sysdeps/unix/sysv/linux/setegid.c

   1 /* Copyright (C) 1998, 2000, 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 <sys/syscall.h>
  21 #include <sys/types.h>
  22 #include <unistd.h>
  23
  24 #ifdef __NR_setresgid
  25
  26 extern int __setresgid (gid_t rgid, gid_t egid, gid_t sgid);
  27
  28 int
  29 setegid (gid_t gid)
  30 {
  31   int result;
  32
  33   if (gid == (gid_t) ~0)
  34     {
  35       __set_errno (EINVAL);
  36       return -1;
  37     }
  38
  39   /* First try the syscall.  */
  40   result = __setresgid (-1, gid, -1);
  41   if (result == -1 && errno == ENOSYS)
  42     /* No system call available.  Use emulation.  This may not work
  43        since `setregid' also sets the saved group ID when GID is not
  44        equal to the real group ID, making it impossible to switch back. */
  45     result = __setregid (-1, gid);
  46
  47   return result;
  48 }
  49 libc_hidden_def (setegid)
  50 #else
  51 # include <sysdeps/unix/bsd/setegid.c>
  52 #endif