posix/wordexp.c

   1 /* POSIX.2 wordexp implementation.
   2    Copyright (C) 1997-2017 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 Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <alloca.h>
  21 #include <ctype.h>
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <fnmatch.h>
  25 #include <glob.h>
  26 #include <libintl.h>
  27 #include <paths.h>
  28 #include <pwd.h>
  29 #include <signal.h>
  30 #include <stdbool.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include <sys/param.h>
  35 #include <sys/stat.h>
  36 #include <sys/time.h>
  37 #include <sys/types.h>
  38 #include <sys/types.h>
  39 #include <sys/wait.h>
  40 #include <unistd.h>
  41 #include <wchar.h>
  42 #include <wordexp.h>
  43 #include <kernel-features.h>
  44
  45 #include <libc-lock.h>
  46 #include <_itoa.h>
  47
  48 /* Undefine the following line for the production version.  */
  49 /* #define NDEBUG 1 */
  50 #include <assert.h>
  51
  52 /* Get some device information.  */
  53 #include <device-nrs.h>
  54
  55 /*
  56  * This is a recursive-descent-style word expansion routine.
  57  */
  58
  59 /* These variables are defined and initialized in the startup code.  */
  60 extern int __libc_argc attribute_hidden;
  61 extern char **__libc_argv attribute_hidden;
  62
  63 /* Some forward declarations */
  64 static int parse_dollars (char **word, size_t *word_length, size_t *max_length,
  65                           const char *words, size_t *offset, int flags,
  66                           wordexp_t *pwordexp, const char *ifs,
  67                           const char *ifs_white, int quoted)
  68      internal_function;
  69 static int parse_backtick (char **word, size_t *word_length,
  70                            size_t *max_length, const char *words,
  71                            size_t *offset, int flags, wordexp_t *pwordexp,
  72                            const char *ifs, const char *ifs_white)
  73      internal_function;
  74 static int parse_dquote (char **word, size_t *word_length, size_t *max_length,
  75                          const char *words, size_t *offset, int flags,
  76                          wordexp_t *pwordexp, const char *ifs,
  77                          const char *ifs_white)
  78      internal_function;
  79 static int eval_expr (char *expr, long int *result) internal_function;
  80
  81 /* The w_*() functions manipulate word lists. */
  82
  83 #define W_CHUNK (100)
  84
  85 /* Result of w_newword will be ignored if it's the last word. */
  86 static inline char *
  87 w_newword (size_t *actlen, size_t *maxlen)
  88 {
  89   *actlen = *maxlen = 0;
  90   return NULL;
  91 }
  92
  93 static char *
  94 w_addchar (char *buffer, size_t *actlen, size_t *maxlen, char ch)
  95      /* (lengths exclude trailing zero) */
  96 {
  97   /* Add a character to the buffer, allocating room for it if needed.  */
  98
  99   if (*actlen == *maxlen)
 100     {
 101       char *old_buffer = buffer;
 102       assert (buffer == NULL || *maxlen != 0);
 103       *maxlen += W_CHUNK;
 104       buffer = (char *) realloc (buffer, 1 + *maxlen);
 105
 106       if (buffer == NULL)
 107         free (old_buffer);
 108     }
 109
 110   if (buffer != NULL)
 111     {
 112       buffer[*actlen] = ch;
 113       buffer[++(*actlen)] = '\0';
 114     }
 115
 116   return buffer;
 117 }
 118
 119 static char *
 120 internal_function
 121 w_addmem (char *buffer, size_t *actlen, size_t *maxlen, const char *str,
 122           size_t len)
 123 {
 124   /* Add a string to the buffer, allocating room for it if needed.
 125    */
 126   if (*actlen + len > *maxlen)
 127     {
 128       char *old_buffer = buffer;
 129       assert (buffer == NULL || *maxlen != 0);
 130       *maxlen += MAX (2 * len, W_CHUNK);
 131       buffer = realloc (old_buffer, 1 + *maxlen);
 132
 133       if (buffer == NULL)
 134         free (old_buffer);
 135     }
 136
 137   if (buffer != NULL)
 138     {
 139       *((char *) __mempcpy (&buffer[*actlen], str, len)) = '\0';
 140       *actlen += len;
 141     }
 142
 143   return buffer;
 144 }
 145
 146 static char *
 147 internal_function
 148 w_addstr (char *buffer, size_t *actlen, size_t *maxlen, const char *str)
 149      /* (lengths exclude trailing zero) */
 150 {
 151   /* Add a string to the buffer, allocating room for it if needed.
 152    */
 153   size_t len;
 154
 155   assert (str != NULL); /* w_addstr only called from this file */
 156   len = strlen (str);
 157
 158   return w_addmem (buffer, actlen, maxlen, str, len);
 159 }
 160
 161 static int
 162 internal_function
 163 w_addword (wordexp_t *pwordexp, char *word)
 164 {
 165   /* Add a word to the wordlist */
 166   size_t num_p;
 167   char **new_wordv;
 168   bool allocated = false;
 169
 170   /* Internally, NULL acts like "".  Convert NULLs to "" before
 171    * the caller sees them.
 172    */
 173   if (word == NULL)
 174     {
 175       word = __strdup ("");
 176       if (word == NULL)
 177         goto no_space;
 178       allocated = true;
 179     }
 180
 181   num_p = 2 + pwordexp->we_wordc + pwordexp->we_offs;
 182   new_wordv = realloc (pwordexp->we_wordv, sizeof (char *) * num_p);
 183   if (new_wordv != NULL)
 184     {
 185       pwordexp->we_wordv = new_wordv;
 186       pwordexp->we_wordv[pwordexp->we_offs + pwordexp->we_wordc++] = word;
 187       pwordexp->we_wordv[pwordexp->we_offs + pwordexp->we_wordc] = NULL;
 188       return 0;
 189     }
 190
 191   if (allocated)
 192     free (word);
 193
 194 no_space:
 195   return WRDE_NOSPACE;
 196 }
 197
 198 /* The parse_*() functions should leave *offset being the offset in 'words'
 199  * to the last character processed.
 200  */
 201
 202 static int
 203 internal_function
 204 parse_backslash (char **word, size_t *word_length, size_t *max_length,
 205                  const char *words, size_t *offset)
 206 {
 207   /* We are poised _at_ a backslash, not in quotes */
 208
 209   switch (words[1 + *offset])
 210     {
 211     case 0:
 212       /* Backslash is last character of input words */
 213       return WRDE_SYNTAX;
 214
 215     case '\n':
 216       ++(*offset);
 217       break;
 218
 219     default:
 220       *word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
 221       if (*word == NULL)
 222         return WRDE_NOSPACE;
 223
 224       ++(*offset);
 225       break;
 226     }
 227
 228   return 0;
 229 }
 230
 231 static int
 232 internal_function
 233 parse_qtd_backslash (char **word, size_t *word_length, size_t *max_length,
 234                      const char *words, size_t *offset)
 235 {
 236   /* We are poised _at_ a backslash, inside quotes */
 237
 238   switch (words[1 + *offset])
 239     {
 240     case 0:
 241       /* Backslash is last character of input words */
 242       return WRDE_SYNTAX;
 243
 244     case '\n':
 245       ++(*offset);
 246       break;
 247
 248     case '$':
 249     case '`':
 250     case '"':
 251     case '\\':
 252       *word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
 253       if (*word == NULL)
 254         return WRDE_NOSPACE;
 255
 256       ++(*offset);
 257       break;
 258
 259     default:
 260       *word = w_addchar (*word, word_length, max_length, words[*offset]);
 261       if (*word != NULL)
 262         *word = w_addchar (*word, word_length, max_length, words[1 + *offset]);
 263
 264       if (*word == NULL)
 265         return WRDE_NOSPACE;
 266
 267       ++(*offset);
 268       break;
 269     }
 270
 271   return 0;
 272 }
 273
 274 static int
 275 internal_function
 276 parse_tilde (char **word, size_t *word_length, size_t *max_length,
 277              const char *words, size_t *offset, size_t wordc)
 278 {
 279   /* We are poised _at_ a tilde */
 280   size_t i;
 281
 282   if (*word_length != 0)
 283     {
 284       if (!((*word)[*word_length - 1] == '=' && wordc == 0))
 285         {
 286           if (!((*word)[*word_length - 1] == ':'
 287                 && strchr (*word, '=') && wordc == 0))
 288             {
 289               *word = w_addchar (*word, word_length, max_length, '~');
 290               return *word ? 0 : WRDE_NOSPACE;
 291             }
 292         }
 293     }
 294
 295   for (i = 1 + *offset; words[i]; i++)
 296     {
 297       if (words[i] == ':' || words[i] == '/' || words[i] == ' ' ||
 298           words[i] == '\t' || words[i] == 0 )
 299         break;
 300
 301       if (words[i] == '\\')
 302         {
 303           *word = w_addchar (*word, word_length, max_length, '~');
 304           return *word ? 0 : WRDE_NOSPACE;
 305         }
 306     }
 307
 308   if (i == 1 + *offset)
 309     {
 310       /* Tilde appears on its own */
 311       uid_t uid;
 312       struct passwd pwd, *tpwd;
 313       int buflen = 1000;
 314       char* home;
 315       char* buffer;
 316       int result;
 317
 318       /* POSIX.2 says ~ expands to $HOME and if HOME is unset the
 319          results are unspecified.  We do a lookup on the uid if
 320          HOME is unset. */
 321
 322       home = getenv ("HOME");
 323       if (home != NULL)
 324         {
 325           *word = w_addstr (*word, word_length, max_length, home);
 326           if (*word == NULL)
 327             return WRDE_NOSPACE;
 328         }
 329       else
 330         {
 331           uid = __getuid ();
 332           buffer = __alloca (buflen);
 333
 334           while ((result = __getpwuid_r (uid, &pwd, buffer, buflen, &tpwd)) != 0
 335                  && errno == ERANGE)
 336             buffer = extend_alloca (buffer, buflen, buflen + 1000);
 337
 338           if (result == 0 && tpwd != NULL && pwd.pw_dir != NULL)
 339             {
 340               *word = w_addstr (*word, word_length, max_length, pwd.pw_dir);
 341               if (*word == NULL)
 342                 return WRDE_NOSPACE;
 343             }
 344           else
 345             {
 346               *word = w_addchar (*word, word_length, max_length, '~');
 347               if (*word == NULL)
 348                 return WRDE_NOSPACE;
 349             }
 350         }
 351     }
 352   else
 353     {
 354       /* Look up user name in database to get home directory */
 355       char *user = strndupa (&words[1 + *offset], i - (1 + *offset));
 356       struct passwd pwd, *tpwd;
 357       int buflen = 1000;
 358       char* buffer = __alloca (buflen);
 359       int result;
 360
 361       while ((result = __getpwnam_r (user, &pwd, buffer, buflen, &tpwd)) != 0
 362              && errno == ERANGE)
 363         buffer = extend_alloca (buffer, buflen, buflen + 1000);
 364
 365       if (result == 0 && tpwd != NULL && pwd.pw_dir)
 366         *word = w_addstr (*word, word_length, max_length, pwd.pw_dir);
 367       else
 368         {
 369           /* (invalid login name) */
 370           *word = w_addchar (*word, word_length, max_length, '~');
 371           if (*word != NULL)
 372             *word = w_addstr (*word, word_length, max_length, user);
 373         }
 374
 375       *offset = i - 1;
 376     }
 377   return *word ? 0 : WRDE_NOSPACE;
 378 }
 379
 380
 381 static int
 382 internal_function
 383 do_parse_glob (const char *glob_word, char **word, size_t *word_length,
 384                size_t *max_length, wordexp_t *pwordexp, const char *ifs,
 385                const char *ifs_white)
 386 {
 387   int error;
 388   unsigned int match;
 389   glob_t globbuf;
 390
 391   error = glob (glob_word, GLOB_NOCHECK, NULL, &globbuf);
 392
 393   if (error != 0)
 394     {
 395       /* We can only run into memory problems.  */
 396       assert (error == GLOB_NOSPACE);
 397       return WRDE_NOSPACE;
 398     }
 399
 400   if (ifs && !*ifs)
 401     {
 402       /* No field splitting allowed. */
 403       assert (globbuf.gl_pathv[0] != NULL);
 404       *word = w_addstr (*word, word_length, max_length, globbuf.gl_pathv[0]);
 405       for (match = 1; match < globbuf.gl_pathc && *word != NULL; ++match)
 406         {
 407           *word = w_addchar (*word, word_length, max_length, ' ');
 408           if (*word != NULL)
 409             *word = w_addstr (*word, word_length, max_length,
 410                               globbuf.gl_pathv[match]);
 411         }
 412
 413       globfree (&globbuf);
 414       return *word ? 0 : WRDE_NOSPACE;
 415     }
 416
 417   assert (ifs == NULL || *ifs != '\0');
 418   if (*word != NULL)
 419     {
 420       free (*word);
 421       *word = w_newword (word_length, max_length);
 422     }
 423
 424   for (match = 0; match < globbuf.gl_pathc; ++match)
 425     {
 426       char *matching_word = __strdup (globbuf.gl_pathv[match]);
 427       if (matching_word == NULL || w_addword (pwordexp, matching_word))
 428         {
 429           globfree (&globbuf);
 430           return WRDE_NOSPACE;
 431         }
 432     }
 433
 434   globfree (&globbuf);
 435   return 0;
 436 }
 437
 438 static int
 439 internal_function
 440 parse_glob (char **word, size_t *word_length, size_t *max_length,
 441             const char *words, size_t *offset, int flags,
 442             wordexp_t *pwordexp, const char *ifs, const char *ifs_white)
 443 {
 444   /* We are poised just after a '*', a '[' or a '?'. */
 445   int error = WRDE_NOSPACE;
 446   int quoted = 0; /* 1 if singly-quoted, 2 if doubly */
 447   size_t i;
 448   wordexp_t glob_list; /* List of words to glob */
 449
 450   glob_list.we_wordc = 0;
 451   glob_list.we_wordv = NULL;
 452   glob_list.we_offs = 0;
 453   for (; words[*offset] != '\0'; ++*offset)
 454     {
 455       if (strchr (ifs, words[*offset]) != NULL)
 456         /* Reached IFS */
 457         break;
 458
 459       /* Sort out quoting */
 460       if (words[*offset] == '\'')
 461         {
 462           if (quoted == 0)
 463             {
 464               quoted = 1;
 465               continue;
 466             }
 467           else if (quoted == 1)
 468             {
 469               quoted = 0;
 470               continue;
 471             }
 472         }
 473       else if (words[*offset] == '"')
 474         {
 475           if (quoted == 0)
 476             {
 477               quoted = 2;
 478               continue;
 479             }
 480           else if (quoted == 2)
 481             {
 482               quoted = 0;
 483               continue;
 484             }
 485         }
 486
 487       /* Sort out other special characters */
 488       if (quoted != 1 && words[*offset] == '$')
 489         {
 490           error = parse_dollars (word, word_length, max_length, words,
 491                                  offset, flags, &glob_list, ifs, ifs_white,
 492                                  quoted == 2);
 493           if (error)
 494             goto tidy_up;
 495
 496           continue;
 497         }
 498       else if (words[*offset] == '\\')
 499         {
 500           if (quoted)
 501             error = parse_qtd_backslash (word, word_length, max_length,
 502                                          words, offset);
 503           else
 504             error = parse_backslash (word, word_length, max_length,
 505                                      words, offset);
 506
 507           if (error)
 508             goto tidy_up;
 509
 510           continue;
 511         }
 512
 513       *word = w_addchar (*word, word_length, max_length, words[*offset]);
 514       if (*word == NULL)
 515         goto tidy_up;
 516     }
 517
 518   /* Don't forget to re-parse the character we stopped at. */
 519   --*offset;
 520
 521   /* Glob the words */
 522   error = w_addword (&glob_list, *word);
 523   *word = w_newword (word_length, max_length);
 524   for (i = 0; error == 0 && i < glob_list.we_wordc; i++)
 525     error = do_parse_glob (glob_list.we_wordv[i], word, word_length,
 526                            max_length, pwordexp, ifs, ifs_white);
 527
 528   /* Now tidy up */
 529 tidy_up:
 530   wordfree (&glob_list);
 531   return error;
 532 }
 533
 534 static int
 535 internal_function
 536 parse_squote (char **word, size_t *word_length, size_t *max_length,
 537               const char *words, size_t *offset)
 538 {
 539   /* We are poised just after a single quote */
 540   for (; words[*offset]; ++(*offset))
 541     {
 542       if (words[*offset] != '\'')
 543         {
 544           *word = w_addchar (*word, word_length, max_length, words[*offset]);
 545           if (*word == NULL)
 546             return WRDE_NOSPACE;
 547         }
 548       else return 0;
 549     }
 550
 551   /* Unterminated string */
 552   return WRDE_SYNTAX;
 553 }
 554
 555 /* Functions to evaluate an arithmetic expression */
 556 static int
 557 internal_function
 558 eval_expr_val (char **expr, long int *result)
 559 {
 560   char *digit;
 561
 562   /* Skip white space */
 563   for (digit = *expr; digit && *digit && isspace (*digit); ++digit);
 564
 565   if (*digit == '(')
 566     {
 567       /* Scan for closing paren */
 568       for (++digit; **expr && **expr != ')'; ++(*expr));
 569
 570       /* Is there one? */
 571       if (!**expr)
 572         return WRDE_SYNTAX;
 573
 574       *(*expr)++ = 0;
 575
 576       if (eval_expr (digit, result))
 577         return WRDE_SYNTAX;
 578
 579       return 0;
 580     }
 581
 582   /* POSIX requires that decimal, octal, and hexadecimal constants are
 583      recognized.  Therefore we pass 0 as the third parameter to strtol.  */
 584   *result = strtol (digit, expr, 0);
 585   if (digit == *expr)
 586     return WRDE_SYNTAX;
 587
 588   return 0;
 589 }
 590
 591 static int
 592 internal_function
 593 eval_expr_multdiv (char **expr, long int *result)
 594 {
 595   long int arg;
 596
 597   /* Read a Value */
 598   if (eval_expr_val (expr, result) != 0)
 599     return WRDE_SYNTAX;
 600
 601   while (**expr)
 602     {
 603       /* Skip white space */
 604       for (; *expr && **expr && isspace (**expr); ++(*expr));
 605
 606       if (**expr == '*')
 607         {
 608           ++(*expr);
 609           if (eval_expr_val (expr, &arg) != 0)
 610             return WRDE_SYNTAX;
 611
 612           *result *= arg;
 613         }
 614       else if (**expr == '/')
 615         {
 616           ++(*expr);
 617           if (eval_expr_val (expr, &arg) != 0)
 618             return WRDE_SYNTAX;
 619
 620           /* Division by zero or integer overflow.  */
 621           if (arg == 0 || (arg == -1 && *result == LONG_MIN))
 622             return WRDE_SYNTAX;
 623
 624           *result /= arg;
 625         }
 626       else break;
 627     }
 628
 629   return 0;
 630 }
 631
 632 static int
 633 internal_function
 634 eval_expr (char *expr, long int *result)
 635 {
 636   long int arg;
 637
 638   /* Read a Multdiv */
 639   if (eval_expr_multdiv (&expr, result) != 0)
 640     return WRDE_SYNTAX;
 641
 642   while (*expr)
 643     {
 644       /* Skip white space */
 645       for (; expr && *expr && isspace (*expr); ++expr);
 646
 647       if (*expr == '+')
 648         {
 649           ++expr;
 650           if (eval_expr_multdiv (&expr, &arg) != 0)
 651             return WRDE_SYNTAX;
 652
 653           *result += arg;
 654         }
 655       else if (*expr == '-')
 656         {
 657           ++expr;
 658           if (eval_expr_multdiv (&expr, &arg) != 0)
 659             return WRDE_SYNTAX;
 660
 661           *result -= arg;
 662         }
 663       else break;
 664     }
 665
 666   return 0;
 667 }
 668
 669 static int
 670 internal_function
 671 parse_arith (char **word, size_t *word_length, size_t *max_length,
 672              const char *words, size_t *offset, int flags, int bracket)
 673 {
 674   /* We are poised just after "$((" or "$[" */
 675   int error;
 676   int paren_depth = 1;
 677   size_t expr_length;
 678   size_t expr_maxlen;
 679   char *expr;
 680
 681   expr = w_newword (&expr_length, &expr_maxlen);
 682   for (; words[*offset]; ++(*offset))
 683     {
 684       switch (words[*offset])
 685         {
 686         case '$':
 687           error = parse_dollars (&expr, &expr_length, &expr_maxlen,
 688                                  words, offset, flags, NULL, NULL, NULL, 1);
 689           /* The ``1'' here is to tell parse_dollars not to
 690            * split the fields.
 691            */
 692           if (error)
 693             {
 694               free (expr);
 695               return error;
 696             }
 697           break;
 698
 699         case '`':
 700           (*offset)++;
 701           error = parse_backtick (&expr, &expr_length, &expr_maxlen,
 702                                   words, offset, flags, NULL, NULL, NULL);
 703           /* The first NULL here is to tell parse_backtick not to
 704            * split the fields.
 705            */
 706           if (error)
 707             {
 708               free (expr);
 709               return error;
 710             }
 711           break;
 712
 713         case '\\':
 714           error = parse_qtd_backslash (&expr, &expr_length, &expr_maxlen,
 715                                        words, offset);
 716           if (error)
 717             {
 718               free (expr);
 719               return error;
 720             }
 721           /* I think that a backslash within an
 722            * arithmetic expansion is bound to
 723            * cause an error sooner or later anyway though.
 724            */
 725           break;
 726
 727         case ')':
 728           if (--paren_depth == 0)
 729             {
 730               char result[21];  /* 21 = ceil(log10(2^64)) + 1 */
 731               long int numresult = 0;
 732               long long int convertme;
 733
 734               if (bracket || words[1 + *offset] != ')')
 735                 {
 736                   free (expr);
 737                   return WRDE_SYNTAX;
 738                 }
 739
 740               ++(*offset);
 741
 742               /* Go - evaluate. */
 743               if (*expr && eval_expr (expr, &numresult) != 0)
 744                 {
 745                   free (expr);
 746                   return WRDE_SYNTAX;
 747                 }
 748
 749               if (numresult < 0)
 750                 {
 751                   convertme = -numresult;
 752                   *word = w_addchar (*word, word_length, max_length, '-');
 753                   if (!*word)
 754                     {
 755                       free (expr);
 756                       return WRDE_NOSPACE;
 757                     }
 758                 }
 759               else
 760                 convertme = numresult;
 761
 762               result[20] = '\0';
 763               *word = w_addstr (*word, word_length, max_length,
 764                                 _itoa (convertme, &result[20], 10, 0));
 765               free (expr);
 766               return *word ? 0 : WRDE_NOSPACE;
 767             }
 768           expr = w_addchar (expr, &expr_length, &expr_maxlen, words[*offset]);
 769           if (expr == NULL)
 770             return WRDE_NOSPACE;
 771
 772           break;
 773
 774         case ']':
 775           if (bracket && paren_depth == 1)
 776             {
 777               char result[21];  /* 21 = ceil(log10(2^64)) + 1 */
 778               long int numresult = 0;
 779
 780               /* Go - evaluate. */
 781               if (*expr && eval_expr (expr, &numresult) != 0)
 782                 {
 783                   free (expr);
 784                   return WRDE_SYNTAX;
 785                 }
 786
 787               result[20] = '\0';
 788               *word = w_addstr (*word, word_length, max_length,
 789                                 _itoa_word (numresult, &result[20], 10, 0));
 790               free (expr);
 791               return *word ? 0 : WRDE_NOSPACE;
 792             }
 793
 794           free (expr);
 795           return WRDE_SYNTAX;
 796
 797         case '\n':
 798         case ';':
 799         case '{':
 800         case '}':
 801           free (expr);
 802           return WRDE_BADCHAR;
 803
 804         case '(':
 805           ++paren_depth;
 806         default:
 807           expr = w_addchar (expr, &expr_length, &expr_maxlen, words[*offset]);
 808           if (expr == NULL)
 809             return WRDE_NOSPACE;
 810         }
 811     }
 812
 813   /* Premature end */
 814   free (expr);
 815   return WRDE_SYNTAX;
 816 }
 817
 818 /* Function called by child process in exec_comm() */
 819 static inline void
 820 internal_function __attribute__ ((always_inline))
 821 exec_comm_child (char *comm, int *fildes, int showerr, int noexec)
 822 {
 823   const char *args[4] = { _PATH_BSHELL, "-c", comm, NULL };
 824
 825   /* Execute the command, or just check syntax? */
 826   if (noexec)
 827     args[1] = "-nc";
 828
 829   /* Redirect output.  */
 830   if (__glibc_likely (fildes[1] != STDOUT_FILENO))
 831     {
 832       __dup2 (fildes[1], STDOUT_FILENO);
 833       __close (fildes[1]);
 834     }
 835   else
 836     /* Reset the close-on-exec flag (if necessary).  */
 837     __fcntl (fildes[1], F_SETFD, 0);
 838
 839   /* Redirect stderr to /dev/null if we have to.  */
 840   if (showerr == 0)
 841     {
 842       struct stat64 st;
 843       int fd;
 844       __close (STDERR_FILENO);
 845       fd = __open (_PATH_DEVNULL, O_WRONLY);
 846       if (fd >= 0 && fd != STDERR_FILENO)
 847         {
 848           __dup2 (fd, STDERR_FILENO);
 849           __close (fd);
 850         }
 851       /* Be paranoid.  Check that we actually opened the /dev/null
 852          device.  */
 853       if (__builtin_expect (__fxstat64 (_STAT_VER, STDERR_FILENO, &st), 0) != 0
 854           || __builtin_expect (S_ISCHR (st.st_mode), 1) == 0
 855 #if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
 856           || st.st_rdev != makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR)
 857 #endif
 858           )
 859         /* It's not the /dev/null device.  Stop right here.  The
 860            problem is: how do we stop?  We use _exit() with an
 861            hopefully unusual exit code.  */
 862         _exit (90);
 863     }
 864
 865   /* Make sure the subshell doesn't field-split on our behalf. */
 866   __unsetenv ("IFS");
 867
 868   __close (fildes[0]);
 869   __execve (_PATH_BSHELL, (char *const *) args, __environ);
 870
 871   /* Bad.  What now?  */
 872   abort ();
 873 }
 874
 875 /* Function to execute a command and retrieve the results */
 876 /* pwordexp contains NULL if field-splitting is forbidden */
 877 static int
 878 internal_function
 879 exec_comm (char *comm, char **word, size_t *word_length, size_t *max_length,
 880            int flags, wordexp_t *pwordexp, const char *ifs,
 881            const char *ifs_white)
 882 {
 883   int fildes[2];
 884 #define bufsize 128
 885   int buflen;
 886   int i;
 887   int status = 0;
 888   size_t maxnewlines = 0;
 889   char buffer[bufsize];
 890   pid_t pid;
 891   int noexec = 0;
 892
 893   /* Do nothing if command substitution should not succeed.  */
 894   if (flags & WRDE_NOCMD)
 895     return WRDE_CMDSUB;
 896
 897   /* Don't fork() unless necessary */
 898   if (!comm || !*comm)
 899     return 0;
 900
 901   if (__pipe2 (fildes, O_CLOEXEC) < 0)
 902     return WRDE_NOSPACE;
 903
 904  again:
 905   if ((pid = __fork ()) < 0)
 906     {
 907       /* Bad */
 908       __close (fildes[0]);
 909       __close (fildes[1]);
 910       return WRDE_NOSPACE;
 911     }
 912
 913   if (pid == 0)
 914     exec_comm_child (comm, fildes, noexec ? 0 : flags & WRDE_SHOWERR, noexec);
 915
 916   /* Parent */
 917
 918   /* If we are just testing the syntax, only wait.  */
 919   if (noexec)
 920     return (TEMP_FAILURE_RETRY (__waitpid (pid, &status, 0)) == pid
 921             && status != 0) ? WRDE_SYNTAX : 0;
 922
 923   __close (fildes[1]);
 924   fildes[1] = -1;
 925
 926   if (!pwordexp)
 927     /* Quoted - no field splitting */
 928     {
 929       while (1)
 930         {
 931           if ((buflen = TEMP_FAILURE_RETRY (__read (fildes[0], buffer,
 932                                                     bufsize))) < 1)
 933             {
 934               /* If read returned 0 then the process has closed its
 935                  stdout.  Don't use WNOHANG in that case to avoid busy
 936                  looping until the process eventually exits.  */
 937               if (TEMP_FAILURE_RETRY (__waitpid (pid, &status,
 938                                                  buflen == 0 ? 0 : WNOHANG))
 939                   == 0)
 940                 continue;
 941               if ((buflen = TEMP_FAILURE_RETRY (__read (fildes[0], buffer,
 942                                                         bufsize))) < 1)
 943                 break;
 944             }
 945
 946           maxnewlines += buflen;
 947
 948           *word = w_addmem (*word, word_length, max_length, buffer, buflen);
 949           if (*word == NULL)
 950             goto no_space;
 951         }
 952     }
 953   else
 954     /* Not quoted - split fields */
 955     {
 956       int copying = 0;
 957       /* 'copying' is:
 958        *  0 when searching for first character in a field not IFS white space
 959        *  1 when copying the text of a field
 960        *  2 when searching for possible non-whitespace IFS
 961        *  3 when searching for non-newline after copying field
 962        */
 963
 964       while (1)
 965         {
 966           if ((buflen = TEMP_FAILURE_RETRY (__read (fildes[0], buffer,
 967                                                     bufsize))) < 1)
 968             {
 969               /* If read returned 0 then the process has closed its
 970                  stdout.  Don't use WNOHANG in that case to avoid busy
 971                  looping until the process eventually exits.  */
 972               if (TEMP_FAILURE_RETRY (__waitpid (pid, &status,
 973                                                  buflen == 0 ? 0 : WNOHANG))
 974                   == 0)
 975                 continue;
 976               if ((buflen = TEMP_FAILURE_RETRY (__read (fildes[0], buffer,
 977                                                         bufsize))) < 1)
 978                 break;
 979             }
 980
 981           for (i = 0; i < buflen; ++i)
 982             {
 983               if (strchr (ifs, buffer[i]) != NULL)
 984                 {
 985                   /* Current character is IFS */
 986                   if (strchr (ifs_white, buffer[i]) == NULL)
 987                     {
 988                       /* Current character is IFS but not whitespace */
 989                       if (copying == 2)
 990                         {
 991                           /*            current character
 992                            *                   |
 993                            *                   V
 994                            * eg: text<space><comma><space>moretext
 995                            *
 996                            * So, strip whitespace IFS (like at the start)
 997                            */
 998                           copying = 0;
 999                           continue;
1000                         }
1001
1002                       copying = 0;
1003                       /* fall through and delimit field.. */
1004                     }
1005                   else
1006                     {
1007                       if (buffer[i] == '\n')
1008                         {
1009                           /* Current character is (IFS) newline */
1010
1011                           /* If copying a field, this is the end of it,
1012                              but maybe all that's left is trailing newlines.
1013                              So start searching for a non-newline. */
1014                           if (copying == 1)
1015                             copying = 3;
1016
1017                           continue;
1018                         }
1019                       else
1020                         {
1021                           /* Current character is IFS white space, but
1022                              not a newline */
1023
1024                           /* If not either copying a field or searching
1025                              for non-newline after a field, ignore it */
1026                           if (copying != 1 && copying != 3)
1027                             continue;
1028
1029                           /* End of field (search for non-ws IFS afterwards) */
1030                           copying = 2;
1031                         }
1032                     }
1033
1034                   /* First IFS white space (non-newline), or IFS non-whitespace.
1035                    * Delimit the field.  Nulls are converted by w_addword. */
1036                   if (w_addword (pwordexp, *word) == WRDE_NOSPACE)
1037                     goto no_space;
1038
1039                   *word = w_newword (word_length, max_length);
1040
1041                   maxnewlines = 0;
1042                   /* fall back round the loop.. */
1043                 }
1044               else
1045                 {
1046                   /* Not IFS character */
1047
1048                   if (copying == 3)
1049                     {
1050                       /* Nothing but (IFS) newlines since the last field,
1051                          so delimit it here before starting new word */
1052                       if (w_addword (pwordexp, *word) == WRDE_NOSPACE)
1053                         goto no_space;
1054
1055                       *word = w_newword (word_length, max_length);
1056                     }
1057
1058                   copying = 1;
1059
1060                   if (buffer[i] == '\n') /* happens if newline not in IFS */
1061                     maxnewlines++;
1062                   else
1063                     maxnewlines = 0;
1064
1065                   *word = w_addchar (*word, word_length, max_length,
1066                                      buffer[i]);
1067                   if (*word == NULL)
1068                     goto no_space;
1069                 }
1070             }
1071         }
1072     }
1073
1074   /* Chop off trailing newlines (required by POSIX.2)  */
1075   /* Ensure we don't go back further than the beginning of the
1076      substitution (i.e. remove maxnewlines bytes at most) */
1077   while (maxnewlines-- != 0 &&
1078          *word_length > 0 && (*word)[*word_length - 1] == '\n')
1079     {
1080       (*word)[--*word_length] = '\0';
1081
1082       /* If the last word was entirely newlines, turn it into a new word
1083        * which can be ignored if there's nothing following it. */
1084       if (*word_length == 0)
1085         {
1086           free (*word);
1087           *word = w_newword (word_length, max_length);
1088           break;
1089         }
1090     }
1091
1092   __close (fildes[0]);
1093   fildes[0] = -1;
1094
1095   /* Check for syntax error (re-execute but with "-n" flag) */
1096   if (buflen < 1 && status != 0)
1097     {
1098       noexec = 1;
1099       goto again;
1100     }
1101
1102   return 0;
1103
1104 no_space:
1105   __kill (pid, SIGKILL);
1106   TEMP_FAILURE_RETRY (__waitpid (pid, NULL, 0));
1107   __close (fildes[0]);
1108   return WRDE_NOSPACE;
1109 }
1110
1111 static int
1112 internal_function
1113 parse_comm (char **word, size_t *word_length, size_t *max_length,
1114             const char *words, size_t *offset, int flags, wordexp_t *pwordexp,
1115             const char *ifs, const char *ifs_white)
1116 {
1117   /* We are poised just after "$(" */
1118   int paren_depth = 1;
1119   int error = 0;
1120   int quoted = 0; /* 1 for singly-quoted, 2 for doubly-quoted */
1121   size_t comm_length;
1122   size_t comm_maxlen;
1123   char *comm = w_newword (&comm_length, &comm_maxlen);
1124
1125   for (; words[*offset]; ++(*offset))
1126     {
1127       switch (words[*offset])
1128         {
1129         case '\'':
1130           if (quoted == 0)
1131             quoted = 1;
1132           else if (quoted == 1)
1133             quoted = 0;
1134
1135           break;
1136
1137         case '"':
1138           if (quoted == 0)
1139             quoted = 2;
1140           else if (quoted == 2)
1141             quoted = 0;
1142
1143           break;
1144
1145         case ')':
1146           if (!quoted && --paren_depth == 0)
1147             {
1148               /* Go -- give script to the shell */
1149               if (comm)
1150                 {
1151 #ifdef __libc_ptf_call
1152                   /* We do not want the exec_comm call to be cut short
1153                      by a thread cancellation since cleanup is very
1154                      ugly.  Therefore disable cancellation for
1155                      now.  */
1156                   // XXX Ideally we do want the thread being cancelable.
1157                   // XXX If demand is there we'll change it.
1158                   int state = PTHREAD_CANCEL_ENABLE;
1159                   __libc_ptf_call (__pthread_setcancelstate,
1160                                    (PTHREAD_CANCEL_DISABLE, &state), 0);
1161 #endif
1162
1163                   error = exec_comm (comm, word, word_length, max_length,
1164                                      flags, pwordexp, ifs, ifs_white);
1165
1166 #ifdef __libc_ptf_call
1167                   __libc_ptf_call (__pthread_setcancelstate,
1168                                    (state, NULL), 0);
1169 #endif
1170
1171                   free (comm);
1172                 }
1173
1174               return error;
1175             }
1176
1177           /* This is just part of the script */
1178           break;
1179
1180         case '(':
1181           if (!quoted)
1182             ++paren_depth;
1183         }
1184
1185       comm = w_addchar (comm, &comm_length, &comm_maxlen, words[*offset]);
1186       if (comm == NULL)
1187         return WRDE_NOSPACE;
1188     }
1189
1190   /* Premature end.  */
1191   free (comm);
1192
1193   return WRDE_SYNTAX;
1194 }
1195
1196 #define CHAR_IN_SET(ch, char_set) \
1197   (memchr (char_set "", ch, sizeof (char_set) - 1) != NULL)
1198
1199 static int
1200 internal_function
1201 parse_param (char **word, size_t *word_length, size_t *max_length,
1202              const char *words, size_t *offset, int flags, wordexp_t *pwordexp,
1203              const char *ifs, const char *ifs_white, int quoted)
1204 {
1205   /* We are poised just after "$" */
1206   enum action
1207   {
1208     ACT_NONE,
1209     ACT_RP_SHORT_LEFT = '#',
1210     ACT_RP_LONG_LEFT = 'L',
1211     ACT_RP_SHORT_RIGHT = '%',
1212     ACT_RP_LONG_RIGHT = 'R',
1213     ACT_NULL_ERROR = '?',
1214     ACT_NULL_SUBST = '-',
1215     ACT_NONNULL_SUBST = '+',
1216     ACT_NULL_ASSIGN = '='
1217   };
1218   size_t env_length;
1219   size_t env_maxlen;
1220   size_t pat_length;
1221   size_t pat_maxlen;
1222   size_t start = *offset;
1223   char *env;
1224   char *pattern;
1225   char *value = NULL;
1226   enum action action = ACT_NONE;
1227   int depth = 0;
1228   int colon_seen = 0;
1229   int seen_hash = 0;
1230   int free_value = 0;
1231   int pattern_is_quoted = 0; /* 1 for singly-quoted, 2 for doubly-quoted */
1232   int error;
1233   int special = 0;
1234   char buffer[21];
1235   int brace = words[*offset] == '{';
1236
1237   env = w_newword (&env_length, &env_maxlen);
1238   pattern = w_newword (&pat_length, &pat_maxlen);
1239
1240   if (brace)
1241     ++*offset;
1242
1243   /* First collect the parameter name. */
1244
1245   if (words[*offset] == '#')
1246     {
1247       seen_hash = 1;
1248       if (!brace)
1249         goto envsubst;
1250       ++*offset;
1251     }
1252
1253   if (isalpha (words[*offset]) || words[*offset] == '_')
1254     {
1255       /* Normal parameter name. */
1256       do
1257         {
1258           env = w_addchar (env, &env_length, &env_maxlen,
1259                            words[*offset]);
1260           if (env == NULL)
1261             goto no_space;
1262         }
1263       while (isalnum (words[++*offset]) || words[*offset] == '_');
1264     }
1265   else if (isdigit (words[*offset]))
1266     {
1267       /* Numeric parameter name. */
1268       special = 1;
1269       do
1270         {
1271           env = w_addchar (env, &env_length, &env_maxlen,
1272                            words[*offset]);
1273           if (env == NULL)
1274             goto no_space;
1275           if (!brace)
1276             goto envsubst;
1277         }
1278       while (isdigit(words[++*offset]));
1279     }
1280   else if (CHAR_IN_SET (words[*offset], "*@$"))
1281     {
1282       /* Special parameter. */
1283       special = 1;
1284       env = w_addchar (env, &env_length, &env_maxlen,
1285                        words[*offset]);
1286       if (env == NULL)
1287         goto no_space;
1288       ++*offset;
1289     }
1290   else
1291     {
1292       if (brace)
1293         goto syntax;
1294     }
1295
1296   if (brace)
1297     {
1298       /* Check for special action to be applied to the value. */
1299       switch (words[*offset])
1300         {
1301         case '}':
1302           /* Evaluate. */
1303           goto envsubst;
1304
1305         case '#':
1306           action = ACT_RP_SHORT_LEFT;
1307           if (words[1 + *offset] == '#')
1308             {
1309               ++*offset;
1310               action = ACT_RP_LONG_LEFT;
1311             }
1312           break;
1313
1314         case '%':
1315           action = ACT_RP_SHORT_RIGHT;
1316           if (words[1 + *offset] == '%')
1317             {
1318               ++*offset;
1319               action = ACT_RP_LONG_RIGHT;
1320             }
1321           break;
1322
1323         case ':':
1324           if (!CHAR_IN_SET (words[1 + *offset], "-=?+"))
1325             goto syntax;
1326
1327           colon_seen = 1;
1328           action = words[++*offset];
1329           break;
1330
1331         case '-':
1332         case '=':
1333         case '?':
1334         case '+':
1335           action = words[*offset];
1336           break;
1337
1338         default:
1339           goto syntax;
1340         }
1341
1342       /* Now collect the pattern, but don't expand it yet. */
1343       ++*offset;
1344       for (; words[*offset]; ++(*offset))
1345         {
1346           switch (words[*offset])
1347             {
1348             case '{':
1349               if (!pattern_is_quoted)
1350                 ++depth;
1351               break;
1352
1353             case '}':
1354               if (!pattern_is_quoted)
1355                 {
1356                   if (depth == 0)
1357                     goto envsubst;
1358                   --depth;
1359                 }
1360               break;
1361
1362             case '\\':
1363               if (pattern_is_quoted)
1364                 /* Quoted; treat as normal character. */
1365                 break;
1366
1367               /* Otherwise, it's an escape: next character is literal. */
1368               if (words[++*offset] == '\0')
1369                 goto syntax;
1370
1371               pattern = w_addchar (pattern, &pat_length, &pat_maxlen, '\\');
1372               if (pattern == NULL)
1373                 goto no_space;
1374
1375               break;
1376
1377             case '\'':
1378               if (pattern_is_quoted == 0)
1379                 pattern_is_quoted = 1;
1380               else if (pattern_is_quoted == 1)
1381                 pattern_is_quoted = 0;
1382
1383               break;
1384
1385             case '"':
1386               if (pattern_is_quoted == 0)
1387                 pattern_is_quoted = 2;
1388               else if (pattern_is_quoted == 2)
1389                 pattern_is_quoted = 0;
1390
1391               break;
1392             }
1393
1394           pattern = w_addchar (pattern, &pat_length, &pat_maxlen,
1395                                words[*offset]);
1396           if (pattern == NULL)
1397             goto no_space;
1398         }
1399     }
1400
1401   /* End of input string -- remember to reparse the character that we
1402    * stopped at.  */
1403   --(*offset);
1404
1405 envsubst:
1406   if (words[start] == '{' && words[*offset] != '}')
1407     goto syntax;
1408
1409   if (env == NULL)
1410     {
1411       if (seen_hash)
1412         {
1413           /* $# expands to the number of positional parameters */
1414           buffer[20] = '\0';
1415           value = _itoa_word (__libc_argc - 1, &buffer[20], 10, 0);
1416           seen_hash = 0;
1417         }
1418       else
1419         {
1420           /* Just $ on its own */
1421           *offset = start - 1;
1422           *word = w_addchar (*word, word_length, max_length, '$');
1423           return *word ? 0 : WRDE_NOSPACE;
1424         }
1425     }
1426   /* Is it a numeric parameter? */
1427   else if (isdigit (env[0]))
1428     {
1429       int n = atoi (env);
1430
1431       if (n >= __libc_argc)
1432         /* Substitute NULL. */
1433         value = NULL;
1434       else
1435         /* Replace with appropriate positional parameter. */
1436         value = __libc_argv[n];
1437     }
1438   /* Is it a special parameter? */
1439   else if (special)
1440     {
1441       /* Is it `$$'? */
1442       if (*env == '$')
1443         {
1444           buffer[20] = '\0';
1445           value = _itoa_word (__getpid (), &buffer[20], 10, 0);
1446         }
1447       /* Is it `${#*}' or `${#@}'? */
1448       else if ((*env == '*' || *env == '@') && seen_hash)
1449         {
1450           buffer[20] = '\0';
1451           value = _itoa_word (__libc_argc > 0 ? __libc_argc - 1 : 0,
1452                               &buffer[20], 10, 0);
1453           *word = w_addstr (*word, word_length, max_length, value);
1454           free (env);
1455           free (pattern);
1456           return *word ? 0 : WRDE_NOSPACE;
1457         }
1458       /* Is it `$*' or `$@' (unquoted) ? */
1459       else if (*env == '*' || (*env == '@' && !quoted))
1460         {
1461           size_t plist_len = 0;
1462           int p;
1463           char *end;
1464
1465           /* Build up value parameter by parameter (copy them) */
1466           for (p = 1; __libc_argv[p]; ++p)
1467             plist_len += strlen (__libc_argv[p]) + 1; /* for space */
1468           value = malloc (plist_len);
1469           if (value == NULL)
1470             goto no_space;
1471           end = value;
1472           *end = 0;
1473           for (p = 1; __libc_argv[p]; ++p)
1474             {
1475               if (p > 1)
1476                 *end++ = ' ';
1477               end = __stpcpy (end, __libc_argv[p]);
1478             }
1479
1480           free_value = 1;
1481         }
1482       else
1483         {
1484           /* Must be a quoted `$@' */
1485           assert (*env == '@' && quoted);
1486
1487           /* Each parameter is a separate word ("$@") */
1488           if (__libc_argc == 2)
1489             value = __libc_argv[1];
1490           else if (__libc_argc > 2)
1491             {
1492               int p;
1493
1494               /* Append first parameter to current word. */
1495               value = w_addstr (*word, word_length, max_length,
1496                                 __libc_argv[1]);
1497               if (value == NULL || w_addword (pwordexp, value))
1498                 goto no_space;
1499
1500               for (p = 2; __libc_argv[p + 1]; p++)
1501                 {
1502                   char *newword = __strdup (__libc_argv[p]);
1503                   if (newword == NULL || w_addword (pwordexp, newword))
1504                     goto no_space;
1505                 }
1506
1507               /* Start a new word with the last parameter. */
1508               *word = w_newword (word_length, max_length);
1509               value = __libc_argv[p];
1510             }
1511           else
1512             {
1513               free (env);
1514               free (pattern);
1515               return 0;
1516             }
1517         }
1518     }
1519   else
1520     value = getenv (env);
1521
1522   if (value == NULL && (flags & WRDE_UNDEF))
1523     {
1524       /* Variable not defined. */
1525       error = WRDE_BADVAL;
1526       goto do_error;
1527     }
1528
1529   if (action != ACT_NONE)
1530     {
1531       int expand_pattern = 0;
1532
1533       /* First, find out if we need to expand pattern (i.e. if we will
1534        * use it). */
1535       switch (action)
1536         {
1537         case ACT_RP_SHORT_LEFT:
1538         case ACT_RP_LONG_LEFT:
1539         case ACT_RP_SHORT_RIGHT:
1540         case ACT_RP_LONG_RIGHT:
1541           /* Always expand for these. */
1542           expand_pattern = 1;
1543           break;
1544
1545         case ACT_NULL_ERROR:
1546         case ACT_NULL_SUBST:
1547         case ACT_NULL_ASSIGN:
1548           if (!value || (!*value && colon_seen))
1549             /* If param is unset, or set but null and a colon has been seen,
1550                the expansion of the pattern will be needed. */
1551             expand_pattern = 1;
1552
1553           break;
1554
1555         case ACT_NONNULL_SUBST:
1556           /* Expansion of word will be needed if parameter is set and not null,
1557              or set null but no colon has been seen. */
1558           if (value && (*value || !colon_seen))
1559             expand_pattern = 1;
1560
1561           break;
1562
1563         default:
1564           assert (! "Unrecognised action!");
1565         }
1566
1567       if (expand_pattern)
1568         {
1569           /* We need to perform tilde expansion, parameter expansion,
1570              command substitution, and arithmetic expansion.  We also
1571              have to be a bit careful with wildcard characters, as
1572              pattern might be given to fnmatch soon.  To do this, we
1573              convert quotes to escapes. */
1574
1575           char *expanded;
1576           size_t exp_len;
1577           size_t exp_maxl;
1578           char *p;
1579           int quoted = 0; /* 1: single quotes; 2: double */
1580
1581           expanded = w_newword (&exp_len, &exp_maxl);
1582           for (p = pattern; p && *p; p++)
1583             {
1584               size_t offset;
1585
1586               switch (*p)
1587                 {
1588                 case '"':
1589                   if (quoted == 2)
1590                     quoted = 0;
1591                   else if (quoted == 0)
1592                     quoted = 2;
1593                   else break;
1594
1595                   continue;
1596
1597                 case '\'':
1598                   if (quoted == 1)
1599                     quoted = 0;
1600                   else if (quoted == 0)
1601                     quoted = 1;
1602                   else break;
1603
1604                   continue;
1605
1606                 case '*':
1607                 case '?':
1608                   if (quoted)
1609                     {
1610                       /* Convert quoted wildchar to escaped wildchar. */
1611                       expanded = w_addchar (expanded, &exp_len,
1612                                             &exp_maxl, '\\');
1613
1614                       if (expanded == NULL)
1615                         goto no_space;
1616                     }
1617                   break;
1618
1619                 case '$':
1620                   offset = 0;
1621                   error = parse_dollars (&expanded, &exp_len, &exp_maxl, p,
1622                                          &offset, flags, NULL, NULL, NULL, 1);
1623                   if (error)
1624                     {
1625                       if (free_value)
1626                         free (value);
1627
1628                       free (expanded);
1629
1630                       goto do_error;
1631                     }
1632
1633                   p += offset;
1634                   continue;
1635
1636                 case '~':
1637                   if (quoted || exp_len)
1638                     break;
1639
1640                   offset = 0;
1641                   error = parse_tilde (&expanded, &exp_len, &exp_maxl, p,
1642                                        &offset, 0);
1643                   if (error)
1644                     {
1645                       if (free_value)
1646                         free (value);
1647
1648                       free (expanded);
1649
1650                       goto do_error;
1651                     }
1652
1653                   p += offset;
1654                   continue;
1655
1656                 case '\\':
1657                   expanded = w_addchar (expanded, &exp_len, &exp_maxl, '\\');
1658                   ++p;
1659                   assert (*p); /* checked when extracted initially */
1660                   if (expanded == NULL)
1661                     goto no_space;
1662                 }
1663
1664               expanded = w_addchar (expanded, &exp_len, &exp_maxl, *p);
1665
1666               if (expanded == NULL)
1667                 goto no_space;
1668             }
1669
1670           free (pattern);
1671
1672           pattern = expanded;
1673         }
1674
1675       switch (action)
1676         {
1677         case ACT_RP_SHORT_LEFT:
1678         case ACT_RP_LONG_LEFT:
1679         case ACT_RP_SHORT_RIGHT:
1680         case ACT_RP_LONG_RIGHT:
1681           {
1682             char *p;
1683             char c;
1684             char *end;
1685
1686             if (value == NULL || pattern == NULL || *pattern == '\0')
1687               break;
1688
1689             end = value + strlen (value);
1690
1691             switch (action)
1692               {
1693               case ACT_RP_SHORT_LEFT:
1694                 for (p = value; p <= end; ++p)
1695                   {
1696                     c = *p;
1697                     *p = '\0';
1698                     if (fnmatch (pattern, value, 0) != FNM_NOMATCH)
1699                       {
1700                         *p = c;
1701                         if (free_value)
1702                           {
1703                             char *newval = __strdup (p);
1704                             if (newval == NULL)
1705                               {
1706                                 free (value);
1707                                 goto no_space;
1708                               }
1709                             free (value);
1710                             value = newval;
1711                           }
1712                         else
1713                           value = p;
1714                         break;
1715                       }
1716                     *p = c;
1717                   }
1718
1719                 break;
1720
1721               case ACT_RP_LONG_LEFT:
1722                 for (p = end; p >= value; --p)
1723                   {
1724                     c = *p;
1725                     *p = '\0';
1726                     if (fnmatch (pattern, value, 0) != FNM_NOMATCH)
1727                       {
1728                         *p = c;
1729                         if (free_value)
1730                           {
1731                             char *newval = __strdup (p);
1732                             if (newval == NULL)
1733                               {
1734                                 free (value);
1735                                 goto no_space;
1736                               }
1737                             free (value);
1738                             value = newval;
1739                           }
1740                         else
1741                           value = p;
1742                         break;
1743                       }
1744                     *p = c;
1745                   }
1746
1747                 break;
1748
1749               case ACT_RP_SHORT_RIGHT:
1750                 for (p = end; p >= value; --p)
1751                   {
1752                     if (fnmatch (pattern, p, 0) != FNM_NOMATCH)
1753                       {
1754                         char *newval;
1755                         newval = malloc (p - value + 1);
1756
1757                         if (newval == NULL)
1758                           {
1759                             if (free_value)
1760                               free (value);
1761                             goto no_space;
1762                           }
1763
1764                         *(char *) __mempcpy (newval, value, p - value) = '\0';
1765                         if (free_value)
1766                           free (value);
1767                         value = newval;
1768                         free_value = 1;
1769                         break;
1770                       }
1771                   }
1772
1773                 break;
1774
1775               case ACT_RP_LONG_RIGHT:
1776                 for (p = value; p <= end; ++p)
1777                   {
1778                     if (fnmatch (pattern, p, 0) != FNM_NOMATCH)
1779                       {
1780                         char *newval;
1781                         newval = malloc (p - value + 1);
1782
1783                         if (newval == NULL)
1784                           {
1785                             if (free_value)
1786                               free (value);
1787                             goto no_space;
1788                           }
1789
1790                         *(char *) __mempcpy (newval, value, p - value) = '\0';
1791                         if (free_value)
1792                           free (value);
1793                         value = newval;
1794                         free_value = 1;
1795                         break;
1796                       }
1797                   }
1798
1799                 break;
1800
1801               default:
1802                 break;
1803               }
1804
1805             break;
1806           }
1807
1808         case ACT_NULL_ERROR:
1809           if (value && *value)
1810             /* Substitute parameter */
1811             break;
1812
1813           error = 0;
1814           if (!colon_seen && value)
1815             /* Substitute NULL */
1816             ;
1817           else
1818             {
1819               const char *str = pattern;
1820
1821               if (str[0] == '\0')
1822                 str = _("parameter null or not set");
1823
1824               __fxprintf (NULL, "%s: %s\n", env, str);
1825             }
1826
1827           if (free_value)
1828             free (value);
1829           goto do_error;
1830
1831         case ACT_NULL_SUBST:
1832           if (value && *value)
1833             /* Substitute parameter */
1834             break;
1835
1836           if (free_value)
1837             free (value);
1838
1839           if (!colon_seen && value)
1840             /* Substitute NULL */
1841             goto success;
1842
1843           value = pattern ? __strdup (pattern) : pattern;
1844           free_value = 1;
1845
1846           if (pattern && !value)
1847             goto no_space;
1848
1849           break;
1850
1851         case ACT_NONNULL_SUBST:
1852           if (value && (*value || !colon_seen))
1853             {
1854               if (free_value)
1855                 free (value);
1856
1857               value = pattern ? __strdup (pattern) : pattern;
1858               free_value = 1;
1859
1860               if (pattern && !value)
1861                 goto no_space;
1862
1863               break;
1864             }
1865
1866           /* Substitute NULL */
1867           if (free_value)
1868             free (value);
1869           goto success;
1870
1871         case ACT_NULL_ASSIGN:
1872           if (value && *value)
1873             /* Substitute parameter */
1874             break;
1875
1876           if (!colon_seen && value)
1877             {
1878               /* Substitute NULL */
1879               if (free_value)
1880                 free (value);
1881               goto success;
1882             }
1883
1884           if (free_value)
1885             free (value);
1886
1887           value = pattern ? __strdup (pattern) : pattern;
1888           free_value = 1;
1889
1890           if (pattern && !value)
1891             goto no_space;
1892
1893           __setenv (env, value ?: "", 1);
1894           break;
1895
1896         default:
1897           assert (! "Unrecognised action!");
1898         }
1899     }
1900
1901   free (env);
1902   env = NULL;
1903   free (pattern);
1904   pattern = NULL;
1905
1906   if (seen_hash)
1907     {
1908       char param_length[21];
1909       param_length[20] = '\0';
1910       *word = w_addstr (*word, word_length, max_length,
1911                         _itoa_word (value ? strlen (value) : 0,
1912                                     &param_length[20], 10, 0));
1913       if (free_value)
1914         {
1915           assert (value != NULL);
1916           free (value);
1917         }
1918
1919       return *word ? 0 : WRDE_NOSPACE;
1920     }
1921
1922   if (value == NULL)
1923     return 0;
1924
1925   if (quoted || !pwordexp)
1926     {
1927       /* Quoted - no field split */
1928       *word = w_addstr (*word, word_length, max_length, value);
1929       if (free_value)
1930         free (value);
1931
1932       return *word ? 0 : WRDE_NOSPACE;
1933     }
1934   else
1935     {
1936       /* Need to field-split */
1937       char *value_copy = __strdup (value); /* Don't modify value */
1938       char *field_begin = value_copy;
1939       int seen_nonws_ifs = 0;
1940
1941       if (free_value)
1942         free (value);
1943
1944       if (value_copy == NULL)
1945         goto no_space;
1946
1947       do
1948         {
1949           char *field_end = field_begin;
1950           char *next_field;
1951
1952           /* If this isn't the first field, start a new word */
1953           if (field_begin != value_copy)
1954             {
1955               if (w_addword (pwordexp, *word) == WRDE_NOSPACE)
1956                 {
1957                   free (value_copy);
1958                   goto no_space;
1959                 }
1960
1961               *word = w_newword (word_length, max_length);
1962             }
1963
1964           /* Skip IFS whitespace before the field */
1965           field_begin += strspn (field_begin, ifs_white);
1966
1967           if (!seen_nonws_ifs && *field_begin == 0)
1968             /* Nothing but whitespace */
1969             break;
1970
1971           /* Search for the end of the field */
1972           field_end = field_begin + strcspn (field_begin, ifs);
1973
1974           /* Set up pointer to the character after end of field and
1975              skip whitespace IFS after it. */
1976           next_field = field_end + strspn (field_end, ifs_white);
1977
1978           /* Skip at most one non-whitespace IFS character after the field */
1979           seen_nonws_ifs = 0;
1980           if (*next_field && strchr (ifs, *next_field))
1981             {
1982               seen_nonws_ifs = 1;
1983               next_field++;
1984             }
1985
1986           /* Null-terminate it */
1987           *field_end = 0;
1988
1989           /* Tag a copy onto the current word */
1990           *word = w_addstr (*word, word_length, max_length, field_begin);
1991
1992           if (*word == NULL && *field_begin != '\0')
1993             {
1994               free (value_copy);
1995               goto no_space;
1996             }
1997
1998           field_begin = next_field;
1999         }
2000       while (seen_nonws_ifs || *field_begin);
2001
2002       free (value_copy);
2003     }
2004
2005   return 0;
2006
2007 success:
2008   error = 0;
2009   goto do_error;
2010
2011 no_space:
2012   error = WRDE_NOSPACE;
2013   goto do_error;
2014
2015 syntax:
2016   error = WRDE_SYNTAX;
2017
2018 do_error:
2019   free (env);
2020
2021   free (pattern);
2022
2023   return error;
2024 }
2025
2026 #undef CHAR_IN_SET
2027
2028 static int
2029 internal_function
2030 parse_dollars (char **word, size_t *word_length, size_t *max_length,
2031                const char *words, size_t *offset, int flags,
2032                wordexp_t *pwordexp, const char *ifs, const char *ifs_white,
2033                int quoted)
2034 {
2035   /* We are poised _at_ "$" */
2036   switch (words[1 + *offset])
2037     {
2038     case '"':
2039     case '\'':
2040     case 0:
2041       *word = w_addchar (*word, word_length, max_length, '$');
2042       return *word ? 0 : WRDE_NOSPACE;
2043
2044     case '(':
2045       if (words[2 + *offset] == '(')
2046         {
2047           /* Differentiate between $((1+3)) and $((echo);(ls)) */
2048           int i = 3 + *offset;
2049           int depth = 0;
2050           while (words[i] && !(depth == 0 && words[i] == ')'))
2051             {
2052               if (words[i] == '(')
2053                 ++depth;
2054               else if (words[i] == ')')
2055                 --depth;
2056
2057               ++i;
2058             }
2059
2060           if (words[i] == ')' && words[i + 1] == ')')
2061             {
2062               (*offset) += 3;
2063               /* Call parse_arith -- 0 is for "no brackets" */
2064               return parse_arith (word, word_length, max_length, words, offset,
2065                                   flags, 0);
2066             }
2067         }
2068
2069       (*offset) += 2;
2070       return parse_comm (word, word_length, max_length, words, offset, flags,
2071                          quoted? NULL : pwordexp, ifs, ifs_white);
2072
2073     case '[':
2074       (*offset) += 2;
2075       /* Call parse_arith -- 1 is for "brackets" */
2076       return parse_arith (word, word_length, max_length, words, offset, flags,
2077                           1);
2078
2079     case '{':
2080     default:
2081       ++(*offset);      /* parse_param needs to know if "{" is there */
2082       return parse_param (word, word_length, max_length, words, offset, flags,
2083                            pwordexp, ifs, ifs_white, quoted);
2084     }
2085 }
2086
2087 static int
2088 internal_function
2089 parse_backtick (char **word, size_t *word_length, size_t *max_length,
2090                 const char *words, size_t *offset, int flags,
2091                 wordexp_t *pwordexp, const char *ifs, const char *ifs_white)
2092 {
2093   /* We are poised just after "`" */
2094   int error;
2095   int squoting = 0;
2096   size_t comm_length;
2097   size_t comm_maxlen;
2098   char *comm = w_newword (&comm_length, &comm_maxlen);
2099
2100   for (; words[*offset]; ++(*offset))
2101     {
2102       switch (words[*offset])
2103         {
2104         case '`':
2105           /* Go -- give the script to the shell */
2106           error = exec_comm (comm, word, word_length, max_length, flags,
2107                              pwordexp, ifs, ifs_white);
2108           free (comm);
2109           return error;
2110
2111         case '\\':
2112           if (squoting)
2113             {
2114               error = parse_qtd_backslash (&comm, &comm_length, &comm_maxlen,
2115                                            words, offset);
2116
2117               if (error)
2118                 {
2119                   free (comm);
2120                   return error;
2121                 }
2122
2123               break;
2124             }
2125
2126           error = parse_backslash (&comm, &comm_length, &comm_maxlen, words,
2127                                    offset);
2128
2129           if (error)
2130             {
2131               free (comm);
2132               return error;
2133             }
2134
2135           break;
2136
2137         case '\'':
2138           squoting = 1 - squoting;
2139         default:
2140           comm = w_addchar (comm, &comm_length, &comm_maxlen, words[*offset]);
2141           if (comm == NULL)
2142             return WRDE_NOSPACE;
2143         }
2144     }
2145
2146   /* Premature end */
2147   free (comm);
2148   return WRDE_SYNTAX;
2149 }
2150
2151 static int
2152 internal_function
2153 parse_dquote (char **word, size_t *word_length, size_t *max_length,
2154               const char *words, size_t *offset, int flags,
2155               wordexp_t *pwordexp, const char * ifs, const char * ifs_white)
2156 {
2157   /* We are poised just after a double-quote */
2158   int error;
2159
2160   for (; words[*offset]; ++(*offset))
2161     {
2162       switch (words[*offset])
2163         {
2164         case '"':
2165           return 0;
2166
2167         case '$':
2168           error = parse_dollars (word, word_length, max_length, words, offset,
2169                                  flags, pwordexp, ifs, ifs_white, 1);
2170           /* The ``1'' here is to tell parse_dollars not to
2171            * split the fields.  It may need to, however ("$@").
2172            */
2173           if (error)
2174             return error;
2175
2176           break;
2177
2178         case '`':
2179           ++(*offset);
2180           error = parse_backtick (word, word_length, max_length, words,
2181                                   offset, flags, NULL, NULL, NULL);
2182           /* The first NULL here is to tell parse_backtick not to
2183            * split the fields.
2184            */
2185           if (error)
2186             return error;
2187
2188           break;
2189
2190         case '\\':
2191           error = parse_qtd_backslash (word, word_length, max_length, words,
2192                                        offset);
2193
2194           if (error)
2195             return error;
2196
2197           break;
2198
2199         default:
2200           *word = w_addchar (*word, word_length, max_length, words[*offset]);
2201           if (*word == NULL)
2202             return WRDE_NOSPACE;
2203         }
2204     }
2205
2206   /* Unterminated string */
2207   return WRDE_SYNTAX;
2208 }
2209
2210 /*
2211  * wordfree() is to be called after pwordexp is finished with.
2212  */
2213
2214 void
2215 wordfree (wordexp_t *pwordexp)
2216 {
2217
2218   /* wordexp can set pwordexp to NULL */
2219   if (pwordexp && pwordexp->we_wordv)
2220     {
2221       char **wordv = pwordexp->we_wordv;
2222
2223       for (wordv += pwordexp->we_offs; *wordv; ++wordv)
2224         free (*wordv);
2225
2226       free (pwordexp->we_wordv);
2227       pwordexp->we_wordv = NULL;
2228     }
2229 }
2230 libc_hidden_def (wordfree)
2231
2232 /*
2233  * wordexp()
2234  */
2235
2236 int
2237 wordexp (const char *words, wordexp_t *pwordexp, int flags)
2238 {
2239   size_t words_offset;
2240   size_t word_length;
2241   size_t max_length;
2242   char *word = w_newword (&word_length, &max_length);
2243   int error;
2244   char *ifs;
2245   char ifs_white[4];
2246   wordexp_t old_word = *pwordexp;
2247
2248   if (flags & WRDE_REUSE)
2249     {
2250       /* Minimal implementation of WRDE_REUSE for now */
2251       wordfree (pwordexp);
2252       old_word.we_wordv = NULL;
2253     }
2254
2255   if ((flags & WRDE_APPEND) == 0)
2256     {
2257       pwordexp->we_wordc = 0;
2258
2259       if (flags & WRDE_DOOFFS)
2260         {
2261           pwordexp->we_wordv = calloc (1 + pwordexp->we_offs, sizeof (char *));
2262           if (pwordexp->we_wordv == NULL)
2263             {
2264               error = WRDE_NOSPACE;
2265               goto do_error;
2266             }
2267         }
2268       else
2269         {
2270           pwordexp->we_wordv = calloc (1, sizeof (char *));
2271           if (pwordexp->we_wordv == NULL)
2272             {
2273               error = WRDE_NOSPACE;
2274               goto do_error;
2275             }
2276
2277           pwordexp->we_offs = 0;
2278         }
2279     }
2280
2281   /* Find out what the field separators are.
2282    * There are two types: whitespace and non-whitespace.
2283    */
2284   ifs = getenv ("IFS");
2285
2286   if (ifs == NULL)
2287     /* IFS unset - use <space><tab><newline>. */
2288     ifs = strcpy (ifs_white, " \t\n");
2289   else
2290     {
2291       char *ifsch = ifs;
2292       char *whch = ifs_white;
2293
2294       while (*ifsch != '\0')
2295         {
2296           if (*ifsch == ' ' || *ifsch == '\t' || *ifsch == '\n')
2297             {
2298               /* Whitespace IFS.  See first whether it is already in our
2299                  collection.  */
2300               char *runp = ifs_white;
2301
2302               while (runp < whch && *runp != *ifsch)
2303                 ++runp;
2304
2305               if (runp == whch)
2306                 *whch++ = *ifsch;
2307             }
2308
2309           ++ifsch;
2310         }
2311       *whch = '\0';
2312     }
2313
2314   for (words_offset = 0 ; words[words_offset] ; ++words_offset)
2315     switch (words[words_offset])
2316       {
2317       case '\\':
2318         error = parse_backslash (&word, &word_length, &max_length, words,
2319                                  &words_offset);
2320
2321         if (error)
2322           goto do_error;
2323
2324         break;
2325
2326       case '$':
2327         error = parse_dollars (&word, &word_length, &max_length, words,
2328                                &words_offset, flags, pwordexp, ifs, ifs_white,
2329                                0);
2330
2331         if (error)
2332           goto do_error;
2333
2334         break;
2335
2336       case '`':
2337         ++words_offset;
2338         error = parse_backtick (&word, &word_length, &max_length, words,
2339                                 &words_offset, flags, pwordexp, ifs,
2340                                 ifs_white);
2341
2342         if (error)
2343           goto do_error;
2344
2345         break;
2346
2347       case '"':
2348         ++words_offset;
2349         error = parse_dquote (&word, &word_length, &max_length, words,
2350                               &words_offset, flags, pwordexp, ifs, ifs_white);
2351
2352         if (error)
2353           goto do_error;
2354
2355         if (!word_length)
2356           {
2357             error = w_addword (pwordexp, NULL);
2358
2359             if (error)
2360               return error;
2361           }
2362
2363         break;
2364
2365       case '\'':
2366         ++words_offset;
2367         error = parse_squote (&word, &word_length, &max_length, words,
2368                               &words_offset);
2369
2370         if (error)
2371           goto do_error;
2372
2373         if (!word_length)
2374           {
2375             error = w_addword (pwordexp, NULL);
2376
2377             if (error)
2378               return error;
2379           }
2380
2381         break;
2382
2383       case '~':
2384         error = parse_tilde (&word, &word_length, &max_length, words,
2385                              &words_offset, pwordexp->we_wordc);
2386
2387         if (error)
2388           goto do_error;
2389
2390         break;
2391
2392       case '*':
2393       case '[':
2394       case '?':
2395         error = parse_glob (&word, &word_length, &max_length, words,
2396                             &words_offset, flags, pwordexp, ifs, ifs_white);
2397
2398         if (error)
2399           goto do_error;
2400
2401         break;
2402
2403       default:
2404         /* Is it a word separator? */
2405         if (strchr (" \t", words[words_offset]) == NULL)
2406           {
2407             char ch = words[words_offset];
2408
2409             /* Not a word separator -- but is it a valid word char? */
2410             if (strchr ("\n|&;<>(){}", ch))
2411               {
2412                 /* Fail */
2413                 error = WRDE_BADCHAR;
2414                 goto do_error;
2415               }
2416
2417             /* "Ordinary" character -- add it to word */
2418             word = w_addchar (word, &word_length, &max_length,
2419                               ch);
2420             if (word == NULL)
2421               {
2422                 error = WRDE_NOSPACE;
2423                 goto do_error;
2424               }
2425
2426             break;
2427           }
2428
2429         /* If a word has been delimited, add it to the list. */
2430         if (word != NULL)
2431           {
2432             error = w_addword (pwordexp, word);
2433             if (error)
2434               goto do_error;
2435           }
2436
2437         word = w_newword (&word_length, &max_length);
2438       }
2439
2440   /* End of string */
2441
2442   /* There was a word separator at the end */
2443   if (word == NULL) /* i.e. w_newword */
2444     return 0;
2445
2446   /* There was no field separator at the end */
2447   return w_addword (pwordexp, word);
2448
2449 do_error:
2450   /* Error:
2451    *    free memory used (unless error is WRDE_NOSPACE), and
2452    *    set pwordexp members back to what they were.
2453    */
2454
2455   free (word);
2456
2457   if (error == WRDE_NOSPACE)
2458     return WRDE_NOSPACE;
2459
2460   if ((flags & WRDE_APPEND) == 0)
2461     wordfree (pwordexp);
2462
2463   *pwordexp = old_word;
2464   return error;
2465 }