posix/wordexp.c

   1 /* POSIX.2 wordexp implementation.
   2    Copyright (C) 1997, 1998 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Tim Waugh <tim@cyberelk.demon.co.uk>.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <wordexp.h>
  22 #include <signal.h>
  23 #include <stdlib.h>
  24 #include <pwd.h>
  25 #include <sys/types.h>
  26 #include <string.h>
  27 #include <glob.h>
  28 #include <ctype.h>
  29 #include <sys/time.h>
  30 #include <sys/types.h>
  31 #include <sys/wait.h>
  32 #include <unistd.h>
  33 #include <fcntl.h>
  34 #include <sys/stat.h>
  35 #include <paths.h>
  36 #include <errno.h>
  37 #include <sys/param.h>
  38 #include <stdio.h>
  39 #include <fnmatch.h>
  40
  41 #include <stdio-common/_itoa.h>
  42
  43 /* Undefine the following line for the production version.  */
  44 /* #define NDEBUG 1 */
  45 #include <assert.h>
  46
  47 /*
  48  * This is a recursive-descent-style word expansion routine.
  49  */
  50
  51 /* These variables are defined and initialized in the startup code.  */
  52 extern int __libc_argc;
  53 extern char **__libc_argv;
  54
  55 /* Some forward declarations */
  56 static int parse_dollars (char **word, size_t *word_length, size_t *max_length,
  57                           const char *words, size_t *offset, int flags,
  58                           wordexp_t *pwordexp, const char *ifs,
  59                           const char *ifs_white, int quoted)
  60      internal_function;
  61 static int parse_backtick (char **word, size_t *word_length,
  62                            size_t *max_length, const char *words,
  63                            size_t *offset, int flags, wordexp_t *pwordexp,
  64                            const char *ifs, const char *ifs_white)
  65      internal_function;
  66 static int parse_dquote (char **word, size_t *word_length, size_t *max_length,
  67                          const char *words, size_t *offset, int flags,
  68                          wordexp_t *pwordexp, const char *ifs,
  69                          const char *ifs_white)
  70      internal_function;
  71 static int eval_expr (char *expr, long int *result) internal_function;
  72
  73 /* The w_*() functions manipulate word lists. */
  74
  75 #define W_CHUNK (100)
  76
  77 /* Result of w_newword will be ignored if it the last word. */
  78 static inline char *
  79 w_newword (size_t *actlen, size_t *maxlen)
  80 {
  81   *actlen = *maxlen = 0;
  82   return NULL;
  83 }
  84
  85 static inline char *
  86 w_addchar (char *buffer, size_t *actlen, size_t *maxlen, char ch)
  87      /* (lengths exclude trailing zero) */
  88 {
  89   /* Add a character to the buffer, allocating room for it if needed.
  90    */
  91
  92   if (*actlen == *maxlen)
  93     {
  94       char *old_buffer = buffer;
  95       assert (buffer == NULL || *maxlen != 0);
  96       *maxlen += W_CHUNK;
  97       buffer = realloc (buffer, 1 + *maxlen);
  98
  99       if (buffer == NULL)
 100         free (old_buffer);
 101     }
 102
 103   if (buffer != NULL)
 104     {
 105       buffer[*actlen] = ch;
 106       buffer[++(*actlen)] = '\0';
 107     }
 108
 109   return buffer;
 110 }
 111
 112 static char *
 113 internal_function
 114 w_addmem (char *buffer, size_t *actlen, size_t *maxlen, const char *str,
 115           size_t len)
 116 {
 117   /* Add a string to the buffer, allocating room for it if needed.
 118    */
 119   if (*actlen + len > *maxlen)
 120     {
 121       char *old_buffer = buffer;
 122       assert (buffer == NULL || *maxlen != 0);
 123       *maxlen += MAX (2 * len, W_CHUNK);
 124       buffer = realloc (old_buffer, 1 + *maxlen);
 125
 126       if (buffer == NULL)
 127         free (old_buffer);
 128     }
 129
 130   if (buffer != NULL)
 131     {
 132       *((char *) __mempcpy (&buffer[*actlen], str, len)) = '\0';
 133       *actlen += len;
 134     }
 135
 136   return buffer;
 137 }
 138
 139 static char *
 140 internal_function
 141 w_addstr (char *buffer, size_t *actlen, size_t *maxlen, const char *str)
 142      /* (lengths exclude trailing zero) */
 143 {
 144   /* Add a string to the buffer, allocating room for it if needed.
 145    */
 146   size_t len;
 147
 148   assert (str != NULL); /* w_addstr only called from this file */
 149   len = strlen (str);
 150
 151   return w_addmem (buffer, actlen, maxlen, str, len);
 152 }
 153
 154 static int
 155 internal_function
 156 w_addword (wordexp_t *pwordexp, char *word)
 157 {
 158   /* Add a word to the wordlist */
 159   size_t num_p;
 160   char **new_wordv;
 161
 162   /* Internally, NULL acts like "".  Convert NULLs to "" before
 163    * the caller sees them.
 164    */
 165   if (word == NULL)
 166     {
 167       word = __strdup ("");
 168       if (word == NULL)
 169         goto no_space;
 170     }
 171
 172   num_p = 2 + pwordexp->we_wordc + pwordexp->we_offs;
 173   new_wordv = realloc (pwordexp->we_wordv, sizeof (char *) * num_p);
 174   if (new_wordv != NULL)
 175     {
 176       pwordexp->we_wordv = new_wordv;
 177       pwordexp->we_wordv[pwordexp->we_wordc++] = word;
 178       pwordexp->we_wordv[pwordexp->we_wordc] = NULL;
 179       return 0;
 180     }
 181
 182 no_space:
 183   return WRDE_NOSPACE;
 184 }
 185
 186 /* The parse_*() functions should leave *offset being the offset in 'words'
 187  * to the last character processed.
 188  */
 189
 190 static int
 191 internal_function
 192 parse_backslash (char **word, size_t *word_length, size_t *max_length,
 193                  const char *words, size_t *offset)
 194 {
 195   /* We are poised _at_ a backslash, not in quotes */
 196
 197   switch (words[1 + *offset])
 198     {
 199     case 0:
 200       /* Backslash is last character of input words */
 201       return WRDE_SYNTAX;
 202
 203     case '\n':
 204       ++(*offset);
 205       break;
 206
 207     default:
 208       *word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
 209       if (*word == NULL)
 210         return WRDE_NOSPACE;
 211
 212       ++(*offset);
 213       break;
 214     }
 215
 216   return 0;
 217 }
 218
 219 static int
 220 internal_function
 221 parse_qtd_backslash (char **word, size_t *word_length, size_t *max_length,
 222                      const char *words, size_t *offset)
 223 {
 224   /* We are poised _at_ a backslash, inside quotes */
 225
 226   switch (words[1 + *offset])
 227     {
 228     case 0:
 229       /* Backslash is last character of input words */
 230       return WRDE_SYNTAX;
 231
 232     case '\n':
 233       ++(*offset);
 234       break;
 235
 236     case '$':
 237     case '`':
 238     case '"':
 239     case '\\':
 240       *word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
 241       if (*word == NULL)
 242         return WRDE_NOSPACE;
 243
 244       ++(*offset);
 245       break;
 246
 247     default:
 248       *word = w_addchar (*word, word_length, max_length, words[*offset]);
 249       if (*word != NULL)
 250         *word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
 251
 252       if (*word == NULL)
 253         return WRDE_NOSPACE;
 254
 255       ++(*offset);
 256       break;
 257     }
 258
 259   return 0;
 260 }
 261
 262 static int
 263 internal_function
 264 parse_tilde (char **word, size_t *word_length, size_t *max_length,
 265              const char *words, size_t *offset, size_t wordc)
 266 {
 267   /* We are poised _at_ a tilde */
 268   size_t i;
 269
 270   if (*word_length != 0)
 271     {
 272       if (!((*word)[*word_length - 1] == '=' && wordc == 0))
 273         {
 274           if (!((*word)[*word_length - 1] == ':'
 275                 && strchr (*word, '=') && wordc == 0))
 276             {
 277               *word = w_addchar (*word, word_length, max_length, '~');
 278               return *word ? 0 : WRDE_NOSPACE;
 279             }
 280         }
 281     }
 282
 283   for (i = 1 + *offset; words[i]; i++)
 284     {
 285       if (words[i] == ':' || words[i] == '/' || words[i] == ' ' ||
 286           words[i] == '\t' || words[i] == 0 )
 287         break;
 288
 289       if (words[i] == '\\')
 290         {
 291           *word = w_addchar (*word, word_length, max_length, '~');
 292           return *word ? 0 : WRDE_NOSPACE;
 293         }
 294     }
 295
 296   if (i == 1 + *offset)
 297     {
 298       /* Tilde appears on its own */
 299       uid_t uid;
 300       struct passwd pwd, *tpwd;
 301       int buflen = 1000;
 302       char* buffer = __alloca (buflen);
 303       int result;
 304
 305       uid = __getuid ();
 306
 307       while ((result = __getpwuid_r (uid, &pwd, buffer, buflen, &tpwd)) != 0
 308              && errno == ERANGE)
 309         {
 310           buflen += 1000;
 311           buffer = __alloca (buflen);
 312         }
 313
 314       if (result == 0 && pwd.pw_dir != NULL)
 315         {
 316           *word = w_addstr (*word, word_length, max_length, pwd.pw_dir);
 317           if (*word == NULL)
 318             return WRDE_NOSPACE;
 319         }
 320       else
 321         {
 322           *word = w_addchar (*word, word_length, max_length, '~');
 323           if (*word == NULL)
 324             return WRDE_NOSPACE;
 325         }
 326     }
 327   else
 328     {
 329       /* Look up user name in database to get home directory */
 330       char *user = __strndup (&words[1 + *offset], i - *offset);
 331       struct passwd pwd, *tpwd;
 332       int buflen = 1000;
 333       char* buffer = __alloca (buflen);
 334       int result;
 335
 336       while ((result = __getpwnam_r (user, &pwd, buffer, buflen, &tpwd)) != 0
 337              && errno == ERANGE)
 338         {
 339           buflen += 1000;
 340           buffer = __alloca (buflen);
 341         }
 342
 343       if (result == 0 && pwd.pw_dir)
 344         *word = w_addstr (*word, word_length, max_length, pwd.pw_dir);
 345       else
 346         {
 347           /* (invalid login name) */
 348           *word = w_addchar (*word, word_length, max_length, '~');
 349           if (*word != NULL)
 350             *word = w_addstr (*word, word_length, max_length, user);
 351         }
 352
 353       *offset = i - 1;
 354     }
 355   return *word ? 0 : WRDE_NOSPACE;
 356 }
 357
 358
 359 static int
 360 internal_function
 361 do_parse_glob (const char *glob_word, char **word, size_t *word_length,
 362                size_t *max_length, wordexp_t *pwordexp, const char *ifs,
 363                const char *ifs_white)
 364 {
 365   int error;
 366   int match;
 367   glob_t globbuf;
 368
 369   error = glob (glob_word, GLOB_NOCHECK, NULL, &globbuf);
 370
 371   if (error != 0)
 372     {
 373       /* We can only run into memory problems.  */
 374       assert (error == GLOB_NOSPACE);
 375       return WRDE_NOSPACE;
 376     }
 377
 378   if (ifs && !*ifs)
 379     {
 380       /* No field splitting allowed. */
 381       assert (globbuf.gl_pathv[0] != NULL);
 382       *word = w_addstr (*word, word_length, max_length, globbuf.gl_pathv[0]);
 383       for (match = 1; match < globbuf.gl_pathc && *word != NULL; ++match)
 384         {
 385           *word = w_addchar (*word, word_length, max_length, ' ');
 386           if (*word != NULL)
 387             *word = w_addstr (*word, word_length, max_length,
 388                               globbuf.gl_pathv[match]);
 389         }
 390
 391       globfree (&globbuf);
 392       return *word ? 0 : WRDE_NOSPACE;
 393     }
 394
 395   assert (ifs == NULL || *ifs != '\0');
 396   if (*word != NULL)
 397     {
 398       free (*word);
 399       *word = w_newword (word_length, max_length);
 400     }
 401
 402   for (match = 0; match < globbuf.gl_pathc; ++match)
 403     {
 404       char *matching_word = __strdup (globbuf.gl_pathv[match]);
 405       if (matching_word == NULL || w_addword (pwordexp, matching_word))
 406         {
 407           globfree (&globbuf);
 408           return WRDE_NOSPACE;
 409         }
 410     }
 411
 412   globfree (&globbuf);
 413   return 0;
 414 }
 415
 416 static int
 417 internal_function
 418 parse_glob (char **word, size_t *word_length, size_t *max_length,
 419             const char *words, size_t *offset, int flags,
 420             wordexp_t *pwordexp, const char *ifs, const char *ifs_white)
 421 {
 422   /* We are poised just after a '*', a '[' or a '?'. */
 423   int error = WRDE_NOSPACE;
 424   int quoted = 0; /* 1 if singly-quoted, 2 if doubly */
 425   int i;
 426   wordexp_t glob_list; /* List of words to glob */
 427
 428   glob_list.we_wordc = 0;
 429   glob_list.we_wordv = NULL;
 430   glob_list.we_offs = 0;
 431   for (; words[*offset] != '\0'; ++*offset)
 432     {
 433       if ((ifs && strchr (ifs, words[*offset])) ||
 434           (!ifs && strchr (" \t\n", words[*offset])))
 435         /* Reached IFS */
 436         break;
 437
 438       /* Sort out quoting */
 439       if (words[*offset] == '\'')
 440         {
 441           if (quoted == 0)
 442             {
 443               quoted = 1;
 444               continue;
 445             }
 446           else if (quoted == 1)
 447             {
 448               quoted = 0;
 449               continue;
 450             }
 451         }
 452       else if (words[*offset] == '"')
 453         {
 454           if (quoted == 0)
 455             {
 456               quoted = 2;
 457               continue;
 458             }
 459           else if (quoted == 2)
 460             {
 461               quoted = 0;
 462               continue;
 463             }
 464         }
 465
 466       /* Sort out other special characters */
 467       if (quoted != 1 && words[*offset] == '$')
 468         {
 469           error = parse_dollars (word, word_length, max_length, words,
 470                                  offset, flags, &glob_list, ifs, ifs_white,
 471                                  quoted == 2);
 472           if (error)
 473             goto tidy_up;
 474
 475           continue;
 476         }
 477       else if (words[*offset] == '\\')
 478         {
 479           if (quoted)
 480             error = parse_qtd_backslash (word, word_length, max_length,
 481                                          words, offset);
 482           else
 483             error = parse_backslash (word, word_length, max_length,
 484                                      words, offset);
 485
 486           if (error)
 487             goto tidy_up;
 488
 489           continue;
 490         }
 491
 492       *word = w_addchar (*word, word_length, max_length, words[*offset]);
 493       if (*word == NULL)
 494         goto tidy_up;
 495     }
 496
 497   /* Don't forget to re-parse the character we stopped at. */
 498   --*offset;
 499
 500   /* Glob the words */
 501   error = w_addword (&glob_list, *word);
 502   *word = w_newword (word_length, max_length);
 503   for (i = 0; error == 0 && i < glob_list.we_wordc; i++)
 504     error = do_parse_glob (glob_list.we_wordv[i], word, word_length,
 505                            max_length, pwordexp, ifs, ifs_white);
 506
 507   /* Now tidy up */
 508 tidy_up:
 509   wordfree (&glob_list);
 510   return error;
 511 }
 512
 513 static int
 514 internal_function
 515 parse_squote (char **word, size_t *word_length, size_t *max_length,
 516               const char *words, size_t *offset)
 517 {
 518   /* We are poised just after a single quote */
 519   for (; words[*offset]; ++(*offset))
 520     {
 521       if (words[*offset] != '\'')
 522         {
 523           *word = w_addchar (*word, word_length, max_length, words[*offset]);
 524           if (*word == NULL)
 525             return WRDE_NOSPACE;
 526         }
 527       else return 0;
 528     }
 529
 530   /* Unterminated string */
 531   return WRDE_SYNTAX;
 532 }
 533
 534 /* Functions to evaluate an arithmetic expression */
 535 static int
 536 internal_function
 537 eval_expr_val (char **expr, long int *result)
 538 {
 539   int sgn = +1;
 540   char *digit;
 541
 542   /* Skip white space */
 543   for (digit = *expr; digit && *digit && isspace (*digit); ++digit);
 544
 545   switch (*digit)
 546     {
 547     case '(':
 548
 549       /* Scan for closing paren */
 550       for (++digit; **expr && **expr != ')'; ++(*expr));
 551
 552       /* Is there one? */
 553       if (!**expr)
 554         return WRDE_SYNTAX;
 555
 556       *(*expr)++ = 0;
 557
 558       if (eval_expr (digit, result))
 559         return WRDE_SYNTAX;
 560
 561       return 0;
 562
 563     case '+':   /* Positive value */
 564       ++digit;
 565       break;
 566
 567     case '-':   /* Negative value */
 568       ++digit;
 569       sgn = -1;
 570       break;
 571
 572     default:
 573       if (!isdigit (*digit))
 574         return WRDE_SYNTAX;
 575     }
 576
 577   *result = 0;
 578   for (; *digit && isdigit (*digit); ++digit)
 579     *result = (*result * 10) + (*digit - '0');
 580
 581   *expr = digit;
 582   *result *= sgn;
 583   return 0;
 584 }
 585
 586 static int
 587 internal_function
 588 eval_expr_multdiv (char **expr, long int *result)
 589 {
 590   long int arg;
 591
 592   /* Read a Value */
 593   if (eval_expr_val (expr, result) != 0)
 594     return WRDE_SYNTAX;
 595
 596   while (**expr)
 597     {
 598       /* Skip white space */
 599       for (; *expr && **expr && isspace (**expr); ++(*expr));
 600
 601       if (**expr == '*')
 602         {
 603           ++(*expr);
 604           if (eval_expr_val (expr, &arg) != 0)
 605             return WRDE_SYNTAX;
 606
 607           *result *= arg;
 608         }
 609       else if (**expr == '/')
 610         {
 611           ++(*expr);
 612           if (eval_expr_val (expr, &arg) != 0)
 613             return WRDE_SYNTAX;
 614
 615           *result /= arg;
 616         }
 617       else break;
 618     }
 619
 620   return 0;
 621 }
 622
 623 static int
 624 internal_function
 625 eval_expr (char *expr, long int *result)
 626 {
 627   long int arg;
 628
 629   /* Read a Multdiv */
 630   if (eval_expr_multdiv (&expr, result) != 0)
 631     return WRDE_SYNTAX;
 632
 633   while (*expr)
 634     {
 635       /* Skip white space */
 636       for (; expr && *expr && isspace (*expr); ++expr);
 637
 638       if (*expr == '+')
 639         {
 640           ++expr;
 641           if (eval_expr_multdiv (&expr, &arg) != 0)
 642             return WRDE_SYNTAX;
 643
 644           *result += arg;
 645         }
 646       else if (*expr == '-')
 647         {
 648           ++expr;
 649           if (eval_expr_multdiv (&expr, &arg) != 0)
 650             return WRDE_SYNTAX;
 651
 652           *result -= arg;
 653         }
 654       else break;
 655     }
 656
 657   return 0;
 658 }
 659
 660 static int
 661 internal_function
 662 parse_arith (char **word, size_t *word_length, size_t *max_length,
 663              const char *words, size_t *offset, int flags, int bracket)
 664 {
 665   /* We are poised just after "$((" or "$[" */
 666   int error;
 667   int paren_depth = 1;
 668   size_t expr_length;
 669   size_t expr_maxlen;
 670   char *expr;
 671
 672   expr = w_newword (&expr_length, &expr_maxlen);
 673   for (; words[*offset]; ++(*offset))
 674     {
 675       switch (words[*offset])
 676         {
 677         case '$':
 678           error = parse_dollars (&expr, &expr_length, &expr_maxlen,
 679                                  words, offset, flags, NULL, NULL, NULL, 1);
 680           /* The ``1'' here is to tell parse_dollars not to
 681            * split the fields.
 682            */
 683           if (error)
 684             {
 685               free (expr);
 686               return error;
 687             }
 688           break;
 689
 690         case '`':
 691           (*offset)++;
 692           error = parse_backtick (&expr, &expr_length, &expr_maxlen,
 693                                   words, offset, flags, NULL, NULL, NULL);
 694           /* The first NULL here is to tell parse_backtick not to
 695            * split the fields.
 696            */
 697           if (error)
 698             {
 699               free (expr);
 700               return error;
 701             }
 702           break;
 703
 704         case '\\':
 705           error = parse_qtd_backslash (&expr, &expr_length, &expr_maxlen,
 706                                        words, offset);
 707           if (error)
 708             {
 709               free (expr);
 710               return error;
 711             }
 712           /* I think that a backslash within an
 713            * arithmetic expansion is bound to
 714            * cause an error sooner or later anyway though.
 715            */
 716           break;
 717
 718         case ')':
 719           if (--paren_depth == 0)
 720             {
 721               char result[21];  /* 21 = ceil(log10(2^64)) + 1 */
 722               long int numresult = 0;
 723               long long int convertme;
 724
 725               if (bracket || words[1 + *offset] != ')')
 726                 {
 727                   free (expr);
 728                   return WRDE_SYNTAX;
 729                 }
 730
 731               ++(*offset);
 732
 733               /* Go - evaluate. */
 734               if (*expr && eval_expr (expr, &numresult) != 0)
 735                 {
 736                   free (expr);
 737                   return WRDE_SYNTAX;
 738                 }
 739
 740               if (numresult < 0)
 741                 {
 742                   convertme = -numresult;
 743                   *word = w_addchar (*word, word_length, max_length, '-');
 744                   if (!*word)
 745                     {
 746                       free (expr);
 747                       return WRDE_NOSPACE;
 748                     }
 749                 }
 750               else
 751                 convertme = numresult;
 752
 753               result[20] = '\0';
 754               *word = w_addstr (*word, word_length, max_length,
 755                                 _itoa (convertme, &result[20], 10, 0));
 756               free (expr);
 757               return *word ? 0 : WRDE_NOSPACE;
 758             }
 759           expr = w_addchar (expr, &expr_length, &expr_maxlen, words[*offset]);
 760           if (expr == NULL)
 761             return WRDE_NOSPACE;
 762
 763           break;
 764
 765         case ']':
 766           if (bracket && paren_depth == 1)
 767             {
 768               char result[21];  /* 21 = ceil(log10(2^64)) + 1 */
 769               long int numresult = 0;
 770
 771               /* Go - evaluate. */
 772               if (*expr && eval_expr (expr, &numresult) != 0)
 773                 {
 774                   free (expr);
 775                   return WRDE_SYNTAX;
 776                 }
 777
 778               result[20] = '\0';
 779               *word = w_addstr (*word, word_length, max_length,
 780                                 _itoa_word (numresult, &result[20], 10, 0));
 781               free (expr);
 782               return *word ? 0 : WRDE_NOSPACE;
 783             }
 784
 785           free (expr);
 786           return WRDE_SYNTAX;
 787
 788         case '\n':
 789         case ';':
 790         case '{':
 791         case '}':
 792           free (expr);
 793           return WRDE_BADCHAR;
 794
 795         case '(':
 796           ++paren_depth;
 797         default:
 798           expr = w_addchar (expr, &expr_length, &expr_maxlen, words[*offset]);
 799           if (expr == NULL)
 800             return WRDE_NOSPACE;
 801         }
 802     }
 803
 804   /* Premature end */
 805   free (expr);
 806   return WRDE_SYNTAX;
 807 }
 808
 809 /* Function to execute a command and retrieve the results */
 810 /* pwordexp contains NULL if field-splitting is forbidden */
 811 static int
 812 internal_function
 813 exec_comm (char *comm, char **word, size_t *word_length, size_t *max_length,
 814            int flags, wordexp_t *pwordexp, const char *ifs,
 815            const char *ifs_white)
 816 {
 817   int fildes[2];
 818   int bufsize = 128;
 819   int buflen;
 820   int i;
 821   char *buffer;
 822   pid_t pid;
 823
 824   /* Don't fork() unless necessary */
 825   if (!comm || !*comm)
 826     return 0;
 827
 828   if (__pipe (fildes))
 829     /* Bad */
 830     return WRDE_NOSPACE;
 831
 832   if ((pid = __fork ()) < 0)
 833     {
 834       /* Bad */
 835       __close (fildes[0]);
 836       __close (fildes[1]);
 837       return WRDE_NOSPACE;
 838     }
 839
 840   if (pid == 0)
 841     {
 842       /* Child */
 843       const char *args[4] = { _PATH_BSHELL, "-c", comm, NULL };
 844
 845       /* Redirect output.  */
 846       __dup2 (fildes[1], 1);
 847       __close (fildes[1]);
 848
 849       /* Redirect stderr to /dev/null if we have to.  */
 850       if ((flags & WRDE_SHOWERR) == 0)
 851         {
 852           int fd;
 853           __close (2);
 854           fd = __open (_PATH_DEVNULL, O_WRONLY);
 855           if (fd >= 0 && fd != 2)
 856             {
 857               __dup2 (fd, 2);
 858               __close (fd);
 859             }
 860         }
 861
 862       __close (fildes[0]);
 863       __execve (_PATH_BSHELL, (char *const *) args, __environ);
 864
 865       /* Bad.  What now?  */
 866       abort ();
 867     }
 868
 869   /* Parent */
 870
 871   __close (fildes[1]);
 872   buffer = __alloca (bufsize);
 873
 874   if (!pwordexp)
 875     { /* Quoted - no field splitting */
 876
 877       while (1)
 878         {
 879           if ((buflen = __read (fildes[0], buffer, bufsize)) < 1)
 880             {
 881               if (__waitpid (pid, NULL, WNOHANG) == 0)
 882                 continue;
 883               if ((buflen = __read (fildes[0], buffer, bufsize)) < 1)
 884                 break;
 885             }
 886
 887           *word = w_addmem (*word, word_length, max_length, buffer, buflen);
 888           if (*word == NULL)
 889             goto no_space;
 890         }
 891     }
 892   else
 893     /* Not quoted - split fields */
 894     {
 895       int copying = 0;
 896       /* 'copying' is:
 897        *  0 when searching for first character in a field not IFS white space
 898        *  1 when copying the text of a field
 899        *  2 when searching for possible non-whitespace IFS
 900        */
 901
 902       while (1)
 903         {
 904           if ((buflen = __read (fildes[0], buffer, bufsize)) < 1)
 905             {
 906               if (__waitpid (pid, NULL, WNOHANG) == 0)
 907                 continue;
 908               if ((__read (fildes[0], buffer, bufsize)) < 1)
 909                 break;
 910             }
 911
 912           for (i = 0; i < buflen; ++i)
 913             {
 914               if (strchr (ifs, buffer[i]) != NULL)
 915                 {
 916                   /* Current character is IFS */
 917                   if (strchr (ifs_white, buffer[i]) == NULL)
 918                     {
 919                       /* Current character is IFS but not whitespace */
 920                       if (copying == 2)
 921                         {
 922                           /*            current character
 923                            *                   |
 924                            *                   V
 925                            * eg: text<space><comma><space>moretext
 926                            *
 927                            * So, strip whitespace IFS (like at the start)
 928                            */
 929                           copying = 0;
 930                           continue;
 931                         }
 932
 933                       copying = 0;
 934                       /* fall through and delimit field.. */
 935                     }
 936                   else
 937                     {
 938                       /* Current character is IFS white space */
 939
 940                       /* If not copying a field, ignore it */
 941                       if (copying != 1)
 942                         continue;
 943
 944                       /* End of field (search for non-ws IFS afterwards) */
 945                       copying = 2;
 946                     }
 947
 948                   /* First IFS white space, or IFS non-whitespace.
 949                    * Delimit the field.  Nulls are converted by w_addword. */
 950                   if (w_addword (pwordexp, *word) == WRDE_NOSPACE)
 951                     goto no_space;
 952
 953                   *word = w_newword (word_length, max_length);
 954                   /* fall back round the loop.. */
 955                 }
 956               else
 957                 {
 958                   /* Not IFS character */
 959                   copying = 1;
 960
 961                   *word = w_addchar (*word, word_length, max_length,
 962                                      buffer[i]);
 963                   if (*word == NULL)
 964                     goto no_space;
 965                 }
 966             }
 967         }
 968     }
 969
 970   /* Bash chops off trailing newlines, which seems sensible.  */
 971   while (*word_length > 0 && (*word)[*word_length - 1] == '\n')
 972     {
 973       (*word)[--*word_length] = '\0';
 974
 975       /* If the last word was entirely newlines, turn it into a new word
 976        * which can be ignored if there's nothing following it. */
 977       if (*word_length == 0)
 978         {
 979           free (*word);
 980           *word = w_newword (word_length, max_length);
 981           break;
 982         }
 983     }
 984
 985   __close (fildes[0]);
 986   return 0;
 987
 988 no_space:
 989   __kill (pid, SIGKILL);
 990   __waitpid (pid, NULL, 0);
 991   __close (fildes[0]);
 992   return WRDE_NOSPACE;
 993 }
 994
 995 static int
 996 internal_function
 997 parse_comm (char **word, size_t *word_length, size_t *max_length,
 998             const char *words, size_t *offset, int flags, wordexp_t *pwordexp,
 999             const char *ifs, const char *ifs_white)
1000 {
1001   /* We are poised just after "$(" */
1002   int paren_depth = 1;
1003   int error = 0;
1004   int quoted = 0; /* 1 for singly-quoted, 2 for doubly-quoted */
1005   size_t comm_length;
1006   size_t comm_maxlen;
1007   char *comm = w_newword (&comm_length, &comm_maxlen);
1008
1009   for (; words[*offset]; ++(*offset))
1010     {
1011       switch (words[*offset])
1012         {
1013         case '\'':
1014           if (quoted == 0)
1015             quoted = 1;
1016           else if (quoted == 1)
1017             quoted = 0;
1018
1019           break;
1020
1021         case '"':
1022           if (quoted == 0)
1023             quoted = 2;
1024           else if (quoted == 2)
1025             quoted = 0;
1026
1027           break;
1028
1029         case ')':
1030           if (!quoted && --paren_depth == 0)
1031             {
1032               /* Go -- give script to the shell */
1033               if (comm)
1034                 {
1035                   error = exec_comm (comm, word, word_length, max_length,
1036                                      flags, pwordexp, ifs, ifs_white);
1037                   free (comm);
1038                 }
1039
1040               return error;
1041             }
1042
1043           /* This is just part of the script */
1044           break;
1045
1046         case '(':
1047           if (!quoted)
1048             ++paren_depth;
1049         }
1050
1051       comm = w_addchar (comm, &comm_length, &comm_maxlen, words[*offset]);
1052       if (comm == NULL)
1053         return WRDE_NOSPACE;
1054     }
1055
1056   /* Premature end */
1057   if (comm)
1058     free (comm);
1059
1060   return WRDE_SYNTAX;
1061 }
1062
1063 static int
1064 internal_function
1065 parse_param (char **word, size_t *word_length, size_t *max_length,
1066              const char *words, size_t *offset, int flags, wordexp_t *pwordexp,
1067              const char *ifs, const char *ifs_white, int quoted)
1068 {
1069   /* We are poised just after "$" */
1070   enum action
1071   {
1072     ACT_NONE,
1073     ACT_RP_SHORT_LEFT = '#',
1074     ACT_RP_LONG_LEFT = 'L',
1075     ACT_RP_SHORT_RIGHT = '%',
1076     ACT_RP_LONG_RIGHT = 'R',
1077     ACT_NULL_ERROR = '?',
1078     ACT_NULL_SUBST = '-',
1079     ACT_NONNULL_SUBST = '+',
1080     ACT_NULL_ASSIGN = '='
1081   };
1082   size_t env_length;
1083   size_t env_maxlen;
1084   size_t pat_length;
1085   size_t pat_maxlen;
1086   size_t start = *offset;
1087   char *env;
1088   char *pattern;
1089   char *value = NULL;
1090   enum action action = ACT_NONE;
1091   int depth = 0;
1092   int colon_seen = 0;
1093   int seen_hash = 0;
1094   int free_value = 0;
1095   int pattern_is_quoted = 0; /* 1 for singly-quoted, 2 for doubly-quoted */
1096   int error;
1097   int special = 0;
1098   char buffer[21];
1099   int brace = words[*offset] == '{';
1100
1101   env = w_newword (&env_length, &env_maxlen);
1102   pattern = w_newword (&pat_length, &pat_maxlen);
1103
1104   if (brace)
1105     ++*offset;
1106
1107   /* First collect the parameter name. */
1108
1109   if (words[*offset] == '#')
1110     {
1111       seen_hash = 1;
1112       if (!brace)
1113         goto envsubst;
1114       ++*offset;
1115     }
1116
1117   if (isalpha (words[*offset]) || words[*offset] == '_')
1118     {
1119       /* Normal parameter name. */
1120       do
1121         {
1122           env = w_addchar (env, &env_length, &env_maxlen,
1123                            words[*offset]);
1124           if (env == NULL)
1125             goto no_space;
1126         }
1127       while (isalnum (words[++*offset]) || words[*offset] == '_');
1128     }
1129   else if (isdigit (words[*offset]))
1130     {
1131       /* Numeric parameter name. */
1132       special = 1;
1133       do
1134         {
1135           env = w_addchar (env, &env_length, &env_maxlen,
1136                            words[*offset]);
1137           if (env == NULL)
1138             goto no_space;
1139           if (!brace)
1140             goto envsubst;
1141         }
1142       while (isdigit(words[++*offset]));
1143     }
1144   else if (strchr ("*@$", words[*offset]) != NULL)
1145     {
1146       /* Special parameter. */
1147       special = 1;
1148       env = w_addchar (env, &env_length, &env_maxlen,
1149                        words[*offset]);
1150       if (env == NULL)
1151         goto no_space;
1152       ++*offset;
1153     }
1154   else
1155     {
1156       if (brace)
1157         goto syntax;
1158     }
1159
1160   if (brace)
1161     {
1162       /* Check for special action to be applied to the value. */
1163       switch (words[*offset])
1164         {
1165         case '}':
1166           /* Evaluate. */
1167           goto envsubst;
1168
1169         case '#':
1170           action = ACT_RP_SHORT_LEFT;
1171           if (words[1 + *offset] == '#')
1172             {
1173               ++*offset;
1174               action = ACT_RP_LONG_LEFT;
1175             }
1176           break;
1177
1178         case '%':
1179           action = ACT_RP_SHORT_RIGHT;
1180           if (words[1 + *offset] == '%')
1181             {
1182               ++*offset;
1183               action = ACT_RP_LONG_RIGHT;
1184             }
1185           break;
1186
1187         case ':':
1188           if (strchr ("-=?+", words[1 + *offset]) == NULL)
1189             goto syntax;
1190
1191           colon_seen = 1;
1192           action = words[++*offset];
1193           break;
1194
1195         case '-':
1196         case '=':
1197         case '?':
1198         case '+':
1199           action = words[*offset];
1200           break;
1201
1202         default:
1203           goto syntax;
1204         }
1205
1206       /* Now collect the pattern. */
1207       ++*offset;
1208       for (; words[*offset]; ++(*offset))
1209         {
1210           switch (words[*offset])
1211             {
1212             case '{':
1213               if (!pattern_is_quoted)
1214                 ++depth;
1215               break;
1216
1217             case '}':
1218               if (!pattern_is_quoted)
1219                 {
1220                   if (depth == 0)
1221                     goto envsubst;
1222                   --depth;
1223                 }
1224               break;
1225
1226             case '\\':
1227               if (!pattern_is_quoted && words[++*offset] == '\0')
1228                 goto syntax;
1229               break;
1230
1231             case '\'':
1232               if (pattern_is_quoted == 0)
1233                 pattern_is_quoted = 1;
1234               else if (pattern_is_quoted == 1)
1235                 pattern_is_quoted = 0;
1236
1237               break;
1238
1239             case '"':
1240               if (pattern_is_quoted == 0)
1241                 pattern_is_quoted = 2;
1242               else if (pattern_is_quoted == 2)
1243                 pattern_is_quoted = 0;
1244
1245               break;
1246             }
1247
1248           pattern = w_addchar (pattern, &pat_length, &pat_maxlen,
1249                                words[*offset]);
1250           if (pattern == NULL)
1251             goto no_space;
1252         }
1253     }
1254
1255   /* End of input string -- remember to reparse the character that we
1256    * stopped at.  */
1257   --(*offset);
1258
1259 envsubst:
1260   if (words[start] == '{' && words[*offset] != '}')
1261     goto syntax;
1262
1263   if (env == NULL)
1264     {
1265       if (seen_hash)
1266         {
1267           /* $# expands to the number of positional parameters */
1268           buffer[20] = '\0';
1269           value = _itoa_word (__libc_argc - 1, &buffer[20], 10, 0);
1270           seen_hash = 0;
1271         }
1272       else
1273         {
1274           /* Just $ on its own */
1275           *offset = start - 1;
1276           *word = w_addchar (*word, word_length, max_length, '$');
1277           return *word ? 0 : WRDE_NOSPACE;
1278         }
1279     }
1280   /* Is it a numeric parameter? */
1281   else if (isdigit (env[0]))
1282     {
1283       int n = atoi (env);
1284
1285       if (n >= __libc_argc)
1286         /* Substitute NULL. */
1287         value = NULL;
1288       else
1289         /* Replace with appropriate positional parameter. */
1290         value = __libc_argv[n];
1291     }
1292   /* Is it a special parameter? */
1293   else if (special)
1294     {
1295       /* Is it `$$'? */
1296       if (*env == '$')
1297         {
1298           buffer[20] = '\0';
1299           value = _itoa_word (__getpid (), &buffer[20], 10, 0);
1300         }
1301       /* Is it `${#*}' or `${#@}'? */
1302       else if ((*env == '*' || *env == '@') && seen_hash)
1303         {
1304           buffer[20] = '\0';
1305           value = _itoa_word (__libc_argc > 0 ? __libc_argc - 1 : 0,
1306                               &buffer[20], 10, 0);
1307           *word = w_addstr (*word, word_length, max_length, value);
1308           free (env);
1309           if (pattern)
1310             free (pattern);
1311           return *word ? 0 : WRDE_NOSPACE;
1312         }
1313       /* Is it `$*' or `$@' (unquoted) ? */
1314       else if (*env == '*' || (*env == '@' && !quoted))
1315         {
1316           size_t plist_len = 0;
1317           int p;
1318           char *end;
1319
1320           /* Build up value parameter by parameter (copy them) */
1321           for (p = 1; __libc_argv[p]; ++p)
1322             plist_len += strlen (__libc_argv[p]) + 1; /* for space */
1323           value = malloc (plist_len);
1324           if (value == NULL)
1325             goto no_space;
1326           end = value;
1327           *end = 0;
1328           for (p = 1; __libc_argv[p]; ++p)
1329             {
1330               if (p > 1)
1331                 *end++ = ' ';
1332               end = __stpcpy (end, __libc_argv[p]);
1333             }
1334
1335           free_value = 1;
1336         }
1337       else
1338         {
1339           /* Must be a quoted `$@' */
1340           assert (*env == '@' && quoted);
1341
1342           /* Each parameter is a separate word ("$@") */
1343           if (__libc_argc == 2)
1344             value = __libc_argv[1];
1345           else if (__libc_argc > 2)
1346             {
1347               int p;
1348
1349               /* Append first parameter to current word. */
1350               value = w_addstr (*word, word_length, max_length,
1351                                 __libc_argv[1]);
1352               if (value == NULL || w_addword (pwordexp, value))
1353                 goto no_space;
1354
1355               for (p = 2; __libc_argv[p + 1]; p++)
1356                 {
1357                   char *newword = __strdup (__libc_argv[p]);
1358                   if (newword == NULL || w_addword (pwordexp, newword))
1359                     goto no_space;
1360                 }
1361
1362               /* Start a new word with the last parameter. */
1363               *word = w_newword (word_length, max_length);
1364               value = __libc_argv[p];
1365             }
1366           else
1367             {
1368               free (env);
1369               free (pattern);
1370               return 0;
1371             }
1372         }
1373     }
1374   else
1375     value = getenv (env);
1376
1377   if (value == NULL && (flags & WRDE_UNDEF))
1378     {
1379       /* Variable not defined. */
1380       error = WRDE_BADVAL;
1381       goto do_error;
1382     }
1383
1384   if (action != ACT_NONE)
1385     {
1386       switch (action)
1387         {
1388         case ACT_RP_SHORT_LEFT:
1389         case ACT_RP_LONG_LEFT:
1390         case ACT_RP_SHORT_RIGHT:
1391         case ACT_RP_LONG_RIGHT:
1392           {
1393             char *p;
1394             char c;
1395             char *end;
1396
1397             if (value == NULL || pattern == NULL || *pattern == '\0')
1398               break;
1399
1400             end = value + strlen (value);
1401
1402             switch (action)
1403               {
1404               case ACT_RP_SHORT_LEFT:
1405                 for (p = value; p <= end; ++p)
1406                   {
1407                     c = *p;
1408                     *p = '\0';
1409                     if (fnmatch (pattern, value, 0) != FNM_NOMATCH)
1410                       {
1411                         *p = c;
1412                         if (free_value)
1413                           {
1414                             char *newval = __strdup (p);
1415                             if (newval == NULL)
1416                               {
1417                                 free (value);
1418                                 goto no_space;
1419                               }
1420                             free (value);
1421                             value = newval;
1422                           }
1423                         else
1424                           value = p;
1425                         break;
1426                       }
1427                     *p = c;
1428                   }
1429
1430                 break;
1431
1432               case ACT_RP_LONG_LEFT:
1433                 for (p = end; p >= value; --p)
1434                   {
1435                     c = *p;
1436                     *p = '\0';
1437                     if (fnmatch (pattern, value, 0) != FNM_NOMATCH)
1438                       {
1439                         *p = c;
1440                         if (free_value)
1441                           {
1442                             char *newval = __strdup (p);
1443                             if (newval == NULL)
1444                               {
1445                                 free (value);
1446                                 goto no_space;
1447                               }
1448                             free (value);
1449                             value = newval;
1450                           }
1451                         else
1452                           value = p;
1453                         break;
1454                       }
1455                     *p = c;
1456                   }
1457
1458                 break;
1459
1460               case ACT_RP_SHORT_RIGHT:
1461                 for (p = end; p >= value; --p)
1462                   {
1463                     if (fnmatch (pattern, p, 0) != FNM_NOMATCH)
1464                       {
1465                         char *newval;
1466                         newval = malloc (p - value + 1);
1467
1468                         if (newval == NULL)
1469                           {
1470                             if (free_value)
1471                               free (value);
1472                             goto no_space;
1473                           }
1474
1475                         *(char *) __mempcpy (newval, value, p - value) = '\0';
1476                         if (free_value)
1477                           free (value);
1478                         value = newval;
1479                         free_value = 1;
1480                         break;
1481                       }
1482                   }
1483
1484                 break;
1485
1486               case ACT_RP_LONG_RIGHT:
1487                 for (p = value; p <= end; ++p)
1488                   {
1489                     if (fnmatch (pattern, p, 0) != FNM_NOMATCH)
1490                       {
1491                         char *newval;
1492                         newval = malloc (p - value + 1);
1493
1494                         if (newval == NULL)
1495                           {
1496                             if (free_value)
1497                               free (value);
1498                             goto no_space;
1499                           }
1500
1501                         *(char *) __mempcpy (newval, value, p - value) = '\0';
1502                         if (free_value)
1503                           free (value);
1504                         value = newval;
1505                         free_value = 1;
1506                         break;
1507                       }
1508                   }
1509
1510                 break;
1511
1512               default:
1513                 break;
1514               }
1515
1516             break;
1517           }
1518
1519         case ACT_NULL_ERROR:
1520           if (value && *value)
1521             /* Substitute parameter */
1522             break;
1523
1524           if (!colon_seen && value)
1525             /* Substitute NULL */
1526             error = 0;
1527           else if (*pattern)
1528             {
1529               /* Expand 'pattern' and write it to stderr */
1530               wordexp_t we;
1531
1532               error = wordexp (pattern, &we, flags);
1533
1534               if (error == 0)
1535                 {
1536                   int i;
1537
1538                   fprintf (stderr, "%s:", env);
1539
1540                   for (i = 0; i < we.we_wordc; ++i)
1541                     {
1542                       fprintf (stderr, " %s", we.we_wordv[i]);
1543                     }
1544
1545                   fprintf (stderr, "\n");
1546                   error = WRDE_BADVAL;
1547                 }
1548
1549               wordfree (&we);
1550             }
1551           else
1552             {
1553               fprintf (stderr, "%s: parameter null or not set\n", env);
1554               error = WRDE_BADVAL;
1555             }
1556
1557           if (free_value)
1558             free (value);
1559           goto do_error;
1560
1561         case ACT_NULL_SUBST:
1562           if (value && *value)
1563             /* Substitute parameter */
1564             break;
1565
1566           if (!colon_seen && value)
1567             {
1568               /* Substitute NULL */
1569               if (free_value)
1570                 free (value);
1571               goto success;
1572             }
1573
1574         subst_word:
1575           {
1576             /* Substitute word */
1577             wordexp_t we;
1578             int i;
1579
1580             if (free_value)
1581               free (value);
1582
1583             if (quoted)
1584               {
1585                 /* No field-splitting is allowed, so imagine
1586                    quotes around the word.  */
1587                 char *qtd_pattern = malloc (3 + strlen (pattern));
1588                 if (qtd_pattern)
1589                   sprintf (qtd_pattern, "\"%s\"", pattern);
1590                 free (pattern);
1591                 pattern = qtd_pattern;
1592               }
1593
1594             if (pattern == NULL && (pattern = __strdup ("")) == NULL)
1595               goto no_space;
1596
1597             error = wordexp (pattern, &we, flags);
1598             if (error)
1599               goto do_error;
1600
1601             /* Fingers crossed that the quotes worked.. */
1602             assert (!quoted || we.we_wordc == 1);
1603
1604             /* Substitute */
1605             for (i = 0; i < we.we_wordc; ++i)
1606               if ((error = w_addword (pwordexp, __strdup (we.we_wordv[i])))
1607                   != 0)
1608                 break;
1609
1610             if (i < we.we_wordc)
1611               {
1612                 /* Ran out of space */
1613                 wordfree (&we);
1614                 goto do_error;
1615               }
1616
1617             if (action == ACT_NULL_ASSIGN)
1618               {
1619                 char *words;
1620                 char *cp;
1621                 size_t words_size = 0;
1622
1623                 if (special)
1624                   /* Cannot assign special parameters. */
1625                   goto syntax;
1626
1627                 for (i = 0; i < we.we_wordc; i++)
1628                   words_size += strlen (we.we_wordv[i]) + 1; /* for <space> */
1629                 words_size++;
1630
1631                 cp = words = __alloca (words_size);
1632                 *words = 0;
1633                 for (i = 0; i < we.we_wordc - 1; i++)
1634                   {
1635                     cp = __stpcpy (cp, we.we_wordv[i]);
1636                     *cp++ = ' ';
1637                   }
1638
1639                 strcpy (cp, we.we_wordv[i]);
1640
1641                 /* Also assign */
1642                 setenv (env, words, 1);
1643               }
1644
1645             wordfree (&we);
1646             goto success;
1647           }
1648
1649         case ACT_NONNULL_SUBST:
1650           if (value && *value)
1651             goto subst_word;
1652
1653           if (!colon_seen && value)
1654             goto subst_word;
1655
1656           /* Substitute NULL */
1657           if (free_value)
1658             free (value);
1659           goto success;
1660
1661         case ACT_NULL_ASSIGN:
1662           if (value && *value)
1663             /* Substitute parameter */
1664             break;
1665
1666           if (!colon_seen && value)
1667             {
1668               /* Substitute NULL */
1669               if (free_value)
1670                 free (value);
1671               goto success;
1672             }
1673
1674           /* This checks for '=' so it knows to assign */
1675           goto subst_word;
1676
1677         default:
1678           assert (! "Unrecognised action!");
1679         }
1680     }
1681
1682   free (env); env = NULL;
1683   free (pattern); pattern = NULL;
1684
1685   if (seen_hash)
1686     {
1687       char param_length[21];
1688       param_length[20] = '\0';
1689       *word = w_addstr (*word, word_length, max_length,
1690                         _itoa_word (value ? strlen (value) : 0,
1691                                     &param_length[20], 10, 0));
1692       if (free_value)
1693         {
1694           assert (value != NULL);
1695           free (value);
1696         }
1697
1698       return *word ? 0 : WRDE_NOSPACE;
1699     }
1700
1701   if (value == NULL)
1702     return 0;
1703
1704   if (quoted || !pwordexp)
1705     {
1706       /* Quoted - no field split */
1707       *word = w_addstr (*word, word_length, max_length, value);
1708       if (free_value)
1709         free (value);
1710
1711       return *word ? 0 : WRDE_NOSPACE;
1712     }
1713   else
1714     {
1715       /* Need to field-split */
1716       char *value_copy = __strdup (value); /* Don't modify value */
1717       char *field_begin = value_copy;
1718       int seen_nonws_ifs = 0;
1719
1720       if (free_value)
1721         free (value);
1722
1723       if (value_copy == NULL)
1724         goto no_space;
1725
1726       do
1727         {
1728           char *field_end = field_begin;
1729           char *next_field;
1730
1731           /* If this isn't the first field, start a new word */
1732           if (field_begin != value_copy)
1733             {
1734               if (w_addword (pwordexp, *word) == WRDE_NOSPACE)
1735                 {
1736                   free (value_copy);
1737                   goto no_space;
1738                 }
1739
1740               *word = w_newword (word_length, max_length);
1741             }
1742
1743           /* Skip IFS whitespace before the field */
1744           field_begin += strspn (field_begin, ifs_white);
1745
1746           if (!seen_nonws_ifs && *field_begin == 0)
1747             /* Nothing but whitespace */
1748             break;
1749
1750           /* Search for the end of the field */
1751           field_end = field_begin + strcspn (field_begin, ifs);
1752
1753           /* Set up pointer to the character after end of field and
1754              skip whitespace IFS after it. */
1755           next_field = field_end + strspn (field_end, ifs_white);
1756
1757           /* Skip at most one non-whitespace IFS character after the field */
1758           seen_nonws_ifs = 0;
1759           if (*next_field && strchr (ifs, *next_field))
1760             {
1761               seen_nonws_ifs = 1;
1762               next_field++;
1763             }
1764
1765           /* Null-terminate it */
1766           *field_end = 0;
1767
1768           /* Tag a copy onto the current word */
1769           *word = w_addstr (*word, word_length, max_length, field_begin);
1770
1771           if (*word == NULL && *field_begin != '\0')
1772             {
1773               free (value_copy);
1774               goto no_space;
1775             }
1776
1777           field_begin = next_field;
1778         }
1779       while (seen_nonws_ifs || *field_begin);
1780
1781       free (value_copy);
1782     }
1783
1784   return 0;
1785
1786 success:
1787   error = 0;
1788   goto do_error;
1789
1790 no_space:
1791   error = WRDE_NOSPACE;
1792   goto do_error;
1793
1794 syntax:
1795   error = WRDE_SYNTAX;
1796
1797 do_error:
1798   if (env)
1799     free (env);
1800
1801   if (pattern)
1802     free (pattern);
1803
1804   return error;
1805 }
1806
1807 static int
1808 internal_function
1809 parse_dollars (char **word, size_t *word_length, size_t *max_length,
1810                const char *words, size_t *offset, int flags,
1811                wordexp_t *pwordexp, const char *ifs, const char *ifs_white,
1812                int quoted)
1813 {
1814   /* We are poised _at_ "$" */
1815   switch (words[1 + *offset])
1816     {
1817     case '"':
1818     case '\'':
1819     case 0:
1820       *word = w_addchar (*word, word_length, max_length, '$');
1821       return *word ? 0 : WRDE_NOSPACE;
1822
1823     case '(':
1824       if (words[2 + *offset] == '(')
1825         {
1826           /* Differentiate between $((1+3)) and $((echo);(ls)) */
1827           int i = 3 + *offset;
1828           int depth = 0;
1829           while (words[i] && !(depth == 0 && words[i] == ')'))
1830             {
1831               if (words[i] == '(')
1832                 ++depth;
1833               else if (words[i] == ')')
1834                 --depth;
1835
1836               ++i;
1837             }
1838
1839           if (words[i] == ')' && words[i + 1] == ')')
1840             {
1841               (*offset) += 3;
1842               /* Call parse_arith -- 0 is for "no brackets" */
1843               return parse_arith (word, word_length, max_length, words, offset,
1844                                   flags, 0);
1845             }
1846         }
1847
1848       if (flags & WRDE_NOCMD)
1849         return WRDE_CMDSUB;
1850
1851       (*offset) += 2;
1852       return parse_comm (word, word_length, max_length, words, offset, flags,
1853                          quoted? NULL : pwordexp, ifs, ifs_white);
1854
1855     case '[':
1856       (*offset) += 2;
1857       /* Call parse_arith -- 1 is for "brackets" */
1858       return parse_arith (word, word_length, max_length, words, offset, flags,
1859                           1);
1860
1861     case '{':
1862     default:
1863       ++(*offset);      /* parse_param needs to know if "{" is there */
1864       return parse_param (word, word_length, max_length, words, offset, flags,
1865                            pwordexp, ifs, ifs_white, quoted);
1866     }
1867 }
1868
1869 static int
1870 internal_function
1871 parse_backtick (char **word, size_t *word_length, size_t *max_length,
1872                 const char *words, size_t *offset, int flags,
1873                 wordexp_t *pwordexp, const char *ifs, const char *ifs_white)
1874 {
1875   /* We are poised just after "`" */
1876   int error;
1877   int squoting = 0;
1878   size_t comm_length;
1879   size_t comm_maxlen;
1880   char *comm = w_newword (&comm_length, &comm_maxlen);
1881
1882   for (; words[*offset]; ++(*offset))
1883     {
1884       switch (words[*offset])
1885         {
1886         case '`':
1887           /* Go -- give the script to the shell */
1888           error = exec_comm (comm, word, word_length, max_length, flags,
1889                              pwordexp, ifs, ifs_white);
1890           free (comm);
1891           return error;
1892
1893         case '\\':
1894           if (squoting)
1895             {
1896               error = parse_qtd_backslash (&comm, &comm_length, &comm_maxlen,
1897                                            words, offset);
1898
1899               if (error)
1900                 {
1901                   free (comm);
1902                   return error;
1903                 }
1904
1905               break;
1906             }
1907
1908           ++(*offset);
1909           error = parse_backslash (&comm, &comm_length, &comm_maxlen, words,
1910                                    offset);
1911
1912           if (error)
1913             {
1914               free (comm);
1915               return error;
1916             }
1917
1918           break;
1919
1920         case '\'':
1921           squoting = 1 - squoting;
1922         default:
1923           comm = w_addchar (comm, &comm_length, &comm_maxlen, words[*offset]);
1924           if (comm == NULL)
1925             return WRDE_NOSPACE;
1926         }
1927     }
1928
1929   /* Premature end */
1930   free (comm);
1931   return WRDE_SYNTAX;
1932 }
1933
1934 static int
1935 internal_function
1936 parse_dquote (char **word, size_t *word_length, size_t *max_length,
1937               const char *words, size_t *offset, int flags,
1938               wordexp_t *pwordexp, const char * ifs, const char * ifs_white)
1939 {
1940   /* We are poised just after a double-quote */
1941   int error;
1942
1943   for (; words[*offset]; ++(*offset))
1944     {
1945       switch (words[*offset])
1946         {
1947         case '"':
1948           return 0;
1949
1950         case '$':
1951           error = parse_dollars (word, word_length, max_length, words, offset,
1952                                  flags, pwordexp, ifs, ifs_white, 1);
1953           /* The ``1'' here is to tell parse_dollars not to
1954            * split the fields.  It may need to, however ("$@").
1955            */
1956           if (error)
1957             return error;
1958
1959           break;
1960
1961         case '`':
1962           if (flags & WRDE_NOCMD)
1963             return WRDE_CMDSUB;
1964
1965           ++(*offset);
1966           error = parse_backtick (word, word_length, max_length, words,
1967                                   offset, flags, NULL, NULL, NULL);
1968           /* The first NULL here is to tell parse_backtick not to
1969            * split the fields.
1970            */
1971           if (error)
1972             return error;
1973
1974           break;
1975
1976         case '\\':
1977           error = parse_qtd_backslash (word, word_length, max_length, words,
1978                                        offset);
1979
1980           if (error)
1981             return error;
1982
1983           break;
1984
1985         default:
1986           *word = w_addchar (*word, word_length, max_length, words[*offset]);
1987           if (*word == NULL)
1988             return WRDE_NOSPACE;
1989         }
1990     }
1991
1992   /* Unterminated string */
1993   return WRDE_SYNTAX;
1994 }
1995
1996 /*
1997  * wordfree() is to be called after pwordexp is finished with.
1998  */
1999
2000 void
2001 wordfree (wordexp_t *pwordexp)
2002 {
2003
2004   /* wordexp can set pwordexp to NULL */
2005   if (pwordexp && pwordexp->we_wordv)
2006     {
2007       char **wordv = pwordexp->we_wordv;
2008
2009       for (wordv += pwordexp->we_offs; *wordv; ++wordv)
2010         free (*wordv);
2011
2012       free (pwordexp->we_wordv);
2013       pwordexp->we_wordv = NULL;
2014     }
2015 }
2016
2017 /*
2018  * wordexp()
2019  */
2020
2021 int
2022 wordexp (const char *words, wordexp_t *pwordexp, int flags)
2023 {
2024   size_t wordv_offset;
2025   size_t words_offset;
2026   size_t word_length;
2027   size_t max_length;
2028   char *word = w_newword (&word_length, &max_length);
2029   int error;
2030   char *ifs;
2031   char ifs_white[4];
2032   char **old_wordv = pwordexp->we_wordv;
2033   size_t old_wordc = (flags & WRDE_REUSE) ? pwordexp->we_wordc : 0;
2034
2035   if (flags & WRDE_REUSE)
2036     {
2037       /* Minimal implementation of WRDE_REUSE for now */
2038       wordfree (pwordexp);
2039       old_wordv = NULL;
2040     }
2041
2042   if (flags & WRDE_DOOFFS)
2043     {
2044       pwordexp->we_wordv = calloc (1 + pwordexp->we_offs, sizeof (char *));
2045       if (pwordexp->we_wordv == NULL)
2046         {
2047           error = WRDE_NOSPACE;
2048           goto do_error;
2049         }
2050     }
2051   else
2052     {
2053       pwordexp->we_wordv = calloc (1, sizeof (char *));
2054       if (pwordexp->we_wordv == NULL)
2055         {
2056           error = WRDE_NOSPACE;
2057           goto do_error;
2058         }
2059
2060       pwordexp->we_offs = 0;
2061     }
2062
2063   if ((flags & WRDE_APPEND) == 0)
2064     pwordexp->we_wordc = 0;
2065
2066   wordv_offset = pwordexp->we_offs + pwordexp->we_wordc;
2067
2068   /* Find out what the field separators are.
2069    * There are two types: whitespace and non-whitespace.
2070    */
2071   ifs = getenv ("IFS");
2072
2073   if (!ifs)
2074     /* IFS unset - use <space><tab><newline>. */
2075     ifs = strcpy (ifs_white, " \t\n");
2076   else
2077     {
2078       char *ifsch = ifs;
2079       char *whch = ifs_white;
2080
2081       /* Start off with no whitespace IFS characters */
2082       ifs_white[0] = '\0';
2083
2084       while (*ifsch != '\0')
2085         {
2086           if ((*ifsch == ' ') || (*ifsch == '\t') || (*ifsch == '\n'))
2087             {
2088               /* Whitespace IFS.  See first whether it is already in our
2089                  collection.  */
2090               char *runp = ifs_white;
2091
2092               while (runp < whch && *runp != '\0' && *runp != *ifsch)
2093                 ++runp;
2094
2095               if (runp == whch)
2096                 *whch++ = *ifsch;
2097             }
2098
2099           ++ifsch;
2100         }
2101       *whch = '\0';
2102     }
2103
2104   for (words_offset = 0 ; words[words_offset] ; ++words_offset)
2105     switch (words[words_offset])
2106       {
2107       case '\\':
2108         error = parse_backslash (&word, &word_length, &max_length, words,
2109                                  &words_offset);
2110
2111         if (error)
2112           goto do_error;
2113
2114         break;
2115
2116       case '$':
2117         error = parse_dollars (&word, &word_length, &max_length, words,
2118                                &words_offset, flags, pwordexp, ifs, ifs_white,
2119                                0);
2120
2121         if (error)
2122           goto do_error;
2123
2124         break;
2125
2126       case '`':
2127         if (flags & WRDE_NOCMD)
2128           {
2129             error = WRDE_CMDSUB;
2130             goto do_error;
2131           }
2132
2133         ++words_offset;
2134         error = parse_backtick (&word, &word_length, &max_length, words,
2135                                 &words_offset, flags, pwordexp, ifs,
2136                                 ifs_white);
2137
2138         if (error)
2139           goto do_error;
2140
2141         break;
2142
2143       case '"':
2144         ++words_offset;
2145         error = parse_dquote (&word, &word_length, &max_length, words,
2146                               &words_offset, flags, pwordexp, ifs, ifs_white);
2147
2148         if (error)
2149           goto do_error;
2150
2151         break;
2152
2153       case '\'':
2154         ++words_offset;
2155         error = parse_squote (&word, &word_length, &max_length, words,
2156                               &words_offset);
2157
2158         if (error)
2159           goto do_error;
2160
2161         break;
2162
2163       case '~':
2164         error = parse_tilde (&word, &word_length, &max_length, words,
2165                              &words_offset, pwordexp->we_wordc);
2166
2167         if (error)
2168           goto do_error;
2169
2170         break;
2171
2172       case '*':
2173       case '[':
2174       case '?':
2175         error = parse_glob (&word, &word_length, &max_length, words,
2176                             &words_offset, flags, pwordexp, ifs, ifs_white);
2177
2178         if (error)
2179           goto do_error;
2180
2181         break;
2182
2183       default:
2184         /* Is it a word separator? */
2185         if (strchr (" \t", words[words_offset]) == NULL)
2186           {
2187             char ch = words[words_offset];
2188
2189             /* Not a word separator -- but is it a valid word char? */
2190             if (strchr ("\n|&;<>(){}", ch))
2191               {
2192                 /* Fail */
2193                 wordfree (pwordexp);
2194                 pwordexp->we_wordc = 0;
2195                 pwordexp->we_wordv = old_wordv;
2196                 return WRDE_BADCHAR;
2197               }
2198
2199             /* "Ordinary" character -- add it to word */
2200             word = w_addchar (word, &word_length, &max_length,
2201                               ch);
2202             if (word == NULL)
2203               {
2204                 error = WRDE_NOSPACE;
2205                 goto do_error;
2206               }
2207
2208             break;
2209           }
2210
2211         /* If a word has been delimited, add it to the list. */
2212         if (word != NULL)
2213           {
2214             error = w_addword (pwordexp, word);
2215             if (error)
2216               goto do_error;
2217           }
2218
2219         word = w_newword (&word_length, &max_length);
2220       }
2221
2222   /* End of string */
2223
2224   /* There was a word separator at the end */
2225   if (word == NULL) /* i.e. w_newword */
2226     return 0;
2227
2228   /* There was no field separator at the end */
2229   return w_addword (pwordexp, word);
2230
2231 do_error:
2232   /* Error:
2233    *    free memory used (unless error is WRDE_NOSPACE), and
2234    *    set we_wordc and wd_wordv back to what they were.
2235    */
2236
2237   if (word != NULL)
2238     free (word);
2239
2240   if (error == WRDE_NOSPACE)
2241     return WRDE_NOSPACE;
2242
2243   wordfree (pwordexp);
2244   pwordexp->we_wordv = old_wordv;
2245   pwordexp->we_wordc = old_wordc;
2246   return error;
2247 }