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glibc  2.9
setegid.c
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00001 /* Copyright (C) 1993, 1994, 1995, 1997 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 <hurd.h>
00022 #include <sys/types.h>
00023 #include <hurd/id.h>
00024 #include <string.h>
00025 
00026 /* Set the effective user ID of the calling process to GID.  */
00027 int
00028 setegid (gid)
00029      gid_t gid;
00030 {
00031   auth_t newauth;
00032   error_t err;
00033 
00034   HURD_CRITICAL_BEGIN;
00035   __mutex_lock (&_hurd_id.lock);
00036   err = _hurd_check_ids ();
00037 
00038   if (!err)
00039     {
00040       /* Make a new auth handle which has EGID as the first element in the
00041          list of effective gids.  */
00042 
00043       if (_hurd_id.gen.ngids > 0)
00044        {
00045          _hurd_id.gen.gids[0] = gid;
00046          _hurd_id.valid = 0;
00047        }
00048 
00049       err = __USEPORT (AUTH, __auth_makeauth
00050                      (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
00051                      _hurd_id.gen.uids, _hurd_id.gen.nuids,
00052                      _hurd_id.aux.uids, _hurd_id.aux.nuids,
00053                      _hurd_id.gen.ngids ? _hurd_id.gen.gids : &gid,
00054                      _hurd_id.gen.ngids ?: 1,
00055                      _hurd_id.aux.gids, _hurd_id.aux.ngids,
00056                      &newauth));
00057     }
00058   __mutex_unlock (&_hurd_id.lock);
00059   HURD_CRITICAL_END;
00060 
00061   if (err)
00062     return __hurd_fail (err);
00063 
00064   /* Install the new handle and reauthenticate everything.  */
00065   err = __setauth (newauth);
00066   __mach_port_deallocate (__mach_task_self (), newauth);
00067   return err;
00068 }
00069 libc_hidden_def (setegid)