sysdeps/unix/sysv/linux/seteuid.c

   1 /* Copyright (C) 1998, 1999, 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 #include "kernel-features.h"
  25
  26 #if defined __NR_setresuid || __ASSUME_SETRESUID_SYSCALL > 0
  27
  28 extern int __setresuid (uid_t ruid, uid_t euid, uid_t suid);
  29
  30 int
  31 seteuid (uid_t uid)
  32 {
  33   int result;
  34
  35   if (uid == (uid_t) ~0)
  36     {
  37       __set_errno (EINVAL);
  38       return -1;
  39     }
  40
  41   /* First try the syscall.  */
  42   result = __setresuid (-1, uid, -1);
  43 # if __ASSUME_SETRESUID_SYSCALL == 0
  44   if (result == -1 && errno == ENOSYS)
  45     /* No system call available.  Use emulation.  This may not work
  46        since `setreuid' also sets the saved user ID when UID is not
  47        equal to the real user ID, making it impossible to switch back.  */
  48     result = __setreuid (-1, uid);
  49 # endif
  50
  51   return result;
  52 }
  53 libc_hidden_def (seteuid)
  54 #else
  55 # include <sysdeps/unix/bsd/seteuid.c>
  56 #endif