n",getpid(),child->argv[i]);
1071                         p = insert_var_value(child->argv[i]);
1072                         putenv(strdup(p));
1073                         if (p != child->argv[i]) free(p);
1074                 }
1075                 child->argv+=i;  /* XXX this hack isn't so horrible, since we are about
1076                                         to exit, and therefore don't need to keep data
1077                                         structures consistent for free() use. */
1078                 /* If a variable is assigned in a forest, and nobody listens,
1079                  * was it ever really set?
1080                  */
1081                 if (child->argv[0] == NULL) {
1082                         _exit(EXIT_SUCCESS);
1083                 }
1084
1085                 /*
1086                  * Check if the command matches any of the builtins.
1087                  * Depending on context, this might be redundant.  But it's
1088                  * easier to waste a few CPU cycles than it is to figure out
1089                  * if this is one of those cases.
1090                  */
1091                 for (x = bltins; x->cmd; x++) {
1092                         if (strcmp(child->argv[0], x->cmd) == 0 ) {
1093                                 debug_printf("builtin exec %s\n", child->argv[0]);
1094                                 rcode = x->function(child);
1095                                 fflush(stdout);
1096                                 _exit(rcode);
1097                         }
1098                 }
1099
1100                 /* Check if the command matches any busybox internal commands
1101                  * ("applets") here.
1102                  * FIXME: This feature is not 100% safe, since
1103                  * BusyBox is not fully reentrant, so we have no guarantee the things
1104                  * from the .bss are still zeroed, or that things from .data are still
1105                  * at their defaults.  We could exec ourself from /proc/self/exe, but I
1106                  * really dislike relying on /proc for things.  We could exec ourself
1107                  * from global_argv[0], but if we are in a chroot, we may not be able
1108                  * to find ourself... */
1109 #ifdef CONFIG_FEATURE_SH_STANDALONE_SHELL
1110                 {
1111                         int argc_l;
1112                         char** argv_l=child->argv;
1113                         char *name = child->argv[0];
1114
1115                         /* Count argc for use in a second... */
1116                         for(argc_l=0;*argv_l!=NULL; argv_l++, argc_l++);
1117                         optind = 1;
1118                         debug_printf("running applet %s\n", name);
1119                         run_applet_by_name(name, argc_l, child->argv);
1120                 }
1121 #endif
1122                 debug_printf("exec of %s\n",child->argv[0]);
1123                 execvp(child->argv[0],child->argv);
1124                 bb_perror_msg("couldn't exec: %s",child->argv[0]);
1125                 _exit(1);
1126         } else if (child->group) {
1127                 debug_printf("runtime nesting to group\n");
1128                 interactive=0;    /* crucial!!!! */
1129                 rcode = run_list_real(child->group);
1130                 /* OK to leak memory by not calling free_pipe_list,
1131                  * since this process is about to exit */
1132                 _exit(rcode);
1133         } else {
1134                 /* Can happen.  See what bash does with ">foo" by itself. */
1135                 debug_printf("trying to pseudo_exec null command\n");
1136                 _exit(EXIT_SUCCESS);
1137         }
1138 }
1139
1140 static void insert_bg_job(struct pipe *pi)
1141 {
1142         struct pipe *thejob;
1143
1144         /* Linear search for the ID of the job to use */
1145         pi->jobid = 1;
1146         for (thejob = job_list; thejob; thejob = thejob->next)
1147                 if (thejob->jobid >= pi->jobid)
1148                         pi->jobid = thejob->jobid + 1;
1149
1150         /* add thejob to the list of running jobs */
1151         if (!job_list) {
1152                 thejob = job_list = xmalloc(sizeof(*thejob));
1153         } else {
1154                 for (thejob = job_list; thejob->next; thejob = thejob->next) /* nothing */;
1155                 thejob->next = xmalloc(sizeof(*thejob));
1156                 thejob = thejob->next;
1157         }
1158
1159         /* physically copy the struct job */
1160         memcpy(thejob, pi, sizeof(struct pipe));
1161         thejob->next = NULL;
1162         thejob->running_progs = thejob->num_progs;
1163         thejob->stopped_progs = 0;
1164         thejob->text = xmalloc(BUFSIZ); /* cmdedit buffer size */
1165
1166         //if (pi->progs[0] && pi->progs[0].argv && pi->progs[0].argv[0])
1167         {
1168                 char *bar=thejob->text;
1169                 char **foo=pi->progs[0].argv;
1170                 while(foo && *foo) {
1171                         bar += sprintf(bar, "%s ", *foo++);
1172                 }
1173         }
1174
1175         /* we don't wait for background thejobs to return -- append it
1176            to the list of backgrounded thejobs and leave it alone */
1177         printf("[%d] %d\n", thejob->jobid, thejob->progs[0].pid);
1178         last_bg_pid = thejob->progs[0].pid;
1179         last_jobid = thejob->jobid;
1180 }
1181
1182 /* remove a backgrounded job */
1183 static void remove_bg_job(struct pipe *pi)
1184 {
1185         struct pipe *prev_pipe;
1186
1187         if (pi == job_list) {
1188                 job_list = pi->next;
1189         } else {
1190                 prev_pipe = job_list;
1191                 while (prev_pipe->next != pi)
1192                         prev_pipe = prev_pipe->next;
1193                 prev_pipe->next = pi->next;
1194         }
1195         if (job_list)
1196                 last_jobid = job_list->jobid;
1197         else
1198                 last_jobid = 0;
1199
1200         pi->stopped_progs = 0;
1201         free_pipe(pi, 0);
1202         free(pi);
1203 }
1204
1205 /* Checks to see if any processes have exited -- if they
1206    have, figure out why and see if a job has completed */
1207 static int checkjobs(struct pipe* fg_pipe)
1208 {
1209         int attributes;
1210         int status;
1211         int prognum = 0;
1212         struct pipe *pi;
1213         pid_t childpid;
1214
1215         attributes = WUNTRACED;
1216         if (fg_pipe==NULL) {
1217                 attributes |= WNOHANG;
1218         }
1219
1220         while ((childpid = waitpid(-1, &status, attributes)) > 0) {
1221                 if (fg_pipe) {
1222                         int i, rcode = 0;
1223                         for (i=0; i < fg_pipe->num_progs; i++) {
1224                                 if (fg_pipe->progs[i].pid == childpid) {
1225                                         if (i==fg_pipe->num_progs-1)
1226                                                 rcode=WEXITSTATUS(status);
1227                                         (fg_pipe->num_progs)--;
1228                                         return(rcode);
1229                                 }
1230                         }
1231                 }
1232
1233                 for (pi = job_list; pi; pi = pi->next) {
1234                         prognum = 0;
1235                         while (prognum < pi->num_progs && pi->progs[prognum].pid != childpid) {
1236                                 prognum++;
1237                         }
1238                         if (prognum < pi->num_progs)
1239                                 break;
1240                 }
1241
1242                 if(pi==NULL) {
1243                         debug_printf("checkjobs: pid %d was not in our list!\n", childpid);
1244                         continue;
1245                 }
1246
1247                 if (WIFEXITED(status) || WIFSIGNALED(status)) {
1248                         /* child exited */
1249                         pi->running_progs--;
1250                         pi->progs[prognum].pid = 0;
1251
1252                         if (!pi->running_progs) {
1253                                 printf(JOB_STATUS_FORMAT, pi->jobid, "Done", pi->text);
1254                                 remove_bg_job(pi);
1255                         }
1256                 } else {
1257                         /* child stopped */
1258                         pi->stopped_progs++;
1259                         pi->progs[prognum].is_stopped = 1;
1260
1261 #if 0
1262                         /* Printing this stuff is a pain, since it tends to
1263                          * overwrite the prompt an inconveinient moments.  So
1264                          * don't do that.  */
1265                         if (pi->stopped_progs == pi->num_progs) {
1266                                 printf("\n"JOB_STATUS_FORMAT, pi->jobid, "Stopped", pi->text);
1267                         }
1268 #endif
1269                 }
1270         }
1271
1272         if (childpid == -1 && errno != ECHILD)
1273                 bb_perror_msg("waitpid");
1274
1275         /* move the shell to the foreground */
1276         //if (interactive && tcsetpgrp(shell_terminal, getpgid(0)))
1277         //      bb_perror_msg("tcsetpgrp-2");
1278         return -1;
1279 }
1280
1281 /* Figure out our controlling tty, checking in order stderr,
1282  * stdin, and stdout.  If check_pgrp is set, also check that
1283  * we belong to the foreground process group associated with
1284  * that tty.  The value of shell_terminal is needed in order to call
1285  * tcsetpgrp(shell_terminal, ...); */
1286 #if 0
1287 static void controlling_tty(int check_pgrp)
1288 {
1289         pid_t curpgrp;
1290
1291         if ((curpgrp = tcgetpgrp(shell_terminal = 2)) < 0
1292                         && (curpgrp = tcgetpgrp(shell_terminal = 0)) < 0
1293                         && (curpgrp = tcgetpgrp(shell_terminal = 1)) < 0)
1294                 goto shell_terminal_error;
1295
1296         if (check_pgrp && curpgrp != getpgid(0))
1297                 goto shell_terminal_error;
1298
1299         return;
1300
1301 shell_terminal_error:
1302                 shell_terminal = -1;
1303                 return;
1304 }
1305 #endif
1306
1307 /* run_pipe_real() starts all the jobs, but doesn't wait for anything
1308  * to finish.  See checkjobs().
1309  *
1310  * return code is normally -1, when the caller has to wait for children
1311  * to finish to determine the exit status of the pipe.  If the pipe
1312  * is a simple builtin command, however, the action is done by the
1313  * time run_pipe_real returns, and the exit code is provided as the
1314  * return value.
1315  *
1316  * The input of the pipe is always stdin, the output is always
1317  * stdout.  The outpipe[] mechanism in BusyBox-0.48 lash is bogus,
1318  * because it tries to avoid running the command substitution in
1319  * subshell, when that is in fact necessary.  The subshell process
1320  * now has its stdout directed to the input of the appropriate pipe,
1321  * so this routine is noticeably simpler.
1322  */
1323 static int run_pipe_real(struct pipe *pi)
1324 {
1325         int i;
1326         int nextin, nextout;
1327         int pipefds[2];                         /* pipefds[0] is for reading */
1328         struct child_prog *child;
1329         const struct built_in_command *x;
1330         char *p;
1331
1332         nextin = 0;
1333         pi->pgrp = -1;
1334
1335         /* Check if this is a simple builtin (not part of a pipe).
1336          * Builtins within pipes have to fork anyway, and are handled in
1337          * pseudo_exec.  "echo foo | read bar" doesn't work on bash, either.
1338          */
1339         if (pi->num_progs == 1) child = & (pi->progs[0]);
1340         if (pi->num_progs == 1 && child->group && child->subshell == 0) {
1341                 int squirrel[] = {-1, -1, -1};
1342                 int rcode;
1343                 debug_printf("non-subshell grouping\n");
1344                 setup_redirects(child, squirrel);
1345                 /* XXX could we merge code with following builtin case,
1346                  * by creating a pseudo builtin that calls run_list_real? */
1347                 rcode = run_list_real(child->group);
1348                 restore_redirects(squirrel);
1349                 return rcode;
1350         } else if (pi->num_progs == 1 && pi->progs[0].argv != NULL) {
1351                 for (i=0; is_assignment(child->argv[i]); i++) { /* nothing */ }
1352                 if (i!=0 && child->argv[i]==NULL) {
1353                         /* assignments, but no command: set the local environment */
1354                         for (i=0; child->argv[i]!=NULL; i++) {
1355
1356                                 /* Ok, this case is tricky.  We have to decide if this is a
1357                                  * local variable, or an already exported variable.  If it is
1358                                  * already exported, we have to export the new value.  If it is
1359                                  * not exported, we need only set this as a local variable.
1360                                  * This junk is all to decide whether or not to export this
1361                                  * variable. */
1362                                 int export_me=0;
1363                                 char *name, *value;
1364                                 name = bb_xstrdup(child->argv[i]);
1365                                 debug_printf("Local environment set: %s\n", name);
1366                                 value = strchr(name, '=');
1367                                 if (value)
1368                                         *value=0;
1369                                 if ( get_local_var(name)) {
1370                                         export_me=1;
1371                                 }
1372                                 free(name);
1373                                 p = insert_var_value(child->argv[i]);
1374                                 set_local_var(p, export_me);
1375                                 if (p != child->argv[i]) free(p);
1376                         }
1377                         return EXIT_SUCCESS;   /* don't worry about errors in set_local_var() yet */
1378                 }
1379                 for (i = 0; is_assignment(child->argv[i]); i++) {
1380                         p = insert_var_value(child->argv[i]);
1381                         putenv(strdup(p));
1382                         if (p != child->argv[i]) {
1383                                 child->sp--;
1384                                 free(p);
1385                         }
1386                 }
1387                 if (child->sp) {
1388                         char * str = NULL;
1389
1390                         str = make_string((child->argv + i));
1391                         parse_string_outer(str, FLAG_EXIT_FROM_LOOP | FLAG_REPARSING);
1392                         free(str);
1393                         return last_return_code;
1394                 }
1395                 for (x = bltins; x->cmd; x++) {
1396                         if (strcmp(child->argv[i], x->cmd) == 0 ) {
1397                                 int squirrel[] = {-1, -1, -1};
1398                                 int rcode;
1399                                 if (x->function == builtin_exec && child->argv[i+1]==NULL) {
1400                                         debug_printf("magic exec\n");
1401                                         setup_redirects(child,NULL);
1402                                         return EXIT_SUCCESS;
1403                                 }
1404                                 debug_printf("builtin inline %s\n", child->argv[0]);
1405                                 /* XXX setup_redirects acts on file descriptors, not FILEs.
1406                                  * This is perfect for work that comes after exec().
1407                                  * Is it really safe for inline use?  Experimentally,
1408                                  * things seem to work with glibc. */
1409                                 setup_redirects(child, squirrel);
1410                                 child->argv+=i;  /* XXX horrible hack */
1411                                 rcode = x->function(child);
1412                                 child->argv-=i;  /* XXX restore hack so free() can work right */
1413                                 restore_redirects(squirrel);
1414                                 return rcode;
1415                         }
1416                 }
1417         }
1418
1419         for (i = 0; i < pi->num_progs; i++) {
1420                 child = & (pi->progs[i]);
1421
1422                 /* pipes are inserted between pairs of commands */
1423                 if ((i + 1) < pi->num_progs) {
1424                         if (pipe(pipefds)<0) bb_perror_msg_and_die("pipe");
1425                         nextout = pipefds[1];
1426                 } else {
1427                         nextout=1;
1428                         pipefds[0] = -1;
1429                 }
1430
1431                 /* XXX test for failed fork()? */
1432 #if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
1433                 if (!(child->pid = fork()))
1434 #else
1435                 if (!(child->pid = vfork()))
1436 #endif
1437                 {
1438                         /* Set the handling for job control signals back to the default.  */
1439                         signal(SIGINT, SIG_DFL);
1440                         signal(SIGQUIT, SIG_DFL);
1441                         signal(SIGTERM, SIG_DFL);
1442                         signal(SIGTSTP, SIG_DFL);
1443                         signal(SIGTTIN, SIG_DFL);
1444                         signal(SIGTTOU, SIG_DFL);
1445                         signal(SIGCHLD, SIG_DFL);
1446
1447                         close_all();
1448
1449                         if (nextin != 0) {
1450                                 dup2(nextin, 0);
1451                                 close(nextin);
1452                         }
1453                         if (nextout != 1) {
1454                                 dup2(nextout, 1);
1455                                 close(nextout);
1456                         }
1457                         if (pipefds[0]!=-1) {
1458                                 close(pipefds[0]);  /* opposite end of our output pipe */
1459                         }
1460
1461                         /* Like bash, explicit redirects override pipes,
1462                          * and the pipe fd is available for dup'ing. */
1463                         setup_redirects(child,NULL);
1464
1465                         if (interactive && pi->followup!=PIPE_BG) {
1466                                 /* If we (the child) win the race, put ourselves in the process
1467                                  * group whose leader is the first process in this pipe. */
1468                                 if (pi->pgrp < 0) {
1469                                         pi->pgrp = getpid();
1470                                 }
1471                                 if (setpgid(0, pi->pgrp) == 0) {
1472                                         tcsetpgrp(2, pi->pgrp);
1473                                 }
1474                         }
1475
1476                         pseudo_exec(child);
1477                 }
1478
1479
1480                 /* put our child in the process group whose leader is the
1481                    first process in this pipe */
1482                 if (pi->pgrp < 0) {
1483                         pi->pgrp = child->pid;
1484                 }
1485                 /* Don't check for errors.  The child may be dead already,
1486                  * in which case setpgid returns error code EACCES. */
1487                 setpgid(child->pid, pi->pgrp);
1488
1489                 if (nextin != 0)
1490                         close(nextin);
1491                 if (nextout != 1)
1492                         close(nextout);
1493
1494                 /* If there isn't another process, nextin is garbage
1495                    but it doesn't matter */
1496                 nextin = pipefds[0];
1497         }
1498         return -1;
1499 }
1500
1501 static int run_list_real(struct pipe *pi)
1502 {
1503         char *save_name = NULL;
1504         char **list = NULL;
1505         char **save_list = NULL;
1506         struct pipe *rpipe;
1507         int flag_rep = 0;
1508         int save_num_progs;
1509         int rcode=0, flag_skip=1;
1510         int flag_restore = 0;
1511         int if_code=0, next_if_code=0;  /* need double-buffer to handle elif */
1512         reserved_style rmode, skip_more_in_this_rmode=RES_XXXX;
1513         /* check syntax for "for" */
1514         for (rpipe = pi; rpipe; rpipe = rpipe->next) {
1515                 if ((rpipe->r_mode == RES_IN ||
1516                     rpipe->r_mode == RES_FOR) &&
1517                     (rpipe->next == NULL)) {
1518                                 syntax();
1519                                 return 1;
1520                 }
1521                 if ((rpipe->r_mode == RES_IN &&
1522                         (rpipe->next->r_mode == RES_IN &&
1523                         rpipe->next->progs->argv != NULL))||
1524                         (rpipe->r_mode == RES_FOR &&
1525                         rpipe->next->r_mode != RES_IN)) {
1526                                 syntax();
1527                                 return 1;
1528                 }
1529         }
1530         for (; pi; pi = (flag_restore != 0) ? rpipe : pi->next) {
1531                 if (pi->r_mode == RES_WHILE || pi->r_mode == RES_UNTIL ||
1532                         pi->r_mode == RES_FOR) {
1533                                 flag_restore = 0;
1534                                 if (!rpipe) {
1535                                         flag_rep = 0;
1536                                         rpipe = pi;
1537                                 }
1538                 }
1539                 rmode = pi->r_mode;
1540                 debug_printf("rmode=%d  if_code=%d  next_if_code=%d skip_more=%d\n", rmode, if_code, next_if_code, skip_more_in_this_rmode);
1541                 if (rmode == skip_more_in_this_rmode && flag_skip) {
1542                         if (pi->followup == PIPE_SEQ) flag_skip=0;
1543                         continue;
1544                 }
1545                 flag_skip = 1;
1546                 skip_more_in_this_rmode = RES_XXXX;
1547                 if (rmode == RES_THEN || rmode == RES_ELSE) if_code = next_if_code;
1548                 if (rmode == RES_THEN &&  if_code) continue;
1549                 if (rmode == RES_ELSE && !if_code) continue;
1550                 if (rmode == RES_ELIF && !if_code) break;
1551                 if (rmode == RES_FOR && pi->num_progs) {
1552                         if (!list) {
1553                                 /* if no variable values after "in" we skip "for" */
1554                                 if (!pi->next->progs->argv) continue;
1555                                 /* create list of variable values */
1556                                 list = make_list_in(pi->next->progs->argv,
1557                                         pi->progs->argv[0]);
1558                                 save_list = list;
1559                                 save_name = pi->progs->argv[0];
1560                                 pi->progs->argv[0] = NULL;
1561                                 flag_rep = 1;
1562                         }
1563                         if (!(*list)) {
1564                                 free(pi->progs->argv[0]);
1565                                 free(save_list);
1566                                 list = NULL;
1567                                 flag_rep = 0;
1568                                 pi->progs->argv[0] = save_name;
1569                                 pi->progs->glob_result.gl_pathv[0] =
1570                                         pi->progs->argv[0];
1571                                 continue;
1572                         } else {
1573                                 /* insert new value from list for variable */
1574                                 if (pi->progs->argv[0])
1575                                         free(pi->progs->argv[0]);
1576                                 pi->progs->argv[0] = *list++;
1577                                 pi->progs->glob_result.gl_pathv[0] =
1578                                         pi->progs->argv[0];
1579                         }
1580                 }
1581                 if (rmode == RES_IN) continue;
1582                 if (rmode == RES_DO) {
1583                         if (!flag_rep) continue;
1584                 }
1585                 if ((rmode == RES_DONE)) {
1586                         if (flag_rep) {
1587                                 flag_restore = 1;
1588                         } else {
1589                                 rpipe = NULL;
1590                         }
1591                 }
1592                 if (pi->num_progs == 0) continue;
1593                 save_num_progs = pi->num_progs; /* save number of programs */
1594                 rcode = run_pipe_real(pi);
1595                 debug_printf("run_pipe_real returned %d\n",rcode);
1596                 if (rcode!=-1) {
1597                         /* We only ran a builtin: rcode was set by the return value
1598                          * of run_pipe_real(), and we don't need to wait for anything. */
1599                 } else if (pi->followup==PIPE_BG) {
1600                         /* XXX check bash's behavior with nontrivial pipes */
1601                         /* XXX compute jobid */
1602                         /* XXX what does bash do with attempts to background builtins? */
1603                         insert_bg_job(pi);
1604                         rcode = EXIT_SUCCESS;
1605                 } else {
1606                         if (interactive) {
1607                                 /* move the new process group into the foreground */
1608                                 if (tcsetpgrp(shell_terminal, pi->pgrp) && errno != ENOTTY)
1609                                         bb_perror_msg("tcsetpgrp-3");
1610                                 rcode = checkjobs(pi);
1611                                 /* move the shell to the foreground */
1612                                 if (tcsetpgrp(shell_terminal, getpgid(0)) && errno != ENOTTY)
1613                                         bb_perror_msg("tcsetpgrp-4");
1614                         } else {
1615                                 rcode = checkjobs(pi);
1616                         }
1617                         debug_printf("checkjobs returned %d\n",rcode);
1618                 }
1619                 last_return_code=rcode;
1620                 pi->num_progs = save_num_progs; /* restore number of programs */
1621                 if ( rmode == RES_IF || rmode == RES_ELIF )
1622                         next_if_code=rcode;  /* can be overwritten a number of times */
1623                 if (rmode == RES_WHILE)
1624                         flag_rep = !last_return_code;
1625                 if (rmode == RES_UNTIL)
1626                         flag_rep = last_return_code;
1627                 if ( (rcode==EXIT_SUCCESS && pi->followup==PIPE_OR) ||
1628                      (rcode!=EXIT_SUCCESS && pi->followup==PIPE_AND) )
1629                         skip_more_in_this_rmode=rmode;
1630                 checkjobs(NULL);
1631         }
1632         return rcode;
1633 }
1634
1635 /* broken, of course, but OK for testing */
1636 static char *indenter(int i)
1637 {
1638         static char blanks[]="                                    ";
1639         return &blanks[sizeof(blanks)-i-1];
1640 }
1641
1642 /* return code is the exit status of the pipe */
1643 static int free_pipe(struct pipe *pi, int indent)
1644 {
1645         char **p;
1646         struct child_prog *child;
1647         struct redir_struct *r, *rnext;
1648         int a, i, ret_code=0;
1649         char *ind = indenter(indent);
1650
1651         if (pi->stopped_progs > 0)
1652                 return ret_code;
1653         final_printf("%s run pipe: (pid %d)\n",ind,getpid());
1654         for (i=0; i<pi->num_progs; i++) {
1655                 child = &pi->progs[i];
1656                 final_printf("%s  command %d:\n",ind,i);
1657                 if (child->argv) {
1658                         for (a=0,p=child->argv; *p; a++,p++) {
1659                                 final_printf("%s   argv[%d] = %s\n",ind,a,*p);
1660                         }
1661                         globfree(&child->glob_result);
1662                         child->argv=NULL;
1663                 } else if (child->group) {
1664                         final_printf("%s   begin group (subshell:%d)\n",ind, child->subshell);
1665                         ret_code = free_pipe_list(child->group,indent+3);
1666                         final_printf("%s   end group\n",ind);
1667                 } else {
1668                         final_printf("%s   (nil)\n",ind);
1669                 }
1670                 for (r=child->redirects; r; r=rnext) {
1671                         final_printf("%s   redirect %d%s", ind, r->fd, redir_table[r->type].descrip);
1672                         if (r->dup == -1) {
1673                                 /* guard against the case >$FOO, where foo is unset or blank */
1674                                 if (r->word.gl_pathv) {
1675                                         final_printf(" %s\n", *r->word.gl_pathv);
1676                                         globfree(&r->word);
1677                                 }
1678                         } else {
1679                                 final_printf("&%d\n", r->dup);
1680                         }
1681                         rnext=r->next;
1682                         free(r);
1683                 }
1684                 child->redirects=NULL;
1685         }
1686         free(pi->progs);   /* children are an array, they get freed all at once */
1687         pi->progs=NULL;
1688         return ret_code;
1689 }
1690
1691 static int free_pipe_list(struct pipe *head, int indent)
1692 {
1693         int rcode=0;   /* if list has no members */
1694         struct pipe *pi, *next;
1695         char *ind = indenter(indent);
1696         for (pi=head; pi; pi=next) {
1697                 final_printf("%s pipe reserved mode %d\n", ind, pi->r_mode);
1698                 rcode = free_pipe(pi, indent);
1699                 final_printf("%s pipe followup code %d\n", ind, pi->followup);
1700                 next=pi->next;
1701                 pi->next=NULL;
1702                 free(pi);
1703         }
1704         return rcode;
1705 }
1706
1707 /* Select which version we will use */
1708 static int run_list(struct pipe *pi)
1709 {
1710         int rcode=0;
1711         if (fake_mode==0) {
1712                 rcode = run_list_real(pi);
1713         }
1714         /* free_pipe_list has the side effect of clearing memory
1715          * In the long run that function can be merged with run_list_real,
1716          * but doing that now would hobble the debugging effort. */
1717         free_pipe_list(pi,0);
1718         return rcode;
1719 }
1720
1721 /* The API for glob is arguably broken.  This routine pushes a non-matching
1722  * string into the output structure, removing non-backslashed backslashes.
1723  * If someone can prove me wrong, by performing this function within the
1724  * original glob(3) api, feel free to rewrite this routine into oblivion.
1725  * Return code (0 vs. GLOB_NOSPACE) matches glob(3).
1726  * XXX broken if the last character is '\\', check that before calling.
1727  */
1728 static int globhack(const char *src, int flags, glob_t *pglob)
1729 {
1730         int cnt=0, pathc;
1731         const char *s;
1732         char *dest;
1733         for (cnt=1, s=src; s && *s; s++) {
1734                 if (*s == '\\') s++;
1735                 cnt++;
1736         }
1737         dest = malloc(cnt);
1738         if (!dest) return GLOB_NOSPACE;
1739         if (!(flags & GLOB_APPEND)) {
1740                 pglob->gl_pathv=NULL;
1741                 pglob->gl_pathc=0;
1742                 pglob->gl_offs=0;
1743                 pglob->gl_offs=0;
1744         }
1745         pathc = ++pglob->gl_pathc;
1746         pglob->gl_pathv = realloc(pglob->gl_pathv, (pathc+1)*sizeof(*pglob->gl_pathv));
1747         if (pglob->gl_pathv == NULL) return GLOB_NOSPACE;
1748         pglob->gl_pathv[pathc-1]=dest;
1749         pglob->gl_pathv[pathc]=NULL;
1750         for (s=src; s && *s; s++, dest++) {
1751                 if (*s == '\\') s++;
1752                 *dest = *s;
1753         }
1754         *dest='\0';
1755         return 0;
1756 }
1757
1758 /* XXX broken if the last character is '\\', check that before calling */
1759 static int glob_needed(const char *s)
1760 {
1761         for (; *s; s++) {
1762                 if (*s == '\\') s++;
1763                 if (strchr("*[?",*s)) return 1;
1764         }
1765         return 0;
1766 }
1767
1768 #if 0
1769 static void globprint(glob_t *pglob)
1770 {
1771         int i;
1772         debug_printf("glob_t at %p:\n", pglob);
1773         debug_printf("  gl_pathc=%d  gl_pathv=%p  gl_offs=%d  gl_flags=%d\n",
1774                 pglob->gl_pathc, pglob->gl_pathv, pglob->gl_offs, pglob->gl_flags);
1775         for (i=0; i<pglob->gl_pathc; i++)
1776                 debug_printf("pglob->gl_pathv[%d] = %p = %s\n", i,
1777                         pglob->gl_pathv[i], pglob->gl_pathv[i]);
1778 }
1779 #endif
1780
1781 static int xglob(o_string *dest, int flags, glob_t *pglob)
1782 {
1783         int gr;
1784
1785         /* short-circuit for null word */
1786         /* we can code this better when the debug_printf's are gone */
1787         if (dest->length == 0) {
1788                 if (dest->nonnull) {
1789                         /* bash man page calls this an "explicit" null */
1790                         gr = globhack(dest->data, flags, pglob);
1791                         debug_printf("globhack returned %d\n",gr);
1792                 } else {
1793                         return 0;
1794                 }
1795         } else if (glob_needed(dest->data)) {
1796                 gr = glob(dest->data, flags, NULL, pglob);
1797                 debug_printf("glob returned %d\n",gr);
1798                 if (gr == GLOB_NOMATCH) {
1799                         /* quote removal, or more accurately, backslash removal */
1800                         gr = globhack(dest->data, flags, pglob);
1801                         debug_printf("globhack returned %d\n",gr);
1802                 }
1803         } else {
1804                 gr = globhack(dest->data, flags, pglob);
1805                 debug_printf("globhack returned %d\n",gr);
1806         }
1807         if (gr == GLOB_NOSPACE)
1808                 bb_error_msg_and_die("out of memory during glob");
1809         if (gr != 0) { /* GLOB_ABORTED ? */
1810                 bb_error_msg("glob(3) error %d",gr);
1811         }
1812         /* globprint(glob_target); */
1813         return gr;
1814 }
1815
1816 /* This is used to get/check local shell variables */
1817 static char *get_local_var(const char *s)
1818 {
1819         struct variables *cur;
1820
1821         if (!s)
1822                 return NULL;
1823         for (cur = top_vars; cur; cur=cur->next)
1824                 if(strcmp(cur->name, s)==0)
1825                         return cur->value;
1826         return NULL;
1827 }
1828
1829 /* This is used to set local shell variables
1830    flg_export==0 if only local (not exporting) variable
1831    flg_export==1 if "new" exporting environ
1832    flg_export>1  if current startup environ (not call putenv()) */
1833 static int set_local_var(const char *s, int flg_export)
1834 {
1835         char *name, *value;
1836         int result=0;
1837         struct variables *cur;
1838
1839         name=strdup(s);
1840
1841         /* Assume when we enter this function that we are already in
1842          * NAME=VALUE format.  So the first order of business is to
1843          * split 's' on the '=' into 'name' and 'value' */
1844         value = strchr(name, '=');
1845         if (value==0 && ++value==0) {
1846                 free(name);
1847                 return -1;
1848         }
1849         *value++ = 0;
1850
1851         for(cur = top_vars; cur; cur = cur->next) {
1852                 if(strcmp(cur->name, name)==0)
1853                         break;
1854         }
1855
1856         if(cur) {
1857                 if(strcmp(cur->value, value)==0) {
1858                         if(flg_export>0 && cur->flg_export==0)
1859                                 cur->flg_export=flg_export;
1860                         else
1861                                 result++;
1862                 } else {
1863                         if(cur->flg_read_only) {
1864                                 bb_error_msg("%s: readonly variable", name);
1865                                 result = -1;
1866                         } else {
1867                                 if(flg_export>0 || cur->flg_export>1)
1868                                         cur->flg_export=1;
1869                                 free(cur->value);
1870
1871                                 cur->value = strdup(value);
1872                         }
1873                 }
1874         } else {
1875                 cur = malloc(sizeof(struct variables));
1876                 if(!cur) {
1877                         result = -1;
1878                 } else {
1879                         cur->name = strdup(name);
1880                         if(cur->name == 0) {
1881                                 free(cur);
1882                                 result = -1;
1883                         } else {
1884                                 struct variables *bottom = top_vars;
1885                                 cur->value = strdup(value);
1886                                 cur->next = 0;
1887                                 cur->flg_export = flg_export;
1888                                 cur->flg_read_only = 0;
1889                                 while(bottom->next) bottom=bottom->next;
1890                                 bottom->next = cur;
1891                         }
1892                 }
1893         }
1894
1895         if(result==0 && cur->flg_export==1) {
1896                 *(value-1) = '=';
1897                 result = putenv(name);
1898         } else {
1899                 free(name);
1900                 if(result>0)            /* equivalent to previous set */
1901                         result = 0;
1902         }
1903         return result;
1904 }
1905
1906 static void unset_local_var(const char *name)
1907 {
1908         struct variables *cur;
1909
1910         if (name) {
1911                 for (cur = top_vars; cur; cur=cur->next) {
1912                         if(strcmp(cur->name, name)==0)
1913                                 break;
1914                 }
1915                 if(cur!=0) {
1916                         struct variables *next = top_vars;
1917                         if(cur->flg_read_only) {
1918                                 bb_error_msg("%s: readonly variable", name);
1919                                 return;
1920                         } else {
1921                                 if(cur->flg_export)
1922                                         unsetenv(cur->name);
1923                                 free(cur->name);
1924                                 free(cur->value);
1925                                 while (next->next != cur)
1926                                         next = next->next;
1927                                 next->next = cur->next;
1928                         }
1929                         free(cur);
1930                 }
1931         }
1932 }
1933
1934 static int is_assignment(const char *s)
1935 {
1936         if (s==NULL || !isalpha(*s)) return 0;
1937         ++s;
1938         while(isalnum(*s) || *s=='_') ++s;
1939         return *s=='=';
1940 }
1941
1942 /* the src parameter allows us to peek forward to a possible &n syntax
1943  * for file descriptor duplication, e.g., "2>&1".
1944  * Return code is 0 normally, 1 if a syntax error is detected in src.
1945  * Resource errors (in xmalloc) cause the process to exit */
1946 static int setup_redirect(struct p_context *ctx, int fd, redir_type style,
1947         struct in_str *input)
1948 {
1949         struct child_prog *child=ctx->child;
1950         struct redir_struct *redir = child->redirects;
1951         struct redir_struct *last_redir=NULL;
1952
1953         /* Create a new redir_struct and drop it onto the end of the linked list */
1954         while(redir) {
1955                 last_redir=redir;
1956                 redir=redir->next;
1957         }
1958         redir = xmalloc(sizeof(struct redir_struct));
1959         redir->next=NULL;
1960         redir->word.gl_pathv=NULL;
1961         if (last_redir) {
1962                 last_redir->next=redir;
1963         } else {
1964                 child->redirects=redir;
1965         }
1966
1967         redir->type=style;
1968         redir->fd= (fd==-1) ? redir_table[style].default_fd : fd ;
1969
1970         debug_printf("Redirect type %d%s\n", redir->fd, redir_table[style].descrip);
1971
1972         /* Check for a '2>&1' type redirect */
1973         redir->dup = redirect_dup_num(input);
1974         if (redir->dup == -2) return 1;  /* syntax error */
1975         if (redir->dup != -1) {
1976                 /* Erik had a check here that the file descriptor in question
1977                  * is legit; I postpone that to "run time"
1978                  * A "-" representation of "close me" shows up as a -3 here */
1979                 debug_printf("Duplicating redirect '%d>&%d'\n", redir->fd, redir->dup);
1980         } else {
1981                 /* We do _not_ try to open the file that src points to,
1982                  * since we need to return and let src be expanded first.
1983                  * Set ctx->pending_redirect, so we know what to do at the
1984                  * end of the next parsed word.
1985                  */
1986                 ctx->pending_redirect = redir;
1987         }
1988         return 0;
1989 }
1990
1991 static struct pipe *new_pipe(void) {
1992         struct pipe *pi;
1993         pi = xmalloc(sizeof(struct pipe));
1994         pi->num_progs = 0;
1995         pi->progs = NULL;
1996         pi->next = NULL;
1997         pi->followup = 0;  /* invalid */
1998         pi->r_mode = RES_NONE;
1999         return pi;
2000 }
2001
2002 static void initialize_context(struct p_context *ctx)
2003 {
2004         ctx->pipe=NULL;
2005         ctx->pending_redirect=NULL;
2006         ctx->child=NULL;
2007         ctx->list_head=new_pipe();
2008         ctx->pipe=ctx->list_head;
2009         ctx->w=RES_NONE;
2010         ctx->stack=NULL;
2011         ctx->old_flag=0;
2012         done_command(ctx);   /* creates the memory for working child */
2013 }
2014
2015 /* normal return is 0
2016  * if a reserved word is found, and processed, return 1
2017  * should handle if, then, elif, else, fi, for, while, until, do, done.
2018  * case, function, and select are obnoxious, save those for later.
2019  */
2020 static int reserved_word(o_string *dest, struct p_context *ctx)
2021 {
2022         struct reserved_combo {
2023                 char *literal;
2024                 int code;
2025                 long flag;
2026         };
2027         /* Mostly a list of accepted follow-up reserved words.
2028          * FLAG_END means we are done with the sequence, and are ready
2029          * to turn the compound list into a command.
2030          * FLAG_START means the word must start a new compound list.
2031          */
2032         static struct reserved_combo reserved_list[] = {
2033                 { "if",    RES_IF,    FLAG_THEN | FLAG_START },
2034                 { "then",  RES_THEN,  FLAG_ELIF | FLAG_ELSE | FLAG_FI },
2035                 { "elif",  RES_ELIF,  FLAG_THEN },
2036                 { "else",  RES_ELSE,  FLAG_FI   },
2037                 { "fi",    RES_FI,    FLAG_END  },
2038                 { "for",   RES_FOR,   FLAG_IN   | FLAG_START },
2039                 { "while", RES_WHILE, FLAG_DO   | FLAG_START },
2040                 { "until", RES_UNTIL, FLAG_DO   | FLAG_START },
2041                 { "in",    RES_IN,    FLAG_DO   },
2042                 { "do",    RES_DO,    FLAG_DONE },
2043                 { "done",  RES_DONE,  FLAG_END  }
2044         };
2045         struct reserved_combo *r;
2046         for (r=reserved_list;
2047 #define NRES sizeof(reserved_list)/sizeof(struct reserved_combo)
2048                 r<reserved_list+NRES; r++) {
2049                 if (strcmp(dest->data, r->literal) == 0) {
2050                         debug_printf("found reserved word %s, code %d\n",r->literal,r->code);
2051                         if (r->flag & FLAG_START) {
2052                                 struct p_context *new = xmalloc(sizeof(struct p_context));
2053                                 debug_printf("push stack\n");
2054                                 if (ctx->w == RES_IN || ctx->w == RES_FOR) {
2055                                         syntax();
2056                                         free(new);
2057                                         ctx->w = RES_SNTX;
2058                                         b_reset(dest);
2059                                         return 1;
2060                                 }
2061                                 *new = *ctx;   /* physical copy */
2062                                 initialize_context(ctx);
2063                                 ctx->stack=new;
2064                         } else if ( ctx->w == RES_NONE || ! (ctx->old_flag & (1<<r->code))) {
2065                                 syntax();
2066                                 ctx->w = RES_SNTX;
2067                                 b_reset(dest);
2068                                 return 1;
2069                         }
2070                         ctx->w=r->code;
2071                         ctx->old_flag = r->flag;
2072                         if (ctx->old_flag & FLAG_END) {
2073                                 struct p_context *old;
2074                                 debug_printf("pop stack\n");
2075                                 done_pipe(ctx,PIPE_SEQ);
2076                                 old = ctx->stack;
2077                                 old->child->group = ctx->list_head;
2078                                 old->child->subshell = 0;
2079                                 *ctx = *old;   /* physical copy */
2080                                 free(old);
2081                         }
2082                         b_reset (dest);
2083                         return 1;
2084                 }
2085         }
2086         return 0;
2087 }
2088
2089 /* normal return is 0.
2090  * Syntax or xglob errors return 1. */
2091 static int done_word(o_string *dest, struct p_context *ctx)
2092 {
2093         struct child_prog *child=ctx->child;
2094         glob_t *glob_target;
2095         int gr, flags = 0;
2096
2097         debug_printf("done_word: %s %p\n", dest->data, child);
2098         if (dest->length == 0 && !dest->nonnull) {
2099                 debug_printf("  true null, ignored\n");
2100                 return 0;
2101         }
2102         if (ctx->pending_redirect) {
2103                 glob_target = &ctx->pending_redirect->word;
2104         } else {
2105                 if (child->group) {
2106                         syntax();
2107                         return 1;  /* syntax error, groups and arglists don't mix */
2108                 }
2109                 if (!child->argv && (ctx->type & FLAG_PARSE_SEMICOLON)) {
2110                         debug_printf("checking %s for reserved-ness\n",dest->data);
2111                         if (reserved_word(dest,ctx)) return ctx->w==RES_SNTX;
2112                 }
2113                 glob_target = &child->glob_result;
2114                 if (child->argv) flags |= GLOB_APPEND;
2115         }
2116         gr = xglob(dest, flags, glob_target);
2117         if (gr != 0) return 1;
2118
2119         b_reset(dest);
2120         if (ctx->pending_redirect) {
2121                 ctx->pending_redirect=NULL;
2122                 if (glob_target->gl_pathc != 1) {
2123                         bb_error_msg("ambiguous redirect");
2124                         return 1;
2125                 }
2126         } else {
2127                 child->argv = glob_target->gl_pathv;
2128         }
2129         if (ctx->w == RES_FOR) {
2130                 done_word(dest,ctx);
2131                 done_pipe(ctx,PIPE_SEQ);
2132         }
2133         return 0;
2134 }
2135
2136 /* The only possible error here is out of memory, in which case
2137  * xmalloc exits. */
2138 static int done_command(struct p_context *ctx)
2139 {
2140         /* The child is really already in the pipe structure, so
2141          * advance the pipe counter and make a new, null child.
2142          * Only real trickiness here is that the uncommitted
2143          * child structure, to which ctx->child points, is not
2144          * counted in pi->num_progs. */
2145         struct pipe *pi=ctx->pipe;
2146         struct child_prog *prog=ctx->child;
2147
2148         if (prog && prog->group == NULL
2149                  && prog->argv == NULL
2150                  && prog->redirects == NULL) {
2151                 debug_printf("done_command: skipping null command\n");
2152                 return 0;
2153         } else if (prog) {
2154                 pi->num_progs++;
2155                 debug_printf("done_command: num_progs incremented to %d\n",pi->num_progs);
2156         } else {
2157                 debug_printf("done_command: initializing\n");
2158         }
2159         pi->progs = xrealloc(pi->progs, sizeof(*pi->progs) * (pi->num_progs+1));
2160
2161         prog = pi->progs + pi->num_progs;
2162         prog->redirects = NULL;
2163         prog->argv = NULL;
2164         prog->is_stopped = 0;
2165         prog->group = NULL;
2166         prog->glob_result.gl_pathv = NULL;
2167         prog->family = pi;
2168         prog->sp = 0;
2169         ctx->child = prog;
2170         prog->type = ctx->type;
2171
2172         /* but ctx->pipe and ctx->list_head remain unchanged */
2173         return 0;
2174 }
2175
2176 static int done_pipe(struct p_context *ctx, pipe_style type)
2177 {
2178         struct pipe *new_p;
2179         done_command(ctx);  /* implicit closure of previous command */
2180         debug_printf("done_pipe, type %d\n", type);
2181         ctx->pipe->followup = type;
2182         ctx->pipe->r_mode = ctx->w;
2183         new_p=new_pipe();
2184         ctx->pipe->next = new_p;
2185         ctx->pipe = new_p;
2186         ctx->child = NULL;
2187         done_command(ctx);  /* set up new pipe to accept commands */
2188         return 0;
2189 }
2190
2191 /* peek ahead in the in_str to find out if we have a "&n" construct,
2192  * as in "2>&1", that represents duplicating a file descriptor.
2193  * returns either -2 (syntax error), -1 (no &), or the number found.
2194  */
2195 static int redirect_dup_num(struct in_str *input)
2196 {
2197         int ch, d=0, ok=0;
2198         ch = b_peek(input);
2199         if (ch != '&') return -1;
2200
2201         b_getch(input);  /* get the & */
2202         ch=b_peek(input);
2203         if (ch == '-') {
2204                 b_getch(input);
2205                 return -3;  /* "-" represents "close me" */
2206         }
2207         while (isdigit(ch)) {
2208                 d = d*10+(ch-'0');
2209                 ok=1;
2210                 b_getch(input);
2211                 ch = b_peek(input);
2212         }
2213         if (ok) return d;
2214
2215         bb_error_msg("ambiguous redirect");
2216         return -2;
2217 }
2218
2219 /* If a redirect is immediately preceded by a number, that number is
2220  * supposed to tell which file descriptor to redirect.  This routine
2221  * looks for such preceding numbers.  In an ideal world this routine
2222  * needs to handle all the following classes of redirects...
2223  *     echo 2>foo     # redirects fd  2 to file "foo", nothing passed to echo
2224  *     echo 49>foo    # redirects fd 49 to file "foo", nothing passed to echo
2225  *     echo -2>foo    # redirects fd  1 to file "foo",    "-2" passed to echo
2226  *     echo 49x>foo   # redirects fd  1 to file "foo",   "49x" passed to echo
2227  * A -1 output from this program means no valid number was found, so the
2228  * caller should use the appropriate default for this redirection.
2229  */
2230 static int redirect_opt_num(o_string *o)
2231 {
2232         int num;
2233
2234         if (o->length==0) return -1;
2235         for(num=0; num<o->length; num++) {
2236                 if (!isdigit(*(o->data+num))) {
2237                         return -1;
2238                 }
2239         }
2240         /* reuse num (and save an int) */
2241         num=atoi(o->data);
2242         b_reset(o);
2243         return num;
2244 }
2245
2246 static FILE *generate_stream_from_list(struct pipe *head)
2247 {
2248         FILE *pf;
2249 #if 1
2250         int pid, channel[2];
2251         if (pipe(channel)<0) bb_perror_msg_and_die("pipe");
2252 #if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
2253         pid=fork();
2254 #else
2255         pid=vfork();
2256 #endif
2257         if (pid<0) {
2258                 bb_perror_msg_and_die("fork");
2259         } else if (pid==0) {
2260                 close(channel[0]);
2261                 if (channel[1] != 1) {
2262                         dup2(channel[1],1);
2263                         close(channel[1]);
2264                 }
2265 #if 0
2266 #define SURROGATE "surrogate response"
2267                 write(1,SURROGATE,sizeof(SURROGATE));
2268                 _exit(run_list(head));
2269 #else
2270                 _exit(run_list_real(head));   /* leaks memory */
2271 #endif
2272         }
2273         debug_printf("forked child %d\n",pid);
2274         close(channel[1]);
2275         pf = fdopen(channel[0],"r");
2276         debug_printf("pipe on FILE *%p\n",pf);
2277 #else
2278         free_pipe_list(head,0);
2279         pf=popen("echo surrogate response","r");
2280         debug_printf("started fake pipe on FILE *%p\n",pf);
2281 #endif
2282         return pf;
2283 }
2284
2285 /* this version hacked for testing purposes */
2286 /* return code is exit status of the process that is run. */
2287 static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end)
2288 {
2289         int retcode;
2290         o_string result=NULL_O_STRING;
2291         struct p_context inner;
2292         FILE *p;
2293         struct in_str pipe_str;
2294         initialize_context(&inner);
2295
2296         /* recursion to generate command */
2297         retcode = parse_stream(&result, &inner, input, subst_end);
2298         if (retcode != 0) return retcode;  /* syntax error or EOF */
2299         done_word(&result, &inner);
2300         done_pipe(&inner, PIPE_SEQ);
2301         b_free(&result);
2302
2303         p=generate_stream_from_list(inner.list_head);
2304         if (p==NULL) return 1;
2305         mark_open(fileno(p));
2306         setup_file_in_str(&pipe_str, p);
2307
2308         /* now send results of command back into original context */
2309         retcode = parse_stream(dest, ctx, &pipe_str, '\0');
2310         /* XXX In case of a syntax error, should we try to kill the child?
2311          * That would be tough to do right, so just read until EOF. */
2312         if (retcode == 1) {
2313                 while (b_getch(&pipe_str)!=EOF) { /* discard */ };
2314         }
2315
2316         debug_printf("done reading from pipe, pclose()ing\n");
2317         /* This is the step that wait()s for the child.  Should be pretty
2318          * safe, since we just read an EOF from its stdout.  We could try
2319          * to better, by using wait(), and keeping track of background jobs
2320          * at the same time.  That would be a lot of work, and contrary
2321          * to the KISS philosophy of this program. */
2322         mark_closed(fileno(p));
2323         retcode=pclose(p);
2324         free_pipe_list(inner.list_head,0);
2325         debug_printf("pclosed, retcode=%d\n",retcode);
2326         /* XXX this process fails to trim a single trailing newline */
2327         return retcode;
2328 }
2329
2330 static int parse_group(o_string *dest, struct p_context *ctx,
2331         struct in_str *input, int ch)
2332 {
2333         int rcode, endch=0;
2334         struct p_context sub;
2335         struct child_prog *child = ctx->child;
2336         if (child->argv) {
2337                 syntax();
2338                 return 1;  /* syntax error, groups and arglists don't mix */
2339         }
2340         initialize_context(&sub);
2341         switch(ch) {
2342                 case '(': endch=')'; child->subshell=1; break;
2343                 case '{': endch='}'; break;
2344                 default: syntax();   /* really logic error */
2345         }
2346         rcode=parse_stream(dest,&sub,input,endch);
2347         done_word(dest,&sub); /* finish off the final word in the subcontext */
2348         done_pipe(&sub, PIPE_SEQ);  /* and the final command there, too */
2349         child->group = sub.list_head;
2350         return rcode;
2351         /* child remains "open", available for possible redirects */
2352 }
2353
2354 /* basically useful version until someone wants to get fancier,
2355  * see the bash man page under "Parameter Expansion" */
2356 static char *lookup_param(char *src)
2357 {
2358         char *p=NULL;
2359         if (src) {
2360                 p = getenv(src);
2361                 if (!p)
2362                         p = get_local_var(src);
2363         }
2364         return p;
2365 }
2366
2367 /* return code: 0 for OK, 1 for syntax error */
2368 static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input)
2369 {
2370         int i, advance=0;
2371         char sep[]=" ";
2372         int ch = input->peek(input);  /* first character after the $ */
2373         debug_printf("handle_dollar: ch=%c\n",ch);
2374         if (isalpha(ch)) {
2375                 b_addchr(dest, SPECIAL_VAR_SYMBOL);
2376                 ctx->child->sp++;
2377                 while(ch=b_peek(input),isalnum(ch) || ch=='_') {
2378                         b_getch(input);
2379                         b_addchr(dest,ch);
2380                 }
2381                 b_addchr(dest, SPECIAL_VAR_SYMBOL);
2382         } else if (isdigit(ch)) {
2383                 i = ch-'0';  /* XXX is $0 special? */
2384                 if (i<global_argc) {
2385                         parse_string(dest, ctx, global_argv[i]); /* recursion */
2386                 }
2387                 advance = 1;
2388         } else switch (ch) {
2389                 case '$':
2390                         b_adduint(dest,getpid());
2391                         advance = 1;
2392                         break;
2393                 case '!':
2394                         if (last_bg_pid > 0) b_adduint(dest, last_bg_pid);
2395                         advance = 1;
2396                         break;
2397                 case '?':
2398                         b_adduint(dest,last_return_code);
2399                         advance = 1;
2400                         break;
2401                 case '#':
2402                         b_adduint(dest,global_argc ? global_argc-1 : 0);
2403                         advance = 1;
2404                         break;
2405                 case '{':
2406                         b_addchr(dest, SPECIAL_VAR_SYMBOL);
2407                         ctx->child->sp++;
2408                         b_getch(input);
2409                         /* XXX maybe someone will try to escape the '}' */
2410                         while(ch=b_getch(input),ch!=EOF && ch!='}') {
2411                                 b_addchr(dest,ch);
2412                         }
2413                         if (ch != '}') {
2414                                 syntax();
2415                                 return 1;
2416                         }
2417                         b_addchr(dest, SPECIAL_VAR_SYMBOL);
2418                         break;
2419                 case '(':
2420                         b_getch(input);
2421                         process_command_subs(dest, ctx, input, ')');
2422                         break;
2423                 case '*':
2424                         sep[0]=ifs[0];
2425                         for (i=1; i<global_argc; i++) {
2426                                 parse_string(dest, ctx, global_argv[i]);
2427                                 if (i+1 < global_argc) parse_string(dest, ctx, sep);
2428                         }
2429                         break;
2430                 case '@':
2431                 case '-':
2432                 case '_':
2433                         /* still unhandled, but should be eventually */
2434                         bb_error_msg("unhandled syntax: $%c",ch);
2435                         return 1;
2436                         break;
2437                 default:
2438                         b_addqchr(dest,'$',dest->quote);
2439         }
2440         /* Eat the character if the flag was set.  If the compiler
2441          * is smart enough, we could substitute "b_getch(input);"
2442          * for all the "advance = 1;" above, and also end up with
2443          * a nice size-optimized program.  Hah!  That'll be the day.
2444          */
2445         if (advance) b_getch(input);
2446         return 0;
2447 }
2448
2449 int parse_string(o_string *dest, struct p_context *ctx, const char *src)
2450 {
2451         struct in_str foo;
2452         setup_string_in_str(&foo, src);
2453         return parse_stream(dest, ctx, &foo, '\0');
2454 }
2455
2456 /* return code is 0 for normal exit, 1 for syntax error */
2457 int parse_stream(o_string *dest, struct p_context *ctx,
2458         struct in_str *input, int end_trigger)
2459 {
2460         int ch, m;
2461         int redir_fd;
2462         redir_type redir_style;
2463         int next;
2464
2465         /* Only double-quote state is handled in the state variable dest->quote.
2466          * A single-quote triggers a bypass of the main loop until its mate is
2467          * found.  When recursing, quote state is passed in via dest->quote. */
2468
2469         debug_printf("parse_stream, end_trigger=%d\n",end_trigger);
2470         while ((ch=b_getch(input))!=EOF) {
2471                 m = map[ch];
2472                 next = (ch == '\n') ? 0 : b_peek(input);
2473                 debug_printf("parse_stream: ch=%c (%d) m=%d quote=%d\n",
2474                         ch,ch,m,dest->quote);
2475                 if (m==0 || ((m==1 || m==2) && dest->quote)) {
2476                         b_addqchr(dest, ch, dest->quote);
2477                 } else {
2478                         if (m==2) {  /* unquoted IFS */
2479                                 if (done_word(dest, ctx)) {
2480                                         return 1;
2481                                 }
2482                                 /* If we aren't performing a substitution, treat a newline as a
2483                                  * command separator.  */
2484                                 if (end_trigger != '\0' && ch=='\n')
2485                                         done_pipe(ctx,PIPE_SEQ);
2486                         }
2487                         if (ch == end_trigger && !dest->quote && ctx->w==RES_NONE) {
2488                                 debug_printf("leaving parse_stream (triggered)\n");
2489                                 return 0;
2490                         }
2491 #if 0
2492                         if (ch=='\n') {
2493                                 /* Yahoo!  Time to run with it! */
2494                                 done_pipe(ctx,PIPE_SEQ);
2495                                 run_list(ctx->list_head);
2496                                 initialize_context(ctx);
2497                         }
2498 #endif
2499                         if (m!=2) switch (ch) {
2500                 case '#':
2501                         if (dest->length == 0 && !dest->quote) {
2502                                 while(ch=b_peek(input),ch!=EOF && ch!='\n') { b_getch(input); }
2503                         } else {
2504                                 b_addqchr(dest, ch, dest->quote);
2505                         }
2506                         break;
2507                 case '\\':
2508                         if (next == EOF) {
2509                                 syntax();
2510                                 return 1;
2511                         }
2512                         b_addqchr(dest, '\\', dest->quote);
2513                         b_addqchr(dest, b_getch(input), dest->quote);
2514                         break;
2515                 case '$':
2516                         if (handle_dollar(dest, ctx, input)!=0) return 1;
2517                         break;
2518                 case '\'':
2519                         dest->nonnull = 1;
2520                         while(ch=b_getch(input),ch!=EOF && ch!='\'') {
2521                                 b_addchr(dest,ch);
2522                         }
2523                         if (ch==EOF) {
2524                                 syntax();
2525                                 return 1;
2526                         }
2527                         break;
2528                 case '"':
2529                         dest->nonnull = 1;
2530                         dest->quote = !dest->quote;
2531                         break;
2532                 case '`':
2533                         process_command_subs(dest, ctx, input, '`');
2534                         break;
2535                 case '>':
2536                         redir_fd = redirect_opt_num(dest);
2537                         done_word(dest, ctx);
2538                         redir_style=REDIRECT_OVERWRITE;
2539                         if (next == '>') {
2540                                 redir_style=REDIRECT_APPEND;
2541                                 b_getch(input);
2542                         } else if (next == '(') {
2543                                 syntax();   /* until we support >(list) Process Substitution */
2544                                 return 1;
2545                         }
2546                         setup_redirect(ctx, redir_fd, redir_style, input);
2547                         break;
2548                 case '<':
2549                         redir_fd = redirect_opt_num(dest);
2550                         done_word(dest, ctx);
2551                         redir_style=REDIRECT_INPUT;
2552                         if (next == '<') {
2553                                 redir_style=REDIRECT_HEREIS;
2554                                 b_getch(input);
2555                         } else if (next == '>') {
2556                                 redir_style=REDIRECT_IO;
2557                                 b_getch(input);
2558                         } else if (next == '(') {
2559                                 syntax();   /* until we support <(list) Process Substitution */
2560                                 return 1;
2561                         }
2562                         setup_redirect(ctx, redir_fd, redir_style, input);
2563                         break;
2564                 case ';':
2565                         done_word(dest, ctx);
2566                         done_pipe(ctx,PIPE_SEQ);
2567                         break;
2568                 case '&':
2569                         done_word(dest, ctx);
2570                         if (next=='&') {
2571                                 b_getch(input);
2572                                 done_pipe(ctx,PIPE_AND);
2573                         } else {
2574                                 done_pipe(ctx,PIPE_BG);
2575                         }
2576                         break;
2577                 case '|':
2578                         done_word(dest, ctx);
2579                         if (next=='|') {
2580                                 b_getch(input);
2581                                 done_pipe(ctx,PIPE_OR);
2582                         } else {
2583                                 /* we could pick up a file descriptor choice here
2584                                  * with redirect_opt_num(), but bash doesn't do it.
2585                                  * "echo foo 2| cat" yields "foo 2". */
2586                                 done_command(ctx);
2587                         }
2588                         break;
2589                 case '(':
2590                 case '{':
2591                         if (parse_group(dest, ctx, input, ch)!=0) return 1;
2592                         break;
2593                 case ')':
2594                 case '}':
2595                         syntax();   /* Proper use of this character caught by end_trigger */
2596                         return 1;
2597                         break;
2598                 default:
2599                         syntax();   /* this is really an internal logic error */
2600                         return 1;
2601                         }
2602                 }
2603         }
2604         /* complain if quote?  No, maybe we just finished a command substitution
2605          * that was quoted.  Example:
2606          * $ echo "`cat foo` plus more"
2607          * and we just got the EOF generated by the subshell that ran "cat foo"
2608          * The only real complaint is if we got an EOF when end_trigger != '\0',
2609          * that is, we were really supposed to get end_trigger, and never got
2610          * one before the EOF.  Can't use the standard "syntax error" return code,
2611          * so that parse_stream_outer can distinguish the EOF and exit smoothly. */
2612         debug_printf("leaving parse_stream (EOF)\n");
2613         if (end_trigger != '\0') return -1;
2614         return 0;
2615 }
2616
2617 static void mapset(const char *set, int code)
2618 {
2619         const unsigned char *s;
2620         for (s = (const unsigned char *)set; *s; s++) map[(int)*s] = code;
2621 }
2622
2623 static void update_ifs_map(void)
2624 {
2625         /* char *ifs and char map[256] are both globals. */
2626         ifs = getenv("IFS");
2627         if (ifs == NULL) ifs=" \t\n";
2628         /* Precompute a list of 'flow through' behavior so it can be treated
2629          * quickly up front.  Computation is necessary because of IFS.
2630          * Special case handling of IFS == " \t\n" is not implemented.
2631          * The map[] array only really needs two bits each, and on most machines
2632          * that would be faster because of the reduced L1 cache footprint.
2633          */
2634         memset(map,0,sizeof(map)); /* most characters flow through always */
2635         mapset("\\$'\"`", 3);      /* never flow through */
2636         mapset("<>;&|(){}#", 1);   /* flow through if quoted */
2637         mapset(ifs, 2);            /* also flow through if quoted */
2638 }
2639
2640 /* most recursion does not come through here, the exception is
2641  * from builtin_source() */
2642 int parse_stream_outer(struct in_str *inp, int flag)
2643 {
2644
2645         struct p_context ctx;
2646         o_string temp=NULL_O_STRING;
2647         int rcode;
2648         do {
2649                 ctx.type = flag;
2650                 initialize_context(&ctx);
2651                 update_ifs_map();
2652                 if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) mapset(";$&|", 0);
2653                 inp->promptmode=1;
2654                 rcode = parse_stream(&temp, &ctx, inp, '\n');
2655                 if (rcode != 1 && ctx.old_flag != 0) {
2656                         syntax();
2657                 }
2658                 if (rcode != 1 && ctx.old_flag == 0) {
2659                         done_word(&temp, &ctx);
2660                         done_pipe(&ctx,PIPE_SEQ);
2661                         run_list(ctx.list_head);
2662                 } else {
2663                         if (ctx.old_flag != 0) {
2664                                 free(ctx.stack);
2665                                 b_reset(&temp);
2666                         }
2667                         temp.nonnull = 0;
2668                         temp.quote = 0;
2669                         inp->p = NULL;
2670                         free_pipe_list(ctx.list_head,0);
2671                 }
2672                 b_free(&temp);
2673         } while (rcode != -1 && !(flag & FLAG_EXIT_FROM_LOOP));   /* loop on syntax errors, return on EOF */
2674         return 0;
2675 }
2676
2677 static int parse_string_outer(const char *s, int flag)
2678 {
2679         struct in_str input;
2680         setup_string_in_str(&input, s);
2681         return parse_stream_outer(&input, flag);
2682 }
2683
2684 static int parse_file_outer(FILE *f)
2685 {
2686         int rcode;
2687         struct in_str input;
2688         setup_file_in_str(&input, f);
2689         rcode = parse_stream_outer(&input, FLAG_PARSE_SEMICOLON);
2690         return rcode;
2691 }
2692
2693 /* Make sure we have a controlling tty.  If we get started under a job
2694  * aware app (like bash for example), make sure we are now in charge so
2695  * we don't fight over who gets the foreground */
2696 static void setup_job_control(void)
2697 {
2698         static pid_t shell_pgrp;
2699         /* Loop until we are in the foreground.  */
2700         while (tcgetpgrp (shell_terminal) != (shell_pgrp = getpgrp ()))
2701                 kill (- shell_pgrp, SIGTTIN);
2702
2703         /* Ignore interactive and job-control signals.  */
2704         signal(SIGINT, SIG_IGN);
2705         signal(SIGQUIT, SIG_IGN);
2706         signal(SIGTERM, SIG_IGN);
2707         signal(SIGTSTP, SIG_IGN);
2708         signal(SIGTTIN, SIG_IGN);
2709         signal(SIGTTOU, SIG_IGN);
2710         signal(SIGCHLD, SIG_IGN);
2711
2712         /* Put ourselves in our own process group.  */
2713         setsid();
2714         shell_pgrp = getpid ();
2715         setpgid (shell_pgrp, shell_pgrp);
2716
2717         /* Grab control of the terminal.  */
2718         tcsetpgrp(shell_terminal, shell_pgrp);
2719 }
2720
2721 int hush_main(int argc, char **argv)
2722 {
2723         int opt;
2724         FILE *input;
2725         char **e = environ;
2726
2727         /* XXX what should these be while sourcing /etc/profile? */
2728         global_argc = argc;
2729         global_argv = argv;
2730
2731         /* (re?) initialize globals.  Sometimes hush_main() ends up calling
2732          * hush_main(), therefore we cannot rely on the BSS to zero out this
2733          * stuff.  Reset these to 0 every time. */
2734         ifs = NULL;
2735         /* map[] is taken care of with call to update_ifs_map() */
2736         fake_mode = 0;
2737         interactive = 0;
2738         close_me_head = NULL;
2739         last_bg_pid = 0;
2740         job_list = NULL;
2741         last_jobid = 0;
2742
2743         /* Initialize some more globals to non-zero values */
2744         set_cwd();
2745 #ifdef CONFIG_FEATURE_COMMAND_EDITING
2746         cmdedit_set_initial_prompt();
2747 #else
2748         PS1 = NULL;
2749 #endif
2750         PS2 = "> ";
2751
2752         /* initialize our shell local variables with the values
2753          * currently living in the environment */
2754         if (e) {
2755                 for (; *e; e++)
2756                         set_local_var(*e, 2);   /* without call putenv() */
2757         }
2758
2759         last_return_code=EXIT_SUCCESS;
2760
2761
2762         if (argv[0] && argv[0][0] == '-') {
2763                 debug_printf("\nsourcing /etc/profile\n");
2764                 if ((input = fopen("/etc/profile", "r")) != NULL) {
2765                         mark_open(fileno(input));
2766                         parse_file_outer(input);
2767                         mark_closed(fileno(input));
2768                         fclose(input);
2769                 }
2770         }
2771         input=stdin;
2772
2773         while ((opt = getopt(argc, argv, "c:xif")) > 0) {
2774                 switch (opt) {
2775                         case 'c':
2776                                 {
2777                                         global_argv = argv+optind;
2778                                         global_argc = argc-optind;
2779                                         opt = parse_string_outer(optarg, FLAG_PARSE_SEMICOLON);
2780                                         goto final_return;
2781                                 }
2782                                 break;
2783                         case 'i':
2784                                 interactive++;
2785                                 break;
2786                         case 'f':
2787                                 fake_mode++;
2788                                 break;
2789                         default:
2790 #ifndef BB_VER
2791                                 fprintf(stderr, "Usage: sh [FILE]...\n"
2792                                                 "   or: sh -c command [args]...\n\n");
2793                                 exit(EXIT_FAILURE);
2794 #else
2795                                 bb_show_usage();
2796 #endif
2797                 }
2798         }
2799         /* A shell is interactive if the `-i' flag was given, or if all of
2800          * the following conditions are met:
2801          *        no -c command
2802          *    no arguments remaining or the -s flag given
2803          *    standard input is a terminal
2804          *    standard output is a terminal
2805          *    Refer to Posix.2, the description of the `sh' utility. */
2806         if (argv[optind]==NULL && input==stdin &&
2807                         isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
2808                 interactive++;
2809         }
2810
2811         debug_printf("\ninteractive=%d\n", interactive);
2812         if (interactive) {
2813                 /* Looks like they want an interactive shell */
2814 #ifndef CONFIG_FEATURE_SH_EXTRA_QUIET
2815                 printf( "\n\n%s hush - the humble shell v0.01 (testing)\n",
2816                         BB_BANNER);
2817                 printf( "Enter 'help' for a list of built-in commands.\n\n");
2818 #endif
2819                 setup_job_control();
2820         }
2821
2822         if (argv[optind]==NULL) {
2823                 opt=parse_file_outer(stdin);
2824                 goto final_return;
2825         }
2826
2827         debug_printf("\nrunning script '%s'\n", argv[optind]);
2828         global_argv = argv+optind;
2829         global_argc = argc-optind;
2830         input = bb_xfopen(argv[optind], "r");
2831         opt = parse_file_outer(input);
2832
2833 #ifdef CONFIG_FEATURE_CLEAN_UP
2834         fclose(input);
2835         if (cwd && cwd != bb_msg_unknown)
2836                 free((char*)cwd);
2837         {
2838                 struct variables *cur, *tmp;
2839                 for(cur = top_vars; cur; cur = tmp) {
2840                         tmp = cur->next;
2841                         if (!cur->flg_read_only) {
2842                                 free(cur->name);
2843                                 free(cur->value);
2844                                 free(cur);
2845                         }
2846                 }
2847         }
2848 #endif
2849
2850 final_return:
2851         return(opt?opt:last_return_code);
2852 }
2853
2854 static char *insert_var_value(char *inp)
2855 {
2856         int res_str_len = 0;
2857         int len;
2858         int done = 0;
2859         char *p, *p1, *res_str = NULL;
2860
2861         while ((p = strchr(inp, SPECIAL_VAR_SYMBOL))) {
2862                 if (p != inp) {
2863                         len = p - inp;
2864                         res_str = xrealloc(res_str, (res_str_len + len));
2865                         strncpy((res_str + res_str_len), inp, len);
2866                         res_str_len += len;
2867                 }
2868                 inp = ++p;
2869                 p = strchr(inp, SPECIAL_VAR_SYMBOL);
2870                 *p = '\0';
2871                 if ((p1 = lookup_param(inp))) {
2872                         len = res_str_len + strlen(p1);
2873                         res_str = xrealloc(res_str, (1 + len));
2874                         strcpy((res_str + res_str_len), p1);
2875                         res_str_len = len;
2876                 }
2877                 *p = SPECIAL_VAR_SYMBOL;
2878                 inp = ++p;
2879                 done = 1;
2880         }
2881         if (done) {
2882                 res_str = xrealloc(res_str, (1 + res_str_len + strlen(inp)));
2883                 strcpy((res_str + res_str_len), inp);
2884                 while ((p = strchr(res_str, '\n'))) {
2885                         *p = ' ';
2886                 }
2887         }
2888         return (res_str == NULL) ? inp : res_str;
2889 }
2890
2891 static char **make_list_in(char **inp, char *name)
2892 {
2893         int len, i;
2894         int name_len = strlen(name);
2895         int n = 0;
2896         char **list;
2897         char *p1, *p2, *p3;
2898
2899         /* create list of variable values */
2900         list = xmalloc(sizeof(*list));
2901         for (i = 0; inp[i]; i++) {
2902                 p3 = insert_var_value(inp[i]);
2903                 p1 = p3;
2904                 while (*p1) {
2905                         if ((*p1 == ' ')) {
2906                                 p1++;
2907                                 continue;
2908                         }
2909                         if ((p2 = strchr(p1, ' '))) {
2910                                 len = p2 - p1;
2911                         } else {
2912                                 len = strlen(p1);
2913                                 p2 = p1 + len;
2914                         }
2915                         /* we use n + 2 in realloc for list,because we add
2916                          * new element and then we will add NULL element */
2917                         list = xrealloc(list, sizeof(*list) * (n + 2));
2918                         list[n] = xmalloc(2 + name_len + len);
2919                         strcpy(list[n], name);
2920                         strcat(list[n], "=");
2921                         strncat(list[n], p1, len);
2922                         list[n++][name_len + len + 1] = '\0';
2923                         p1 = p2;
2924                 }
2925                 if (p3 != inp[i]) free(p3);
2926         }
2927         list[n] = NULL;
2928         return list;
2929 }
2930
2931 /* Make new string for parser */
2932 static char * make_string(char ** inp)
2933 {
2934         char *p;
2935         char *str = NULL;
2936         int n;
2937         int len = 2;
2938
2939         for (n = 0; inp[n]; n++) {
2940                 p = insert_var_value(inp[n]);
2941                 str = xrealloc(str, (len + strlen(p)));
2942                 if (n) {
2943                         strcat(str, " ");
2944                 } else {
2945                         *str = '\0';
2946                 }
2947                 strcat(str, p);
2948                 len = strlen(str) + 3;
2949                 if (p != inp[n]) free(p);
2950         }
2951         len = strlen(str);
2952         *(str + len) = '\n';
2953         *(str + len + 1) = '\0';
2954         return str;
2955 }