posix/wordexp.c

   1 /* Copyright (C) 1992, 1997 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 not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <sys/types.h>
  20 #include <wordexp.h>
  21 #include <stdio.h>
  22 #include <unistd.h>
  23 #include <sys/wait.h>
  24 #include <signal.h>
  25
  26
  27 /* We do word expansion with a pipe to the shell.
  28    The shell command `sh [-P] [-u] -w "words ..."' expands words.
  29    If -P, command substitution is an error.
  30    If -u, reference to an undefined variable is an error.
  31    The shell writes on its stdout:
  32         %u\0    Number of words.
  33         %u\0    Number of bytes in all words together (not counting \0s).
  34         word1\0
  35         word2\0
  36         ...
  37         wordN\0
  38    */
  39
  40 #define SHELL_PATH      "/bin/sh"
  41 #define SHELL_NAME      "sh"
  42
  43
  44 int
  45 wordexp (string, pwordexp, flags)
  46      const char *string;
  47      wordexp_t *pwordexp;
  48      int flags;
  49 {
  50   int error;
  51   pid_t pid;
  52   int d[2];
  53   int status;
  54
  55   FILE *f;
  56   size_t wordc, start, buflen;
  57   char *buf;
  58
  59   /* Create the pipe through which we will communicate to the shell.  */
  60   if (pipe (d) < 0)
  61     return -1;
  62
  63   pid = fork ();
  64   if (pid < 0)
  65     return -1;
  66
  67   if (pid == 0)
  68     {
  69       /* Child.  Run the shell.  */
  70
  71       const char *argv[5];
  72
  73       close (d[STDIN_FILENO]);
  74       dup2 (d[STDOUT_FILENO], STDOUT_FILENO);
  75       if (!(flags & WRDE_SHOWERR))
  76         close (STDERR_FILENO);
  77
  78       i = 0;
  79       argv[i++] = SHELL_NAME;
  80       if (flags & WRDE_NOCMD)
  81         argv[i++] = "-P";
  82       if (flags & WRDE_UNDEF)
  83         argv[i++] = "-u";
  84       argv[i++] = "-w";
  85       argv[i++] = string;
  86       argv[i++] = NULL;
  87
  88       execv (SHELL_PATH, argv);
  89       _exit (WRDE_NOSPACE);
  90     }
  91
  92   /* Parent.  */
  93
  94   buf = NULL;
  95   error = WRDE_NOSPACE;
  96
  97   close (d[STDOUT_FILENO]);
  98   f = fdopen (d[STDIN_FILENO]);
  99   if (f == NULL)
 100     goto lose;
 101
 102   /* Read the number of words and number of bytes from the shell.  */
 103   if (fscanf (f, "%u", &wordc) != 1 || getc (f) != '\0' ||
 104       fscanf (f, "%u", &buflen) != 1 || getc (f) != '\0')
 105     goto lose;
 106
 107   /* Read the words from the shell, and wait for it to return.  */
 108   buflen += wordc;
 109   buf = malloc (buflen);
 110   if (buf == NULL ||
 111       fread (buf, buflen, 1, f) != 1 ||
 112       waitpid (pid, &status, 0) != pid)
 113     goto lose;
 114
 115   if (WIFEXITED (status))
 116     {
 117       if (WEXITSTATUS (status) != 0)
 118         {
 119           error = WEXITSTATUS (status);
 120           goto lose;
 121         }
 122     }
 123   else
 124     goto lose;
 125
 126   /* Pack the structure.  */
 127
 128   start = 0;
 129   if (flags & WRDE_DOOFFS)
 130     start += pwordexp->we_offs;
 131   if (flags & WRDE_APPEND)
 132     start += pwordexp->we_wordc;
 133   wordc = start + wordc + 1;
 134
 135   if (flags & WRDE_APPEND)
 136     wordv = (char **) realloc ((void *) pwordexp->we_wordv,
 137                                wordc * sizeof (char *));
 138   else
 139     wordv = (char **) malloc (wordc * sizeof (char *));
 140   if (wordv == NULL)
 141     goto lose;
 142
 143   if (flags & WRDE_DOOFFS)
 144     for (i = 0; i < pwordexp->we_offs; ++i)
 145       wordv[i] = NULL;
 146
 147   for (i = start; i < wordc; ++i)
 148     {
 149       pwordexp->we_wordv[i] = buf;
 150       buf = strchr (buf, '\0') + 1;
 151     }
 152   wordv[i] = NULL;
 153
 154   if (flags & WRDE_REUSE)
 155     {
 156       free (pwordexp->we_wordv[0]);
 157       if (!(flags & WRDE_APPEND))
 158         free (pwordexp->we_wordv);
 159     }
 160
 161   pwordexp->we_wordc = wordc;
 162   pwordexp->we_wordv = wordv;
 163
 164   return 0;
 165
 166  lose:
 167   {
 168     int save;
 169     save = errno;
 170     (void) kill (pid, SIGKILL);
 171     free (buf);
 172     (void) waitpid (pid, (int *) NULL, 0);
 173     errno = save;
 174     return error;
 175   }
 176 }
 177
 178
 179 void
 180 DEFUN(wordexp, (pwordexp), wordexp_t *pwordexp)
 181 {
 182   /* All the other elts point into the first.  */
 183   free (pwordexp->we_wordv[0]);
 184   free (pwordexp->we_wordv);
 185 }