sysdeps/unix/sysv/linux/setegid.c

   1 /* Copyright (C) 1998, 2000, 2002, 2003 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 #include <sysdep.h>
  25 #include "kernel-features.h"
  26
  27 #if defined __NR_setresgid || __ASSUME_SETRESGID_SYSCALL > 0
  28
  29 extern int __setresgid (gid_t rgid, gid_t egid, gid_t sgid);
  30
  31 int
  32 setegid (gid_t gid)
  33 {
  34   int result;
  35
  36   if (gid == (gid_t) ~0)
  37     {
  38       __set_errno (EINVAL);
  39       return -1;
  40     }
  41
  42 # if __ASSUME_32BITUIDS > 0 && defined __NR_setresgid32
  43   return INLINE_SYSCALL (setresgid32, 3, -1, gid, -1);
  44 # else
  45   /* First try the syscall.  */
  46   result = __setresgid (-1, gid, -1);
  47 #  if __ASSUME_SETRESGID_SYSCALL == 0
  48   if (result == -1 && errno == ENOSYS)
  49     /* No system call available.  Use emulation.  This may not work
  50        since `setregid' also sets the saved group ID when GID is not
  51        equal to the real group ID, making it impossible to switch back. */
  52     result = __setregid (-1, gid);
  53 #  endif
  54
  55   return result;
  56 # endif
  57 }
  58 libc_hidden_def (setegid)
  59 #else
  60 # include <sysdeps/unix/bsd/setegid.c>
  61 #endif