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glibc  2.9
seteuid.c
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00001 /* Copyright (C) 1998,2000,2002,2003,2004,2006 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <errno.h>
00020 #include <unistd.h>
00021 #include <setxid.h>
00022 #include <kernel-features.h>
00023 
00024 
00025 #ifdef __NR_setresuid
00026 extern int __setresuid (uid_t ruid, uid_t euid, uid_t suid);
00027 #endif
00028 
00029 int
00030 seteuid (uid_t uid)
00031 {
00032   int result;
00033 
00034   if (uid == (uid_t) ~0)
00035     {
00036       __set_errno (EINVAL);
00037       return -1;
00038     }
00039 
00040 #if __ASSUME_32BITUIDS > 0
00041   result = INLINE_SETXID_SYSCALL (setresuid32, 3, -1, uid, -1);
00042 #else
00043   /* First try the syscall.  */
00044 # ifdef __NR_setresuid
00045   result = __setresuid (-1, uid, -1);
00046 #  if __ASSUME_SETRESUID_SYSCALL > 0
00047   if (0)
00048 #  else
00049   if (result == -1 && errno == ENOSYS)
00050 #  endif
00051     /* No system call available.  Use emulation.  This may not work
00052        since `setreuid' also sets the saved user ID when UID is not
00053        equal to the real user ID, making it impossible to switch back.  */
00054 # endif
00055     result = __setreuid (-1, uid);
00056 #endif
00057 
00058   return result;
00059 }
00060 libc_hidden_def (seteuid)