sysdeps/unix/sysv/linux/i386/setegid.c

   1 /* Copyright (C) 1995-1998,2000,2002,2003,2004 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 <unistd.h>
  21 #include <setxid.h>
  22 #include "kernel-features.h"
  23
  24
  25 #ifdef __NR_setresgid
  26 extern int __setresgid (uid_t rgid, uid_t egid, uid_t sgid);
  27 #endif
  28
  29 int
  30 setegid (gid)
  31      gid_t gid;
  32 {
  33   int result;
  34
  35   if (gid == (gid_t) ~0)
  36     {
  37       __set_errno (EINVAL);
  38       return -1;
  39     }
  40
  41 #if __ASSUME_32BITUIDS > 0
  42   result = INLINE_SETXID_SYSCALL (setresgid32, 3, -1, gid, -1);
  43 #else
  44   /* First try the syscall.  */
  45 # ifdef __NR_setresgid
  46   result = __setresgid (-1, gid, -1);
  47 #  if __ASSUME_SETRESGID_SYSCALL > 0
  48   if (0)
  49 #  else
  50   if (result == -1 && errno == ENOSYS)
  51 #  endif
  52     /* No system call available.  Use emulation.  This may not work
  53        since `setregid' also sets the saved user ID when GID is not
  54        equal to the real user ID, making it impossible to switch back.  */
  55 # endif
  56     result = __setregid (-1, gid);
  57 #endif
  58
  59   return result;
  60 }
  61 libc_hidden_def (setegid)