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  * This program is free software; you can redistribute it and/or modify
  79  * it under the terms of the GNU General Public License as published by
  80  * the Free Software Foundation; either version 2 of the License, or
  81  * (at your option) any later version.
  82  *
  83  * This program is distributed in the hope that it will be useful,
  84  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  85  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  86  * General Public License for more details.
  87  *
  88  * You should have received a copy of the GNU General Public License
  89  * along with this program; if not, write to the Free Software
  90  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  91  */
  92 #include <ctype.h>     /* isalpha, isdigit */
  93 #include <unistd.h>    /* getpid */
  94 #include <stdlib.h>    /* getenv, atoi */
  95 #include <string.h>    /* strchr */
  96 #include <stdio.h>     /* popen etc. */
  97 #include <glob.h>      /* glob, of course */
  98 #include <stdarg.h>    /* va_list */
  99 #include <errno.h>
 100 #include <fcntl.h>
 101 #include <getopt.h>    /* should be pretty obvious */
 102
 103 #include <sys/stat.h>  /* ulimit */
 104 #include <sys/types.h>
 105 #include <sys/wait.h>
 106 #include <signal.h>
 107
 108 /* #include <dmalloc.h> */
 109 /* #define DEBUG_SHELL */
 110
 111 #if 1
 112 #include "busybox.h"
 113 #include "cmdedit.h"
 114 #else
 115 #define bb_applet_name "hush"
 116 #include "standalone.h"
 117 #define hush_main main
 118 #undef CONFIG_FEATURE_SH_FANCY_PROMPT
 119 #define BB_BANNER
 120 #endif
 121 #define SPECIAL_VAR_SYMBOL 03
 122 #define FLAG_EXIT_FROM_LOOP 1
 123 #define FLAG_PARSE_SEMICOLON (1 << 1)           /* symbol ';' is special for parser */
 124 #define FLAG_REPARSING           (1 << 2)               /* >=2nd pass */
 125
 126 typedef enum {
 127         REDIRECT_INPUT     = 1,
 128         REDIRECT_OVERWRITE = 2,
 129         REDIRECT_APPEND    = 3,
 130         REDIRECT_HEREIS    = 4,
 131         REDIRECT_IO        = 5
 132 } redir_type;
 133
 134 /* The descrip member of this structure is only used to make debugging
 135  * output pretty */
 136 static struct {int mode; int default_fd; char *descrip;} redir_table[] = {
 137         { 0,                         0, "()" },
 138         { O_RDONLY,                  0, "<"  },
 139         { O_CREAT|O_TRUNC|O_WRONLY,  1, ">"  },
 140         { O_CREAT|O_APPEND|O_WRONLY, 1, ">>" },
 141         { O_RDONLY,                 -1, "<<" },
 142         { O_RDWR,                    1, "<>" }
 143 };
 144
 145 typedef enum {
 146         PIPE_SEQ = 1,
 147         PIPE_AND = 2,
 148         PIPE_OR  = 3,
 149         PIPE_BG  = 4,
 150 } pipe_style;
 151
 152 /* might eventually control execution */
 153 typedef enum {
 154         RES_NONE  = 0,
 155         RES_IF    = 1,
 156         RES_THEN  = 2,
 157         RES_ELIF  = 3,
 158         RES_ELSE  = 4,
 159         RES_FI    = 5,
 160         RES_FOR   = 6,
 161         RES_WHILE = 7,
 162         RES_UNTIL = 8,
 163         RES_DO    = 9,
 164         RES_DONE  = 10,
 165         RES_XXXX  = 11,
 166         RES_IN    = 12,
 167         RES_SNTX  = 13
 168 } reserved_style;
 169 #define FLAG_END   (1<<RES_NONE)
 170 #define FLAG_IF    (1<<RES_IF)
 171 #define FLAG_THEN  (1<<RES_THEN)
 172 #define FLAG_ELIF  (1<<RES_ELIF)
 173 #define FLAG_ELSE  (1<<RES_ELSE)
 174 #define FLAG_FI    (1<<RES_FI)
 175 #define FLAG_FOR   (1<<RES_FOR)
 176 #define FLAG_WHILE (1<<RES_WHILE)
 177 #define FLAG_UNTIL (1<<RES_UNTIL)
 178 #define FLAG_DO    (1<<RES_DO)
 179 #define FLAG_DONE  (1<<RES_DONE)
 180 #define FLAG_IN    (1<<RES_IN)
 181 #define FLAG_START (1<<RES_XXXX)
 182
 183 /* This holds pointers to the various results of parsing */
 184 struct p_context {
 185         struct child_prog *child;
 186         struct pipe *list_head;
 187         struct pipe *pipe;
 188         struct redir_struct *pending_redirect;
 189         reserved_style w;
 190         int old_flag;                           /* for figuring out valid reserved words */
 191         struct p_context *stack;
 192         int type;                       /* define type of parser : ";$" common or special symbol */
 193         /* How about quoting status? */
 194 };
 195
 196 struct redir_struct {
 197         redir_type type;                        /* type of redirection */
 198         int fd;                                         /* file descriptor being redirected */
 199         int dup;                                        /* -1, or file descriptor being duplicated */
 200         struct redir_struct *next;      /* pointer to the next redirect in the list */
 201         glob_t word;                            /* *word.gl_pathv is the filename */
 202 };
 203
 204 struct child_prog {
 205         pid_t pid;                                      /* 0 if exited */
 206         char **argv;                            /* program name and arguments */
 207         struct pipe *group;                     /* if non-NULL, first in group or subshell */
 208         int subshell;                           /* flag, non-zero if group must be forked */
 209         struct redir_struct *redirects; /* I/O redirections */
 210         glob_t glob_result;                     /* result of parameter globbing */
 211         int is_stopped;                         /* is the program currently running? */
 212         struct pipe *family;            /* pointer back to the child's parent pipe */
 213         int sp;                         /* number of SPECIAL_VAR_SYMBOL */
 214         int type;
 215 };
 216
 217 struct pipe {
 218         int jobid;                                      /* job number */
 219         int num_progs;                          /* total number of programs in job */
 220         int running_progs;                      /* number of programs running */
 221         char *text;                                     /* name of job */
 222         char *cmdbuf;                           /* buffer various argv's point into */
 223         pid_t pgrp;                                     /* process group ID for the job */
 224         struct child_prog *progs;       /* array of commands in pipe */
 225         struct pipe *next;                      /* to track background commands */
 226         int stopped_progs;                      /* number of programs alive, but stopped */
 227         int job_context;                        /* bitmask defining current context */
 228         pipe_style followup;            /* PIPE_BG, PIPE_SEQ, PIPE_OR, PIPE_AND */
 229         reserved_style r_mode;          /* supports if, for, while, until */
 230 };
 231
 232 struct close_me {
 233         int fd;
 234         struct close_me *next;
 235 };
 236
 237 struct variables {
 238         char *name;
 239         char *value;
 240         int flg_export;
 241         int flg_read_only;
 242         struct variables *next;
 243 };
 244
 245 /* globals, connect us to the outside world
 246  * the first three support $?, $#, and $1 */
 247 static char **global_argv;
 248 static unsigned int global_argc;
 249 static unsigned int last_return_code;
 250 extern char **environ; /* This is in <unistd.h>, but protected with __USE_GNU */
 251
 252 /* "globals" within this file */
 253 static char *ifs;
 254 static char map[256];
 255 static int fake_mode;
 256 static int interactive;
 257 static struct close_me *close_me_head;
 258 static const char *cwd;
 259 static struct pipe *job_list;
 260 static unsigned int last_bg_pid;
 261 static unsigned int last_jobid;
 262 static unsigned int shell_terminal;
 263 static char *PS1;
 264 static char *PS2;
 265 static struct variables shell_ver = { "HUSH_VERSION", "0.01", 1, 1, 0 };
 266 static struct variables *top_vars = &shell_ver;
 267
 268
 269 #define B_CHUNK (100)
 270 #define B_NOSPAC 1
 271
 272 typedef struct {
 273         char *data;
 274         int length;
 275         int maxlen;
 276         int quote;
 277         int nonnull;
 278 } o_string;
 279 #define NULL_O_STRING {NULL,0,0,0,0}
 280 /* used for initialization:
 281         o_string foo = NULL_O_STRING; */
 282
 283 /* I can almost use ordinary FILE *.  Is open_memstream() universally
 284  * available?  Where is it documented? */
 285 struct in_str {
 286         const char *p;
 287         char peek_buf[2];
 288         int __promptme;
 289         int promptmode;
 290         FILE *file;
 291         int (*get) (struct in_str *);
 292         int (*peek) (struct in_str *);
 293 };
 294 #define b_getch(input) ((input)->get(input))
 295 #define b_peek(input) ((input)->peek(input))
 296
 297 #define JOB_STATUS_FORMAT "[%d] %-22s %.40s\n"
 298
 299 struct built_in_command {
 300         char *cmd;                                      /* name */
 301         char *descr;                            /* description */
 302         int (*function) (struct child_prog *);  /* function ptr */
 303 };
 304
 305 /* belongs in busybox.h */
 306 static inline int max(int a, int b) {
 307         return (a>b)?a:b;
 308 }
 309
 310 /* This should be in utility.c */
 311 #ifdef DEBUG_SHELL
 312 static void debug_printf(const char *format, ...)
 313 {
 314         va_list args;
 315         va_start(args, format);
 316         vfprintf(stderr, format, args);
 317         va_end(args);
 318 }
 319 #else
 320 static inline void debug_printf(const char *format, ...) { }
 321 #endif
 322 #define final_printf debug_printf
 323
 324 static void __syntax(char *file, int line) {
 325         bb_error_msg("syntax error %s:%d", file, line);
 326 }
 327 #define syntax() __syntax(__FILE__, __LINE__)
 328
 329 /* Index of subroutines: */
 330 /*   function prototypes for builtins */
 331 static int builtin_cd(struct child_prog *child);
 332 static int builtin_env(struct child_prog *child);
 333 static int builtin_eval(struct child_prog *child);
 334 static int builtin_exec(struct child_prog *child);
 335 static int builtin_exit(struct child_prog *child);
 336 static int builtin_export(struct child_prog *child);
 337 static int builtin_fg_bg(struct child_prog *child);
 338 static int builtin_help(struct child_prog *child);
 339 static int builtin_jobs(struct child_prog *child);
 340 static int builtin_pwd(struct child_prog *child);
 341 static int builtin_read(struct child_prog *child);
 342 static int builtin_set(struct child_prog *child);
 343 static int builtin_shift(struct child_prog *child);
 344 static int builtin_source(struct child_prog *child);
 345 static int builtin_umask(struct child_prog *child);
 346 static int builtin_unset(struct child_prog *child);
 347 static int builtin_not_written(struct child_prog *child);
 348 /*   o_string manipulation: */
 349 static int b_check_space(o_string *o, int len);
 350 static int b_addchr(o_string *o, int ch);
 351 static void b_reset(o_string *o);
 352 static int b_addqchr(o_string *o, int ch, int quote);
 353 static int b_adduint(o_string *o, unsigned int i);
 354 /*  in_str manipulations: */
 355 static int static_get(struct in_str *i);
 356 static int static_peek(struct in_str *i);
 357 static int file_get(struct in_str *i);
 358 static int file_peek(struct in_str *i);
 359 static void setup_file_in_str(struct in_str *i, FILE *f);
 360 static void setup_string_in_str(struct in_str *i, const char *s);
 361 /*  close_me manipulations: */
 362 static void mark_open(int fd);
 363 static void mark_closed(int fd);
 364 static void close_all(void);
 365 /*  "run" the final data structures: */
 366 static char *indenter(int i);
 367 static int free_pipe_list(struct pipe *head, int indent);
 368 static int free_pipe(struct pipe *pi, int indent);
 369 /*  really run the final data structures: */
 370 static int setup_redirects(struct child_prog *prog, int squirrel[]);
 371 static int run_list_real(struct pipe *pi);
 372 static void pseudo_exec(struct child_prog *child) __attribute__ ((noreturn));
 373 static int run_pipe_real(struct pipe *pi);
 374 /*   extended glob support: */
 375 static int globhack(const char *src, int flags, glob_t *pglob);
 376 static int glob_needed(const char *s);
 377 static int xglob(o_string *dest, int flags, glob_t *pglob);
 378 /*   variable assignment: */
 379 static int is_assignment(const char *s);
 380 /*   data structure manipulation: */
 381 static int setup_redirect(struct p_context *ctx, int fd, redir_type style, struct in_str *input);
 382 static void initialize_context(struct p_context *ctx);
 383 static int done_word(o_string *dest, struct p_context *ctx);
 384 static int done_command(struct p_context *ctx);
 385 static int done_pipe(struct p_context *ctx, pipe_style type);
 386 /*   primary string parsing: */
 387 static int redirect_dup_num(struct in_str *input);
 388 static int redirect_opt_num(o_string *o);
 389 static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end);
 390 static int parse_group(o_string *dest, struct p_context *ctx, struct in_str *input, int ch);
 391 static char *lookup_param(char *src);
 392 static char *make_string(char **inp);
 393 static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input);
 394 static int parse_string(o_string *dest, struct p_context *ctx, const char *src);
 395 static int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input0, int end_trigger);
 396 /*   setup: */
 397 static int parse_stream_outer(struct in_str *inp, int flag);
 398 static int parse_string_outer(const char *s, int flag);
 399 static int parse_file_outer(FILE *f);
 400 /*   job management: */
 401 static int checkjobs(struct pipe* fg_pipe);
 402 static void insert_bg_job(struct pipe *pi);
 403 static void remove_bg_job(struct pipe *pi);
 404 /*     local variable support */
 405 static char **make_list_in(char **inp, char *name);
 406 static char *insert_var_value(char *inp);
 407 static char *get_local_var(const char *var);
 408 static void  unset_local_var(const char *name);
 409 static int set_local_var(const char *s, int flg_export);
 410
 411 /* Table of built-in functions.  They can be forked or not, depending on
 412  * context: within pipes, they fork.  As simple commands, they do not.
 413  * When used in non-forking context, they can change global variables
 414  * in the parent shell process.  If forked, of course they can not.
 415  * For example, 'unset foo | whatever' will parse and run, but foo will
 416  * still be set at the end. */
 417 static struct built_in_command bltins[] = {
 418         {"bg", "Resume a job in the background", builtin_fg_bg},
 419         {"break", "Exit for, while or until loop", builtin_not_written},
 420         {"cd", "Change working directory", builtin_cd},
 421         {"continue", "Continue for, while or until loop", builtin_not_written},
 422         {"env", "Print all environment variables", builtin_env},
 423         {"eval", "Construct and run shell command", builtin_eval},
 424         {"exec", "Exec command, replacing this shell with the exec'd process",
 425                 builtin_exec},
 426         {"exit", "Exit from shell()", builtin_exit},
 427         {"export", "Set environment variable", builtin_export},
 428         {"fg", "Bring job into the foreground", builtin_fg_bg},
 429         {"jobs", "Lists the active jobs", builtin_jobs},
 430         {"pwd", "Print current directory", builtin_pwd},
 431         {"read", "Input environment variable", builtin_read},
 432         {"return", "Return from a function", builtin_not_written},
 433         {"set", "Set/unset shell local variables", builtin_set},
 434         {"shift", "Shift positional parameters", builtin_shift},
 435         {"trap", "Trap signals", builtin_not_written},
 436         {"ulimit","Controls resource limits", builtin_not_written},
 437         {"umask","Sets file creation mask", builtin_umask},
 438         {"unset", "Unset environment variable", builtin_unset},
 439         {".", "Source-in and run commands in a file", builtin_source},
 440         {"help", "List shell built-in commands", builtin_help},
 441         {NULL, NULL, NULL}
 442 };
 443
 444 static const char *set_cwd(void)
 445 {
 446         if(cwd==bb_msg_unknown)
 447                 cwd = NULL;     /* xgetcwd(arg) called free(arg) */
 448         cwd = xgetcwd((char *)cwd);
 449         if (!cwd)
 450                 cwd = bb_msg_unknown;
 451         return cwd;
 452 }
 453
 454 /* built-in 'eval' handler */
 455 static int builtin_eval(struct child_prog *child)
 456 {
 457         char *str = NULL;
 458         int rcode = EXIT_SUCCESS;
 459
 460         if (child->argv[1]) {
 461                 str = make_string(child->argv + 1);
 462                 parse_string_outer(str, FLAG_EXIT_FROM_LOOP |
 463                                         FLAG_PARSE_SEMICOLON);
 464                 free(str);
 465                 rcode = last_return_code;
 466         }
 467         return rcode;
 468 }
 469
 470 /* built-in 'cd <path>' handler */
 471 static int builtin_cd(struct child_prog *child)
 472 {
 473         char *newdir;
 474         if (child->argv[1] == NULL)
 475                 newdir = getenv("HOME");
 476         else
 477                 newdir = child->argv[1];
 478         if (chdir(newdir)) {
 479                 printf("cd: %s: %s\n", newdir, strerror(errno));
 480                 return EXIT_FAILURE;
 481         }
 482         set_cwd();
 483         return EXIT_SUCCESS;
 484 }
 485
 486 /* built-in 'env' handler */
 487 static int builtin_env(struct child_prog *dummy)
 488 {
 489         char **e = environ;
 490         if (e == NULL) return EXIT_FAILURE;
 491         for (; *e; e++) {
 492                 puts(*e);
 493         }
 494         return EXIT_SUCCESS;
 495 }
 496
 497 /* built-in 'exec' handler */
 498 static int builtin_exec(struct child_prog *child)
 499 {
 500         if (child->argv[1] == NULL)
 501                 return EXIT_SUCCESS;   /* Really? */
 502         child->argv++;
 503         pseudo_exec(child);
 504         /* never returns */
 505 }
 506
 507 /* built-in 'exit' handler */
 508 static int builtin_exit(struct child_prog *child)
 509 {
 510         if (child->argv[1] == NULL)
 511                 exit(last_return_code);
 512         exit (atoi(child->argv[1]));
 513 }
 514
 515 /* built-in 'export VAR=value' handler */
 516 static int builtin_export(struct child_prog *child)
 517 {
 518         int res = 0;
 519         char *name = child->argv[1];
 520
 521         if (name == NULL) {
 522                 return (builtin_env(child));
 523         }
 524
 525         name = strdup(name);
 526
 527         if(name) {
 528                 char *value = strchr(name, '=');
 529
 530                 if (!value) {
 531                         char *tmp;
 532                         /* They are exporting something without an =VALUE */
 533
 534                         value = get_local_var(name);
 535                         if (value) {
 536                                 size_t ln = strlen(name);
 537
 538                                 tmp = realloc(name, ln+strlen(value)+2);
 539                                 if(tmp==NULL)
 540                                         res = -1;
 541                                 else {
 542                                         sprintf(tmp+ln, "=%s", value);
 543                                         name = tmp;
 544                                 }
 545                         } else {
 546                                 /* bash does not return an error when trying to export
 547                                  * an undefined variable.  Do likewise. */
 548                                 res = 1;
 549                         }
 550                 }
 551         }
 552         if (res<0)
 553                 bb_perror_msg("export");
 554         else if(res==0)
 555                 res = set_local_var(name, 1);
 556         else
 557                 res = 0;
 558         free(name);
 559         return res;
 560 }
 561
 562 /* built-in 'fg' and 'bg' handler */
 563 static int builtin_fg_bg(struct child_prog *child)
 564 {
 565         int i, jobnum;
 566         struct pipe *pi=NULL;
 567
 568         if (!interactive)
 569                 return EXIT_FAILURE;
 570         /* If they gave us no args, assume they want the last backgrounded task */
 571         if (!child->argv[1]) {
 572                 for (pi = job_list; pi; pi = pi->next) {
 573                         if (pi->jobid == last_jobid) {
 574                                 break;
 575                         }
 576                 }
 577                 if (!pi) {
 578                         bb_error_msg("%s: no current job", child->argv[0]);
 579                         return EXIT_FAILURE;
 580                 }
 581         } else {
 582                 if (sscanf(child->argv[1], "%%%d", &jobnum) != 1) {
 583                         bb_error_msg("%s: bad argument '%s'", child->argv[0], child->argv[1]);
 584                         return EXIT_FAILURE;
 585                 }
 586                 for (pi = job_list; pi; pi = pi->next) {
 587                         if (pi->jobid == jobnum) {
 588                                 break;
 589                         }
 590                 }
 591                 if (!pi) {
 592                         bb_error_msg("%s: %d: no such job", child->argv[0], jobnum);
 593                         return EXIT_FAILURE;
 594                 }
 595         }
 596
 597         if (*child->argv[0] == 'f') {
 598                 /* Put the job into the foreground.  */
 599                 tcsetpgrp(shell_terminal, pi->pgrp);
 600         }
 601
 602         /* Restart the processes in the job */
 603         for (i = 0; i < pi->num_progs; i++)
 604                 pi->progs[i].is_stopped = 0;
 605
 606         if ( (i=kill(- pi->pgrp, SIGCONT)) < 0) {
 607                 if (i == ESRCH) {
 608                         remove_bg_job(pi);
 609                 } else {
 610                         bb_perror_msg("kill (SIGCONT)");
 611                 }
 612         }
 613
 614         pi->stopped_progs = 0;
 615         return EXIT_SUCCESS;
 616 }
 617
 618 /* built-in 'help' handler */
 619 static int builtin_help(struct child_prog *dummy)
 620 {
 621         struct built_in_command *x;
 622
 623         printf("\nBuilt-in commands:\n");
 624         printf("-------------------\n");
 625         for (x = bltins; x->cmd; x++) {
 626                 if (x->descr==NULL)
 627                         continue;
 628                 printf("%s\t%s\n", x->cmd, x->descr);
 629         }
 630         printf("\n\n");
 631         return EXIT_SUCCESS;
 632 }
 633
 634 /* built-in 'jobs' handler */
 635 static int builtin_jobs(struct child_prog *child)
 636 {
 637         struct pipe *job;
 638         char *status_string;
 639
 640         for (job = job_list; job; job = job->next) {
 641                 if (job->running_progs == job->stopped_progs)
 642                         status_string = "Stopped";
 643                 else
 644                         status_string = "Running";
 645
 646                 printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->text);
 647         }
 648         return EXIT_SUCCESS;
 649 }
 650
 651
 652 /* built-in 'pwd' handler */
 653 static int builtin_pwd(struct child_prog *dummy)
 654 {
 655         puts(set_cwd());
 656         return EXIT_SUCCESS;
 657 }
 658
 659 /* built-in 'read VAR' handler */
 660 static int builtin_read(struct child_prog *child)
 661 {
 662         int res;
 663
 664         if (child->argv[1]) {
 665                 char string[BUFSIZ];
 666                 char *var = 0;
 667
 668                 string[0] = 0;  /* In case stdin has only EOF */
 669                 /* read string */
 670                 fgets(string, sizeof(string), stdin);
 671                 chomp(string);
 672                 var = malloc(strlen(child->argv[1])+strlen(string)+2);
 673                 if(var) {
 674                         sprintf(var, "%s=%s", child->argv[1], string);
 675                         res = set_local_var(var, 0);
 676                 } else
 677                         res = -1;
 678                 if (res)
 679                         fprintf(stderr, "read: %m\n");
 680                 free(var);      /* So not move up to avoid breaking errno */
 681                 return res;
 682         } else {
 683                 do res=getchar(); while(res!='\n' && res!=EOF);
 684                 return 0;
 685         }
 686 }
 687
 688 /* built-in 'set VAR=value' handler */
 689 static int builtin_set(struct child_prog *child)
 690 {
 691         char *temp = child->argv[1];
 692         struct variables *e;
 693
 694         if (temp == NULL)
 695                 for(e = top_vars; e; e=e->next)
 696                         printf("%s=%s\n", e->name, e->value);
 697         else
 698                 set_local_var(temp, 0);
 699
 700                 return EXIT_SUCCESS;
 701 }
 702
 703
 704 /* Built-in 'shift' handler */
 705 static int builtin_shift(struct child_prog *child)
 706 {
 707         int n=1;
 708         if (child->argv[1]) {
 709                 n=atoi(child->argv[1]);
 710         }
 711         if (n>=0 && n<global_argc) {
 712                 /* XXX This probably breaks $0 */
 713                 global_argc -= n;
 714                 global_argv += n;
 715                 return EXIT_SUCCESS;
 716         } else {
 717                 return EXIT_FAILURE;
 718         }
 719 }
 720
 721 /* Built-in '.' handler (read-in and execute commands from file) */
 722 static int builtin_source(struct child_prog *child)
 723 {
 724         FILE *input;
 725         int status;
 726
 727         if (child->argv[1] == NULL)
 728                 return EXIT_FAILURE;
 729
 730         /* XXX search through $PATH is missing */
 731         input = fopen(child->argv[1], "r");
 732         if (!input) {
 733                 bb_error_msg("Couldn't open file '%s'", child->argv[1]);
 734                 return EXIT_FAILURE;
 735         }
 736
 737         /* Now run the file */
 738         /* XXX argv and argc are broken; need to save old global_argv
 739          * (pointer only is OK!) on this stack frame,
 740          * set global_argv=child->argv+1, recurse, and restore. */
 741         mark_open(fileno(input));
 742         status = parse_file_outer(input);
 743         mark_closed(fileno(input));
 744         fclose(input);
 745         return (status);
 746 }
 747
 748 static int builtin_umask(struct child_prog *child)
 749 {
 750         mode_t new_umask;
 751         const char *arg = child->argv[1];
 752         char *end;
 753         if (arg) {
 754                 new_umask=strtoul(arg, &end, 8);
 755                 if (*end!='\0' || end == arg) {
 756                         return EXIT_FAILURE;
 757                 }
 758         } else {
 759                 printf("%.3o\n", (unsigned int) (new_umask=umask(0)));
 760         }
 761         umask(new_umask);
 762         return EXIT_SUCCESS;
 763 }
 764
 765 /* built-in 'unset VAR' handler */
 766 static int builtin_unset(struct child_prog *child)
 767 {
 768         /* bash returned already true */
 769         unset_local_var(child->argv[1]);
 770         return EXIT_SUCCESS;
 771 }
 772
 773 static int builtin_not_written(struct child_prog *child)
 774 {
 775         printf("builtin_%s not written\n",child->argv[0]);
 776         return EXIT_FAILURE;
 777 }
 778
 779 static int b_check_space(o_string *o, int len)
 780 {
 781         /* It would be easy to drop a more restrictive policy
 782          * in here, such as setting a maximum string length */
 783         if (o->length + len > o->maxlen) {
 784                 char *old_data = o->data;
 785                 /* assert (data == NULL || o->maxlen != 0); */
 786                 o->maxlen += max(2*len, B_CHUNK);
 787                 o->data = realloc(o->data, 1 + o->maxlen);
 788                 if (o->data == NULL) {
 789                         free(old_data);
 790                 }
 791         }
 792         return o->data == NULL;
 793 }
 794
 795 static int b_addchr(o_string *o, int ch)
 796 {
 797         debug_printf("b_addchr: %c %d %p\n", ch, o->length, o);
 798         if (b_check_space(o, 1)) return B_NOSPAC;
 799         o->data[o->length] = ch;
 800         o->length++;
 801         o->data[o->length] = '\0';
 802         return 0;
 803 }
 804
 805 static void b_reset(o_string *o)
 806 {
 807         o->length = 0;
 808         o->nonnull = 0;
 809         if (o->data != NULL) *o->data = '\0';
 810 }
 811
 812 static void b_free(o_string *o)
 813 {
 814         b_reset(o);
 815         free(o->data);
 816         o->data = NULL;
 817         o->maxlen = 0;
 818 }
 819
 820 /* My analysis of quoting semantics tells me that state information
 821  * is associated with a destination, not a source.
 822  */
 823 static int b_addqchr(o_string *o, int ch, int quote)
 824 {
 825         if (quote && strchr("*?[\\",ch)) {
 826                 int rc;
 827                 rc = b_addchr(o, '\\');
 828                 if (rc) return rc;
 829         }
 830         return b_addchr(o, ch);
 831 }
 832
 833 /* belongs in utility.c */
 834 static char *simple_itoa(unsigned int i)
 835 {
 836         /* 21 digits plus null terminator, good for 64-bit or smaller ints */
 837         static char local[22];
 838         char *p = &local[21];
 839         *p-- = '\0';
 840         do {
 841                 *p-- = '0' + i % 10;
 842                 i /= 10;
 843         } while (i > 0);
 844         return p + 1;
 845 }
 846
 847 static int b_adduint(o_string *o, unsigned int i)
 848 {
 849         int r;
 850         char *p = simple_itoa(i);
 851         /* no escape checking necessary */
 852         do r=b_addchr(o, *p++); while (r==0 && *p);
 853         return r;
 854 }
 855
 856 static int static_get(struct in_str *i)
 857 {
 858         int ch=*i->p++;
 859         if (ch=='\0') return EOF;
 860         return ch;
 861 }
 862
 863 static int static_peek(struct in_str *i)
 864 {
 865         return *i->p;
 866 }
 867
 868 static inline void cmdedit_set_initial_prompt(void)
 869 {
 870 #ifndef CONFIG_FEATURE_SH_FANCY_PROMPT
 871         PS1 = NULL;
 872 #else
 873         PS1 = getenv("PS1");
 874         if(PS1==0)
 875                 PS1 = "\\w \\$ ";
 876 #endif
 877 }
 878
 879 static inline void setup_prompt_string(int promptmode, char **prompt_str)
 880 {
 881         debug_printf("setup_prompt_string %d ",promptmode);
 882 #ifndef CONFIG_FEATURE_SH_FANCY_PROMPT
 883         /* Set up the prompt */
 884         if (promptmode == 1) {
 885                 free(PS1);
 886                 PS1=xmalloc(strlen(cwd)+4);
 887                 sprintf(PS1, "%s %s", cwd, ( geteuid() != 0 ) ?  "$ ":"# ");
 888                 *prompt_str = PS1;
 889         } else {
 890                 *prompt_str = PS2;
 891         }
 892 #else
 893         *prompt_str = (promptmode==1)? PS1 : PS2;
 894 #endif
 895         debug_printf("result %s\n",*prompt_str);
 896 }
 897
 898 static void get_user_input(struct in_str *i)
 899 {
 900         char *prompt_str;
 901         static char the_command[BUFSIZ];
 902
 903         setup_prompt_string(i->promptmode, &prompt_str);
 904 #ifdef CONFIG_FEATURE_COMMAND_EDITING
 905         /*
 906          ** enable command line editing only while a command line
 907          ** is actually being read; otherwise, we'll end up bequeathing
 908          ** atexit() handlers and other unwanted stuff to our
 909          ** child processes (rob@sysgo.de)
 910          */
 911         cmdedit_read_input(prompt_str, the_command);
 912 #else
 913         fputs(prompt_str, stdout);
 914         fflush(stdout);
 915         the_command[0]=fgetc(i->file);
 916         the_command[1]='\0';
 917 #endif
 918         fflush(stdout);
 919         i->p = the_command;
 920 }
 921
 922 /* This is the magic location that prints prompts
 923  * and gets data back from the user */
 924 static int file_get(struct in_str *i)
 925 {
 926         int ch;
 927
 928         ch = 0;
 929         /* If there is data waiting, eat it up */
 930         if (i->p && *i->p) {
 931                 ch=*i->p++;
 932         } else {
 933                 /* need to double check i->file because we might be doing something
 934                  * more complicated by now, like sourcing or substituting. */
 935                 if (i->__promptme && interactive && i->file == stdin) {
 936                         while(! i->p || (interactive && strlen(i->p)==0) ) {
 937                                 get_user_input(i);
 938                         }
 939                         i->promptmode=2;
 940                         i->__promptme = 0;
 941                         if (i->p && *i->p) {
 942                                 ch=*i->p++;
 943                         }
 944                 } else {
 945                         ch = fgetc(i->file);
 946                 }
 947
 948                 debug_printf("b_getch: got a %d\n", ch);
 949         }
 950         if (ch == '\n') i->__promptme=1;
 951         return ch;
 952 }
 953
 954 /* All the callers guarantee this routine will never be
 955  * used right after a newline, so prompting is not needed.
 956  */
 957 static int file_peek(struct in_str *i)
 958 {
 959         if (i->p && *i->p) {
 960                 return *i->p;
 961         } else {
 962                 i->peek_buf[0] = fgetc(i->file);
 963                 i->peek_buf[1] = '\0';
 964                 i->p = i->peek_buf;
 965                 debug_printf("b_peek: got a %d\n", *i->p);
 966                 return *i->p;
 967         }
 968 }
 969
 970 static void setup_file_in_str(struct in_str *i, FILE *f)
 971 {
 972         i->peek = file_peek;
 973         i->get = file_get;
 974         i->__promptme=1;
 975         i->promptmode=1;
 976         i->file = f;
 977         i->p = NULL;
 978 }
 979
 980 static void setup_string_in_str(struct in_str *i, const char *s)
 981 {
 982         i->peek = static_peek;
 983         i->get = static_get;
 984         i->__promptme=1;
 985         i->promptmode=1;
 986         i->p = s;
 987 }
 988
 989 static void mark_open(int fd)
 990 {
 991         struct close_me *new = xmalloc(sizeof(struct close_me));
 992         new->fd = fd;
 993         new->next = close_me_head;
 994         close_me_head = new;
 995 }
 996
 997 static void mark_closed(int fd)
 998 {
 999         struct close_me *tmp;
1000         if (close_me_head == NULL || close_me_head->fd != fd)
1001                 bb_error_msg_and_die("corrupt close_me");
1002         tmp = close_me_head;
1003         close_me_head = close_me_head->next;
1004         free(tmp);
1005 }
1006
1007 static void close_all(void)
1008 {
1009         struct close_me *c;
1010         for (c=close_me_head; c; c=c->next) {
1011                 close(c->fd);
1012         }
1013         close_me_head = NULL;
1014 }
1015
1016 /* squirrel != NULL means we squirrel away copies of stdin, stdout,
1017  * and stderr if they are redirected. */
1018 static int setup_redirects(struct child_prog *prog, int squirrel[])
1019 {
1020         int openfd, mode;
1021         struct redir_struct *redir;
1022
1023         for (redir=prog->redirects; redir; redir=redir->next) {
1024                 if (redir->dup == -1 && redir->word.gl_pathv == NULL) {
1025                         /* something went wrong in the parse.  Pretend it didn't happen */
1026                         continue;
1027                 }
1028                 if (redir->dup == -1) {
1029                         mode=redir_table[redir->type].mode;
1030                         openfd = open(redir->word.gl_pathv[0], mode, 0666);
1031                         if (openfd < 0) {
1032                         /* this could get lost if stderr has been redirected, but
1033                            bash and ash both lose it as well (though zsh doesn't!) */
1034                                 bb_perror_msg("error opening %s", redir->word.gl_pathv[0]);
1035                                 return 1;
1036                         }
1037                 } else {
1038                         openfd = redir->dup;
1039                 }
1040
1041                 if (openfd != redir->fd) {
1042                         if (squirrel && redir->fd < 3) {
1043                                 squirrel[redir->fd] = dup(redir->fd);
1044                         }
1045                         if (openfd == -3) {
1046                                 close(openfd);
1047                         } else {
1048                                 dup2(openfd, redir->fd);
1049                                 if (redir->dup == -1)
1050                                         close (openfd);
1051                         }
1052                 }
1053         }
1054         return 0;
1055 }
1056
1057 static void restore_redirects(int squirrel[])
1058 {
1059         int i, fd;
1060         for (i=0; i<3; i++) {
1061                 fd = squirrel[i];
1062                 if (fd != -1) {
1063                         /* No error checking.  I sure wouldn't know what
1064                          * to do with an error if I found one! */
1065                         dup2(fd, i);
1066                         close(fd);
1067                 }
1068         }
1069 }
1070
1071 /* never returns */
1072 /* XXX no exit() here.  If you don't exec, use _exit instead.
1073  * The at_exit handlers apparently confuse the calling process,
1074  * in particular stdin handling.  Not sure why? */
1075 static void pseudo_exec(struct child_prog *child)
1076 {
1077         int i, rcode;
1078         char *p;
1079         struct built_in_command *x;
1080         if (child->argv) {
1081                 for (i=0; is_assignment(child->argv[i]); i++) {
1082                         debug_printf("pid %d environment modification: %s\n",getpid(),child->argv[i]);
1083                         p = insert_var_value(child->argv[i]);
1084                         putenv(strdup(p));
1085                         if (p != child->argv[i]) free(p);
1086                 }
1087                 child->argv+=i;  /* XXX this hack isn't so horrible, since we are about
1088                                         to exit, and therefore don't need to keep data
1089                                         structures consistent for free() use. */
1090                 /* If a variable is assigned in a forest, and nobody listens,
1091                  * was it ever really set?
1092                  */
1093                 if (child->argv[0] == NULL) {
1094                         _exit(EXIT_SUCCESS);
1095                 }
1096
1097                 /*
1098                  * Check if the command matches any of the builtins.
1099                  * Depending on context, this might be redundant.  But it's
1100                  * easier to waste a few CPU cycles than it is to figure out
1101                  * if this is one of those cases.
1102                  */
1103                 for (x = bltins; x->cmd; x++) {
1104                         if (strcmp(child->argv[0], x->cmd) == 0 ) {
1105                                 debug_printf("builtin exec %s\n", child->argv[0]);
1106                                 rcode = x->function(child);
1107                                 fflush(stdout);
1108                                 _exit(rcode);
1109                         }
1110                 }
1111
1112                 /* Check if the command matches any busybox internal commands
1113                  * ("applets") here.
1114                  * FIXME: This feature is not 100% safe, since
1115                  * BusyBox is not fully reentrant, so we have no guarantee the things
1116                  * from the .bss are still zeroed, or that things from .data are still
1117                  * at their defaults.  We could exec ourself from /proc/self/exe, but I
1118                  * really dislike relying on /proc for things.  We could exec ourself
1119                  * from global_argv[0], but if we are in a chroot, we may not be able
1120                  * to find ourself... */
1121 #ifdef CONFIG_FEATURE_SH_STANDALONE_SHELL
1122                 {
1123                         int argc_l;
1124                         char** argv_l=child->argv;
1125                         char *name = child->argv[0];
1126
1127                         /* Count argc for use in a second... */
1128                         for(argc_l=0;*argv_l!=NULL; argv_l++, argc_l++);
1129                         optind = 1;
1130                         debug_printf("running applet %s\n", name);
1131                         run_applet_by_name(name, argc_l, child->argv);
1132                 }
1133 #endif
1134                 debug_printf("exec of %s\n",child->argv[0]);
1135                 execvp(child->argv[0],child->argv);
1136                 bb_perror_msg("couldn't exec: %s",child->argv[0]);
1137                 _exit(1);
1138         } else if (child->group) {
1139                 debug_printf("runtime nesting to group\n");
1140                 interactive=0;    /* crucial!!!! */
1141                 rcode = run_list_real(child->group);
1142                 /* OK to leak memory by not calling free_pipe_list,
1143                  * since this process is about to exit */
1144                 _exit(rcode);
1145         } else {
1146                 /* Can happen.  See what bash does with ">foo" by itself. */
1147                 debug_printf("trying to pseudo_exec null command\n");
1148                 _exit(EXIT_SUCCESS);
1149         }
1150 }
1151
1152 static void insert_bg_job(struct pipe *pi)
1153 {
1154         struct pipe *thejob;
1155
1156         /* Linear search for the ID of the job to use */
1157         pi->jobid = 1;
1158         for (thejob = job_list; thejob; thejob = thejob->next)
1159                 if (thejob->jobid >= pi->jobid)
1160                         pi->jobid = thejob->jobid + 1;
1161
1162         /* add thejob to the list of running jobs */
1163         if (!job_list) {
1164                 thejob = job_list = xmalloc(sizeof(*thejob));
1165         } else {
1166                 for (thejob = job_list; thejob->next; thejob = thejob->next) /* nothing */;
1167                 thejob->next = xmalloc(sizeof(*thejob));
1168                 thejob = thejob->next;
1169         }
1170
1171         /* physically copy the struct job */
1172         memcpy(thejob, pi, sizeof(struct pipe));
1173         thejob->next = NULL;
1174         thejob->running_progs = thejob->num_progs;
1175         thejob->stopped_progs = 0;
1176         thejob->text = xmalloc(BUFSIZ); /* cmdedit buffer size */
1177
1178         //if (pi->progs[0] && pi->progs[0].argv && pi->progs[0].argv[0])
1179         {
1180                 char *bar=thejob->text;
1181                 char **foo=pi->progs[0].argv;
1182                 while(foo && *foo) {
1183                         bar += sprintf(bar, "%s ", *foo++);
1184                 }
1185         }
1186
1187         /* we don't wait for background thejobs to return -- append it
1188            to the list of backgrounded thejobs and leave it alone */
1189         printf("[%d] %d\n", thejob->jobid, thejob->progs[0].pid);
1190         last_bg_pid = thejob->progs[0].pid;
1191         last_jobid = thejob->jobid;
1192 }
1193
1194 /* remove a backgrounded job */
1195 static void remove_bg_job(struct pipe *pi)
1196 {
1197         struct pipe *prev_pipe;
1198
1199         if (pi == job_list) {
1200                 job_list = pi->next;
1201         } else {
1202                 prev_pipe = job_list;
1203                 while (prev_pipe->next != pi)
1204                         prev_pipe = prev_pipe->next;
1205                 prev_pipe->next = pi->next;
1206         }
1207         if (job_list)
1208                 last_jobid = job_list->jobid;
1209         else
1210                 last_jobid = 0;
1211
1212         pi->stopped_progs = 0;
1213         free_pipe(pi, 0);
1214         free(pi);
1215 }
1216
1217 /* Checks to see if any processes have exited -- if they
1218    have, figure out why and see if a job has completed */
1219 static int checkjobs(struct pipe* fg_pipe)
1220 {
1221         int attributes;
1222         int status;
1223         int prognum = 0;
1224         struct pipe *pi;
1225         pid_t childpid;
1226
1227         attributes = WUNTRACED;
1228         if (fg_pipe==NULL) {
1229                 attributes |= WNOHANG;
1230         }
1231
1232         while ((childpid = waitpid(-1, &status, attributes)) > 0) {
1233                 if (fg_pipe) {
1234                         int i, rcode = 0;
1235                         for (i=0; i < fg_pipe->num_progs; i++) {
1236                                 if (fg_pipe->progs[i].pid == childpid) {
1237                                         if (i==fg_pipe->num_progs-1)
1238                                                 rcode=WEXITSTATUS(status);
1239                                         (fg_pipe->num_progs)--;
1240                                         return(rcode);
1241                                 }
1242                         }
1243                 }
1244
1245                 for (pi = job_list; pi; pi = pi->next) {
1246                         prognum = 0;
1247                         while (prognum < pi->num_progs && pi->progs[prognum].pid != childpid) {
1248                                 prognum++;
1249                         }
1250                         if (prognum < pi->num_progs)
1251                                 break;
1252                 }
1253
1254                 if(pi==NULL) {
1255                         debug_printf("checkjobs: pid %d was not in our list!\n", childpid);
1256                         continue;
1257                 }
1258
1259                 if (WIFEXITED(status) || WIFSIGNALED(status)) {
1260                         /* child exited */
1261                         pi->running_progs--;
1262                         pi->progs[prognum].pid = 0;
1263
1264                         if (!pi->running_progs) {
1265                                 printf(JOB_STATUS_FORMAT, pi->jobid, "Done", pi->text);
1266                                 remove_bg_job(pi);
1267                         }
1268                 } else {
1269                         /* child stopped */
1270                         pi->stopped_progs++;
1271                         pi->progs[prognum].is_stopped = 1;
1272
1273 #if 0
1274                         /* Printing this stuff is a pain, since it tends to
1275                          * overwrite the prompt an inconveinient moments.  So
1276                          * don't do that.  */
1277                         if (pi->stopped_progs == pi->num_progs) {
1278                                 printf("\n"JOB_STATUS_FORMAT, pi->jobid, "Stopped", pi->text);
1279                         }
1280 #endif
1281                 }
1282         }
1283
1284         if (childpid == -1 && errno != ECHILD)
1285                 bb_perror_msg("waitpid");
1286
1287         /* move the shell to the foreground */
1288         //if (interactive && tcsetpgrp(shell_terminal, getpgid(0)))
1289         //      bb_perror_msg("tcsetpgrp-2");
1290         return -1;
1291 }
1292
1293 /* Figure out our controlling tty, checking in order stderr,
1294  * stdin, and stdout.  If check_pgrp is set, also check that
1295  * we belong to the foreground process group associated with
1296  * that tty.  The value of shell_terminal is needed in order to call
1297  * tcsetpgrp(shell_terminal, ...); */
1298 #if 0
1299 static void controlling_tty(int check_pgrp)
1300 {
1301         pid_t curpgrp;
1302
1303         if ((curpgrp = tcgetpgrp(shell_terminal = 2)) < 0
1304                         && (curpgrp = tcgetpgrp(shell_terminal = 0)) < 0
1305                         && (curpgrp = tcgetpgrp(shell_terminal = 1)) < 0)
1306                 goto shell_terminal_error;
1307
1308         if (check_pgrp && curpgrp != getpgid(0))
1309                 goto shell_terminal_error;
1310
1311         return;
1312
1313 shell_terminal_error:
1314                 shell_terminal = -1;
1315                 return;
1316 }
1317 #endif
1318
1319 /* run_pipe_real() starts all the jobs, but doesn't wait for anything
1320  * to finish.  See checkjobs().
1321  *
1322  * return code is normally -1, when the caller has to wait for children
1323  * to finish to determine the exit status of the pipe.  If the pipe
1324  * is a simple builtin command, however, the action is done by the
1325  * time run_pipe_real returns, and the exit code is provided as the
1326  * return value.
1327  *
1328  * The input of the pipe is always stdin, the output is always
1329  * stdout.  The outpipe[] mechanism in BusyBox-0.48 lash is bogus,
1330  * because it tries to avoid running the command substitution in
1331  * subshell, when that is in fact necessary.  The subshell process
1332  * now has its stdout directed to the input of the appropriate pipe,
1333  * so this routine is noticeably simpler.
1334  */
1335 static int run_pipe_real(struct pipe *pi)
1336 {
1337         int i;
1338         int nextin, nextout;
1339         int pipefds[2];                         /* pipefds[0] is for reading */
1340         struct child_prog *child;
1341         struct built_in_command *x;
1342         char *p;
1343
1344         nextin = 0;
1345         pi->pgrp = -1;
1346
1347         /* Check if this is a simple builtin (not part of a pipe).
1348          * Builtins within pipes have to fork anyway, and are handled in
1349          * pseudo_exec.  "echo foo | read bar" doesn't work on bash, either.
1350          */
1351         if (pi->num_progs == 1) child = & (pi->progs[0]);
1352         if (pi->num_progs == 1 && child->group && child->subshell == 0) {
1353                 int squirrel[] = {-1, -1, -1};
1354                 int rcode;
1355                 debug_printf("non-subshell grouping\n");
1356                 setup_redirects(child, squirrel);
1357                 /* XXX could we merge code with following builtin case,
1358                  * by creating a pseudo builtin that calls run_list_real? */
1359                 rcode = run_list_real(child->group);
1360                 restore_redirects(squirrel);
1361                 return rcode;
1362         } else if (pi->num_progs == 1 && pi->progs[0].argv != NULL) {
1363                 for (i=0; is_assignment(child->argv[i]); i++) { /* nothing */ }
1364                 if (i!=0 && child->argv[i]==NULL) {
1365                         /* assignments, but no command: set the local environment */
1366                         for (i=0; child->argv[i]!=NULL; i++) {
1367
1368                                 /* Ok, this case is tricky.  We have to decide if this is a
1369                                  * local variable, or an already exported variable.  If it is
1370                                  * already exported, we have to export the new value.  If it is
1371                                  * not exported, we need only set this as a local variable.
1372                                  * This junk is all to decide whether or not to export this
1373                                  * variable. */
1374                                 int export_me=0;
1375                                 char *name, *value;
1376                                 name = bb_xstrdup(child->argv[i]);
1377                                 debug_printf("Local environment set: %s\n", name);
1378                                 value = strchr(name, '=');
1379                                 if (value)
1380                                         *value=0;
1381                                 if ( get_local_var(name)) {
1382                                         export_me=1;
1383                                 }
1384                                 free(name);
1385                                 p = insert_var_value(child->argv[i]);
1386                                 set_local_var(p, export_me);
1387                                 if (p != child->argv[i]) free(p);
1388                         }
1389                         return EXIT_SUCCESS;   /* don't worry about errors in set_local_var() yet */
1390                 }
1391                 for (i = 0; is_assignment(child->argv[i]); i++) {
1392                         p = insert_var_value(child->argv[i]);
1393                         putenv(strdup(p));
1394                         if (p != child->argv[i]) {
1395                                 child->sp--;
1396                                 free(p);
1397                         }
1398                 }
1399                 if (child->sp) {
1400                         char * str = NULL;
1401
1402                         str = make_string((child->argv + i));
1403                         parse_string_outer(str, FLAG_EXIT_FROM_LOOP | FLAG_REPARSING);
1404                         free(str);
1405                         return last_return_code;
1406                 }
1407                 for (x = bltins; x->cmd; x++) {
1408                         if (strcmp(child->argv[i], x->cmd) == 0 ) {
1409                                 int squirrel[] = {-1, -1, -1};
1410                                 int rcode;
1411                                 if (x->function == builtin_exec && child->argv[i+1]==NULL) {
1412                                         debug_printf("magic exec\n");
1413                                         setup_redirects(child,NULL);
1414                                         return EXIT_SUCCESS;
1415                                 }
1416                                 debug_printf("builtin inline %s\n", child->argv[0]);
1417                                 /* XXX setup_redirects acts on file descriptors, not FILEs.
1418                                  * This is perfect for work that comes after exec().
1419                                  * Is it really safe for inline use?  Experimentally,
1420                                  * things seem to work with glibc. */
1421                                 setup_redirects(child, squirrel);
1422                                 child->argv+=i;  /* XXX horrible hack */
1423                                 rcode = x->function(child);
1424                                 child->argv-=i;  /* XXX restore hack so free() can work right */
1425                                 restore_redirects(squirrel);
1426                                 return rcode;
1427                         }
1428                 }
1429         }
1430
1431         for (i = 0; i < pi->num_progs; i++) {
1432                 child = & (pi->progs[i]);
1433
1434                 /* pipes are inserted between pairs of commands */
1435                 if ((i + 1) < pi->num_progs) {
1436                         if (pipe(pipefds)<0) bb_perror_msg_and_die("pipe");
1437                         nextout = pipefds[1];
1438                 } else {
1439                         nextout=1;
1440                         pipefds[0] = -1;
1441                 }
1442
1443                 /* XXX test for failed fork()? */
1444 #if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
1445                 if (!(child->pid = fork()))
1446 #else
1447                 if (!(child->pid = vfork()))
1448 #endif
1449                 {
1450                         /* Set the handling for job control signals back to the default.  */
1451                         signal(SIGINT, SIG_DFL);
1452                         signal(SIGQUIT, SIG_DFL);
1453                         signal(SIGTERM, SIG_DFL);
1454                         signal(SIGTSTP, SIG_DFL);
1455                         signal(SIGTTIN, SIG_DFL);
1456                         signal(SIGTTOU, SIG_DFL);
1457                         signal(SIGCHLD, SIG_DFL);
1458
1459                         close_all();
1460
1461                         if (nextin != 0) {
1462                                 dup2(nextin, 0);
1463                                 close(nextin);
1464                         }
1465                         if (nextout != 1) {
1466                                 dup2(nextout, 1);
1467                                 close(nextout);
1468                         }
1469                         if (pipefds[0]!=-1) {
1470                                 close(pipefds[0]);  /* opposite end of our output pipe */
1471                         }
1472
1473                         /* Like bash, explicit redirects override pipes,
1474                          * and the pipe fd is available for dup'ing. */
1475                         setup_redirects(child,NULL);
1476
1477                         if (interactive && pi->followup!=PIPE_BG) {
1478                                 /* If we (the child) win the race, put ourselves in the process
1479                                  * group whose leader is the first process in this pipe. */
1480                                 if (pi->pgrp < 0) {
1481                                         pi->pgrp = getpid();
1482                                 }
1483                                 if (setpgid(0, pi->pgrp) == 0) {
1484                                         tcsetpgrp(2, pi->pgrp);
1485                                 }
1486                         }
1487
1488                         pseudo_exec(child);
1489                 }
1490
1491
1492                 /* put our child in the process group whose leader is the
1493                    first process in this pipe */
1494                 if (pi->pgrp < 0) {
1495                         pi->pgrp = child->pid;
1496                 }
1497                 /* Don't check for errors.  The child may be dead already,
1498                  * in which case setpgid returns error code EACCES. */
1499                 setpgid(child->pid, pi->pgrp);
1500
1501                 if (nextin != 0)
1502                         close(nextin);
1503                 if (nextout != 1)
1504                         close(nextout);
1505
1506                 /* If there isn't another process, nextin is garbage
1507                    but it doesn't matter */
1508                 nextin = pipefds[0];
1509         }
1510         return -1;
1511 }
1512
1513 static int run_list_real(struct pipe *pi)
1514 {
1515         char *save_name = NULL;
1516         char **list = NULL;
1517         char **save_list = NULL;
1518         struct pipe *rpipe;
1519         int flag_rep = 0;
1520         int save_num_progs;
1521         int rcode=0, flag_skip=1;
1522         int flag_restore = 0;
1523         int if_code=0, next_if_code=0;  /* need double-buffer to handle elif */
1524         reserved_style rmode, skip_more_in_this_rmode=RES_XXXX;
1525         /* check syntax for "for" */
1526         for (rpipe = pi; rpipe; rpipe = rpipe->next) {
1527                 if ((rpipe->r_mode == RES_IN ||
1528                     rpipe->r_mode == RES_FOR) &&
1529                     (rpipe->next == NULL)) {
1530                                 syntax();
1531                                 return 1;
1532                 }
1533                 if ((rpipe->r_mode == RES_IN &&
1534                         (rpipe->next->r_mode == RES_IN &&
1535                         rpipe->next->progs->argv != NULL))||
1536                         (rpipe->r_mode == RES_FOR &&
1537                         rpipe->next->r_mode != RES_IN)) {
1538                                 syntax();
1539                                 return 1;
1540                 }
1541         }
1542         for (; pi; pi = (flag_restore != 0) ? rpipe : pi->next) {
1543                 if (pi->r_mode == RES_WHILE || pi->r_mode == RES_UNTIL ||
1544                         pi->r_mode == RES_FOR) {
1545                                 flag_restore = 0;
1546                                 if (!rpipe) {
1547                                         flag_rep = 0;
1548                                         rpipe = pi;
1549                                 }
1550                 }
1551                 rmode = pi->r_mode;
1552                 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);
1553                 if (rmode == skip_more_in_this_rmode && flag_skip) {
1554                         if (pi->followup == PIPE_SEQ) flag_skip=0;
1555                         continue;
1556                 }
1557                 flag_skip = 1;
1558                 skip_more_in_this_rmode = RES_XXXX;
1559                 if (rmode == RES_THEN || rmode == RES_ELSE) if_code = next_if_code;
1560                 if (rmode == RES_THEN &&  if_code) continue;
1561                 if (rmode == RES_ELSE && !if_code) continue;
1562                 if (rmode == RES_ELIF && !if_code) break;
1563                 if (rmode == RES_FOR && pi->num_progs) {
1564                         if (!list) {
1565                                 /* if no variable values after "in" we skip "for" */
1566                                 if (!pi->next->progs->argv) continue;
1567                                 /* create list of variable values */
1568                                 list = make_list_in(pi->next->progs->argv,
1569                                         pi->progs->argv[0]);
1570                                 save_list = list;
1571                                 save_name = pi->progs->argv[0];
1572                                 pi->progs->argv[0] = NULL;
1573                                 flag_rep = 1;
1574                         }
1575                         if (!(*list)) {
1576                                 free(pi->progs->argv[0]);
1577                                 free(save_list);
1578                                 list = NULL;
1579                                 flag_rep = 0;
1580                                 pi->progs->argv[0] = save_name;
1581                                 pi->progs->glob_result.gl_pathv[0] =
1582                                         pi->progs->argv[0];
1583                                 continue;
1584                         } else {
1585                                 /* insert new value from list for variable */
1586                                 if (pi->progs->argv[0])
1587                                         free(pi->progs->argv[0]);
1588                                 pi->progs->argv[0] = *list++;
1589                                 pi->progs->glob_result.gl_pathv[0] =
1590                                         pi->progs->argv[0];
1591                         }
1592                 }
1593                 if (rmode == RES_IN) continue;
1594                 if (rmode == RES_DO) {
1595                         if (!flag_rep) continue;
1596                 }
1597                 if ((rmode == RES_DONE)) {
1598                         if (flag_rep) {
1599                                 flag_restore = 1;
1600                         } else {
1601                                 rpipe = NULL;
1602                         }
1603                 }
1604                 if (pi->num_progs == 0) continue;
1605                 save_num_progs = pi->num_progs; /* save number of programs */
1606                 rcode = run_pipe_real(pi);
1607                 debug_printf("run_pipe_real returned %d\n",rcode);
1608                 if (rcode!=-1) {
1609                         /* We only ran a builtin: rcode was set by the return value
1610                          * of run_pipe_real(), and we don't need to wait for anything. */
1611                 } else if (pi->followup==PIPE_BG) {
1612                         /* XXX check bash's behavior with nontrivial pipes */
1613                         /* XXX compute jobid */
1614                         /* XXX what does bash do with attempts to background builtins? */
1615                         insert_bg_job(pi);
1616                         rcode = EXIT_SUCCESS;
1617                 } else {
1618                         if (interactive) {
1619                                 /* move the new process group into the foreground */
1620                                 if (tcsetpgrp(shell_terminal, pi->pgrp) && errno != ENOTTY)
1621                                         bb_perror_msg("tcsetpgrp-3");
1622                                 rcode = checkjobs(pi);
1623                                 /* move the shell to the foreground */
1624                                 if (tcsetpgrp(shell_terminal, getpgid(0)) && errno != ENOTTY)
1625                                         bb_perror_msg("tcsetpgrp-4");
1626                         } else {
1627                                 rcode = checkjobs(pi);
1628                         }
1629                         debug_printf("checkjobs returned %d\n",rcode);
1630                 }
1631                 last_return_code=rcode;
1632                 pi->num_progs = save_num_progs; /* restore number of programs */
1633                 if ( rmode == RES_IF || rmode == RES_ELIF )
1634                         next_if_code=rcode;  /* can be overwritten a number of times */
1635                 if (rmode == RES_WHILE)
1636                         flag_rep = !last_return_code;
1637                 if (rmode == RES_UNTIL)
1638                         flag_rep = last_return_code;
1639                 if ( (rcode==EXIT_SUCCESS && pi->followup==PIPE_OR) ||
1640                      (rcode!=EXIT_SUCCESS && pi->followup==PIPE_AND) )
1641                         skip_more_in_this_rmode=rmode;
1642                 checkjobs(NULL);
1643         }
1644         return rcode;
1645 }
1646
1647 /* broken, of course, but OK for testing */
1648 static char *indenter(int i)
1649 {
1650         static char blanks[]="                                    ";
1651         return &blanks[sizeof(blanks)-i-1];
1652 }
1653
1654 /* return code is the exit status of the pipe */
1655 static int free_pipe(struct pipe *pi, int indent)
1656 {
1657         char **p;
1658         struct child_prog *child;
1659         struct redir_struct *r, *rnext;
1660         int a, i, ret_code=0;
1661         char *ind = indenter(indent);
1662
1663         if (pi->stopped_progs > 0)
1664                 return ret_code;
1665         final_printf("%s run pipe: (pid %d)\n",ind,getpid());
1666         for (i=0; i<pi->num_progs; i++) {
1667                 child = &pi->progs[i];
1668                 final_printf("%s  command %d:\n",ind,i);
1669                 if (child->argv) {
1670                         for (a=0,p=child->argv; *p; a++,p++) {
1671                                 final_printf("%s   argv[%d] = %s\n",ind,a,*p);
1672                         }
1673                         globfree(&child->glob_result);
1674                         child->argv=NULL;
1675                 } else if (child->group) {
1676                         final_printf("%s   begin group (subshell:%d)\n",ind, child->subshell);
1677                         ret_code = free_pipe_list(child->group,indent+3);
1678                         final_printf("%s   end group\n",ind);
1679                 } else {
1680                         final_printf("%s   (nil)\n",ind);
1681                 }
1682                 for (r=child->redirects; r; r=rnext) {
1683                         final_printf("%s   redirect %d%s", ind, r->fd, redir_table[r->type].descrip);
1684                         if (r->dup == -1) {
1685                                 /* guard against the case >$FOO, where foo is unset or blank */
1686                                 if (r->word.gl_pathv) {
1687                                         final_printf(" %s\n", *r->word.gl_pathv);
1688                                         globfree(&r->word);
1689                                 }
1690                         } else {
1691                                 final_printf("&%d\n", r->dup);
1692                         }
1693                         rnext=r->next;
1694                         free(r);
1695                 }
1696                 child->redirects=NULL;
1697         }
1698         free(pi->progs);   /* children are an array, they get freed all at once */
1699         pi->progs=NULL;
1700         return ret_code;
1701 }
1702
1703 static int free_pipe_list(struct pipe *head, int indent)
1704 {
1705         int rcode=0;   /* if list has no members */
1706         struct pipe *pi, *next;
1707         char *ind = indenter(indent);
1708         for (pi=head; pi; pi=next) {
1709                 final_printf("%s pipe reserved mode %d\n", ind, pi->r_mode);
1710                 rcode = free_pipe(pi, indent);
1711                 final_printf("%s pipe followup code %d\n", ind, pi->followup);
1712                 next=pi->next;
1713                 pi->next=NULL;
1714                 free(pi);
1715         }
1716         return rcode;
1717 }
1718
1719 /* Select which version we will use */
1720 static int run_list(struct pipe *pi)
1721 {
1722         int rcode=0;
1723         if (fake_mode==0) {
1724                 rcode = run_list_real(pi);
1725         }
1726         /* free_pipe_list has the side effect of clearing memory
1727          * In the long run that function can be merged with run_list_real,
1728          * but doing that now would hobble the debugging effort. */
1729         free_pipe_list(pi,0);
1730         return rcode;
1731 }
1732
1733 /* The API for glob is arguably broken.  This routine pushes a non-matching
1734  * string into the output structure, removing non-backslashed backslashes.
1735  * If someone can prove me wrong, by performing this function within the
1736  * original glob(3) api, feel free to rewrite this routine into oblivion.
1737  * Return code (0 vs. GLOB_NOSPACE) matches glob(3).
1738  * XXX broken if the last character is '\\', check that before calling.
1739  */
1740 static int globhack(const char *src, int flags, glob_t *pglob)
1741 {
1742         int cnt=0, pathc;
1743         const char *s;
1744         char *dest;
1745         for (cnt=1, s=src; s && *s; s++) {
1746                 if (*s == '\\') s++;
1747                 cnt++;
1748         }
1749         dest = malloc(cnt);
1750         if (!dest) return GLOB_NOSPACE;
1751         if (!(flags & GLOB_APPEND)) {
1752                 pglob->gl_pathv=NULL;
1753                 pglob->gl_pathc=0;
1754                 pglob->gl_offs=0;
1755                 pglob->gl_offs=0;
1756         }
1757         pathc = ++pglob->gl_pathc;
1758         pglob->gl_pathv = realloc(pglob->gl_pathv, (pathc+1)*sizeof(*pglob->gl_pathv));
1759         if (pglob->gl_pathv == NULL) return GLOB_NOSPACE;
1760         pglob->gl_pathv[pathc-1]=dest;
1761         pglob->gl_pathv[pathc]=NULL;
1762         for (s=src; s && *s; s++, dest++) {
1763                 if (*s == '\\') s++;
1764                 *dest = *s;
1765         }
1766         *dest='\0';
1767         return 0;
1768 }
1769
1770 /* XXX broken if the last character is '\\', check that before calling */
1771 static int glob_needed(const char *s)
1772 {
1773         for (; *s; s++) {
1774                 if (*s == '\\') s++;
1775                 if (strchr("*[?",*s)) return 1;
1776         }
1777         return 0;
1778 }
1779
1780 #if 0
1781 static void globprint(glob_t *pglob)
1782 {
1783         int i;
1784         debug_printf("glob_t at %p:\n", pglob);
1785         debug_printf("  gl_pathc=%d  gl_pathv=%p  gl_offs=%d  gl_flags=%d\n",
1786                 pglob->gl_pathc, pglob->gl_pathv, pglob->gl_offs, pglob->gl_flags);
1787         for (i=0; i<pglob->gl_pathc; i++)
1788                 debug_printf("pglob->gl_pathv[%d] = %p = %s\n", i,
1789                         pglob->gl_pathv[i], pglob->gl_pathv[i]);
1790 }
1791 #endif
1792
1793 static int xglob(o_string *dest, int flags, glob_t *pglob)
1794 {
1795         int gr;
1796
1797         /* short-circuit for null word */
1798         /* we can code this better when the debug_printf's are gone */
1799         if (dest->length == 0) {
1800                 if (dest->nonnull) {
1801                         /* bash man page calls this an "explicit" null */
1802                         gr = globhack(dest->data, flags, pglob);
1803                         debug_printf("globhack returned %d\n",gr);
1804                 } else {
1805                         return 0;
1806                 }
1807         } else if (glob_needed(dest->data)) {
1808                 gr = glob(dest->data, flags, NULL, pglob);
1809                 debug_printf("glob returned %d\n",gr);
1810                 if (gr == GLOB_NOMATCH) {
1811                         /* quote removal, or more accurately, backslash removal */
1812                         gr = globhack(dest->data, flags, pglob);
1813                         debug_printf("globhack returned %d\n",gr);
1814                 }
1815         } else {
1816                 gr = globhack(dest->data, flags, pglob);
1817                 debug_printf("globhack returned %d\n",gr);
1818         }
1819         if (gr == GLOB_NOSPACE)
1820                 bb_error_msg_and_die("out of memory during glob");
1821         if (gr != 0) { /* GLOB_ABORTED ? */
1822                 bb_error_msg("glob(3) error %d",gr);
1823         }
1824         /* globprint(glob_target); */
1825         return gr;
1826 }
1827
1828 /* This is used to get/check local shell variables */
1829 static char *get_local_var(const char *s)
1830 {
1831         struct variables *cur;
1832
1833         if (!s)
1834                 return NULL;
1835         for (cur = top_vars; cur; cur=cur->next)
1836                 if(strcmp(cur->name, s)==0)
1837                         return cur->value;
1838         return NULL;
1839 }
1840
1841 /* This is used to set local shell variables
1842    flg_export==0 if only local (not exporting) variable
1843    flg_export==1 if "new" exporting environ
1844    flg_export>1  if current startup environ (not call putenv()) */
1845 static int set_local_var(const char *s, int flg_export)
1846 {
1847         char *name, *value;
1848         int result=0;
1849         struct variables *cur;
1850
1851         name=strdup(s);
1852
1853         /* Assume when we enter this function that we are already in
1854          * NAME=VALUE format.  So the first order of business is to
1855          * split 's' on the '=' into 'name' and 'value' */
1856         value = strchr(name, '=');
1857         if (value==0 && ++value==0) {
1858                 free(name);
1859                 return -1;
1860         }
1861         *value++ = 0;
1862
1863         for(cur = top_vars; cur; cur = cur->next) {
1864                 if(strcmp(cur->name, name)==0)
1865                         break;
1866         }
1867
1868         if(cur) {
1869                 if(strcmp(cur->value, value)==0) {
1870                         if(flg_export>0 && cur->flg_export==0)
1871                                 cur->flg_export=flg_export;
1872                         else
1873                                 result++;
1874                 } else {
1875                         if(cur->flg_read_only) {
1876                                 bb_error_msg("%s: readonly variable", name);
1877                                 result = -1;
1878                         } else {
1879                                 if(flg_export>0 || cur->flg_export>1)
1880                                         cur->flg_export=1;
1881                                 free(cur->value);
1882
1883                                 cur->value = strdup(value);
1884                         }
1885                 }
1886         } else {
1887                 cur = malloc(sizeof(struct variables));
1888                 if(!cur) {
1889                         result = -1;
1890                 } else {
1891                         cur->name = strdup(name);
1892                         if(cur->name == 0) {
1893                                 free(cur);
1894                                 result = -1;
1895                         } else {
1896                                 struct variables *bottom = top_vars;
1897                                 cur->value = strdup(value);
1898                                 cur->next = 0;
1899                                 cur->flg_export = flg_export;
1900                                 cur->flg_read_only = 0;
1901                                 while(bottom->next) bottom=bottom->next;
1902                                 bottom->next = cur;
1903                         }
1904                 }
1905         }
1906
1907         if(result==0 && cur->flg_export==1) {
1908                 *(value-1) = '=';
1909                 result = putenv(name);
1910         } else {
1911                 free(name);
1912                 if(result>0)            /* equivalent to previous set */
1913                         result = 0;
1914         }
1915         return result;
1916 }
1917
1918 static void unset_local_var(const char *name)
1919 {
1920         struct variables *cur;
1921
1922         if (name) {
1923                 for (cur = top_vars; cur; cur=cur->next) {
1924                         if(strcmp(cur->name, name)==0)
1925                                 break;
1926                 }
1927                 if(cur!=0) {
1928                         struct variables *next = top_vars;
1929                         if(cur->flg_read_only) {
1930                                 bb_error_msg("%s: readonly variable", name);
1931                                 return;
1932                         } else {
1933                                 if(cur->flg_export)
1934                                         unsetenv(cur->name);
1935                                 free(cur->name);
1936                                 free(cur->value);
1937                                 while (next->next != cur)
1938                                         next = next->next;
1939                                 next->next = cur->next;
1940                         }
1941                         free(cur);
1942                 }
1943         }
1944 }
1945
1946 static int is_assignment(const char *s)
1947 {
1948         if (s==NULL || !isalpha(*s)) return 0;
1949         ++s;
1950         while(isalnum(*s) || *s=='_') ++s;
1951         return *s=='=';
1952 }
1953
1954 /* the src parameter allows us to peek forward to a possible &n syntax
1955  * for file descriptor duplication, e.g., "2>&1".
1956  * Return code is 0 normally, 1 if a syntax error is detected in src.
1957  * Resource errors (in xmalloc) cause the process to exit */
1958 static int setup_redirect(struct p_context *ctx, int fd, redir_type style,
1959         struct in_str *input)
1960 {
1961         struct child_prog *child=ctx->child;
1962         struct redir_struct *redir = child->redirects;
1963         struct redir_struct *last_redir=NULL;
1964
1965         /* Create a new redir_struct and drop it onto the end of the linked list */
1966         while(redir) {
1967                 last_redir=redir;
1968                 redir=redir->next;
1969         }
1970         redir = xmalloc(sizeof(struct redir_struct));
1971         redir->next=NULL;
1972         redir->word.gl_pathv=NULL;
1973         if (last_redir) {
1974                 last_redir->next=redir;
1975         } else {
1976                 child->redirects=redir;
1977         }
1978
1979         redir->type=style;
1980         redir->fd= (fd==-1) ? redir_table[style].default_fd : fd ;
1981
1982         debug_printf("Redirect type %d%s\n", redir->fd, redir_table[style].descrip);
1983
1984         /* Check for a '2>&1' type redirect */
1985         redir->dup = redirect_dup_num(input);
1986         if (redir->dup == -2) return 1;  /* syntax error */
1987         if (redir->dup != -1) {
1988                 /* Erik had a check here that the file descriptor in question
1989                  * is legit; I postpone that to "run time"
1990                  * A "-" representation of "close me" shows up as a -3 here */
1991                 debug_printf("Duplicating redirect '%d>&%d'\n", redir->fd, redir->dup);
1992         } else {
1993                 /* We do _not_ try to open the file that src points to,
1994                  * since we need to return and let src be expanded first.
1995                  * Set ctx->pending_redirect, so we know what to do at the
1996                  * end of the next parsed word.
1997                  */
1998                 ctx->pending_redirect = redir;
1999         }
2000         return 0;
2001 }
2002
2003 static struct pipe *new_pipe(void) {
2004         struct pipe *pi;
2005         pi = xmalloc(sizeof(struct pipe));
2006         pi->num_progs = 0;
2007         pi->progs = NULL;
2008         pi->next = NULL;
2009         pi->followup = 0;  /* invalid */
2010         return pi;
2011 }
2012
2013 static void initialize_context(struct p_context *ctx)
2014 {
2015         ctx->pipe=NULL;
2016         ctx->pending_redirect=NULL;
2017         ctx->child=NULL;
2018         ctx->list_head=new_pipe();
2019         ctx->pipe=ctx->list_head;
2020         ctx->w=RES_NONE;
2021         ctx->stack=NULL;
2022         ctx->old_flag=0;
2023         done_command(ctx);   /* creates the memory for working child */
2024 }
2025
2026 /* normal return is 0
2027  * if a reserved word is found, and processed, return 1
2028  * should handle if, then, elif, else, fi, for, while, until, do, done.
2029  * case, function, and select are obnoxious, save those for later.
2030  */
2031 static int reserved_word(o_string *dest, struct p_context *ctx)
2032 {
2033         struct reserved_combo {
2034                 char *literal;
2035                 int code;
2036                 long flag;
2037         };
2038         /* Mostly a list of accepted follow-up reserved words.
2039          * FLAG_END means we are done with the sequence, and are ready
2040          * to turn the compound list into a command.
2041          * FLAG_START means the word must start a new compound list.
2042          */
2043         static struct reserved_combo reserved_list[] = {
2044                 { "if",    RES_IF,    FLAG_THEN | FLAG_START },
2045                 { "then",  RES_THEN,  FLAG_ELIF | FLAG_ELSE | FLAG_FI },
2046                 { "elif",  RES_ELIF,  FLAG_THEN },
2047                 { "else",  RES_ELSE,  FLAG_FI   },
2048                 { "fi",    RES_FI,    FLAG_END  },
2049                 { "for",   RES_FOR,   FLAG_IN   | FLAG_START },
2050                 { "while", RES_WHILE, FLAG_DO   | FLAG_START },
2051                 { "until", RES_UNTIL, FLAG_DO   | FLAG_START },
2052                 { "in",    RES_IN,    FLAG_DO   },
2053                 { "do",    RES_DO,    FLAG_DONE },
2054                 { "done",  RES_DONE,  FLAG_END  }
2055         };
2056         struct reserved_combo *r;
2057         for (r=reserved_list;
2058 #define NRES sizeof(reserved_list)/sizeof(struct reserved_combo)
2059                 r<reserved_list+NRES; r++) {
2060                 if (strcmp(dest->data, r->literal) == 0) {
2061                         debug_printf("found reserved word %s, code %d\n",r->literal,r->code);
2062                         if (r->flag & FLAG_START) {
2063                                 struct p_context *new = xmalloc(sizeof(struct p_context));
2064                                 debug_printf("push stack\n");
2065                                 if (ctx->w == RES_IN || ctx->w == RES_FOR) {
2066                                         syntax();
2067                                         free(new);
2068                                         ctx->w = RES_SNTX;
2069                                         b_reset(dest);
2070                                         return 1;
2071                                 }
2072                                 *new = *ctx;   /* physical copy */
2073                                 initialize_context(ctx);
2074                                 ctx->stack=new;
2075                         } else if ( ctx->w == RES_NONE || ! (ctx->old_flag & (1<<r->code))) {
2076                                 syntax();
2077                                 ctx->w = RES_SNTX;
2078                                 b_reset(dest);
2079                                 return 1;
2080                         }
2081                         ctx->w=r->code;
2082                         ctx->old_flag = r->flag;
2083                         if (ctx->old_flag & FLAG_END) {
2084                                 struct p_context *old;
2085                                 debug_printf("pop stack\n");
2086                                 done_pipe(ctx,PIPE_SEQ);
2087                                 old = ctx->stack;
2088                                 old->child->group = ctx->list_head;
2089                                 old->child->subshell = 0;
2090                                 *ctx = *old;   /* physical copy */
2091                                 free(old);
2092                         }
2093                         b_reset (dest);
2094                         return 1;
2095                 }
2096         }
2097         return 0;
2098 }
2099
2100 /* normal return is 0.
2101  * Syntax or xglob errors return 1. */
2102 static int done_word(o_string *dest, struct p_context *ctx)
2103 {
2104         struct child_prog *child=ctx->child;
2105         glob_t *glob_target;
2106         int gr, flags = 0;
2107
2108         debug_printf("done_word: %s %p\n", dest->data, child);
2109         if (dest->length == 0 && !dest->nonnull) {
2110                 debug_printf("  true null, ignored\n");
2111                 return 0;
2112         }
2113         if (ctx->pending_redirect) {
2114                 glob_target = &ctx->pending_redirect->word;
2115         } else {
2116                 if (child->group) {
2117                         syntax();
2118                         return 1;  /* syntax error, groups and arglists don't mix */
2119                 }
2120                 if (!child->argv && (ctx->type & FLAG_PARSE_SEMICOLON)) {
2121                         debug_printf("checking %s for reserved-ness\n",dest->data);
2122                         if (reserved_word(dest,ctx)) return ctx->w==RES_SNTX;
2123                 }
2124                 glob_target = &child->glob_result;
2125                 if (child->argv) flags |= GLOB_APPEND;
2126         }
2127         gr = xglob(dest, flags, glob_target);
2128         if (gr != 0) return 1;
2129
2130         b_reset(dest);
2131         if (ctx->pending_redirect) {
2132                 ctx->pending_redirect=NULL;
2133                 if (glob_target->gl_pathc != 1) {
2134                         bb_error_msg("ambiguous redirect");
2135                         return 1;
2136                 }
2137         } else {
2138                 child->argv = glob_target->gl_pathv;
2139         }
2140         if (ctx->w == RES_FOR) {
2141                 done_word(dest,ctx);
2142                 done_pipe(ctx,PIPE_SEQ);
2143         }
2144         return 0;
2145 }
2146
2147 /* The only possible error here is out of memory, in which case
2148  * xmalloc exits. */
2149 static int done_command(struct p_context *ctx)
2150 {
2151         /* The child is really already in the pipe structure, so
2152          * advance the pipe counter and make a new, null child.
2153          * Only real trickiness here is that the uncommitted
2154          * child structure, to which ctx->child points, is not
2155          * counted in pi->num_progs. */
2156         struct pipe *pi=ctx->pipe;
2157         struct child_prog *prog=ctx->child;
2158
2159         if (prog && prog->group == NULL
2160                  && prog->argv == NULL
2161                  && prog->redirects == NULL) {
2162                 debug_printf("done_command: skipping null command\n");
2163                 return 0;
2164         } else if (prog) {
2165                 pi->num_progs++;
2166                 debug_printf("done_command: num_progs incremented to %d\n",pi->num_progs);
2167         } else {
2168                 debug_printf("done_command: initializing\n");
2169         }
2170         pi->progs = xrealloc(pi->progs, sizeof(*pi->progs) * (pi->num_progs+1));
2171
2172         prog = pi->progs + pi->num_progs;
2173         prog->redirects = NULL;
2174         prog->argv = NULL;
2175         prog->is_stopped = 0;
2176         prog->group = NULL;
2177         prog->glob_result.gl_pathv = NULL;
2178         prog->family = pi;
2179         prog->sp = 0;
2180         ctx->child = prog;
2181         prog->type = ctx->type;
2182
2183         /* but ctx->pipe and ctx->list_head remain unchanged */
2184         return 0;
2185 }
2186
2187 static int done_pipe(struct p_context *ctx, pipe_style type)
2188 {
2189         struct pipe *new_p;
2190         done_command(ctx);  /* implicit closure of previous command */
2191         debug_printf("done_pipe, type %d\n", type);
2192         ctx->pipe->followup = type;
2193         ctx->pipe->r_mode = ctx->w;
2194         new_p=new_pipe();
2195         ctx->pipe->next = new_p;
2196         ctx->pipe = new_p;
2197         ctx->child = NULL;
2198         done_command(ctx);  /* set up new pipe to accept commands */
2199         return 0;
2200 }
2201
2202 /* peek ahead in the in_str to find out if we have a "&n" construct,
2203  * as in "2>&1", that represents duplicating a file descriptor.
2204  * returns either -2 (syntax error), -1 (no &), or the number found.
2205  */
2206 static int redirect_dup_num(struct in_str *input)
2207 {
2208         int ch, d=0, ok=0;
2209         ch = b_peek(input);
2210         if (ch != '&') return -1;
2211
2212         b_getch(input);  /* get the & */
2213         ch=b_peek(input);
2214         if (ch == '-') {
2215                 b_getch(input);
2216                 return -3;  /* "-" represents "close me" */
2217         }
2218         while (isdigit(ch)) {
2219                 d = d*10+(ch-'0');
2220                 ok=1;
2221                 b_getch(input);
2222                 ch = b_peek(input);
2223         }
2224         if (ok) return d;
2225
2226         bb_error_msg("ambiguous redirect");
2227         return -2;
2228 }
2229
2230 /* If a redirect is immediately preceded by a number, that number is
2231  * supposed to tell which file descriptor to redirect.  This routine
2232  * looks for such preceding numbers.  In an ideal world this routine
2233  * needs to handle all the following classes of redirects...
2234  *     echo 2>foo     # redirects fd  2 to file "foo", nothing passed to echo
2235  *     echo 49>foo    # redirects fd 49 to file "foo", nothing passed to echo
2236  *     echo -2>foo    # redirects fd  1 to file "foo",    "-2" passed to echo
2237  *     echo 49x>foo   # redirects fd  1 to file "foo",   "49x" passed to echo
2238  * A -1 output from this program means no valid number was found, so the
2239  * caller should use the appropriate default for this redirection.
2240  */
2241 static int redirect_opt_num(o_string *o)
2242 {
2243         int num;
2244
2245         if (o->length==0) return -1;
2246         for(num=0; num<o->length; num++) {
2247                 if (!isdigit(*(o->data+num))) {
2248                         return -1;
2249                 }
2250         }
2251         /* reuse num (and save an int) */
2252         num=atoi(o->data);
2253         b_reset(o);
2254         return num;
2255 }
2256
2257 static FILE *generate_stream_from_list(struct pipe *head)
2258 {
2259         FILE *pf;
2260 #if 1
2261         int pid, channel[2];
2262         if (pipe(channel)<0) bb_perror_msg_and_die("pipe");
2263 #if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
2264         pid=fork();
2265 #else
2266         pid=vfork();
2267 #endif
2268         if (pid<0) {
2269                 bb_perror_msg_and_die("fork");
2270         } else if (pid==0) {
2271                 close(channel[0]);
2272                 if (channel[1] != 1) {
2273                         dup2(channel[1],1);
2274                         close(channel[1]);
2275                 }
2276 #if 0
2277 #define SURROGATE "surrogate response"
2278                 write(1,SURROGATE,sizeof(SURROGATE));
2279                 _exit(run_list(head));
2280 #else
2281                 _exit(run_list_real(head));   /* leaks memory */
2282 #endif
2283         }
2284         debug_printf("forked child %d\n",pid);
2285         close(channel[1]);
2286         pf = fdopen(channel[0],"r");
2287         debug_printf("pipe on FILE *%p\n",pf);
2288 #else
2289         free_pipe_list(head,0);
2290         pf=popen("echo surrogate response","r");
2291         debug_printf("started fake pipe on FILE *%p\n",pf);
2292 #endif
2293         return pf;
2294 }
2295
2296 /* this version hacked for testing purposes */
2297 /* return code is exit status of the process that is run. */
2298 static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end)
2299 {
2300         int retcode;
2301         o_string result=NULL_O_STRING;
2302         struct p_context inner;
2303         FILE *p;
2304         struct in_str pipe_str;
2305         initialize_context(&inner);
2306
2307         /* recursion to generate command */
2308         retcode = parse_stream(&result, &inner, input, subst_end);
2309         if (retcode != 0) return retcode;  /* syntax error or EOF */
2310         done_word(&result, &inner);
2311         done_pipe(&inner, PIPE_SEQ);
2312         b_free(&result);
2313
2314         p=generate_stream_from_list(inner.list_head);
2315         if (p==NULL) return 1;
2316         mark_open(fileno(p));
2317         setup_file_in_str(&pipe_str, p);
2318
2319         /* now send results of command back into original context */
2320         retcode = parse_stream(dest, ctx, &pipe_str, '\0');
2321         /* XXX In case of a syntax error, should we try to kill the child?
2322          * That would be tough to do right, so just read until EOF. */
2323         if (retcode == 1) {
2324                 while (b_getch(&pipe_str)!=EOF) { /* discard */ };
2325         }
2326
2327         debug_printf("done reading from pipe, pclose()ing\n");
2328         /* This is the step that wait()s for the child.  Should be pretty
2329          * safe, since we just read an EOF from its stdout.  We could try
2330          * to better, by using wait(), and keeping track of background jobs
2331          * at the same time.  That would be a lot of work, and contrary
2332          * to the KISS philosophy of this program. */
2333         mark_closed(fileno(p));
2334         retcode=pclose(p);
2335         free_pipe_list(inner.list_head,0);
2336         debug_printf("pclosed, retcode=%d\n",retcode);
2337         /* XXX this process fails to trim a single trailing newline */
2338         return retcode;
2339 }
2340
2341 static int parse_group(o_string *dest, struct p_context *ctx,
2342         struct in_str *input, int ch)
2343 {
2344         int rcode, endch=0;
2345         struct p_context sub;
2346         struct child_prog *child = ctx->child;
2347         if (child->argv) {
2348                 syntax();
2349                 return 1;  /* syntax error, groups and arglists don't mix */
2350         }
2351         initialize_context(&sub);
2352         switch(ch) {
2353                 case '(': endch=')'; child->subshell=1; break;
2354                 case '{': endch='}'; break;
2355                 default: syntax();   /* really logic error */
2356         }
2357         rcode=parse_stream(dest,&sub,input,endch);
2358         done_word(dest,&sub); /* finish off the final word in the subcontext */
2359         done_pipe(&sub, PIPE_SEQ);  /* and the final command there, too */
2360         child->group = sub.list_head;
2361         return rcode;
2362         /* child remains "open", available for possible redirects */
2363 }
2364
2365 /* basically useful version until someone wants to get fancier,
2366  * see the bash man page under "Parameter Expansion" */
2367 static char *lookup_param(char *src)
2368 {
2369         char *p=NULL;
2370         if (src) {
2371                 p = getenv(src);
2372                 if (!p)
2373                         p = get_local_var(src);
2374         }
2375         return p;
2376 }
2377
2378 /* return code: 0 for OK, 1 for syntax error */
2379 static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input)
2380 {
2381         int i, advance=0;
2382         char sep[]=" ";
2383         int ch = input->peek(input);  /* first character after the $ */
2384         debug_printf("handle_dollar: ch=%c\n",ch);
2385         if (isalpha(ch)) {
2386                 b_addchr(dest, SPECIAL_VAR_SYMBOL);
2387                 ctx->child->sp++;
2388                 while(ch=b_peek(input),isalnum(ch) || ch=='_') {
2389                         b_getch(input);
2390                         b_addchr(dest,ch);
2391                 }
2392                 b_addchr(dest, SPECIAL_VAR_SYMBOL);
2393         } else if (isdigit(ch)) {
2394                 i = ch-'0';  /* XXX is $0 special? */
2395                 if (i<global_argc) {
2396                         parse_string(dest, ctx, global_argv[i]); /* recursion */
2397                 }
2398                 advance = 1;
2399         } else switch (ch) {
2400                 case '$':
2401                         b_adduint(dest,getpid());
2402                         advance = 1;
2403                         break;
2404                 case '!':
2405                         if (last_bg_pid > 0) b_adduint(dest, last_bg_pid);
2406                         advance = 1;
2407                         break;
2408                 case '?':
2409                         b_adduint(dest,last_return_code);
2410                         advance = 1;
2411                         break;
2412                 case '#':
2413                         b_adduint(dest,global_argc ? global_argc-1 : 0);
2414                         advance = 1;
2415                         break;
2416                 case '{':
2417                         b_addchr(dest, SPECIAL_VAR_SYMBOL);
2418                         ctx->child->sp++;
2419                         b_getch(input);
2420                         /* XXX maybe someone will try to escape the '}' */
2421                         while(ch=b_getch(input),ch!=EOF && ch!='}') {
2422                                 b_addchr(dest,ch);
2423                         }
2424                         if (ch != '}') {
2425                                 syntax();
2426                                 return 1;
2427                         }
2428                         b_addchr(dest, SPECIAL_VAR_SYMBOL);
2429                         break;
2430                 case '(':
2431                         b_getch(input);
2432                         process_command_subs(dest, ctx, input, ')');
2433                         break;
2434                 case '*':
2435                         sep[0]=ifs[0];
2436                         for (i=1; i<global_argc; i++) {
2437                                 parse_string(dest, ctx, global_argv[i]);
2438                                 if (i+1 < global_argc) parse_string(dest, ctx, sep);
2439                         }
2440                         break;
2441                 case '@':
2442                 case '-':
2443                 case '_':
2444                         /* still unhandled, but should be eventually */
2445                         bb_error_msg("unhandled syntax: $%c",ch);
2446                         return 1;
2447                         break;
2448                 default:
2449                         b_addqchr(dest,'$',dest->quote);
2450         }
2451         /* Eat the character if the flag was set.  If the compiler
2452          * is smart enough, we could substitute "b_getch(input);"
2453          * for all the "advance = 1;" above, and also end up with
2454          * a nice size-optimized program.  Hah!  That'll be the day.
2455          */
2456         if (advance) b_getch(input);
2457         return 0;
2458 }
2459
2460 int parse_string(o_string *dest, struct p_context *ctx, const char *src)
2461 {
2462         struct in_str foo;
2463         setup_string_in_str(&foo, src);
2464         return parse_stream(dest, ctx, &foo, '\0');
2465 }
2466
2467 /* return code is 0 for normal exit, 1 for syntax error */
2468 int parse_stream(o_string *dest, struct p_context *ctx,
2469         struct in_str *input, int end_trigger)
2470 {
2471         unsigned int ch, m;
2472         int redir_fd;
2473         redir_type redir_style;
2474         int next;
2475
2476         /* Only double-quote state is handled in the state variable dest->quote.
2477          * A single-quote triggers a bypass of the main loop until its mate is
2478          * found.  When recursing, quote state is passed in via dest->quote. */
2479
2480         debug_printf("parse_stream, end_trigger=%d\n",end_trigger);
2481         while ((ch=b_getch(input))!=EOF) {
2482                 m = map[ch];
2483                 next = (ch == '\n') ? 0 : b_peek(input);
2484                 debug_printf("parse_stream: ch=%c (%d) m=%d quote=%d\n",
2485                         ch,ch,m,dest->quote);
2486                 if (m==0 || ((m==1 || m==2) && dest->quote)) {
2487                         b_addqchr(dest, ch, dest->quote);
2488                 } else {
2489                         if (m==2) {  /* unquoted IFS */
2490                                 if (done_word(dest, ctx)) {
2491                                         return 1;
2492                                 }
2493                                 /* If we aren't performing a substitution, treat a newline as a
2494                                  * command separator.  */
2495                                 if (end_trigger != '\0' && ch=='\n')
2496                                         done_pipe(ctx,PIPE_SEQ);
2497                         }
2498                         if (ch == end_trigger && !dest->quote && ctx->w==RES_NONE) {
2499                                 debug_printf("leaving parse_stream (triggered)\n");
2500                                 return 0;
2501                         }
2502 #if 0
2503                         if (ch=='\n') {
2504                                 /* Yahoo!  Time to run with it! */
2505                                 done_pipe(ctx,PIPE_SEQ);
2506                                 run_list(ctx->list_head);
2507                                 initialize_context(ctx);
2508                         }
2509 #endif
2510                         if (m!=2) switch (ch) {
2511                 case '#':
2512                         if (dest->length == 0 && !dest->quote) {
2513                                 while(ch=b_peek(input),ch!=EOF && ch!='\n') { b_getch(input); }
2514                         } else {
2515                                 b_addqchr(dest, ch, dest->quote);
2516                         }
2517                         break;
2518                 case '\\':
2519                         if (next == EOF) {
2520                                 syntax();
2521                                 return 1;
2522                         }
2523                         b_addqchr(dest, '\\', dest->quote);
2524                         b_addqchr(dest, b_getch(input), dest->quote);
2525                         break;
2526                 case '$':
2527                         if (handle_dollar(dest, ctx, input)!=0) return 1;
2528                         break;
2529                 case '\'':
2530                         dest->nonnull = 1;
2531                         while(ch=b_getch(input),ch!=EOF && ch!='\'') {
2532                                 b_addchr(dest,ch);
2533                         }
2534                         if (ch==EOF) {
2535                                 syntax();
2536                                 return 1;
2537                         }
2538                         break;
2539                 case '"':
2540                         dest->nonnull = 1;
2541                         dest->quote = !dest->quote;
2542                         break;
2543                 case '`':
2544                         process_command_subs(dest, ctx, input, '`');
2545                         break;
2546                 case '>':
2547                         redir_fd = redirect_opt_num(dest);
2548                         done_word(dest, ctx);
2549                         redir_style=REDIRECT_OVERWRITE;
2550                         if (next == '>') {
2551                                 redir_style=REDIRECT_APPEND;
2552                                 b_getch(input);
2553                         } else if (next == '(') {
2554                                 syntax();   /* until we support >(list) Process Substitution */
2555                                 return 1;
2556                         }
2557                         setup_redirect(ctx, redir_fd, redir_style, input);
2558                         break;
2559                 case '<':
2560                         redir_fd = redirect_opt_num(dest);
2561                         done_word(dest, ctx);
2562                         redir_style=REDIRECT_INPUT;
2563                         if (next == '<') {
2564                                 redir_style=REDIRECT_HEREIS;
2565                                 b_getch(input);
2566                         } else if (next == '>') {
2567                                 redir_style=REDIRECT_IO;
2568                                 b_getch(input);
2569                         } else if (next == '(') {
2570                                 syntax();   /* until we support <(list) Process Substitution */
2571                                 return 1;
2572                         }
2573                         setup_redirect(ctx, redir_fd, redir_style, input);
2574                         break;
2575                 case ';':
2576                         done_word(dest, ctx);
2577                         done_pipe(ctx,PIPE_SEQ);
2578                         break;
2579                 case '&':
2580                         done_word(dest, ctx);
2581                         if (next=='&') {
2582                                 b_getch(input);
2583                                 done_pipe(ctx,PIPE_AND);
2584                         } else {
2585                                 done_pipe(ctx,PIPE_BG);
2586                         }
2587                         break;
2588                 case '|':
2589                         done_word(dest, ctx);
2590                         if (next=='|') {
2591                                 b_getch(input);
2592                                 done_pipe(ctx,PIPE_OR);
2593                         } else {
2594                                 /* we could pick up a file descriptor choice here
2595                                  * with redirect_opt_num(), but bash doesn't do it.
2596                                  * "echo foo 2| cat" yields "foo 2". */
2597                                 done_command(ctx);
2598                         }
2599                         break;
2600                 case '(':
2601                 case '{':
2602                         if (parse_group(dest, ctx, input, ch)!=0) return 1;
2603                         break;
2604                 case ')':
2605                 case '}':
2606                         syntax();   /* Proper use of this character caught by end_trigger */
2607                         return 1;
2608                         break;
2609                 default:
2610                         syntax();   /* this is really an internal logic error */
2611                         return 1;
2612                         }
2613                 }
2614         }
2615         /* complain if quote?  No, maybe we just finished a command substitution
2616          * that was quoted.  Example:
2617          * $ echo "`cat foo` plus more"
2618          * and we just got the EOF generated by the subshell that ran "cat foo"
2619          * The only real complaint is if we got an EOF when end_trigger != '\0',
2620          * that is, we were really supposed to get end_trigger, and never got
2621          * one before the EOF.  Can't use the standard "syntax error" return code,
2622          * so that parse_stream_outer can distinguish the EOF and exit smoothly. */
2623         debug_printf("leaving parse_stream (EOF)\n");
2624         if (end_trigger != '\0') return -1;
2625         return 0;
2626 }
2627
2628 static void mapset(const unsigned char *set, int code)
2629 {
2630         const unsigned char *s;
2631         for (s=set; *s; s++) map[*s] = code;
2632 }
2633
2634 static void update_ifs_map(void)
2635 {
2636         /* char *ifs and char map[256] are both globals. */
2637         ifs = getenv("IFS");
2638         if (ifs == NULL) ifs=" \t\n";
2639         /* Precompute a list of 'flow through' behavior so it can be treated
2640          * quickly up front.  Computation is necessary because of IFS.
2641          * Special case handling of IFS == " \t\n" is not implemented.
2642          * The map[] array only really needs two bits each, and on most machines
2643          * that would be faster because of the reduced L1 cache footprint.
2644          */
2645         memset(map,0,sizeof(map)); /* most characters flow through always */
2646         mapset("\\$'\"`", 3);      /* never flow through */
2647         mapset("<>;&|(){}#", 1);   /* flow through if quoted */
2648         mapset(ifs, 2);            /* also flow through if quoted */
2649 }
2650
2651 /* most recursion does not come through here, the exception is
2652  * from builtin_source() */
2653 int parse_stream_outer(struct in_str *inp, int flag)
2654 {
2655
2656         struct p_context ctx;
2657         o_string temp=NULL_O_STRING;
2658         int rcode;
2659         do {
2660                 ctx.type = flag;
2661                 initialize_context(&ctx);
2662                 update_ifs_map();
2663                 if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) mapset(";$&|", 0);
2664                 inp->promptmode=1;
2665                 rcode = parse_stream(&temp, &ctx, inp, '\n');
2666                 if (rcode != 1 && ctx.old_flag != 0) {
2667                         syntax();
2668                 }
2669                 if (rcode != 1 && ctx.old_flag == 0) {
2670                         done_word(&temp, &ctx);
2671                         done_pipe(&ctx,PIPE_SEQ);
2672                         run_list(ctx.list_head);
2673                 } else {
2674                         if (ctx.old_flag != 0) {
2675                                 free(ctx.stack);
2676                                 b_reset(&temp);
2677                         }
2678                         temp.nonnull = 0;
2679                         temp.quote = 0;
2680                         inp->p = NULL;
2681                         free_pipe_list(ctx.list_head,0);
2682                 }
2683                 b_free(&temp);
2684         } while (rcode != -1 && !(flag & FLAG_EXIT_FROM_LOOP));   /* loop on syntax errors, return on EOF */
2685         return 0;
2686 }
2687
2688 static int parse_string_outer(const char *s, int flag)
2689 {
2690         struct in_str input;
2691         setup_string_in_str(&input, s);
2692         return parse_stream_outer(&input, flag);
2693 }
2694
2695 static int parse_file_outer(FILE *f)
2696 {
2697         int rcode;
2698         struct in_str input;
2699         setup_file_in_str(&input, f);
2700         rcode = parse_stream_outer(&input, FLAG_PARSE_SEMICOLON);
2701         return rcode;
2702 }
2703
2704 /* Make sure we have a controlling tty.  If we get started under a job
2705  * aware app (like bash for example), make sure we are now in charge so
2706  * we don't fight over who gets the foreground */
2707 static void setup_job_control(void)
2708 {
2709         static pid_t shell_pgrp;
2710         /* Loop until we are in the foreground.  */
2711         while (tcgetpgrp (shell_terminal) != (shell_pgrp = getpgrp ()))
2712                 kill (- shell_pgrp, SIGTTIN);
2713
2714         /* Ignore interactive and job-control signals.  */
2715         signal(SIGINT, SIG_IGN);
2716         signal(SIGQUIT, SIG_IGN);
2717         signal(SIGTERM, SIG_IGN);
2718         signal(SIGTSTP, SIG_IGN);
2719         signal(SIGTTIN, SIG_IGN);
2720         signal(SIGTTOU, SIG_IGN);
2721         signal(SIGCHLD, SIG_IGN);
2722
2723         /* Put ourselves in our own process group.  */
2724         setsid();
2725         shell_pgrp = getpid ();
2726         setpgid (shell_pgrp, shell_pgrp);
2727
2728         /* Grab control of the terminal.  */
2729         tcsetpgrp(shell_terminal, shell_pgrp);
2730 }
2731
2732 int hush_main(int argc, char **argv)
2733 {
2734         int opt;
2735         FILE *input;
2736         char **e = environ;
2737
2738         /* XXX what should these be while sourcing /etc/profile? */
2739         global_argc = argc;
2740         global_argv = argv;
2741
2742         /* (re?) initialize globals.  Sometimes hush_main() ends up calling
2743          * hush_main(), therefore we cannot rely on the BSS to zero out this
2744          * stuff.  Reset these to 0 every time. */
2745         ifs = NULL;
2746         /* map[] is taken care of with call to update_ifs_map() */
2747         fake_mode = 0;
2748         interactive = 0;
2749         close_me_head = NULL;
2750         last_bg_pid = 0;
2751         job_list = NULL;
2752         last_jobid = 0;
2753
2754         /* Initialize some more globals to non-zero values */
2755         set_cwd();
2756 #ifdef CONFIG_FEATURE_COMMAND_EDITING
2757         cmdedit_set_initial_prompt();
2758 #else
2759         PS1 = NULL;
2760 #endif
2761         PS2 = "> ";
2762
2763         /* initialize our shell local variables with the values
2764          * currently living in the environment */
2765         if (e) {
2766                 for (; *e; e++)
2767                         set_local_var(*e, 2);   /* without call putenv() */
2768         }
2769
2770         last_return_code=EXIT_SUCCESS;
2771
2772
2773         if (argv[0] && argv[0][0] == '-') {
2774                 debug_printf("\nsourcing /etc/profile\n");
2775                 if ((input = fopen("/etc/profile", "r")) != NULL) {
2776                         mark_open(fileno(input));
2777                         parse_file_outer(input);
2778                         mark_closed(fileno(input));
2779                         fclose(input);
2780                 }
2781         }
2782         input=stdin;
2783
2784         while ((opt = getopt(argc, argv, "c:xif")) > 0) {
2785                 switch (opt) {
2786                         case 'c':
2787                                 {
2788                                         global_argv = argv+optind;
2789                                         global_argc = argc-optind;
2790                                         opt = parse_string_outer(optarg, FLAG_PARSE_SEMICOLON);
2791                                         goto final_return;
2792                                 }
2793                                 break;
2794                         case 'i':
2795                                 interactive++;
2796                                 break;
2797                         case 'f':
2798                                 fake_mode++;
2799                                 break;
2800                         default:
2801 #ifndef BB_VER
2802                                 fprintf(stderr, "Usage: sh [FILE]...\n"
2803                                                 "   or: sh -c command [args]...\n\n");
2804                                 exit(EXIT_FAILURE);
2805 #else
2806                                 bb_show_usage();
2807 #endif
2808                 }
2809         }
2810         /* A shell is interactive if the `-i' flag was given, or if all of
2811          * the following conditions are met:
2812          *        no -c command
2813          *    no arguments remaining or the -s flag given
2814          *    standard input is a terminal
2815          *    standard output is a terminal
2816          *    Refer to Posix.2, the description of the `sh' utility. */
2817         if (argv[optind]==NULL && input==stdin &&
2818                         isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
2819                 interactive++;
2820         }
2821
2822         debug_printf("\ninteractive=%d\n", interactive);
2823         if (interactive) {
2824                 /* Looks like they want an interactive shell */
2825 #ifndef CONFIG_FEATURE_SH_EXTRA_QUIET
2826                 printf( "\n\n" BB_BANNER " hush - the humble shell v0.01 (testing)\n");
2827                 printf( "Enter 'help' for a list of built-in commands.\n\n");
2828 #endif
2829                 setup_job_control();
2830         }
2831
2832         if (argv[optind]==NULL) {
2833                 opt=parse_file_outer(stdin);
2834                 goto final_return;
2835         }
2836
2837         debug_printf("\nrunning script '%s'\n", argv[optind]);
2838         global_argv = argv+optind;
2839         global_argc = argc-optind;
2840         input = bb_xfopen(argv[optind], "r");
2841         opt = parse_file_outer(input);
2842
2843 #ifdef CONFIG_FEATURE_CLEAN_UP
2844         fclose(input);
2845         if (cwd && cwd != bb_msg_unknown)
2846                 free((char*)cwd);
2847         {
2848                 struct variables *cur, *tmp;
2849                 for(cur = top_vars; cur; cur = tmp) {
2850                         tmp = cur->next;
2851                         if (!cur->flg_read_only) {
2852                                 free(cur->name);
2853                                 free(cur->value);
2854                                 free(cur);
2855                         }
2856                 }
2857         }
2858 #endif
2859
2860 final_return:
2861         return(opt?opt:last_return_code);
2862 }
2863
2864 static char *insert_var_value(char *inp)
2865 {
2866         int res_str_len = 0;
2867         int len;
2868         int done = 0;
2869         char *p, *p1, *res_str = NULL;
2870
2871         while ((p = strchr(inp, SPECIAL_VAR_SYMBOL))) {
2872                 if (p != inp) {
2873                         len = p - inp;
2874                         res_str = xrealloc(res_str, (res_str_len + len));
2875                         strncpy((res_str + res_str_len), inp, len);
2876                         res_str_len += len;
2877                 }
2878                 inp = ++p;
2879                 p = strchr(inp, SPECIAL_VAR_SYMBOL);
2880                 *p = '\0';
2881                 if ((p1 = lookup_param(inp))) {
2882                         len = res_str_len + strlen(p1);
2883                         res_str = xrealloc(res_str, (1 + len));
2884                         strcpy((res_str + res_str_len), p1);
2885                         res_str_len = len;
2886                 }
2887                 *p = SPECIAL_VAR_SYMBOL;
2888                 inp = ++p;
2889                 done = 1;
2890         }
2891         if (done) {
2892                 res_str = xrealloc(res_str, (1 + res_str_len + strlen(inp)));
2893                 strcpy((res_str + res_str_len), inp);
2894                 while ((p = strchr(res_str, '\n'))) {
2895                         *p = ' ';
2896                 }
2897         }
2898         return (res_str == NULL) ? inp : res_str;
2899 }
2900
2901 static char **make_list_in(char **inp, char *name)
2902 {
2903         int len, i;
2904         int name_len = strlen(name);
2905         int n = 0;
2906         char **list;
2907         char *p1, *p2, *p3;
2908
2909         /* create list of variable values */
2910         list = xmalloc(sizeof(*list));
2911         for (i = 0; inp[i]; i++) {
2912                 p3 = insert_var_value(inp[i]);
2913                 p1 = p3;
2914                 while (*p1) {
2915                         if ((*p1 == ' ')) {
2916                                 p1++;
2917                                 continue;
2918                         }
2919                         if ((p2 = strchr(p1, ' '))) {
2920                                 len = p2 - p1;
2921                         } else {
2922                                 len = strlen(p1);
2923                                 p2 = p1 + len;
2924                         }
2925                         /* we use n + 2 in realloc for list,because we add
2926                          * new element and then we will add NULL element */
2927                         list = xrealloc(list, sizeof(*list) * (n + 2));
2928                         list[n] = xmalloc(2 + name_len + len);
2929                         strcpy(list[n], name);
2930                         strcat(list[n], "=");
2931                         strncat(list[n], p1, len);
2932                         list[n++][name_len + len + 1] = '\0';
2933                         p1 = p2;
2934                 }
2935                 if (p3 != inp[i]) free(p3);
2936         }
2937         list[n] = NULL;
2938         return list;
2939 }
2940
2941 /* Make new string for parser */
2942 static char * make_string(char ** inp)
2943 {
2944         char *p;
2945         char *str = NULL;
2946         int n;
2947         int len = 2;
2948
2949         for (n = 0; inp[n]; n++) {
2950                 p = insert_var_value(inp[n]);
2951                 str = xrealloc(str, (len + strlen(p)));
2952                 if (n) {
2953                         strcat(str, " ");
2954                 } else {
2955                         *str = '\0';
2956                 }
2957                 strcat(str, p);
2958                 len = strlen(str) + 3;
2959                 if (p != inp[n]) free(p);
2960         }
2961         len = strlen(str);
2962         *(str + len) = '\n';
2963         *(str + len + 1) = '\0';
2964         return str;
2965 }