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glibc  2.9
fexecve.c
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00001 /* Copyright (C) 1994, 1995, 1996, 1997, 2002 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <errno.h>
00020 #include <stddef.h>
00021 #include <stdio.h>
00022 #include <unistd.h>
00023 #include <sys/stat.h>
00024 
00025 
00026 /* Execute the file FD refers to, overlaying the running program image.
00027    ARGV and ENVP are passed to the new program, as for `execve'.  */
00028 int
00029 fexecve (fd, argv, envp)
00030      int fd;
00031      char *const argv[];
00032      char *const envp[];
00033 {
00034   if (fd < 0 || argv == NULL || envp == NULL)
00035     {
00036       __set_errno (EINVAL);
00037       return -1;
00038     }
00039 
00040   /* We use the /proc filesystem to get the information.  If it is not
00041      mounted we fail.  */
00042   char buf[sizeof "/proc/self/fd/" + sizeof (int) * 3];
00043   __snprintf (buf, sizeof (buf), "/proc/self/fd/%d", fd);
00044 
00045   /* We do not need the return value.  */
00046   __execve (buf, argv, envp);
00047 
00048   int save = errno;
00049 
00050   /* We come here only if the 'execve' call fails.  Determine whether
00051      /proc is mounted.  If not we return ENOSYS.  */
00052   struct stat st;
00053   if (stat ("/proc/self/fd", &st) != 0 && errno == ENOENT)
00054     save = ENOSYS;
00055 
00056   __set_errno (save);
00057 
00058   return -1;
00059 }