posix/wordexp.c

   1 /* Copyright (C) 1992 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <sys/types.h>
  21 #include <wordexp.h>
  22 #include <stdio.h>
  23 #include <unistd.h>
  24 #include <sys/wait.h>
  25 #include <signal.h>
  26
  27
  28 /* We do word expansion with a pipe to the shell.
  29    The shell command `sh [-P] [-u] -w "words ..."' expands words.
  30    If -P, command substitution is an error.
  31    If -u, reference to an undefined variable is an error.
  32    The shell writes on its stdout:
  33         %u\0    Number of words.
  34         %u\0    Number of bytes in all words together (not counting \0s).
  35         word1\0
  36         word2\0
  37         ...
  38         wordN\0
  39    */
  40
  41 #define SHELL_PATH      "/bin/sh"
  42 #define SHELL_NAME      "sh"
  43
  44
  45 int
  46 DEFUN(wordexp, (string, pwordexp, flags),
  47       CONST char *string AND wordexp_t *pwordexp AND int flags)
  48 {
  49   int error;
  50   pid_t pid;
  51   int d[2];
  52   int status;
  53
  54   FILE *f;
  55   size_t wordc, start, buflen;
  56   char *buf;
  57
  58   /* Create the pipe through which we will communicate to the shell.  */
  59   if (pipe (d) < 0)
  60     return -1;
  61
  62   pid = fork ();
  63   if (pid < 0)
  64     return -1;
  65
  66   if (pid == 0)
  67     {
  68       /* Child.  Run the shell.  */
  69
  70       CONST char *argv[5];
  71
  72       close (d[STDIN_FILENO]);
  73       dup2 (d[STDOUT_FILENO], STDOUT_FILENO);
  74       if (!(flags & WRDE_SHOWERR))
  75         close (STDERR_FILENO);
  76
  77       i = 0;
  78       argv[i++] = SHELL_NAME;
  79       if (flags & WRDE_NOCMD)
  80         argv[i++] = "-P";
  81       if (flags & WRDE_UNDEF)
  82         argv[i++] = "-u";
  83       argv[i++] = "-w";
  84       argv[i++] = string;
  85       argv[i++] = NULL;
  86
  87       execv (SHELL_PATH, argv);
  88       _exit (WRDE_NOSPACE);
  89     }
  90
  91   /* Parent.  */
  92
  93   buf = NULL;
  94   error = WRDE_NOSPACE;
  95
  96   close (d[STDOUT_FILENO]);
  97   f = fdopen (d[STDIN_FILENO]);
  98   if (f == NULL)
  99     goto lose;
 100
 101   /* Read the number of words and number of bytes from the shell.  */
 102   if (fscanf (f, "%u", &wordc) != 1 || getc (f) != '\0' ||
 103       fscanf (f, "%u", &buflen) != 1 || getc (f) != '\0')
 104     goto lose;
 105
 106   /* Read the words from the shell, and wait for it to return.  */
 107   buflen += wordc;
 108   buf = malloc (buflen);
 109   if (buf == NULL ||
 110       fread (buf, buflen, 1, f) != 1 ||
 111       waitpid (pid, &status, 0) != pid)
 112     goto lose;
 113
 114   if (WIFEXITED (status))
 115     {
 116       if (WEXITSTATUS (status) != 0)
 117         {
 118           error = WEXITSTATUS (status);
 119           goto lose;
 120         }
 121     }
 122   else
 123     goto lose;
 124
 125   /* Pack the structure.  */
 126
 127   start = 0;
 128   if (flags & WRDE_DOOFFS)
 129     start += pwordexp->we_offs;
 130   if (flags & WRDE_APPEND)
 131     start += pwordexp->we_wordc;
 132   wordc = start + wordc + 1;
 133
 134   if (flags & WRDE_APPEND)
 135     wordv = (char **) realloc ((PTR) pwordexp->we_wordv,
 136                                wordc * sizeof (char *));
 137   else
 138     wordv = (char **) malloc (wordc * sizeof (char *));
 139   if (wordv == NULL)
 140     goto lose;
 141
 142   if (flags & WRDE_DOOFFS)
 143     for (i = 0; i < pwordexp->we_offs; ++i)
 144       wordv[i] = NULL;
 145
 146   for (i = start; i < wordc; ++i)
 147     {
 148       pwordexp->we_wordv[i] = buf;
 149       buf = strchr (buf, '\0') + 1;
 150     }
 151   wordv[i] = NULL;
 152
 153   if (flags & WRDE_REUSE)
 154     {
 155       free (pwordexp->we_wordv[0]);
 156       if (!(flags & WRDE_APPEND))
 157         free (pwordexp->we_wordv);
 158     }
 159
 160   pwordexp->we_wordc = wordc;
 161   pwordexp->we_wordv = wordv;
 162
 163   return 0;
 164
 165  lose:
 166   {
 167     int save;
 168     save = errno;
 169     (void) kill (pid, SIGKILL);
 170     free (buf);
 171     (void) waitpid (pid, (int *) NULL, 0);
 172     errno = save;
 173     return error;
 174   }
 175 }
 176
 177
 178 void
 179 DEFUN(wordexp, (pwordexp), wordexp_t *pwordexp)
 180 {
 181   /* All the other elts point into the first.  */
 182   free (pwordexp->we_wordv[0]);
 183   free (pwordexp->we_wordv);
 184 }