sysdeps/unix/sysv/linux/seteuid.c

   1 /* Copyright (C) 1998, 1999, 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_setresuid || __ASSUME_SETRESUID_SYSCALL > 0
  28
  29 extern int __setresuid (uid_t ruid, uid_t euid, uid_t suid);
  30
  31 int
  32 seteuid (uid_t uid)
  33 {
  34   int result;
  35
  36   if (uid == (uid_t) ~0)
  37     {
  38       __set_errno (EINVAL);
  39       return -1;
  40     }
  41
  42 # if __ASSUME_32BITUIDS > 0 && defined __NR_setresuid32
  43   return INLINE_SYSCALL (setresuid32, 3, -1, uid, -1);
  44 # else
  45   /* First try the syscall.  */
  46   result = __setresuid (-1, uid, -1);
  47 # if __ASSUME_SETRESUID_SYSCALL == 0
  48   if (result == -1 && errno == ENOSYS)
  49     /* No system call available.  Use emulation.  This may not work
  50        since `setreuid' also sets the saved user ID when UID is not
  51        equal to the real user ID, making it impossible to switch back.  */
  52     result = __setreuid (-1, uid);
  53 # endif
  54
  55   return result;
  56 # endif
  57 }
  58 libc_hidden_def (seteuid)
  59 #else
  60 # include <sysdeps/unix/bsd/seteuid.c>
  61 #endif