posix/execle.c

   1 /* Copyright (C) 1991, 1997, 1998, 1999 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 <alloca.h>
  20 #include <unistd.h>
  21 #include <stdarg.h>
  22 #include <stddef.h>
  23 #include <string.h>
  24
  25 #include <stackinfo.h>
  26
  27 /* Execute PATH with all arguments after PATH until a NULL pointer,
  28    and the argument after that for environment.  */
  29 int
  30 execle (const char *path, const char *arg, ...)
  31 {
  32   size_t argv_max = 1024;
  33   const char **argv = alloca (argv_max * sizeof (const char *));
  34   const char *const *envp;
  35   unsigned int i;
  36   va_list args;
  37   argv[0] = arg;
  38
  39   va_start (args, arg);
  40   i = 0;
  41   while (argv[i++] != NULL)
  42     {
  43       if (i == argv_max)
  44         {
  45           const char **nptr = alloca ((argv_max *= 2) * sizeof (const char *));
  46
  47 #ifndef _STACK_GROWS_UP
  48           if ((char *) nptr + argv_max == (char *) argv)
  49             {
  50               /* Stack grows down.  */
  51               argv = (const char **) memcpy (nptr, argv,
  52                                              i * sizeof (const char *));
  53               argv_max += i;
  54             }
  55           else
  56 #endif
  57 #ifndef _STACK_GROWS_DOWN
  58             if ((char *) argv + i == (char *) nptr)
  59             /* Stack grows up.  */
  60             argv_max += i;
  61           else
  62 #endif
  63             /* We have a hole in the stack.  */
  64             argv = (const char **) memcpy (nptr, argv,
  65                                            i * sizeof (const char *));
  66         }
  67
  68       argv[i] = va_arg (args, const char *);
  69     }
  70
  71   envp = va_arg (args, const char *const *);
  72   va_end (args);
  73
  74   return __execve (path, (char *const *) argv, (char *const *) envp);
  75 }