sysdeps/unix/sysv/linux/fexecve.c

   1 /* Copyright (C) 1994, 1995, 1996, 1997, 2002 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <stddef.h>
  21 #include <stdio.h>
  22 #include <unistd.h>
  23 #include <sys/stat.h>
  24
  25
  26 /* Execute the file FD refers to, overlaying the running program image.
  27    ARGV and ENVP are passed to the new program, as for `execve'.  */
  28 int
  29 fexecve (fd, argv, envp)
  30      int fd;
  31      char *const argv[];
  32      char *const envp[];
  33 {
  34   if (fd < 0 || argv == NULL || envp == NULL)
  35     {
  36       __set_errno (EINVAL);
  37       return -1;
  38     }
  39
  40   /* We use the /proc filesystem to get the information.  If it is not
  41      mounted we fail.  */
  42   char buf[sizeof "/proc/self/fd/" + sizeof (int) * 3];
  43   __snprintf (buf, sizeof (buf), "/proc/self/fd/%d", fd);
  44
  45   /* We do not need the return value.  */
  46   __execve (buf, argv, envp);
  47
  48   int save = errno;
  49
  50   /* We come here only if the 'execve' call fails.  Determine whether
  51      /proc is mounted.  If not we return ENOSYS.  */
  52   struct stat st;
  53   if (stat ("/proc/self/fd", &st) != 0 && errno == ENOENT)
  54     save = ENOSYS;
  55
  56   __set_errno (save);
  57
  58   return -1;
  59 }