sysdeps/unix/sysv/linux/seteuid.c

   1 /* Copyright (C) 1998,1999,2002,2003,2004,2006 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, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <unistd.h>
  20 #include <setxid.h>
  21 #include <kernel-features.h>
  22
  23
  24 #if defined __NR_setresuid || __ASSUME_SETRESUID_SYSCALL > 0
  25
  26 extern int __setresuid (uid_t ruid, uid_t euid, uid_t suid);
  27
  28 int
  29 seteuid (uid_t uid)
  30 {
  31   int result;
  32
  33   if (uid == (uid_t) ~0)
  34     {
  35       __set_errno (EINVAL);
  36       return -1;
  37     }
  38
  39 # if __ASSUME_32BITUIDS > 0 && defined __NR_setresuid32
  40   result = INLINE_SETXID_SYSCALL (setresuid32, 3, -1, uid, -1);
  41 # else
  42   /* First try the syscall.  */
  43   result = INLINE_SETXID_SYSCALL (setresuid, 3, -1, uid, -1);
  44 #  if __ASSUME_SETRESUID_SYSCALL == 0
  45   if (result == -1 && errno == ENOSYS)
  46     /* No system call available.  Use emulation.  This may not work
  47        since `setreuid' also sets the saved user ID when UID is not
  48        equal to the real user ID, making it impossible to switch back.  */
  49     result = __setreuid (-1, uid);
  50 #  endif
  51 # endif
  52
  53   return result;
  54 }
  55 #ifndef seteuid
  56 libc_hidden_def (seteuid)
  57 #endif
  58 #else
  59 # include <sysdeps/unix/bsd/seteuid.c>
  60 #endif