shell/hush.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * sh.c -- a prototype Bourne shell grammar parser
   4  *      Intended to follow the original Thompson and Ritchie
   5  *      "small and simple is beautiful" philosophy, which
   6  *      incidentally is a good match to today's BusyBox.
   7  *
   8  * Copyright (C) 2000,2001  Larry Doolittle  <larry@doolittle.boa.org>
   9  *
  10  * Credits:
  11  *      The parser routines proper are all original material, first
  12  *      written Dec 2000 and Jan 2001 by Larry Doolittle.  The
  13  *      execution engine, the builtins, and much of the underlying
  14  *      support has been adapted from busybox-0.49pre's lash, which is
  15  *      Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
  16  *      written by Erik Andersen <andersen@codepoet.org>.  That, in turn,
  17  *      is based in part on ladsh.c, by Michael K. Johnson and Erik W.
  18  *      Troan, which they placed in the public domain.  I don't know
  19  *      how much of the Johnson/Troan code has survived the repeated
  20  *      rewrites.
  21  *
  22  * Other credits:
  23  *      simple_itoa() was lifted from boa-0.93.15
  24  *      b_addchr() derived from similar w_addchar function in glibc-2.2
  25  *      setup_redirect(), redirect_opt_num(), and big chunks of main()
  26  *        and many builtins derived from contributions by Erik Andersen
  27  *      miscellaneous bugfixes from Matt Kraai
  28  *
  29  * There are two big (and related) architecture differences between
  30  * this parser and the lash parser.  One is that this version is
  31  * actually designed from the ground up to understand nearly all
  32  * of the Bourne grammar.  The second, consequential change is that
  33  * the parser and input reader have been turned inside out.  Now,
  34  * the parser is in control, and asks for input as needed.  The old
  35  * way had the input reader in control, and it asked for parsing to
  36  * take place as needed.  The new way makes it much easier to properly
  37  * handle the recursion implicit in the various substitutions, especially
  38  * across continuation lines.
  39  *
  40  * Bash grammar not implemented: (how many of these were in original sh?)
  41  *      $@ (those sure look like weird quoting rules)
  42  *      $_
  43  *      ! negation operator for pipes
  44  *      &> and >& redirection of stdout+stderr
  45  *      Brace Expansion
  46  *      Tilde Expansion
  47  *      fancy forms of Parameter Expansion
  48  *      aliases
  49  *      Arithmetic Expansion
  50  *      <(list) and >(list) Process Substitution
  51  *      reserved words: case, esac, select, function
  52  *      Here Documents ( << word )
  53  *      Functions
  54  * Major bugs:
  55  *      job handling woefully incomplete and buggy
  56  *      reserved word execution woefully incomplete and buggy
  57  * to-do:
  58  *      port selected bugfixes from post-0.49 busybox lash - done?
  59  *      finish implementing reserved words: for, while, until, do, done
  60  *      change { and } from special chars to reserved words
  61  *      builtins: break, continue, eval, return, set, trap, ulimit
  62  *      test magic exec
  63  *      handle children going into background
  64  *      clean up recognition of null pipes
  65  *      check setting of global_argc and global_argv
  66  *      control-C handling, probably with longjmp
  67  *      follow IFS rules more precisely, including update semantics
  68  *      figure out what to do with backslash-newline
  69  *      explain why we use signal instead of sigaction
  70  *      propagate syntax errors, die on resource errors?
  71  *      continuation lines, both explicit and implicit - done?
  72  *      memory leak finding and plugging - done?
  73  *      more testing, especially quoting rules and redirection
  74  *      document how quoting rules not precisely followed for variable assignments
  75  *      maybe change map[] to use 2-bit entries
  76  *      (eventually) remove all the printf's
  77  *
  78  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  79  */
  80
  81 #include "busybox.h"
  82 #include <ctype.h>     /* isalpha, isdigit */
  83 #include <unistd.h>    /* getpid */
  84 #include <stdlib.h>    /* getenv, atoi */
  85 #include <string.h>    /* strchr */
  86 #include <stdio.h>     /* popen etc. */
  87 #include <glob.h>      /* glob, of course */
  88 #include <stdarg.h>    /* va_list */
  89 #include <errno.h>
  90 #include <fcntl.h>
  91 #include <getopt.h>    /* should be pretty obvious */
  92
  93 #include <sys/stat.h>  /* ulimit */
  94 #include <sys/types.h>
  95 #include <sys/wait.h>
  96 #include <signal.h>
  97
  98 /* #include <dmalloc.h> */
  99 /* #define DEBUG_SHELL */
 100
 101 #if 1
 102 #include "cmdedit.h"
 103 #else
 104 #define bb_applet_name "hush"
 105 //#include "standalone.h"
 106 #define hush_main main
 107 #undef CONFIG_FEATURE_SH_FANCY_PROMPT
 108 #define BB_BANNER ""
 109 #endif
 110 #define SPECIAL_VAR_SYMBOL 03
 111 #define FLAG_EXIT_FROM_LOOP 1
 112 #define FLAG_PARSE_SEMICOLON (1 << 1)           /* symbol ';' is special for parser */
 113 #define FLAG_REPARSING           (1 << 2)               /* >=2nd pass */
 114
 115 typedef enum {
 116         REDIRECT_INPUT     = 1,
 117         REDIRECT_OVERWRITE = 2,
 118         REDIRECT_APPEND    = 3,
 119         REDIRECT_HEREIS    = 4,
 120         REDIRECT_IO        = 5
 121 } redir_type;
 122
 123 /* The descrip member of this structure is only used to make debugging
 124  * output pretty */
 125 static const struct {int mode; int default_fd; const char *descrip;} redir_table[] = {
 126         { 0,                         0, "()" },
 127         { O_RDONLY,                  0, "<"  },
 128         { O_CREAT|O_TRUNC|O_WRONLY,  1, ">"  },
 129         { O_CREAT|O_APPEND|O_WRONLY, 1, ">>" },
 130         { O_RDONLY,                 -1, "<<" },
 131         { O_RDWR,                    1, "<>" }
 132 };
 133
 134 typedef enum {
 135         PIPE_SEQ = 1,
 136         PIPE_AND = 2,
 137         PIPE_OR  = 3,
 138         PIPE_BG  = 4,
 139 } pipe_style;
 140
 141 /* might eventually control execution */
 142 typedef enum {
 143         RES_NONE  = 0,
 144         RES_IF    = 1,
 145         RES_THEN  = 2,
 146         RES_ELIF  = 3,
 147         RES_ELSE  = 4,
 148         RES_FI    = 5,
 149         RES_FOR   = 6,
 150         RES_WHILE = 7,
 151         RES_UNTIL = 8,
 152         RES_DO    = 9,
 153         RES_DONE  = 10,
 154         RES_XXXX  = 11,
 155         RES_IN    = 12,
 156         RES_SNTX  = 13
 157 } reserved_style;
 158 #define FLAG_END   (1<<RES_NONE)
 159 #define FLAG_IF    (1<<RES_IF)
 160 #define FLAG_THEN  (1<<RES_THEN)
 161 #define FLAG_ELIF  (1<<RES_ELIF)
 162 #define FLAG_ELSE  (1<<RES_ELSE)
 163 #define FLAG_FI    (1<<RES_FI)
 164 #define FLAG_FOR   (1<<RES_FOR)
 165 #define FLAG_WHILE (1<<RES_WHILE)
 166 #define FLAG_UNTIL (1<<RES_UNTIL)
 167 #define FLAG_DO    (1<<RES_DO)
 168 #define FLAG_DONE  (1<<RES_DONE)
 169 #define FLAG_IN    (1<<RES_IN)
 170 #define FLAG_START (1<<RES_XXXX)
 171
 172 /* This holds pointers to the various results of parsing */
 173 struct p_context {
 174         struct child_prog *child;
 175         struct pipe *list_head;
 176         struct pipe *pipe;
 177         struct redir_struct *pending_redirect;
 178         reserved_style w;
 179         int old_flag;                           /* for figuring out valid reserved words */
 180         struct p_context *stack;
 181         int type;                       /* define type of parser : ";$" common or special symbol */
 182         /* How about quoting status? */
 183 };
 184
 185 struct redir_struct {
 186         redir_type type;                        /* type of redirection */
 187         int fd;                                         /* file descriptor being redirected */
 188         int dup;                                        /* -1, or file descriptor being duplicated */
 189         struct redir_struct *next;      /* pointer to the next redirect in the list */
 190         glob_t word;                            /* *word.gl_pathv is the filename */
 191 };
 192
 193 struct child_prog {
 194         pid_t pid;                                      /* 0 if exited */
 195         char **argv;                            /* program name and arguments */
 196         struct pipe *group;                     /* if non-NULL, first in group or subshell */
 197         int subshell;                           /* flag, non-zero if group must be forked */
 198         struct redir_struct *redirects; /* I/O redirections */
 199         glob_t glob_result;                     /* result of parameter globbing */
 200         int is_stopped;                         /* is the program currently running? */
 201         struct pipe *family;            /* pointer back to the child's parent pipe */
 202         int sp;                         /* number of SPECIAL_VAR_SYMBOL */
 203         int type;
 204 };
 205
 206 struct pipe {
 207         int jobid;                                      /* job number */
 208         int num_progs;                          /* total number of programs in job */
 209         int running_progs;                      /* number of programs running */
 210         char *text;                                     /* name of job */
 211         char *cmdbuf;                           /* buffer various argv's point into */
 212         pid_t pgrp;                                     /* process group ID for the job */
 213         struct child_prog *progs;       /* array of commands in pipe */
 214         struct pipe *next;                      /* to track background commands */
 215         int stopped_progs;                      /* number of programs alive, but stopped */
 216         int job_context;                        /* bitmask defining current context */
 217         pipe_style followup;            /* PIPE_BG, PIPE_SEQ, PIPE_OR, PIPE_AND */
 218         reserved_style r_mode;          /* supports if, for, while, until */
 219 };
 220
 221 struct close_me {
 222         int fd;
 223         struct close_me *next;
 224 };
 225
 226 struct variables {
 227         char *name;
 228         char *value;
 229         int flg_export;
 230         int flg_read_only;
 231         struct variables *next;
 232 };
 233
 234 /* globals, connect us to the outside world
 235  * the first three support $?, $#, and $1 */
 236 static char **global_argv;
 237 static int global_argc;
 238 static int last_return_code;
 239 extern char **environ; /* This is in <unistd.h>, but protected with __USE_GNU */
 240
 241 /* "globals" within this file */
 242 static char *ifs;
 243 static unsigned char map[256];
 244 static int fake_mode;
 245 static int interactive;
 246 static struct close_me *close_me_head;
 247 static const char *cwd;
 248 static struct pipe *job_list;
 249 static unsigned int last_bg_pid;
 250 static int last_jobid;
 251 static unsigned int shell_terminal;
 252 static char *PS1;
 253 static char *PS2;
 254 static struct variables shell_ver = { "HUSH_VERSION", "0.01", 1, 1, 0 };
 255 static struct variables *top_vars = &shell_ver;
 256
 257
 258 #define B_CHUNK (100)
 259 #define B_NOSPAC 1
 260
 261 typedef struct {
 262         char *data;
 263         int length;
 264         int maxlen;
 265         int quote;
 266         int nonnull;
 267 } o_string;
 268 #define NULL_O_STRING {NULL,0,0,0,0}
 269 /* used for initialization:
 270         o_string foo = NULL_O_STRING; */
 271
 272 /* I can almost use ordinary FILE *.  Is open_memstream() universally
 273  * available?  Where is it documented? */
 274 struct in_str {
 275         const char *p;
 276         char peek_buf[2];
 277         int __promptme;
 278         int promptmode;
 279         FILE *file;
 280         int (*get) (struct in_str *);
 281         int (*peek) (struct in_str *);
 282 };
 283 #define b_getch(input) ((input)->get(input))
 284 #define b_peek(input) ((input)->peek(input))
 285
 286 #define JOB_STATUS_FORMAT "[%d] %-22s %.40s\n"
 287
 288 struct built_in_command {
 289         const char *cmd;                        /* name */
 290         const char *descr;                      /* description */
 291         int (*function) (struct child_prog *);  /* function ptr */
 292 };
 293
 294 /* belongs in busybox.h */
 295 static inline int max(int a, int b) {
 296         return (a>b)?a:b;
 297 }
 298
 299 /* This should be in utility.c */
 300 #ifdef DEBUG_SHELL
 301 static void debug_printf(const char *format, ...)
 302 {
 303         va_list args;
 304         va_start(args, format);
 305         vfprintf(stderr, format, args);
 306         va_end(args);
 307 }
 308 #else
 309 static inline void debug_printf(const char *format ATTRIBUTE_UNUSED, ...) { }
 310 #endif
 311 #define final_printf debug_printf
 312
 313 static void __syntax(char *file, int line) {
 314         bb_error_msg("syntax error %s:%d", file, line);
 315 }
 316 #define syntax() __syntax(__FILE__, __LINE__)
 317
 318 /* Index of subroutines: */
 319 /*   function prototypes for builtins */
 320 static int builtin_cd(struct child_prog *child);
 321 static int builtin_env(struct child_prog *child);
 322 static int builtin_eval(struct child_prog *child);
 323 static int builtin_exec(struct child_prog *child);
 324 static int builtin_exit(struct child_prog *child);
 325 static int builtin_export(struct child_prog *child);
 326 static int builtin_fg_bg(struct child_prog *child);
 327 static int builtin_help(struct child_prog *child);
 328 static int builtin_jobs(struct child_prog *child);
 329 static int builtin_pwd(struct child_prog *child);
 330 static int builtin_read(struct child_prog *child);
 331 static int builtin_set(struct child_prog *child);
 332 static int builtin_shift(struct child_prog *child);
 333 static int builtin_source(struct child_prog *child);
 334 static int builtin_umask(struct child_prog *child);
 335 static int builtin_unset(struct child_prog *child);
 336 static int builtin_not_written(struct child_prog *child);
 337 /*   o_string manipulation: */
 338 static int b_check_space(o_string *o, int len);
 339 static int b_addchr(o_string *o, int ch);
 340 static void b_reset(o_string *o);
 341 static int b_addqchr(o_string *o, int ch, int quote);
 342 static int b_adduint(o_string *o, unsigned int i);
 343 /*  in_str manipulations: */
 344 static int static_get(struct in_str *i);
 345 static int static_peek(struct in_str *i);
 346 static int file_get(struct in_str *i);
 347 static int file_peek(struct in_str *i);
 348 static void setup_file_in_str(struct in_str *i, FILE *f);
 349 static void setup_string_in_str(struct in_str *i, const char *s);
 350 /*  close_me manipulations: */
 351 static void mark_open(int fd);
 352 static void mark_closed(int fd);
 353 static void close_all(void);
 354 /*  "run" the final data structures: */
 355 static char *indenter(int i);
 356 static int free_pipe_list(struct pipe *head, int indent);
 357 static int free_pipe(struct pipe *pi, int indent);
 358 /*  really run the final data structures: */
 359 static int setup_redirects(struct child_prog *prog, int squirrel[]);
 360 static int run_list_real(struct pipe *pi);
 361 static void pseudo_exec(struct child_prog *child) ATTRIBUTE_NORETURN;
 362 static int run_pipe_real(struct pipe *pi);
 363 /*   extended glob support: */
 364 static int globhack(const char *src, int flags, glob_t *pglob);
 365 static int glob_needed(const char *s);
 366 static int xglob(o_string *dest, int flags, glob_t *pglob);
 367 /*   variable assignment: */
 368 static int is_assignment(const char *s);
 369 /*   data structure manipulation: */
 370 static int setup_redirect(struct p_context *ctx, int fd, redir_type style, struct in_str *input);
 371 static void initialize_context(struct p_context *ctx);
 372 static int done_word(o_string *dest, struct p_context *ctx);
 373 static int done_command(struct p_context *ctx);
 374 static int done_pipe(struct p_context *ctx, pipe_style type);
 375 /*   primary string parsing: */
 376 static int redirect_dup_num(struct in_str *input);
 377 static int redirect_opt_num(o_string *o);
 378 static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end);
 379 static int parse_group(o_string *dest, struct p_context *ctx, struct in_str *input, int ch);
 380 static char *lookup_param(char *src);
 381 static char *make_string(char **inp);
 382 static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input);
 383 static int parse_string(o_string *dest, struct p_context *ctx, const char *src);
 384 static int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input0, int end_trigger);
 385 /*   setup: */
 386 static int parse_stream_outer(struct in_str *inp, int flag);
 387 static int parse_string_outer(const char *s, int flag);
 388 static int parse_file_outer(FILE *f);
 389 /*   job management: */
 390 static int checkjobs(struct pipe* fg_pipe);
 391 static void insert_bg_job(struct pipe *pi);
 392 static void remove_bg_job(struct pipe *pi);
 393 /*     local variable support */
 394 static char **make_list_in(char **inp, char *name);
 395 static char *insert_var_value(char *inp);
 396 static char *get_local_var(const char *var);
 397 static void  unset_local_var(const char *name);
 398 static int set_local_var(const char *s, int flg_export);
 399
 400 /* Table of built-in functions.  They can be forked or not, depending on
 401  * context: within pipes, they fork.  As simple commands, they do not.
 402  * When used in non-forking context, they can change global variables
 403  * in the parent shell process.  If forked, of course they can not.
 404  * For example, 'unset foo | whatever' will parse and run, but foo will
 405  * still be set at the end. */
 406 static const struct built_in_command bltins[] = {
 407         {"bg", "Resume a job in the background", builtin_fg_bg},
 408         {"break", "Exit for, while or until loop", builtin_not_written},
 409         {"cd", "Change working directory", builtin_cd},
 410         {"continue", "Continue for, while or until loop", builtin_not_written},
 411         {"env", "Print all environment variables", builtin_env},
 412         {"eval", "Construct and run shell command", builtin_eval},
 413         {"exec", "Exec command, replacing this shell with the exec'd process",
 414                 builtin_exec},
 415         {"exit", "Exit from shell()", builtin_exit},
 416         {"export", "Set environment variable", builtin_export},
 417         {"fg", "Bring job into the foreground", builtin_fg_bg},
 418         {"jobs", "Lists the active jobs", builtin_jobs},
 419         {"pwd", "Print current directory", builtin_pwd},
 420         {"read", "Input environment variable", builtin_read},
 421         {"return", "Return from a function", builtin_not_written},
 422         {"set", "Set/unset shell local variables", builtin_set},
 423         {"shift", "Shift positional parameters", builtin_shift},
 424         {"trap", "Trap signals", builtin_not_written},
 425         {"ulimit","Controls resource limits", builtin_not_written},
 426         {"umask","Sets file creation mask", builtin_umask},
 427         {"unset", "Unset environment variable", builtin_unset},
 428         {".", "Source-in and run commands in a file", builtin_source},
 429         {"help", "List shell built-in commands", builtin_help},
 430         {NULL, NULL, NULL}
 431 };
 432
 433 static const char *set_cwd(void)
 434 {
 435         if(cwd==bb_msg_unknown)
 436                 cwd = NULL;     /* xgetcwd(arg) called free(arg) */
 437         cwd = xgetcwd((char *)cwd);
 438         if (!cwd)
 439                 cwd = bb_msg_unknown;
 440         return cwd;
 441 }
 442
 443 /* built-in 'eval' handler */
 444 static int builtin_eval(struct child_prog *child)
 445 {
 446         char *str = NULL;
 447         int rcode = EXIT_SUCCESS;
 448
 449         if (child->argv[1]) {
 450                 str = make_string(child->argv + 1);
 451                 parse_string_outer(str, FLAG_EXIT_FROM_LOOP |
 452                                         FLAG_PARSE_SEMICOLON);
 453                 free(str);
 454                 rcode = last_return_code;
 455         }
 456         return rcode;
 457 }
 458
 459 /* built-in 'cd <path>' handler */
 460 static int builtin_cd(struct child_prog *child)
 461 {
 462         char *newdir;
 463         if (child->argv[1] == NULL)
 464                 newdir = getenv("HOME");
 465         else
 466                 newdir = child->argv[1];
 467         if (chdir(newdir)) {
 468                 printf("cd: %s: %s\n", newdir, strerror(errno));
 469                 return EXIT_FAILURE;
 470         }
 471         set_cwd();
 472         return EXIT_SUCCESS;
 473 }
 474
 475 /* built-in 'env' handler */
 476 static int builtin_env(struct child_prog *dummy ATTRIBUTE_UNUSED)
 477 {
 478         char **e = environ;
 479         if (e == NULL) return EXIT_FAILURE;
 480         for (; *e; e++) {
 481                 puts(*e);
 482         }
 483         return EXIT_SUCCESS;
 484 }
 485
 486 /* built-in 'exec' handler */
 487 static int builtin_exec(struct child_prog *child)
 488 {
 489         if (child->argv[1] == NULL)
 490                 return EXIT_SUCCESS;   /* Really? */
 491         child->argv++;
 492         pseudo_exec(child);
 493         /* never returns */
 494 }
 495
 496 /* built-in 'exit' handler */
 497 static int builtin_exit(struct child_prog *child)
 498 {
 499         if (child->argv[1] == NULL)
 500                 exit(last_return_code);
 501         exit (atoi(child->argv[1]));
 502 }
 503
 504 /* built-in 'export VAR=value' handler */
 505 static int builtin_export(struct child_prog *child)
 506 {
 507         int res = 0;
 508         char *name = child->argv[1];
 509
 510         if (name == NULL) {
 511                 return (builtin_env(child));
 512         }
 513
 514         name = strdup(name);
 515
 516         if(name) {
 517                 char *value = strchr(name, '=');
 518
 519                 if (!value) {
 520                         char *tmp;
 521                         /* They are exporting something without an =VALUE */
 522
 523                         value = get_local_var(name);
 524                         if (value) {
 525                                 size_t ln = strlen(name);
 526
 527                                 tmp = realloc(name, ln+strlen(value)+2);
 528                                 if(tmp==NULL)
 529                                         res = -1;
 530                                 else {
 531                                         sprintf(tmp+ln, "=%s", value);
 532                                         name = tmp;
 533                                 }
 534                         } else {
 535                                 /* bash does not return an error when trying to export
 536                                  * an undefined variable.  Do likewise. */
 537                                 res = 1;
 538                         }
 539                 }
 540         }
 541         if (res<0)
 542                 bb_perror_msg("export");
 543         else if(res==0)
 544                 res = set_local_var(name, 1);
 545         else
 546                 res = 0;
 547         free(name);
 548         return res;
 549 }
 550
 551 /* built-in 'fg' and 'bg' handler */
 552 static int builtin_fg_bg(struct child_prog *child)
 553 {
 554         int i, jobnum;
 555         struct pipe *pi=NULL;
 556
 557         if (!interactive)
 558                 return EXIT_FAILURE;
 559         /* If they gave us no args, assume they want the last backgrounded task */
 560         if (!child->argv[1]) {
 561                 for (pi = job_list; pi; pi = pi->next) {
 562                         if (pi->jobid == last_jobid) {
 563                                 break;
 564                         }
 565                 }
 566                 if (!pi) {
 567                         bb_error_msg("%s: no current job", child->argv[0]);
 568                         return EXIT_FAILURE;
 569                 }
 570         } else {
 571                 if (sscanf(child->argv[1], "%%%d", &jobnum) != 1) {
 572                         bb_error_msg("%s: bad argument '%s'", child->argv[0], child->argv[1]);
 573                         return EXIT_FAILURE;
 574                 }
 575                 for (pi = job_list; pi; pi = pi->next) {
 576                         if (pi->jobid == jobnum) {
 577                                 break;
 578                         }
 579                 }
 580                 if (!pi) {
 581                         bb_error_msg("%s: %d: no such job", child->argv[0], jobnum);
 582                         return EXIT_FAILURE;
 583                 }
 584         }
 585
 586         if (*child->argv[0] == 'f') {
 587                 /* Put the job into the foreground.  */
 588                 tcsetpgrp(shell_terminal, pi->pgrp);
 589         }
 590
 591         /* Restart the processes in the job */
 592         for (i = 0; i < pi->num_progs; i++)
 593                 pi->progs[i].is_stopped = 0;
 594
 595         if ( (i=kill(- pi->pgrp, SIGCONT)) < 0) {
 596                 if (i == ESRCH) {
 597                         remove_bg_job(pi);
 598                 } else {
 599                         bb_perror_msg("kill (SIGCONT)");
 600                 }
 601         }
 602
 603         pi->stopped_progs = 0;
 604         return EXIT_SUCCESS;
 605 }
 606
 607 /* built-in 'help' handler */
 608 static int builtin_help(struct child_prog *dummy ATTRIBUTE_UNUSED)
 609 {
 610         const struct built_in_command *x;
 611
 612         printf("\nBuilt-in commands:\n");
 613         printf("-------------------\n");
 614         for (x = bltins; x->cmd; x++) {
 615                 if (x->descr==NULL)
 616                         continue;
 617                 printf("%s\t%s\n", x->cmd, x->descr);
 618         }
 619         printf("\n\n");
 620         return EXIT_SUCCESS;
 621 }
 622
 623 /* built-in 'jobs' handler */
 624 static int builtin_jobs(struct child_prog *child ATTRIBUTE_UNUSED)
 625 {
 626         struct pipe *job;
 627         char *status_string;
 628
 629         for (job = job_list; job; job = job->next) {
 630                 if (job->running_progs == job->stopped_progs)
 631                         status_string = "Stopped";
 632                 else
 633                         status_string = "Running";
 634
 635                 printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->text);
 636         }
 637         return EXIT_SUCCESS;
 638 }
 639
 640
 641 /* built-in 'pwd' handler */
 642 static int builtin_pwd(struct child_prog *dummy ATTRIBUTE_UNUSED)
 643 {
 644         puts(set_cwd());
 645         return EXIT_SUCCESS;
 646 }
 647
 648 /* built-in 'read VAR' handler */
 649 static int builtin_read(struct child_prog *child)
 650 {
 651         int res;
 652
 653         if (child->argv[1]) {
 654                 char string[BUFSIZ];
 655                 char *var = 0;
 656
 657                 string[0] = 0;  /* In case stdin has only EOF */
 658                 /* read string */
 659                 fgets(string, sizeof(string), stdin);
 660                 chomp(string);
 661                 var = malloc(strlen(child->argv[1])+strlen(string)+2);
 662                 if(var) {
 663                         sprintf(var, "%s=%s", child->argv[1], string);
 664                         res = set_local_var(var, 0);
 665                 } else
 666                         res = -1;
 667                 if (res)
 668                         fprintf(stderr, "read: %m\n");
 669                 free(var);      /* So not move up to avoid breaking errno */
 670                 return res;
 671         } else {
 672                 do res=getchar(); while(res!='\n' && res!=EOF);
 673                 return 0;
 674         }
 675 }
 676
 677 /* built-in 'set VAR=value' handler */
 678 static int builtin_set(struct child_prog *child)
 679 {
 680         char *temp = child->argv[1];
 681         struct variables *e;
 682
 683         if (temp == NULL)
 684                 for(e = top_vars; e; e=e->next)
 685                         printf("%s=%s\n", e->name, e->value);
 686         else
 687                 set_local_var(temp, 0);
 688
 689                 return EXIT_SUCCESS;
 690 }
 691
 692
 693 /* Built-in 'shift' handler */
 694 static int builtin_shift(struct child_prog *child)
 695 {
 696         int n=1;
 697         if (child->argv[1]) {
 698                 n=atoi(child->argv[1]);
 699         }
 700         if (n>=0 && n<global_argc) {
 701                 /* XXX This probably breaks $0 */
 702                 global_argc -= n;
 703                 global_argv += n;
 704                 return EXIT_SUCCESS;
 705         } else {
 706                 return EXIT_FAILURE;
 707         }
 708 }
 709
 710 /* Built-in '.' handler (read-in and execute commands from file) */
 711 static int builtin_source(struct child_prog *child)
 712 {
 713         FILE *input;
 714         int status;
 715
 716         if (child->argv[1] == NULL)
 717                 return EXIT_FAILURE;
 718
 719         /* XXX search through $PATH is missing */
 720         input = fopen(child->argv[1], "r");
 721         if (!input) {
 722                 bb_error_msg("Couldn't open file '%s'", child->argv[1]);
 723                 return EXIT_FAILURE;
 724         }
 725
 726         /* Now run the file */
 727         /* XXX argv and argc are broken; need to save old global_argv
 728          * (pointer only is OK!) on this stack frame,
 729          * set global_argv=child->argv+1, recurse, and restore. */
 730         mark_open(fileno(input));
 731         status = parse_file_outer(input);
 732         mark_closed(fileno(input));
 733         fclose(input);
 734         return (status);
 735 }
 736
 737 static int builtin_umask(struct child_prog *child)
 738 {
 739         mode_t new_umask;
 740         const char *arg = child->argv[1];
 741         char *end;
 742         if (arg) {
 743                 new_umask=strtoul(arg, &end, 8);
 744                 if (*end!='\0' || end == arg) {
 745                         return EXIT_FAILURE;
 746                 }
 747         } else {
 748                 printf("%.3o\n", (unsigned int) (new_umask=umask(0)));
 749         }
 750         umask(new_umask);
 751         return EXIT_SUCCESS;
 752 }
 753
 754 /* built-in 'unset VAR' handler */
 755 static int builtin_unset(struct child_prog *child)
 756 {
 757         /* bash returned already true */
 758         unset_local_var(child->argv[1]);
 759         return EXIT_SUCCESS;
 760 }
 761
 762 static int builtin_not_written(struct child_prog *child)
 763 {
 764         printf("builtin_%s not written\n",child->argv[0]);
 765         return EXIT_FAILURE;
 766 }
 767
 768 static int b_check_space(o_string *o, int len)
 769 {
 770         /* It would be easy to drop a more restrictive policy
 771          * in here, such as setting a maximum string length */
 772         if (o->length + len > o->maxlen) {
 773                 char *old_data = o->data;
 774                 /* assert (data == NULL || o->maxlen != 0); */
 775                 o->maxlen += max(2*len, B_CHUNK);
 776                 o->data = realloc(o->data, 1 + o->maxlen);
 777                 if (o->data == NULL) {
 778                         free(old_data);
 779                 }
 780         }
 781         return o->data == NULL;
 782 }
 783
 784 static int b_addchr(o_string *o, int ch)
 785 {
 786         debug_printf("b_addchr: %c %d %p\n", ch, o->length, o);
 787         if (b_check_space(o, 1)) return B_NOSPAC;
 788         o->data[o->length] = ch;
 789         o->length++;
 790         o->data[o->length] = '\0';
 791         return 0;
 792 }
 793
 794 static void b_reset(o_string *o)
 795 {
 796         o->length = 0;
 797         o->nonnull = 0;
 798         if (o->data != NULL) *o->data = '\0';
 799 }
 800
 801 static void b_free(o_string *o)
 802 {
 803         b_reset(o);
 804         free(o->data);
 805         o->data = NULL;
 806         o->maxlen = 0;
 807 }
 808
 809 /* My analysis of quoting semantics tells me that state information
 810  * is associated with a destination, not a source.
 811  */
 812 static int b_addqchr(o_string *o, int ch, int quote)
 813 {
 814         if (quote && strchr("*?[\\",ch)) {
 815                 int rc;
 816                 rc = b_addchr(o, '\\');
 817                 if (rc) return rc;
 818         }
 819         return b_addchr(o, ch);
 820 }
 821
 822 /* belongs in utility.c */
 823 static char *simple_itoa(unsigned int i)
 824 {
 825         /* 21 digits plus null terminator, good for 64-bit or smaller ints */
 826         static char local[22];
 827         char *p = &local[21];
 828         *p-- = '\0';
 829         do {
 830                 *p-- = '0' + i % 10;
 831                 i /= 10;
 832         } while (i > 0);
 833         return p + 1;
 834 }
 835
 836 static int b_adduint(o_string *o, unsigned int i)
 837 {
 838         int r;
 839         char *p = simple_itoa(i);
 840         /* no escape checking necessary */
 841         do r=b_addchr(o, *p++); while (r==0 && *p);
 842         return r;
 843 }
 844
 845 static int static_get(struct in_str *i)
 846 {
 847         int ch=*i->p++;
 848         if (ch=='\0') return EOF;
 849         return ch;
 850 }
 851
 852 static int static_peek(struct in_str *i)
 853 {
 854         return *i->p;
 855 }
 856
 857 static inline void cmdedit_set_initial_prompt(void)
 858 {
 859 #ifndef CONFIG_FEATURE_SH_FANCY_PROMPT
 860         PS1 = NULL;
 861 #else
 862         PS1 = getenv("PS1");
 863         if(PS1==0)
 864                 PS1 = "\\w \\$ ";
 865 #endif
 866 }
 867
 868 static inline void setup_prompt_string(int promptmode, char **prompt_str)
 869 {
 870         debug_printf("setup_prompt_string %d ",promptmode);
 871 #ifndef CONFIG_FEATURE_SH_FANCY_PROMPT
 872         /* Set up the prompt */
 873         if (promptmode == 1) {
 874                 free(PS1);
 875                 PS1=xmalloc(strlen(cwd)+4);
 876                 sprintf(PS1, "%s %s", cwd, ( geteuid() != 0 ) ?  "$ ":"# ");
 877                 *prompt_str = PS1;
 878         } else {
 879                 *prompt_str = PS2;
 880         }
 881 #else
 882         *prompt_str = (promptmode==1)? PS1 : PS2;
 883 #endif
 884         debug_printf("result %s\n",*prompt_str);
 885 }
 886
 887 static void get_user_input(struct in_str *i)
 888 {
 889         char *prompt_str;
 890         static char the_command[BUFSIZ];
 891
 892         setup_prompt_string(i->promptmode, &prompt_str);
 893 #ifdef CONFIG_FEATURE_COMMAND_EDITING
 894         /*
 895          ** enable command line editing only while a command line
 896          ** is actually being read; otherwise, we'll end up bequeathing
 897          ** atexit() handlers and other unwanted stuff to our
 898          ** child processes (rob@sysgo.de)
 899          */
 900         cmdedit_read_input(prompt_str, the_command);
 901 #else
 902         fputs(prompt_str, stdout);
 903         fflush(stdout);
 904         the_command[0]=fgetc(i->file);
 905         the_command[1]='\0';
 906 #endif
 907         fflush(stdout);
 908         i->p = the_command;
 909 }
 910
 911 /* This is the magic location that prints prompts
 912  * and gets data back from the user */
 913 static int file_get(struct in_str *i)
 914 {
 915         int ch;
 916
 917         ch = 0;
 918         /* If there is data waiting, eat it up */
 919         if (i->p && *i->p) {
 920                 ch=*i->p++;
 921         } else {
 922                 /* need to double check i->file because we might be doing something
 923                  * more complicated by now, like sourcing or substituting. */
 924                 if (i->__promptme && interactive && i->file == stdin) {
 925                         while(! i->p || (interactive && strlen(i->p)==0) ) {
 926                                 get_user_input(i);
 927                         }
 928                         i->promptmode=2;
 929                         i->__promptme = 0;
 930                         if (i->p && *i->p) {
 931                                 ch=*i->p++;
 932                         }
 933                 } else {
 934                         ch = fgetc(i->file);
 935                 }
 936
 937                 debug_printf("b_getch: got a %d\n", ch);
 938         }
 939         if (ch == '\n') i->__promptme=1;
 940         return ch;
 941 }
 942
 943 /* All the callers guarantee this routine will never be
 944  * used right after a newline, so prompting is not needed.
 945  */
 946 static int file_peek(struct in_str *i)
 947 {
 948         if (i->p && *i->p) {
 949                 return *i->p;
 950         } else {
 951                 i->peek_buf[0] = fgetc(i->file);
 952                 i->peek_buf[1] = '\0';
 953                 i->p = i->peek_buf;
 954                 debug_printf("b_peek: got a %d\n", *i->p);
 955                 return *i->p;
 956         }
 957 }
 958
 959 static void setup_file_in_str(struct in_str *i, FILE *f)
 960 {
 961         i->peek = file_peek;
 962         i->get = file_get;
 963         i->__promptme=1;
 964         i->promptmode=1;
 965         i->file = f;
 966         i->p = NULL;
 967 }
 968
 969 static void setup_string_in_str(struct in_str *i, const char *s)
 970 {
 971         i->peek = static_peek;
 972         i->get = static_get;
 973         i->__promptme=1;
 974         i->promptmode=1;
 975         i->p = s;
 976 }
 977
 978 static void mark_open(int fd)
 979 {
 980         struct close_me *new = xmalloc(sizeof(struct close_me));
 981         new->fd = fd;
 982         new->next = close_me_head;
 983         close_me_head = new;
 984 }
 985
 986 static void mark_closed(int fd)
 987 {
 988         struct close_me *tmp;
 989         if (close_me_head == NULL || close_me_head->fd != fd)
 990                 bb_error_msg_and_die("corrupt close_me");
 991         tmp = close_me_head;
 992         close_me_head = close_me_head->next;
 993         free(tmp);
 994 }
 995
 996 static void close_all(void)
 997 {
 998         struct close_me *c;
 999         for (c=close_me_head; c; c=c->next) {
1000                 close(c->fd);
1001         }
1002         close_me_head = NULL;
1003 }
1004
1005 /* squirrel != NULL means we squirrel away copies of stdin, stdout,
1006  * and stderr if they are redirected. */
1007 static int setup_redirects(struct child_prog *prog, int squirrel[])
1008 {
1009         int openfd, mode;
1010         struct redir_struct *redir;
1011
1012         for (redir=prog->redirects; redir; redir=redir->next) {
1013                 if (redir->dup == -1 && redir->word.gl_pathv == NULL) {
1014                         /* something went wrong in the parse.  Pretend it didn't happen */
1015                         continue;
1016                 }
1017                 if (redir->dup == -1) {
1018                         mode=redir_table[redir->type].mode;
1019                         openfd = open(redir->word.gl_pathv[0], mode, 0666);
1020                         if (openfd < 0) {
1021                         /* this could get lost if stderr has been redirected, but
1022                            bash and ash both lose it as well (though zsh doesn't!) */
1023                                 bb_perror_msg("error opening %s", redir->word.gl_pathv[0]);
1024                                 return 1;
1025                         }
1026                 } else {
1027                         openfd = redir->dup;
1028                 }
1029
1030                 if (openfd != redir->fd) {
1031                         if (squirrel && redir->fd < 3) {
1032                                 squirrel[redir->fd] = dup(redir->fd);
1033                         }
1034                         if (openfd == -3) {
1035                                 close(openfd);
1036                         } else {
1037                                 dup2(openfd, redir->fd);
1038                                 if (redir->dup == -1)
1039                                         close (openfd);
1040                         }
1041                 }
1042         }
1043         return 0;
1044 }
1045
1046 static void restore_redirects(int squirrel[])
1047 {
1048         int i, fd;
1049         for (i=0; i<3; i++) {
1050                 fd = squirrel[i];
1051                 if (fd != -1) {
1052                         /* No error checking.  I sure wouldn't know what
1053                          * to do with an error if I found one! */
1054                         dup2(fd, i);
1055                         close(fd);
1056                 }
1057         }
1058 }
1059
1060 /* never returns */
1061 /* XXX no exit() here.  If you don't exec, use _exit instead.
1062  * The at_exit handlers apparently confuse the calling process,
1063  * in particular stdin handling.  Not sure why? */
1064 static void pseudo_exec(struct child_prog *child)
1065 {
1066         int i, rcode;
1067         char *p;
1068         const struct built_in_command *x;
1069         if (child->argv) {
1070                 for (i=0; is_assignment(child->argv[i]); i++) {
1071                         debug_printf("pid %d environment modification: %s\n",getpid(),child->argv[i]);
1072                         p = insert_var_value(child->argv[i]);
1073                         putenv(strdup(p));
1074                         if (p != child->argv[i]) free(p);
1075                 }
1076                 child->argv+=i;  /* XXX this hack isn't so horrible, since we are about
1077                                         to exit, and therefore don't need to keep data
1078                                         structures consistent for free() use. */
1079                 /* If a variable is assigned in a forest, and nobody listens,
1080                  * was it ever really set?
1081                  */
1082                 if (child->argv[0] == NULL) {
1083                         _exit(EXIT_SUCCESS);
1084                 }
1085
1086                 /*
1087                  * Check if the command matches any of the builtins.
1088                  * Depending on context, this might be redundant.  But it's
1089                  * easier to waste a few CPU cycles than it is to figure out
1090                  * if this is one of those cases.
1091                  */
1092                 for (x = bltins; x->cmd; x++) {
1093                         if (strcmp(child->argv[0], x->cmd) == 0 ) {
1094                                 debug_printf("builtin exec %s\n", child->argv[0]);
1095                                 rcode = x->function(child);
1096                                 fflush(stdout);
1097                                 _exit(rcode);
1098                         }
1099                 }
1100
1101                 /* Check if the command matches any busybox internal commands
1102                  * ("applets") here.
1103                  * FIXME: This feature is not 100% safe, since
1104                  * BusyBox is not fully reentrant, so we have no guarantee the things
1105                  * from the .bss are still zeroed, or that things from .data are still
1106                  * at their defaults.  We could exec ourself from /proc/self/exe, but I
1107                  * really dislike relying on /proc for things.  We could exec ourself
1108                  * from global_argv[0], but if we are in a chroot, we may not be able
1109                  * to find ourself... */
1110 #ifdef CONFIG_FEATURE_SH_STANDALONE_SHELL
1111                 {
1112                         int argc_l;
1113                         char** argv_l=child->argv;
1114                         char *name = child->argv[0];
1115
1116                         /* Count argc for use in a second... */
1117                         for(argc_l=0;*argv_l!=NULL; argv_l++, argc_l++);
1118                         optind = 1;
1119                         debug_printf("running applet %s\n", name);
1120                         run_applet_by_name(name, argc_l, child->argv);
1121                 }
1122 #endif
1123                 debug_printf("exec of %s\n",child->argv[0]);
1124                 execvp(child->argv[0],child->argv);
1125                 bb_perror_msg("couldn't exec: %s",child->argv[0]);
1126                 _exit(1);
1127         } else if (child->group) {
1128                 debug_printf("runtime nesting to group\n");
1129                 interactive=0;    /* crucial!!!! */
1130                 rcode = run_list_real(child->group);
1131                 /* OK to leak memory by not calling free_pipe_list,
1132                  * since this process is about to exit */
1133                 _exit(rcode);
1134         } else {
1135                 /* Can happen.  See what bash does with ">foo" by itself. */
1136                 debug_printf("trying to pseudo_exec null command\n");
1137                 _exit(EXIT_SUCCESS);
1138         }
1139 }
1140
1141 static void insert_bg_job(struct pipe *pi)
1142 {
1143         struct pipe *thejob;
1144
1145         /* Linear search for the ID of the job to use */
1146         pi->jobid = 1;
1147         for (thejob = job_list; thejob; thejob = thejob->next)
1148                 if (thejob->jobid >= pi->jobid)
1149                         pi->jobid = thejob->jobid + 1;
1150
1151         /* add thejob to the list of running jobs */
1152         if (!job_list) {
1153                 thejob = job_list = xmalloc(sizeof(*thejob));
1154         } else {
1155                 for (thejob = job_list; thejob->next; thejob = thejob->next) /* nothing */;
1156                 thejob->next = xmalloc(sizeof(*thejob));
1157                 thejob = thejob->next;
1158         }
1159
1160         /* physically copy the struct job */
1161         memcpy(thejob, pi, sizeof(struct pipe));
1162         thejob->next = NULL;
1163         thejob->running_progs = thejob->num_progs;
1164         thejob->stopped_progs = 0;
1165         thejob->text = xmalloc(BUFSIZ); /* cmdedit buffer size */
1166
1167         //if (pi->progs[0] && pi->progs[0].argv && pi->progs[0].argv[0])
1168         {
1169                 char *bar=thejob->text;
1170                 char **foo=pi->progs[0].argv;
1171                 while(foo && *foo) {
1172                         bar += sprintf(bar, "%s ", *foo++);
1173                 }
1174         }
1175
1176         /* we don't wait for background thejobs to return -- append it
1177            to the list of backgrounded thejobs and leave it alone */
1178         printf("[%d] %d\n", thejob->jobid, thejob->progs[0].pid);
1179         last_bg_pid = thejob->progs[0].pid;
1180         last_jobid = thejob->jobid;
1181 }
1182
1183 /* remove a backgrounded job */
1184 static void remove_bg_job(struct pipe *pi)
1185 {
1186         struct pipe *prev_pipe;
1187
1188         if (pi == job_list) {
1189                 job_list = pi->next;
1190         } else {
1191                 prev_pipe = job_list;
1192                 while (prev_pipe->next != pi)
1193                         prev_pipe = prev_pipe->next;
1194                 prev_pipe->next = pi->next;
1195         }
1196         if (job_list)
1197                 last_jobid = job_list->jobid;
1198         else
1199                 last_jobid = 0;
1200
1201         pi->stopped_progs = 0;
1202         free_pipe(pi, 0);
1203         free(pi);
1204 }
1205
1206 /* Checks to see if any processes have exited -- if they
1207    have, figure out why and see if a job has completed */
1208 static int checkjobs(struct pipe* fg_pipe)
1209 {
1210         int attributes;
1211         int status;
1212         int prognum = 0;
1213         struct pipe *pi;
1214         pid_t childpid;
1215
1216         attributes = WUNTRACED;
1217         if (fg_pipe==NULL) {
1218                 attributes |= WNOHANG;
1219         }
1220
1221         while ((childpid = waitpid(-1, &status, attributes)) > 0) {
1222                 if (fg_pipe) {
1223                         int i, rcode = 0;
1224                         for (i=0; i < fg_pipe->num_progs; i++) {
1225                                 if (fg_pipe->progs[i].pid == childpid) {
1226                                         if (i==fg_pipe->num_progs-1)
1227                                                 rcode=WEXITSTATUS(status);
1228                                         (fg_pipe->num_progs)--;
1229                                         return(rcode);
1230                                 }
1231                         }
1232                 }
1233
1234                 for (pi = job_list; pi; pi = pi->next) {
1235                         prognum = 0;
1236                         while (prognum < pi->num_progs && pi->progs[prognum].pid != childpid) {
1237                                 prognum++;
1238                         }
1239                         if (prognum < pi->num_progs)
1240                                 break;
1241                 }
1242
1243                 if(pi==NULL) {
1244                         debug_printf("checkjobs: pid %d was not in our list!\n", childpid);
1245                         continue;
1246                 }
1247
1248                 if (WIFEXITED(status) || WIFSIGNALED(status)) {
1249                         /* child exited */
1250                         pi->running_progs--;
1251                         pi->progs[prognum].pid = 0;
1252
1253                         if (!pi->running_progs) {
1254                                 printf(JOB_STATUS_FORMAT, pi->jobid, "Done", pi->text);
1255                                 remove_bg_job(pi);
1256                         }
1257                 } else {
1258                         /* child stopped */
1259                         pi->stopped_progs++;
1260                         pi->progs[prognum].is_stopped = 1;
1261
1262 #if 0
1263                         /* Printing this stuff is a pain, since it tends to
1264                          * overwrite the prompt an inconveinient moments.  So
1265                          * don't do that.  */
1266                         if (pi->stopped_progs == pi->num_progs) {
1267                                 printf("\n"JOB_STATUS_FORMAT, pi->jobid, "Stopped", pi->text);
1268                         }
1269 #endif
1270                 }
1271         }
1272
1273         if (childpid == -1 && errno != ECHILD)
1274                 bb_perror_msg("waitpid");
1275
1276         /* move the shell to the foreground */
1277         //if (interactive && tcsetpgrp(shell_terminal, getpgid(0)))
1278         //      bb_perror_msg("tcsetpgrp-2");
1279         return -1;
1280 }
1281
1282 /* Figure out our controlling tty, checking in order stderr,
1283  * stdin, and stdout.  If check_pgrp is set, also check that
1284  * we belong to the foreground process group associated with
1285  * that tty.  The value of shell_terminal is needed in order to call
1286  * tcsetpgrp(shell_terminal, ...); */
1287 #if 0
1288 static void controlling_tty(int check_pgrp)
1289 {
1290         pid_t curpgrp;
1291
1292         if ((curpgrp = tcgetpgrp(shell_terminal = 2)) < 0
1293                         && (curpgrp = tcgetpgrp(shell_terminal = 0)) < 0
1294                         && (curpgrp = tcgetpgrp(shell_terminal = 1)) < 0)
1295                 goto shell_terminal_error;
1296
1297         if (check_pgrp && curpgrp != getpgid(0))
1298                 goto shell_terminal_error;
1299
1300         return;
1301
1302 shell_terminal_error:
1303                 shell_terminal = -1;
1304                 return;
1305 }
1306 #endif
1307
1308 /* run_pipe_real() starts all the jobs, but doesn't wait for anything
1309  * to finish.  See checkjobs().
1310  *
1311  * return code is normally -1, when the caller has to wait for children
1312  * to finish to determine the exit status of the pipe.  If the pipe
1313  * is a simple builtin command, however, the action is done by the
1314  * time run_pipe_real returns, and the exit code is provided as the
1315  * return value.
1316  *
1317  * The input of the pipe is always stdin, the output is always
1318  * stdout.  The outpipe[] mechanism in BusyBox-0.48 lash is bogus,
1319  * because it tries to avoid running the command substitution in
1320  * subshell, when that is in fact necessary.  The subshell process
1321  * now has its stdout directed to the input of the appropriate pipe,
1322  * so this routine is noticeably simpler.
1323  */
1324 static int run_pipe_real(struct pipe *pi)
1325 {
1326         int i;
1327         int nextin, nextout;
1328         int pipefds[2];                         /* pipefds[0] is for reading */
1329         struct child_prog *child;
1330         const struct built_in_command *x;
1331         char *p;
1332
1333         nextin = 0;
1334         pi->pgrp = -1;
1335
1336         /* Check if this is a simple builtin (not part of a pipe).
1337          * Builtins within pipes have to fork anyway, and are handled in
1338          * pseudo_exec.  "echo foo | read bar" doesn't work on bash, either.
1339          */
1340         if (pi->num_progs == 1) child = & (pi->progs[0]);
1341         if (pi->num_progs == 1 && child->group && child->subshell == 0) {
1342                 int squirrel[] = {-1, -1, -1};
1343                 int rcode;
1344                 debug_printf("non-subshell grouping\n");
1345                 setup_redirects(child, squirrel);
1346                 /* XXX could we merge code with following builtin case,
1347                  * by creating a pseudo builtin that calls run_list_real? */
1348                 rcode = run_list_real(child->group);
1349                 restore_redirects(squirrel);
1350                 return rcode;
1351         } else if (pi->num_progs == 1 && pi->progs[0].argv != NULL) {
1352                 for (i=0; is_assignment(child->argv[i]); i++) { /* nothing */ }
1353                 if (i!=0 && child->argv[i]==NULL) {
1354                         /* assignments, but no command: set the local environment */
1355                         for (i=0; child->argv[i]!=NULL; i++) {
1356
1357                                 /* Ok, this case is tricky.  We have to decide if this is a
1358                                  * local variable, or an already exported variable.  If it is
1359                                  * already exported, we have to export the new value.  If it is
1360                                  * not exported, we need only set this as a local variable.
1361                                  * This junk is all to decide whether or not to export this
1362                                  * variable. */
1363                                 int export_me=0;
1364                                 char *name, *value;
1365                                 name = bb_xstrdup(child->argv[i]);
1366                                 debug_printf("Local environment set: %s\n", name);
1367                                 value = strchr(name, '=');
1368                                 if (value)
1369                                         *value=0;
1370                                 if ( get_local_var(name)) {
1371                                         export_me=1;
1372                                 }
1373                                 free(name);
1374                                 p = insert_var_value(child->argv[i]);
1375                                 set_local_var(p, export_me);
1376                                 if (p != child->argv[i]) free(p);
1377                         }
1378                         return EXIT_SUCCESS;   /* don't worry about errors in set_local_var() yet */
1379                 }
1380                 for (i = 0; is_assignment(child->argv[i]); i++) {
1381                         p = insert_var_value(child->argv[i]);
1382                         putenv(strdup(p));
1383                         if (p != child->argv[i]) {
1384                                 child->sp--;
1385                                 free(p);
1386                         }
1387                 }
1388                 if (child->sp) {
1389                         char * str = NULL;
1390
1391                         str = make_string((child->argv + i));
1392                         parse_string_outer(str, FLAG_EXIT_FROM_LOOP | FLAG_REPARSING);
1393                         free(str);
1394                         return last_return_code;
1395                 }
1396                 for (x = bltins; x->cmd; x++) {
1397                         if (strcmp(child->argv[i], x->cmd) == 0 ) {
1398                                 int squirrel[] = {-1, -1, -1};
1399                                 int rcode;
1400                                 if (x->function == builtin_exec && child->argv[i+1]==NULL) {
1401                                         debug_printf("magic exec\n");
1402                                         setup_redirects(child,NULL);
1403                                         return EXIT_SUCCESS;
1404                                 }
1405                                 debug_printf("builtin inline %s\n", child->argv[0]);
1406                                 /* XXX setup_redirects acts on file descriptors, not FILEs.
1407                                  * This is perfect for work that comes after exec().
1408                                  * Is it really safe for inline use?  Experimentally,
1409                                  * things seem to work with glibc. */
1410                                 setup_redirects(child, squirrel);
1411                                 child->argv+=i;  /* XXX horrible hack */
1412                                 rcode = x->function(child);
1413                                 child->argv-=i;  /* XXX restore hack so free() can work right */
1414                                 restore_redirects(squirrel);
1415                                 return rcode;
1416                         }
1417                 }
1418         }
1419
1420         for (i = 0; i < pi->num_progs; i++) {
1421                 child = & (pi->progs[i]);
1422
1423                 /* pipes are inserted between pairs of commands */
1424                 if ((i + 1) < pi->num_progs) {
1425                         if (pipe(pipefds)<0) bb_perror_msg_and_die("pipe");
1426                         nextout = pipefds[1];
1427                 } else {
1428                         nextout=1;
1429                         pipefds[0] = -1;
1430                 }
1431
1432                 /* XXX test for failed fork()? */
1433 #if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
1434                 if (!(child->pid = fork()))
1435 #else
1436                 if (!(child->pid = vfork()))
1437 #endif
1438                 {
1439                         /* Set the handling for job control signals back to the default.  */
1440                         signal(SIGINT, SIG_DFL);
1441                         signal(SIGQUIT, SIG_DFL);
1442                         signal(SIGTERM, SIG_DFL);
1443                         signal(SIGTSTP, SIG_DFL);
1444                         signal(SIGTTIN, SIG_DFL);
1445                         signal(SIGTTOU, SIG_DFL);
1446                         signal(SIGCHLD, SIG_DFL);
1447
1448                         close_all();
1449
1450                         if (nextin != 0) {
1451                                 dup2(nextin, 0);
1452                                 close(nextin);
1453                         }
1454                         if (nextout != 1) {
1455                                 dup2(nextout, 1);
1456                                 close(nextout);
1457                         }
1458                         if (pipefds[0]!=-1) {
1459                                 close(pipefds[0]);  /* opposite end of our output pipe */
1460                         }
1461
1462                         /* Like bash, explicit redirects override pipes,
1463                          * and the pipe fd is available for dup'ing. */
1464                         setup_redirects(child,NULL);
1465
1466                         if (interactive && pi->followup!=PIPE_BG) {
1467                                 /* If we (the child) win the race, put ourselves in the process
1468                                  * group whose leader is the first process in this pipe. */
1469                                 if (pi->pgrp < 0) {
1470                                         pi->pgrp = getpid();
1471                                 }
1472                                 if (setpgid(0, pi->pgrp) == 0) {
1473                                         tcsetpgrp(2, pi->pgrp);
1474                                 }
1475                         }
1476
1477                         pseudo_exec(child);
1478                 }
1479
1480
1481                 /* put our child in the process group whose leader is the
1482                    first process in this pipe */
1483                 if (pi->pgrp < 0) {
1484                         pi->pgrp = child->pid;
1485                 }
1486                 /* Don't check for errors.  The child may be dead already,
1487                  * in which case setpgid returns error code EACCES. */
1488                 setpgid(child->pid, pi->pgrp);
1489
1490                 if (nextin != 0)
1491                         close(nextin);
1492                 if (nextout != 1)
1493                         close(nextout);
1494
1495                 /* If there isn't another process, nextin is garbage
1496                    but it doesn't matter */
1497                 nextin = pipefds[0];
1498         }
1499         return -1;
1500 }
1501
1502 static int run_list_real(struct pipe *pi)
1503 {
1504         char *save_name = NULL;
1505         char **list = NULL;
1506         char **save_list = NULL;
1507         struct pipe *rpipe;
1508         int flag_rep = 0;
1509         int save_num_progs;
1510         int rcode=0, flag_skip=1;
1511         int flag_restore = 0;
1512         int if_code=0, next_if_code=0;  /* need double-buffer to handle elif */
1513         reserved_style rmode, skip_more_in_this_rmode=RES_XXXX;
1514         /* check syntax for "for" */
1515         for (rpipe = pi; rpipe; rpipe = rpipe->next) {
1516                 if ((rpipe->r_mode == RES_IN ||
1517                     rpipe->r_mode == RES_FOR) &&
1518                     (rpipe->next == NULL)) {
1519                                 syntax();
1520                                 return 1;
1521                 }
1522                 if ((rpipe->r_mode == RES_IN &&
1523                         (rpipe->next->r_mode == RES_IN &&
1524                         rpipe->next->progs->argv != NULL))||
1525                         (rpipe->r_mode == RES_FOR &&
1526                         rpipe->next->r_mode != RES_IN)) {
1527                                 syntax();
1528                                 return 1;
1529                 }
1530         }
1531         for (; pi; pi = (flag_restore != 0) ? rpipe : pi->next) {
1532                 if (pi->r_mode == RES_WHILE || pi->r_mode == RES_UNTIL ||
1533                         pi->r_mode == RES_FOR) {
1534                                 flag_restore = 0;
1535                                 if (!rpipe) {
1536                                         flag_rep = 0;
1537                                         rpipe = pi;
1538                                 }
1539                 }
1540                 rmode = pi->r_mode;
1541                 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);
1542                 if (rmode == skip_more_in_this_rmode && flag_skip) {
1543                         if (pi->followup == PIPE_SEQ) flag_skip=0;
1544                         continue;
1545                 }
1546                 flag_skip = 1;
1547                 skip_more_in_this_rmode = RES_XXXX;
1548                 if (rmode == RES_THEN || rmode == RES_ELSE) if_code = next_if_code;
1549                 if (rmode == RES_THEN &&  if_code) continue;
1550                 if (rmode == RES_ELSE && !if_code) continue;
1551                 if (rmode == RES_ELIF && !if_code) break;
1552                 if (rmode == RES_FOR && pi->num_progs) {
1553                         if (!list) {
1554                                 /* if no variable values after "in" we skip "for" */
1555                                 if (!pi->next->progs->argv) continue;
1556                                 /* create list of variable values */
1557                                 list = make_list_in(pi->next->progs->argv,
1558                                         pi->progs->argv[0]);
1559                                 save_list = list;
1560                                 save_name = pi->progs->argv[0];
1561                                 pi->progs->argv[0] = NULL;
1562                                 flag_rep = 1;
1563                         }
1564                         if (!(*list)) {
1565                                 free(pi->progs->argv[0]);
1566                                 free(save_list);
1567                                 list = NULL;
1568                                 flag_rep = 0;
1569                                 pi->progs->argv[0] = save_name;
1570                                 pi->progs->glob_result.gl_pathv[0] =
1571                                         pi->progs->argv[0];
1572                                 continue;
1573                         } else {
1574                                 /* insert new value from list for variable */
1575                                 if (pi->progs->argv[0])
1576                                         free(pi->progs->argv[0]);
1577                                 pi->progs->argv[0] = *list++;
1578                                 pi->progs->glob_result.gl_pathv[0] =
1579                                         pi->progs->argv[0];
1580                         }
1581                 }
1582                 if (rmode == RES_IN) continue;
1583                 if (rmode == RES_DO) {
1584                         if (!flag_rep) continue;
1585                 }
1586                 if ((rmode == RES_DONE)) {
1587                         if (flag_rep) {
1588                                 flag_restore = 1;
1589                         } else {
1590                                 rpipe = NULL;
1591                         }
1592                 }
1593                 if (pi->num_progs == 0) continue;
1594                 save_num_progs = pi->num_progs; /* save number of programs */
1595                 rcode = run_pipe_real(pi);
1596                 debug_printf("run_pipe_real returned %d\n",rcode);
1597                 if (rcode!=-1) {
1598                         /* We only ran a builtin: rcode was set by the return value
1599                          * of run_pipe_real(), and we don't need to wait for anything. */
1600                 } else if (pi->followup==PIPE_BG) {
1601                         /* XXX check bash's behavior with nontrivial pipes */
1602                         /* XXX compute jobid */
1603                         /* XXX what does bash do with attempts to background builtins? */
1604                         insert_bg_job(pi);
1605                         rcode = EXIT_SUCCESS;
1606                 } else {
1607                         if (interactive) {
1608                                 /* move the new process group into the foreground */
1609                                 if (tcsetpgrp(shell_terminal, pi->pgrp) && errno != ENOTTY)
1610                                         bb_perror_msg("tcsetpgrp-3");
1611                                 rcode = checkjobs(pi);
1612                                 /* move the shell to the foreground */
1613                                 if (tcsetpgrp(shell_terminal, getpgid(0)) && errno != ENOTTY)
1614                                         bb_perror_msg("tcsetpgrp-4");
1615                         } else {
1616                                 rcode = checkjobs(pi);
1617                         }
1618                         debug_printf("checkjobs returned %d\n",rcode);
1619                 }
1620                 last_return_code=rcode;
1621                 pi->num_progs = save_num_progs; /* restore number of programs */
1622                 if ( rmode == RES_IF || rmode == RES_ELIF )
1623                         next_if_code=rcode;  /* can be overwritten a number of times */
1624                 if (rmode == RES_WHILE)
1625                         flag_rep = !last_return_code;
1626                 if (rmode == RES_UNTIL)
1627                         flag_rep = last_return_code;
1628                 if ( (rcode==EXIT_SUCCESS && pi->followup==PIPE_OR) ||
1629                      (rcode!=EXIT_SUCCESS && pi->followup==PIPE_AND) )
1630                         skip_more_in_this_rmode=rmode;
1631                 checkjobs(NULL);
1632         }
1633         return rcode;
1634 }
1635
1636 /* broken, of course, but OK for testing */
1637 static char *indenter(int i)
1638 {
1639         static char blanks[]="                                    ";
1640         return &blanks[sizeof(blanks)-i-1];
1641 }
1642
1643 /* return code is the exit status of the pipe */
1644 static int free_pipe(struct pipe *pi, int indent)
1645 {
1646         char **p;
1647         struct child_prog *child;
1648         struct redir_struct *r, *rnext;
1649         int a, i, ret_code=0;
1650         char *ind = indenter(indent);
1651
1652         if (pi->stopped_progs > 0)
1653                 return ret_code;
1654         final_printf("%s run pipe: (pid %d)\n",ind,getpid());
1655         for (i=0; i<pi->num_progs; i++) {
1656                 child = &pi->progs[i];
1657                 final_printf("%s  command %d:\n",ind,i);
1658                 if (child->argv) {
1659                         for (a=0,p=child->argv; *p; a++,p++) {
1660                                 final_printf("%s   argv[%d] = %s\n",ind,a,*p);
1661                         }
1662                         globfree(&child->glob_result);
1663                         child->argv=NULL;
1664                 } else if (child->group) {
1665                         final_printf("%s   begin group (subshell:%d)\n",ind, child->subshell);
1666                         ret_code = free_pipe_list(child->group,indent+3);
1667                         final_printf("%s   end group\n",ind);
1668                 } else {
1669                         final_printf("%s   (nil)\n",ind);
1670                 }
1671                 for (r=child->redirects; r; r=rnext) {
1672                         final_printf("%s   redirect %d%s", ind, r->fd, redir_table[r->type].descrip);
1673                         if (r->dup == -1) {
1674                                 /* guard against the case >$FOO, where foo is unset or blank */
1675                                 if (r->word.gl_pathv) {
1676                                         final_printf(" %s\n", *r->word.gl_pathv);
1677                                         globfree(&r->word);
1678                                 }
1679                         } else {
1680                                 final_printf("&%d\n", r->dup);
1681                         }
1682                         rnext=r->next;
1683                         free(r);
1684                 }
1685                 child->redirects=NULL;
1686         }
1687         free(pi->progs);   /* children are an array, they get freed all at once */
1688         pi->progs=NULL;
1689         return ret_code;
1690 }
1691
1692 static int free_pipe_list(struct pipe *head, int indent)
1693 {
1694         int rcode=0;   /* if list has no members */
1695         struct pipe *pi, *next;
1696         char *ind = indenter(indent);
1697         for (pi=head; pi; pi=next) {
1698                 final_printf("%s pipe reserved mode %d\n", ind, pi->r_mode);
1699                 rcode = free_pipe(pi, indent);
1700                 final_printf("%s pipe followup code %d\n", ind, pi->followup);
1701                 next=pi->next;
1702                 pi->next=NULL;
1703                 free(pi);
1704         }
1705         return rcode;
1706 }
1707
1708 /* Select which version we will use */
1709 static int run_list(struct pipe *pi)
1710 {
1711         int rcode=0;
1712         if (fake_mode==0) {
1713                 rcode = run_list_real(pi);
1714         }
1715         /* free_pipe_list has the side effect of clearing memory
1716          * In the long run that function can be merged with run_list_real,
1717          * but doing that now would hobble the debugging effort. */
1718         free_pipe_list(pi,0);
1719         return rcode;
1720 }
1721
1722 /* The API for glob is arguably broken.  This routine pushes a non-matching
1723  * string into the output structure, removing non-backslashed backslashes.
1724  * If someone can prove me wrong, by performing this function within the
1725  * original glob(3) api, feel free to rewrite this routine into oblivion.
1726  * Return code (0 vs. GLOB_NOSPACE) matches glob(3).
1727  * XXX broken if the last character is '\\', check that before calling.
1728  */
1729 static int globhack(const char *src, int flags, glob_t *pglob)
1730 {
1731         int cnt=0, pathc;
1732         const char *s;
1733         char *dest;
1734         for (cnt=1, s=src; s && *s; s++) {
1735                 if (*s == '\\') s++;
1736                 cnt++;
1737         }
1738         dest = malloc(cnt);
1739         if (!dest) return GLOB_NOSPACE;
1740         if (!(flags & GLOB_APPEND)) {
1741                 pglob->gl_pathv=NULL;
1742                 pglob->gl_pathc=0;
1743                 pglob->gl_offs=0;
1744                 pglob->gl_offs=0;
1745         }
1746         pathc = ++pglob->gl_pathc;
1747         pglob->gl_pathv = realloc(pglob->gl_pathv, (pathc+1)*sizeof(*pglob->gl_pathv));
1748         if (pglob->gl_pathv == NULL) return GLOB_NOSPACE;
1749         pglob->gl_pathv[pathc-1]=dest;
1750         pglob->gl_pathv[pathc]=NULL;
1751         for (s=src; s && *s; s++, dest++) {
1752                 if (*s == '\\') s++;
1753                 *dest = *s;
1754         }
1755         *dest='\0';
1756         return 0;
1757 }
1758
1759 /* XXX broken if the last character is '\\', check that before calling */
1760 static int glob_needed(const char *s)
1761 {
1762         for (; *s; s++) {
1763                 if (*s == '\\') s++;
1764                 if (strchr("*[?",*s)) return 1;
1765         }
1766         return 0;
1767 }
1768
1769 #if 0
1770 static void globprint(glob_t *pglob)
1771 {
1772         int i;
1773         debug_printf("glob_t at %p:\n", pglob);
1774         debug_printf("  gl_pathc=%d  gl_pathv=%p  gl_offs=%d  gl_flags=%d\n",
1775                 pglob->gl_pathc, pglob->gl_pathv, pglob->gl_offs, pglob->gl_flags);
1776         for (i=0; i<pglob->gl_pathc; i++)
1777                 debug_printf("pglob->gl_pathv[%d] = %p = %s\n", i,
1778                         pglob->gl_pathv[i], pglob->gl_pathv[i]);
1779 }
1780 #endif
1781
1782 static int xglob(o_string *dest, int flags, glob_t *pglob)
1783 {
1784         int gr;
1785
1786         /* short-circuit for null word */
1787         /* we can code this better when the debug_printf's are gone */
1788         if (dest->length == 0) {
1789                 if (dest->nonnull) {
1790                         /* bash man page calls this an "explicit" null */
1791                         gr = globhack(dest->data, flags, pglob);
1792                         debug_printf("globhack returned %d\n",gr);
1793                 } else {
1794                         return 0;
1795                 }
1796         } else if (glob_needed(dest->data)) {
1797                 gr = glob(dest->data, flags, NULL, pglob);
1798                 debug_printf("glob returned %d\n",gr);
1799                 if (gr == GLOB_NOMATCH) {
1800                         /* quote removal, or more accurately, backslash removal */
1801                         gr = globhack(dest->data, flags, pglob);
1802                         debug_printf("globhack returned %d\n",gr);
1803                 }
1804         } else {
1805                 gr = globhack(dest->data, flags, pglob);
1806                 debug_printf("globhack returned %d\n",gr);
1807         }
1808         if (gr == GLOB_NOSPACE)
1809                 bb_error_msg_and_die("out of memory during glob");
1810         if (gr != 0) { /* GLOB_ABORTED ? */
1811                 bb_error_msg("glob(3) error %d",gr);
1812         }
1813         /* globprint(glob_target); */
1814         return gr;
1815 }
1816
1817 /* This is used to get/check local shell variables */
1818 static char *get_local_var(const char *s)
1819 {
1820         struct variables *cur;
1821
1822         if (!s)
1823                 return NULL;
1824         for (cur = top_vars; cur; cur=cur->next)
1825                 if(strcmp(cur->name, s)==0)
1826                         return cur->value;
1827         return NULL;
1828 }
1829
1830 /* This is used to set local shell variables
1831    flg_export==0 if only local (not exporting) variable
1832    flg_export==1 if "new" exporting environ
1833    flg_export>1  if current startup environ (not call putenv()) */
1834 static int set_local_var(const char *s, int flg_export)
1835 {
1836         char *name, *value;
1837         int result=0;
1838         struct variables *cur;
1839
1840         name=strdup(s);
1841
1842         /* Assume when we enter this function that we are already in
1843          * NAME=VALUE format.  So the first order of business is to
1844          * split 's' on the '=' into 'name' and 'value' */
1845         value = strchr(name, '=');
1846         if (value==0 && ++value==0) {
1847                 free(name);
1848                 return -1;
1849         }
1850         *value++ = 0;
1851
1852         for(cur = top_vars; cur; cur = cur->next) {
1853                 if(strcmp(cur->name, name)==0)
1854                         break;
1855         }
1856
1857         if(cur) {
1858                 if(strcmp(cur->value, value)==0) {
1859                         if(flg_export>0 && cur->flg_export==0)
1860                                 cur->flg_export=flg_export;
1861                         else
1862                                 result++;
1863                 } else {
1864                         if(cur->flg_read_only) {
1865                                 bb_error_msg("%s: readonly variable", name);
1866                                 result = -1;
1867                         } else {
1868                                 if(flg_export>0 || cur->flg_export>1)
1869                                         cur->flg_export=1;
1870                                 free(cur->value);
1871
1872                                 cur->value = strdup(value);
1873                         }
1874                 }
1875         } else {
1876                 cur = malloc(sizeof(struct variables));
1877                 if(!cur) {
1878                         result = -1;
1879                 } else {
1880                         cur->name = strdup(name);
1881                         if(cur->name == 0) {
1882                                 free(cur);
1883                                 result = -1;
1884                         } else {
1885                                 struct variables *bottom = top_vars;
1886                                 cur->value = strdup(value);
1887                                 cur->next = 0;
1888                                 cur->flg_export = flg_export;
1889                                 cur->flg_read_only = 0;
1890                                 while(bottom->next) bottom=bottom->next;
1891                                 bottom->next = cur;
1892                         }
1893                 }
1894         }
1895
1896         if(result==0 && cur->flg_export==1) {
1897                 *(value-1) = '=';
1898                 result = putenv(name);
1899         } else {
1900                 free(name);
1901                 if(result>0)            /* equivalent to previous set */
1902                         result = 0;
1903         }
1904         return result;
1905 }
1906
1907 static void unset_local_var(const char *name)
1908 {
1909         struct variables *cur;
1910
1911         if (name) {
1912                 for (cur = top_vars; cur; cur=cur->next) {
1913                         if(strcmp(cur->name, name)==0)
1914                                 break;
1915                 }
1916                 if(cur!=0) {
1917                         struct variables *next = top_vars;
1918                         if(cur->flg_read_only) {
1919                                 bb_error_msg("%s: readonly variable", name);
1920                                 return;
1921                         } else {
1922                                 if(cur->flg_export)
1923                                         unsetenv(cur->name);
1924                                 free(cur->name);
1925                                 free(cur->value);
1926                                 while (next->next != cur)
1927                                         next = next->next;
1928                                 next->next = cur->next;
1929                         }
1930                         free(cur);
1931                 }
1932         }
1933 }
1934
1935 static int is_assignment(const char *s)
1936 {
1937         if (s==NULL || !isalpha(*s)) return 0;
1938         ++s;
1939         while(isalnum(*s) || *s=='_') ++s;
1940         return *s=='=';
1941 }
1942
1943 /* the src parameter allows us to peek forward to a possible &n syntax
1944  * for file descriptor duplication, e.g., "2>&1".
1945  * Return code is 0 normally, 1 if a syntax error is detected in src.
1946  * Resource errors (in xmalloc) cause the process to exit */
1947 static int setup_redirect(struct p_context *ctx, int fd, redir_type style,
1948         struct in_str *input)
1949 {
1950         struct child_prog *child=ctx->child;
1951         struct redir_struct *redir = child->redirects;
1952         struct redir_struct *last_redir=NULL;
1953
1954         /* Create a new redir_struct and drop it onto the end of the linked list */
1955         while(redir) {
1956                 last_redir=redir;
1957                 redir=redir->next;
1958         }
1959         redir = xmalloc(sizeof(struct redir_struct));
1960         redir->next=NULL;
1961         redir->word.gl_pathv=NULL;
1962         if (last_redir) {
1963                 last_redir->next=redir;
1964         } else {
1965                 child->redirects=redir;
1966         }
1967
1968         redir->type=style;
1969         redir->fd= (fd==-1) ? redir_table[style].default_fd : fd ;
1970
1971         debug_printf("Redirect type %d%s\n", redir->fd, redir_table[style].descrip);
1972
1973         /* Check for a '2>&1' type redirect */
1974         redir->dup = redirect_dup_num(input);
1975         if (redir->dup == -2) return 1;  /* syntax error */
1976         if (redir->dup != -1) {
1977                 /* Erik had a check here that the file descriptor in question
1978                  * is legit; I postpone that to "run time"
1979                  * A "-" representation of "close me" shows up as a -3 here */
1980                 debug_printf("Duplicating redirect '%d>&%d'\n", redir->fd, redir->dup);
1981         } else {
1982                 /* We do _not_ try to open the file that src points to,
1983                  * since we need to return and let src be expanded first.
1984                  * Set ctx->pending_redirect, so we know what to do at the
1985                  * end of the next parsed word.
1986                  */
1987                 ctx->pending_redirect = redir;
1988         }
1989         return 0;
1990 }
1991
1992 static struct pipe *new_pipe(void) {
1993         struct pipe *pi;
1994         pi = xmalloc(sizeof(struct pipe));
1995         pi->num_progs = 0;
1996         pi->progs = NULL;
1997         pi->next = NULL;
1998         pi->followup = 0;  /* invalid */
1999         pi->r_mode = RES_NONE;
2000         return pi;
2001 }
2002
2003 static void initialize_context(struct p_context *ctx)
2004 {
2005         ctx->pipe=NULL;
2006         ctx->pending_redirect=NULL;
2007         ctx->child=NULL;
2008         ctx->list_head=new_pipe();
2009         ctx->pipe=ctx->list_head;
2010         ctx->w=RES_NONE;
2011         ctx->stack=NULL;
2012         ctx->old_flag=0;
2013         done_command(ctx);   /* creates the memory for working child */
2014 }
2015
2016 /* normal return is 0
2017  * if a reserved word is found, and processed, return 1
2018  * should handle if, then, elif, else, fi, for, while, until, do, done.
2019  * case, function, and select are obnoxious, save those for later.
2020  */
2021 static int reserved_word(o_string *dest, struct p_context *ctx)
2022 {
2023         struct reserved_combo {
2024                 char *literal;
2025                 int code;
2026                 long flag;
2027         };
2028         /* Mostly a list of accepted follow-up reserved words.
2029          * FLAG_END means we are done with the sequence, and are ready
2030          * to turn the compound list into a command.
2031          * FLAG_START means the word must start a new compound list.
2032          */
2033         static struct reserved_combo reserved_list[] = {
2034                 { "if",    RES_IF,    FLAG_THEN | FLAG_START },
2035                 { "then",  RES_THEN,  FLAG_ELIF | FLAG_ELSE | FLAG_FI },
2036                 { "elif",  RES_ELIF,  FLAG_THEN },
2037                 { "else",  RES_ELSE,  FLAG_FI   },
2038                 { "fi",    RES_FI,    FLAG_END  },
2039                 { "for",   RES_FOR,   FLAG_IN   | FLAG_START },
2040                 { "while", RES_WHILE, FLAG_DO   | FLAG_START },
2041                 { "until", RES_UNTIL, FLAG_DO   | FLAG_START },
2042                 { "in",    RES_IN,    FLAG_DO   },
2043                 { "do",    RES_DO,    FLAG_DONE },
2044                 { "done",  RES_DONE,  FLAG_END  }
2045         };
2046         struct reserved_combo *r;
2047         for (r=reserved_list;
2048 #define NRES sizeof(reserved_list)/sizeof(struct reserved_combo)
2049                 r<reserved_list+NRES; r++) {
2050                 if (strcmp(dest->data, r->literal) == 0) {
2051                         debug_printf("found reserved word %s, code %d\n",r->literal,r->code);
2052                         if (r->flag & FLAG_START) {
2053                                 struct p_context *new = xmalloc(sizeof(struct p_context));
2054                                 debug_printf("push stack\n");
2055                                 if (ctx->w == RES_IN || ctx->w == RES_FOR) {
2056                                         syntax();
2057                                         free(new);
2058                                         ctx->w = RES_SNTX;
2059                                         b_reset(dest);
2060                                         return 1;
2061                                 }
2062                                 *new = *ctx;   /* physical copy */
2063                                 initialize_context(ctx);
2064                                 ctx->stack=new;
2065                         } else if ( ctx->w == RES_NONE || ! (ctx->old_flag & (1<<r->code))) {
2066                                 syntax();
2067                                 ctx->w = RES_SNTX;
2068                                 b_reset(dest);
2069                                 return 1;
2070                         }
2071                         ctx->w=r->code;
2072                         ctx->old_flag = r->flag;
2073                         if (ctx->old_flag & FLAG_END) {
2074                                 struct p_context *old;
2075                                 debug_printf("pop stack\n");
2076                                 done_pipe(ctx,PIPE_SEQ);
2077                                 old = ctx->stack;
2078                                 old->child->group = ctx->list_head;
2079                                 old->child->subshell = 0;
2080                                 *ctx = *old;   /* physical copy */
2081                                 free(old);
2082                         }
2083                         b_reset (dest);
2084                         return 1;
2085                 }
2086         }
2087         return 0;
2088 }
2089
2090 /* normal return is 0.
2091  * Syntax or xglob errors return 1. */
2092 static int done_word(o_string *dest, struct p_context *ctx)
2093 {
2094         struct child_prog *child=ctx->child;
2095         glob_t *glob_target;
2096         int gr, flags = 0;
2097
2098         debug_printf("done_word: %s %p\n", dest->data, child);
2099         if (dest->length == 0 && !dest->nonnull) {
2100                 debug_printf("  true null, ignored\n");
2101                 return 0;
2102         }
2103         if (ctx->pending_redirect) {
2104                 glob_target = &ctx->pending_redirect->word;
2105         } else {
2106                 if (child->group) {
2107                         syntax();
2108                         return 1;  /* syntax error, groups and arglists don't mix */
2109                 }
2110                 if (!child->argv && (ctx->type & FLAG_PARSE_SEMICOLON)) {
2111                         debug_printf("checking %s for reserved-ness\n",dest->data);
2112                         if (reserved_word(dest,ctx)) return ctx->w==RES_SNTX;
2113                 }
2114                 glob_target = &child->glob_result;
2115                 if (child->argv) flags |= GLOB_APPEND;
2116         }
2117         gr = xglob(dest, flags, glob_target);
2118         if (gr != 0) return 1;
2119
2120         b_reset(dest);
2121         if (ctx->pending_redirect) {
2122                 ctx->pending_redirect=NULL;
2123                 if (glob_target->gl_pathc != 1) {
2124                         bb_error_msg("ambiguous redirect");
2125                         return 1;
2126                 }
2127         } else {
2128                 child->argv = glob_target->gl_pathv;
2129         }
2130         if (ctx->w == RES_FOR) {
2131                 done_word(dest,ctx);
2132                 done_pipe(ctx,PIPE_SEQ);
2133         }
2134         return 0;
2135 }
2136
2137 /* The only possible error here is out of memory, in which case
2138  * xmalloc exits. */
2139 static int done_command(struct p_context *ctx)
2140 {
2141         /* The child is really already in the pipe structure, so
2142          * advance the pipe counter and make a new, null child.
2143          * Only real trickiness here is that the uncommitted
2144          * child structure, to which ctx->child points, is not
2145          * counted in pi->num_progs. */
2146         struct pipe *pi=ctx->pipe;
2147         struct child_prog *prog=ctx->child;
2148
2149         if (prog && prog->group == NULL
2150                  && prog->argv == NULL
2151                  && prog->redirects == NULL) {
2152                 debug_printf("done_command: skipping null command\n");
2153                 return 0;
2154         } else if (prog) {
2155                 pi->num_progs++;
2156                 debug_printf("done_command: num_progs incremented to %d\n",pi->num_progs);
2157         } else {
2158                 debug_printf("done_command: initializing\n");
2159         }
2160         pi->progs = xrealloc(pi->progs, sizeof(*pi->progs) * (pi->num_progs+1));
2161
2162         prog = pi->progs + pi->num_progs;
2163         prog->redirects = NULL;
2164         prog->argv = NULL;
2165         prog->is_stopped = 0;
2166         prog->group = NULL;
2167         prog->glob_result.gl_pathv = NULL;
2168         prog->family = pi;
2169         prog->sp = 0;
2170         ctx->child = prog;
2171         prog->type = ctx->type;
2172
2173         /* but ctx->pipe and ctx->list_head remain unchanged */
2174         return 0;
2175 }
2176
2177 static int done_pipe(struct p_context *ctx, pipe_style type)
2178 {
2179         struct pipe *new_p;
2180         done_command(ctx);  /* implicit closure of previous command */
2181         debug_printf("done_pipe, type %d\n", type);
2182         ctx->pipe->followup = type;
2183         ctx->pipe->r_mode = ctx->w;
2184         new_p=new_pipe();
2185         ctx->pipe->next = new_p;
2186         ctx->pipe = new_p;
2187         ctx->child = NULL;
2188         done_command(ctx);  /* set up new pipe to accept commands */
2189         return 0;
2190 }
2191
2192 /* peek ahead in the in_str to find out if we have a "&n" construct,
2193  * as in "2>&1", that represents duplicating a file descriptor.
2194  * returns either -2 (syntax error), -1 (no &), or the number found.
2195  */
2196 static int redirect_dup_num(struct in_str *input)
2197 {
2198         int ch, d=0, ok=0;
2199         ch = b_peek(input);
2200         if (ch != '&') return -1;
2201
2202         b_getch(input);  /* get the & */
2203         ch=b_peek(input);
2204         if (ch == '-') {
2205                 b_getch(input);
2206                 return -3;  /* "-" represents "close me" */
2207         }
2208         while (isdigit(ch)) {
2209                 d = d*10+(ch-'0');
2210                 ok=1;
2211                 b_getch(input);
2212                 ch = b_peek(input);
2213         }
2214         if (ok) return d;
2215
2216         bb_error_msg("ambiguous redirect");
2217         return -2;
2218 }
2219
2220 /* If a redirect is immediately preceded by a number, that number is
2221  * supposed to tell which file descriptor to redirect.  This routine
2222  * looks for such preceding numbers.  In an ideal world this routine
2223  * needs to handle all the following classes of redirects...
2224  *     echo 2>foo     # redirects fd  2 to file "foo", nothing passed to echo
2225  *     echo 49>foo    # redirects fd 49 to file "foo", nothing passed to echo
2226  *     echo -2>foo    # redirects fd  1 to file "foo",    "-2" passed to echo
2227  *     echo 49x>foo   # redirects fd  1 to file "foo",   "49x" passed to echo
2228  * A -1 output from this program means no valid number was found, so the
2229  * caller should use the appropriate default for this redirection.
2230  */
2231 static int redirect_opt_num(o_string *o)
2232 {
2233         int num;
2234
2235         if (o->length==0) return -1;
2236         for(num=0; num<o->length; num++) {
2237                 if (!isdigit(*(o->data+num))) {
2238                         return -1;
2239                 }
2240         }
2241         /* reuse num (and save an int) */
2242         num=atoi(o->data);
2243         b_reset(o);
2244         return num;
2245 }
2246
2247 static FILE *generate_stream_from_list(struct pipe *head)
2248 {
2249         FILE *pf;
2250 #if 1
2251         int pid, channel[2];
2252         if (pipe(channel)<0) bb_perror_msg_and_die("pipe");
2253 #if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
2254         pid=fork();
2255 #else
2256         pid=vfork();
2257 #endif
2258         if (pid<0) {
2259                 bb_perror_msg_and_die("fork");
2260         } else if (pid==0) {
2261                 close(channel[0]);
2262                 if (channel[1] != 1) {
2263                         dup2(channel[1],1);
2264                         close(channel[1]);
2265                 }
2266 #if 0
2267 #define SURROGATE "surrogate response"
2268                 write(1,SURROGATE,sizeof(SURROGATE));
2269                 _exit(run_list(head));
2270 #else
2271                 _exit(run_list_real(head));   /* leaks memory */
2272 #endif
2273         }
2274         debug_printf("forked child %d\n",pid);
2275         close(channel[1]);
2276         pf = fdopen(channel[0],"r");
2277         debug_printf("pipe on FILE *%p\n",pf);
2278 #else
2279         free_pipe_list(head,0);
2280         pf=popen("echo surrogate response","r");
2281         debug_printf("started fake pipe on FILE *%p\n",pf);
2282 #endif
2283         return pf;
2284 }
2285
2286 /* this version hacked for testing purposes */
2287 /* return code is exit status of the process that is run. */
2288 static int process_command_subs(o_string *dest, struct p_context *ctx, struct in_str *input, int subst_end)
2289 {
2290         int retcode;
2291         o_string result=NULL_O_STRING;
2292         struct p_context inner;
2293         FILE *p;
2294         struct in_str pipe_str;
2295         initialize_context(&inner);
2296
2297         /* recursion to generate command */
2298         retcode = parse_stream(&result, &inner, input, subst_end);
2299         if (retcode != 0) return retcode;  /* syntax error or EOF */
2300         done_word(&result, &inner);
2301         done_pipe(&inner, PIPE_SEQ);
2302         b_free(&result);
2303
2304         p=generate_stream_from_list(inner.list_head);
2305         if (p==NULL) return 1;
2306         mark_open(fileno(p));
2307         setup_file_in_str(&pipe_str, p);
2308
2309         /* now send results of command back into original context */
2310         retcode = parse_stream(dest, ctx, &pipe_str, '\0');
2311         /* XXX In case of a syntax error, should we try to kill the child?
2312          * That would be tough to do right, so just read until EOF. */
2313         if (retcode == 1) {
2314                 while (b_getch(&pipe_str)!=EOF) { /* discard */ };
2315         }
2316
2317         debug_printf("done reading from pipe, pclose()ing\n");
2318         /* This is the step that wait()s for the child.  Should be pretty
2319          * safe, since we just read an EOF from its stdout.  We could try
2320          * to better, by using wait(), and keeping track of background jobs
2321          * at the same time.  That would be a lot of work, and contrary
2322          * to the KISS philosophy of this program. */
2323         mark_closed(fileno(p));
2324         retcode=pclose(p);
2325         free_pipe_list(inner.list_head,0);
2326         debug_printf("pclosed, retcode=%d\n",retcode);
2327         /* XXX this process fails to trim a single trailing newline */
2328         return retcode;
2329 }
2330
2331 static int parse_group(o_string *dest, struct p_context *ctx,
2332         struct in_str *input, int ch)
2333 {
2334         int rcode, endch=0;
2335         struct p_context sub;
2336         struct child_prog *child = ctx->child;
2337         if (child->argv) {
2338                 syntax();
2339                 return 1;  /* syntax error, groups and arglists don't mix */
2340         }
2341         initialize_context(&sub);
2342         switch(ch) {
2343                 case '(': endch=')'; child->subshell=1; break;
2344                 case '{': endch='}'; break;
2345                 default: syntax();   /* really logic error */
2346         }
2347         rcode=parse_stream(dest,&sub,input,endch);
2348         done_word(dest,&sub); /* finish off the final word in the subcontext */
2349         done_pipe(&sub, PIPE_SEQ);  /* and the final command there, too */
2350         child->group = sub.list_head;
2351         return rcode;
2352         /* child remains "open", available for possible redirects */
2353 }
2354
2355 /* basically useful version until someone wants to get fancier,
2356  * see the bash man page under "Parameter Expansion" */
2357 static char *lookup_param(char *src)
2358 {
2359         char *p=NULL;
2360         if (src) {
2361                 p = getenv(src);
2362                 if (!p)
2363                         p = get_local_var(src);
2364         }
2365         return p;
2366 }
2367
2368 /* return code: 0 for OK, 1 for syntax error */
2369 static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input)
2370 {
2371         int i, advance=0;
2372         char sep[]=" ";
2373         int ch = input->peek(input);  /* first character after the $ */
2374         debug_printf("handle_dollar: ch=%c\n",ch);
2375         if (isalpha(ch)) {
2376                 b_addchr(dest, SPECIAL_VAR_SYMBOL);
2377                 ctx->child->sp++;
2378                 while(ch=b_peek(input),isalnum(ch) || ch=='_') {
2379                         b_getch(input);
2380                         b_addchr(dest,ch);
2381                 }
2382                 b_addchr(dest, SPECIAL_VAR_SYMBOL);
2383         } else if (isdigit(ch)) {
2384                 i = ch-'0';  /* XXX is $0 special? */
2385                 if (i<global_argc) {
2386                         parse_string(dest, ctx, global_argv[i]); /* recursion */
2387                 }
2388                 advance = 1;
2389         } else switch (ch) {
2390                 case '$':
2391                         b_adduint(dest,getpid());
2392                         advance = 1;
2393                         break;
2394                 case '!':
2395                         if (last_bg_pid > 0) b_adduint(dest, last_bg_pid);
2396                         advance = 1;
2397                         break;
2398                 case '?':
2399                         b_adduint(dest,last_return_code);
2400                         advance = 1;
2401                         break;
2402                 case '#':
2403                         b_adduint(dest,global_argc ? global_argc-1 : 0);
2404                         advance = 1;
2405                         break;
2406                 case '{':
2407                         b_addchr(dest, SPECIAL_VAR_SYMBOL);
2408                         ctx->child->sp++;
2409                         b_getch(input);
2410                         /* XXX maybe someone will try to escape the '}' */
2411                         while(ch=b_getch(input),ch!=EOF && ch!='}') {
2412                                 b_addchr(dest,ch);
2413                         }
2414                         if (ch != '}') {
2415                                 syntax();
2416                                 return 1;
2417                         }
2418                         b_addchr(dest, SPECIAL_VAR_SYMBOL);
2419                         break;
2420                 case '(':
2421                         b_getch(input);
2422                         process_command_subs(dest, ctx, input, ')');
2423                         break;
2424                 case '*':
2425                         sep[0]=ifs[0];
2426                         for (i=1; i<global_argc; i++) {
2427                                 parse_string(dest, ctx, global_argv[i]);
2428                                 if (i+1 < global_argc) parse_string(dest, ctx, sep);
2429                         }
2430                         break;
2431                 case '@':
2432                 case '-':
2433                 case '_':
2434                         /* still unhandled, but should be eventually */
2435                         bb_error_msg("unhandled syntax: $%c",ch);
2436                         return 1;
2437                         break;
2438                 default:
2439                         b_addqchr(dest,'$',dest->quote);
2440         }
2441         /* Eat the character if the flag was set.  If the compiler
2442          * is smart enough, we could substitute "b_getch(input);"
2443          * for all the "advance = 1;" above, and also end up with
2444          * a nice size-optimized program.  Hah!  That'll be the day.
2445          */
2446         if (advance) b_getch(input);
2447         return 0;
2448 }
2449
2450 int parse_string(o_string *dest, struct p_context *ctx, const char *src)
2451 {
2452         struct in_str foo;
2453         setup_string_in_str(&foo, src);
2454         return parse_stream(dest, ctx, &foo, '\0');
2455 }
2456
2457 /* return code is 0 for normal exit, 1 for syntax error */
2458 int parse_stream(o_string *dest, struct p_context *ctx,
2459         struct in_str *input, int end_trigger)
2460 {
2461         int ch, m;
2462         int redir_fd;
2463         redir_type redir_style;
2464         int next;
2465
2466         /* Only double-quote state is handled in the state variable dest->quote.
2467          * A single-quote triggers a bypass of the main loop until its mate is
2468          * found.  When recursing, quote state is passed in via dest->quote. */
2469
2470         debug_printf("parse_stream, end_trigger=%d\n",end_trigger);
2471         while ((ch=b_getch(input))!=EOF) {
2472                 m = map[ch];
2473                 next = (ch == '\n') ? 0 : b_peek(input);
2474                 debug_printf("parse_stream: ch=%c (%d) m=%d quote=%d\n",
2475                         ch,ch,m,dest->quote);
2476                 if (m==0 || ((m==1 || m==2) && dest->quote)) {
2477                         b_addqchr(dest, ch, dest->quote);
2478                 } else {
2479                         if (m==2) {  /* unquoted IFS */
2480                                 if (done_word(dest, ctx)) {
2481                                         return 1;
2482                                 }
2483                                 /* If we aren't performing a substitution, treat a newline as a
2484                                  * command separator.  */
2485                                 if (end_trigger != '\0' && ch=='\n')
2486                                         done_pipe(ctx,PIPE_SEQ);
2487                         }
2488                         if (ch == end_trigger && !dest->quote && ctx->w==RES_NONE) {
2489                                 debug_printf("leaving parse_stream (triggered)\n");
2490                                 return 0;
2491                         }
2492 #if 0
2493                         if (ch=='\n') {
2494                                 /* Yahoo!  Time to run with it! */
2495                                 done_pipe(ctx,PIPE_SEQ);
2496                                 run_list(ctx->list_head);
2497                                 initialize_context(ctx);
2498                         }
2499 #endif
2500                         if (m!=2) switch (ch) {
2501                 case '#':
2502                         if (dest->length == 0 && !dest->quote) {
2503                                 while(ch=b_peek(input),ch!=EOF && ch!='\n') { b_getch(input); }
2504                         } else {
2505                                 b_addqchr(dest, ch, dest->quote);
2506                         }
2507                         break;
2508                 case '\\':
2509                         if (next == EOF) {
2510                                 syntax();
2511                                 return 1;
2512                         }
2513                         b_addqchr(dest, '\\', dest->quote);
2514                         b_addqchr(dest, b_getch(input), dest->quote);
2515                         break;
2516                 case '$':
2517                         if (handle_dollar(dest, ctx, input)!=0) return 1;
2518                         break;
2519                 case '\'':
2520                         dest->nonnull = 1;
2521                         while(ch=b_getch(input),ch!=EOF && ch!='\'') {
2522                                 b_addchr(dest,ch);
2523                         }
2524                         if (ch==EOF) {
2525                                 syntax();
2526                                 return 1;
2527                         }
2528                         break;
2529                 case '"':
2530                         dest->nonnull = 1;
2531                         dest->quote = !dest->quote;
2532                         break;
2533                 case '`':
2534                         process_command_subs(dest, ctx, input, '`');
2535                         break;
2536                 case '>':
2537                         redir_fd = redirect_opt_num(dest);
2538                         done_word(dest, ctx);
2539                         redir_style=REDIRECT_OVERWRITE;
2540                         if (next == '>') {
2541                                 redir_style=REDIRECT_APPEND;
2542                                 b_getch(input);
2543                         } else if (next == '(') {
2544                                 syntax();   /* until we support >(list) Process Substitution */
2545                                 return 1;
2546                         }
2547                         setup_redirect(ctx, redir_fd, redir_style, input);
2548                         break;
2549                 case '<':
2550                         redir_fd = redirect_opt_num(dest);
2551                         done_word(dest, ctx);
2552                         redir_style=REDIRECT_INPUT;
2553                         if (next == '<') {
2554                                 redir_style=REDIRECT_HEREIS;
2555                                 b_getch(input);
2556                         } else if (next == '>') {
2557                                 redir_style=REDIRECT_IO;
2558                                 b_getch(input);
2559                         } else if (next == '(') {
2560                                 syntax();   /* until we support <(list) Process Substitution */
2561                                 return 1;
2562                         }
2563                         setup_redirect(ctx, redir_fd, redir_style, input);
2564                         break;
2565                 case ';':
2566                         done_word(dest, ctx);
2567                         done_pipe(ctx,PIPE_SEQ);
2568                         break;
2569                 case '&':
2570                         done_word(dest, ctx);
2571                         if (next=='&') {
2572                                 b_getch(input);
2573                                 done_pipe(ctx,PIPE_AND);
2574                         } else {
2575                                 done_pipe(ctx,PIPE_BG);
2576                         }
2577                         break;
2578                 case '|':
2579                         done_word(dest, ctx);
2580                         if (next=='|') {
2581                                 b_getch(input);
2582                                 done_pipe(ctx,PIPE_OR);
2583                         } else {
2584                                 /* we could pick up a file descriptor choice here
2585                                  * with redirect_opt_num(), but bash doesn't do it.
2586                                  * "echo foo 2| cat" yields "foo 2". */
2587                                 done_command(ctx);
2588                         }
2589                         break;
2590                 case '(':
2591                 case '{':
2592                         if (parse_group(dest, ctx, input, ch)!=0) return 1;
2593                         break;
2594                 case ')':
2595                 case '}':
2596                         syntax();   /* Proper use of this character caught by end_trigger */
2597                         return 1;
2598                         break;
2599                 default:
2600                         syntax();   /* this is really an internal logic error */
2601                         return 1;
2602                         }
2603                 }
2604         }
2605         /* complain if quote?  No, maybe we just finished a command substitution
2606          * that was quoted.  Example:
2607          * $ echo "`cat foo` plus more"
2608          * and we just got the EOF generated by the subshell that ran "cat foo"
2609          * The only real complaint is if we got an EOF when end_trigger != '\0',
2610          * that is, we were really supposed to get end_trigger, and never got
2611          * one before the EOF.  Can't use the standard "syntax error" return code,
2612          * so that parse_stream_outer can distinguish the EOF and exit smoothly. */
2613         debug_printf("leaving parse_stream (EOF)\n");
2614         if (end_trigger != '\0') return -1;
2615         return 0;
2616 }
2617
2618 static void mapset(const char *set, int code)
2619 {
2620         const unsigned char *s;
2621         for (s = (const unsigned char *)set; *s; s++) map[(int)*s] = code;
2622 }
2623
2624 static void update_ifs_map(void)
2625 {
2626         /* char *ifs and char map[256] are both globals. */
2627         ifs = getenv("IFS");
2628         if (ifs == NULL) ifs=" \t\n";
2629         /* Precompute a list of 'flow through' behavior so it can be treated
2630          * quickly up front.  Computation is necessary because of IFS.
2631          * Special case handling of IFS == " \t\n" is not implemented.
2632          * The map[] array only really needs two bits each, and on most machines
2633          * that would be faster because of the reduced L1 cache footprint.
2634          */
2635         memset(map,0,sizeof(map)); /* most characters flow through always */
2636         mapset("\\$'\"`", 3);      /* never flow through */
2637         mapset("<>;&|(){}#", 1);   /* flow through if quoted */
2638         mapset(ifs, 2);            /* also flow through if quoted */
2639 }
2640
2641 /* most recursion does not come through here, the exception is
2642  * from builtin_source() */
2643 int parse_stream_outer(struct in_str *inp, int flag)
2644 {
2645
2646         struct p_context ctx;
2647         o_string temp=NULL_O_STRING;
2648         int rcode;
2649         do {
2650                 ctx.type = flag;
2651                 initialize_context(&ctx);
2652                 update_ifs_map();
2653                 if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) mapset(";$&|", 0);
2654                 inp->promptmode=1;
2655                 rcode = parse_stream(&temp, &ctx, inp, '\n');
2656                 if (rcode != 1 && ctx.old_flag != 0) {
2657                         syntax();
2658                 }
2659                 if (rcode != 1 && ctx.old_flag == 0) {
2660                         done_word(&temp, &ctx);
2661                         done_pipe(&ctx,PIPE_SEQ);
2662                         run_list(ctx.list_head);
2663                 } else {
2664                         if (ctx.old_flag != 0) {
2665                                 free(ctx.stack);
2666                                 b_reset(&temp);
2667                         }
2668                         temp.nonnull = 0;
2669                         temp.quote = 0;
2670                         inp->p = NULL;
2671                         free_pipe_list(ctx.list_head,0);
2672                 }
2673                 b_free(&temp);
2674         } while (rcode != -1 && !(flag & FLAG_EXIT_FROM_LOOP));   /* loop on syntax errors, return on EOF */
2675         return 0;
2676 }
2677
2678 static int parse_string_outer(const char *s, int flag)
2679 {
2680         struct in_str input;
2681         setup_string_in_str(&input, s);
2682         return parse_stream_outer(&input, flag);
2683 }
2684
2685 static int parse_file_outer(FILE *f)
2686 {
2687         int rcode;
2688         struct in_str input;
2689         setup_file_in_str(&input, f);
2690         rcode = parse_stream_outer(&input, FLAG_PARSE_SEMICOLON);
2691         return rcode;
2692 }
2693
2694 /* Make sure we have a controlling tty.  If we get started under a job
2695  * aware app (like bash for example), make sure we are now in charge so
2696  * we don't fight over who gets the foreground */
2697 static void setup_job_control(void)
2698 {
2699         static pid_t shell_pgrp;
2700         /* Loop until we are in the foreground.  */
2701         while (tcgetpgrp (shell_terminal) != (shell_pgrp = getpgrp ()))
2702                 kill (- shell_pgrp, SIGTTIN);
2703
2704         /* Ignore interactive and job-control signals.  */
2705         signal(SIGINT, SIG_IGN);
2706         signal(SIGQUIT, SIG_IGN);
2707         signal(SIGTERM, SIG_IGN);
2708         signal(SIGTSTP, SIG_IGN);
2709         signal(SIGTTIN, SIG_IGN);
2710         signal(SIGTTOU, SIG_IGN);
2711         signal(SIGCHLD, SIG_IGN);
2712
2713         /* Put ourselves in our own process group.  */
2714         setsid();
2715         shell_pgrp = getpid ();
2716         setpgid (shell_pgrp, shell_pgrp);
2717
2718         /* Grab control of the terminal.  */
2719         tcsetpgrp(shell_terminal, shell_pgrp);
2720 }
2721
2722 int hush_main(int argc, char **argv)
2723 {
2724         int opt;
2725         FILE *input;
2726         char **e = environ;
2727
2728         /* XXX what should these be while sourcing /etc/profile? */
2729         global_argc = argc;
2730         global_argv = argv;
2731
2732         /* (re?) initialize globals.  Sometimes hush_main() ends up calling
2733          * hush_main(), therefore we cannot rely on the BSS to zero out this
2734          * stuff.  Reset these to 0 every time. */
2735         ifs = NULL;
2736         /* map[] is taken care of with call to update_ifs_map() */
2737         fake_mode = 0;
2738         interactive = 0;
2739         close_me_head = NULL;
2740         last_bg_pid = 0;
2741         job_list = NULL;
2742         last_jobid = 0;
2743
2744         /* Initialize some more globals to non-zero values */
2745         set_cwd();
2746 #ifdef CONFIG_FEATURE_COMMAND_EDITING
2747         cmdedit_set_initial_prompt();
2748 #else
2749         PS1 = NULL;
2750 #endif
2751         PS2 = "> ";
2752
2753         /* initialize our shell local variables with the values
2754          * currently living in the environment */
2755         if (e) {
2756                 for (; *e; e++)
2757                         set_local_var(*e, 2);   /* without call putenv() */
2758         }
2759
2760         last_return_code=EXIT_SUCCESS;
2761
2762
2763         if (argv[0] && argv[0][0] == '-') {
2764                 debug_printf("\nsourcing /etc/profile\n");
2765                 if ((input = fopen("/etc/profile", "r")) != NULL) {
2766                         mark_open(fileno(input));
2767                         parse_file_outer(input);
2768                         mark_closed(fileno(input));
2769                         fclose(input);
2770                 }
2771         }
2772         input=stdin;
2773
2774         while ((opt = getopt(argc, argv, "c:xif")) > 0) {
2775                 switch (opt) {
2776                         case 'c':
2777                                 {
2778                                         global_argv = argv+optind;
2779                                         global_argc = argc-optind;
2780                                         opt = parse_string_outer(optarg, FLAG_PARSE_SEMICOLON);
2781                                         goto final_return;
2782                                 }
2783                                 break;
2784                         case 'i':
2785                                 interactive++;
2786                                 break;
2787                         case 'f':
2788                                 fake_mode++;
2789                                 break;
2790                         default:
2791 #ifndef BB_VER
2792                                 fprintf(stderr, "Usage: sh [FILE]...\n"
2793                                                 "   or: sh -c command [args]...\n\n");
2794                                 exit(EXIT_FAILURE);
2795 #else
2796                                 bb_show_usage();
2797 #endif
2798                 }
2799         }
2800         /* A shell is interactive if the `-i' flag was given, or if all of
2801          * the following conditions are met:
2802          *        no -c command
2803          *    no arguments remaining or the -s flag given
2804          *    standard input is a terminal
2805          *    standard output is a terminal
2806          *    Refer to Posix.2, the description of the `sh' utility. */
2807         if (argv[optind]==NULL && input==stdin &&
2808                         isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
2809                 interactive++;
2810         }
2811
2812         debug_printf("\ninteractive=%d\n", interactive);
2813         if (interactive) {
2814                 /* Looks like they want an interactive shell */
2815 #ifndef CONFIG_FEATURE_SH_EXTRA_QUIET
2816                 printf( "\n\n%s hush - the humble shell v0.01 (testing)\n",
2817                         BB_BANNER);
2818                 printf( "Enter 'help' for a list of built-in commands.\n\n");
2819 #endif
2820                 setup_job_control();
2821         }
2822
2823         if (argv[optind]==NULL) {
2824                 opt=parse_file_outer(stdin);
2825                 goto final_return;
2826         }
2827
2828         debug_printf("\nrunning script '%s'\n", argv[optind]);
2829         global_argv = argv+optind;
2830         global_argc = argc-optind;
2831         input = bb_xfopen(argv[optind], "r");
2832         opt = parse_file_outer(input);
2833
2834 #ifdef CONFIG_FEATURE_CLEAN_UP
2835         fclose(input);
2836         if (cwd && cwd != bb_msg_unknown)
2837                 free((char*)cwd);
2838         {
2839                 struct variables *cur, *tmp;
2840                 for(cur = top_vars; cur; cur = tmp) {
2841                         tmp = cur->next;
2842                         if (!cur->flg_read_only) {
2843                                 free(cur->name);
2844                                 free(cur->value);
2845                                 free(cur);
2846                         }
2847                 }
2848         }
2849 #endif
2850
2851 final_return:
2852         return(opt?opt:last_return_code);
2853 }
2854
2855 static char *insert_var_value(char *inp)
2856 {
2857         int res_str_len = 0;
2858         int len;
2859         int done = 0;
2860         char *p, *p1, *res_str = NULL;
2861
2862         while ((p = strchr(inp, SPECIAL_VAR_SYMBOL))) {
2863                 if (p != inp) {
2864                         len = p - inp;
2865                         res_str = xrealloc(res_str, (res_str_len + len));
2866                         strncpy((res_str + res_str_len), inp, len);
2867                         res_str_len += len;
2868                 }
2869                 inp = ++p;
2870                 p = strchr(inp, SPECIAL_VAR_SYMBOL);
2871                 *p = '\0';
2872                 if ((p1 = lookup_param(inp))) {
2873                         len = res_str_len + strlen(p1);
2874                         res_str = xrealloc(res_str, (1 + len));
2875                         strcpy((res_str + res_str_len), p1);
2876                         res_str_len = len;
2877                 }
2878                 *p = SPECIAL_VAR_SYMBOL;
2879                 inp = ++p;
2880                 done = 1;
2881         }
2882         if (done) {
2883                 res_str = xrealloc(res_str, (1 + res_str_len + strlen(inp)));
2884                 strcpy((res_str + res_str_len), inp);
2885                 while ((p = strchr(res_str, '\n'))) {
2886                         *p = ' ';
2887                 }
2888         }
2889         return (res_str == NULL) ? inp : res_str;
2890 }
2891
2892 static char **make_list_in(char **inp, char *name)
2893 {
2894         int len, i;
2895         int name_len = strlen(name);
2896         int n = 0;
2897         char **list;
2898         char *p1, *p2, *p3;
2899
2900         /* create list of variable values */
2901         list = xmalloc(sizeof(*list));
2902         for (i = 0; inp[i]; i++) {
2903                 p3 = insert_var_value(inp[i]);
2904                 p1 = p3;
2905                 while (*p1) {
2906                         if ((*p1 == ' ')) {
2907                                 p1++;
2908                                 continue;
2909                         }
2910                         if ((p2 = strchr(p1, ' '))) {
2911                                 len = p2 - p1;
2912                         } else {
2913                                 len = strlen(p1);
2914                                 p2 = p1 + len;
2915                         }
2916                         /* we use n + 2 in realloc for list,because we add
2917                          * new element and then we will add NULL element */
2918                         list = xrealloc(list, sizeof(*list) * (n + 2));
2919                         list[n] = xmalloc(2 + name_len + len);
2920                         strcpy(list[n], name);
2921                         strcat(list[n], "=");
2922                         strncat(list[n], p1, len);
2923                         list[n++][name_len + len + 1] = '\0';
2924                         p1 = p2;
2925                 }
2926                 if (p3 != inp[i]) free(p3);
2927         }
2928         list[n] = NULL;
2929         return list;
2930 }
2931
2932 /* Make new string for parser */
2933 static char * make_string(char ** inp)
2934 {
2935         char *p;
2936         char *str = NULL;
2937         int n;
2938         int len = 2;
2939
2940         for (n = 0; inp[n]; n++) {
2941                 p = insert_var_value(inp[n]);
2942                 str = xrealloc(str, (len + strlen(p)));
2943                 if (n) {
2944                         strcat(str, " ");
2945                 } else {
2946                         *str = '\0';
2947                 }
2948                 strcat(str, p);
2949                 len = strlen(str) + 3;
2950                 if (p != inp[n]) free(p);
2951         }
2952         len = strlen(str);
2953         *(str + len) = '\n';
2954         *(str + len + 1) = '\0';
2955         return str;
2956 }