posix/execlp.c

   1 /* Copyright (C) 1991-2016 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <unistd.h>
  19 #include <stdarg.h>
  20 #include <stddef.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23
  24 #include <stackinfo.h>
  25
  26 /* Execute FILE, searching in the `PATH' environment variable if
  27    it contains no slashes, with all arguments after FILE until a
  28    NULL pointer and environment from `environ'.  */
  29 int
  30 execlp (const char *file, const char *arg, ...)
  31 {
  32 #define INITIAL_ARGV_MAX 1024
  33   size_t argv_max = INITIAL_ARGV_MAX;
  34   const char *initial_argv[INITIAL_ARGV_MAX];
  35   const char **argv = initial_argv;
  36   va_list args;
  37
  38   argv[0] = arg;
  39
  40   va_start (args, arg);
  41   unsigned int i = 0;
  42   while (argv[i++] != NULL)
  43     {
  44       if (i == argv_max)
  45         {
  46           argv_max *= 2;
  47           const char **nptr = realloc (argv == initial_argv ? NULL : argv,
  48                                        argv_max * sizeof (const char *));
  49           if (nptr == NULL)
  50             {
  51               if (argv != initial_argv)
  52                 free (argv);
  53               va_end (args);
  54               return -1;
  55             }
  56           if (argv == initial_argv)
  57             /* We have to copy the already filled-in data ourselves.  */
  58             memcpy (nptr, argv, i * sizeof (const char *));
  59
  60           argv = nptr;
  61         }
  62
  63       argv[i] = va_arg (args, const char *);
  64     }
  65   va_end (args);
  66
  67   int ret = execvp (file, (char *const *) argv);
  68   if (argv != initial_argv)
  69     free (argv);
  70
  71   return ret;
  72 }
  73 libc_hidden_def (execlp)