sysdeps/mach/hurd/setegid.c

   1 /* Copyright (C) 1993-2016 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 <hurd.h>
  21 #include <sys/types.h>
  22 #include <hurd/id.h>
  23 #include <string.h>
  24
  25 /* Set the effective user ID of the calling process to GID.  */
  26 int
  27 setegid (gid_t gid)
  28 {
  29   auth_t newauth;
  30   error_t err;
  31
  32   HURD_CRITICAL_BEGIN;
  33   __mutex_lock (&_hurd_id.lock);
  34   err = _hurd_check_ids ();
  35
  36   if (!err)
  37     {
  38       /* Make a new auth handle which has EGID as the first element in the
  39          list of effective gids.  */
  40
  41       if (_hurd_id.gen.ngids > 0)
  42         {
  43           _hurd_id.gen.gids[0] = gid;
  44           _hurd_id.valid = 0;
  45         }
  46
  47       err = __USEPORT (AUTH, __auth_makeauth
  48                        (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
  49                         _hurd_id.gen.uids, _hurd_id.gen.nuids,
  50                         _hurd_id.aux.uids, _hurd_id.aux.nuids,
  51                         _hurd_id.gen.ngids ? _hurd_id.gen.gids : &gid,
  52                         _hurd_id.gen.ngids ?: 1,
  53                         _hurd_id.aux.gids, _hurd_id.aux.ngids,
  54                         &newauth));
  55     }
  56   __mutex_unlock (&_hurd_id.lock);
  57   HURD_CRITICAL_END;
  58
  59   if (err)
  60     return __hurd_fail (err);
  61
  62   /* Install the new handle and reauthenticate everything.  */
  63   err = __setauth (newauth);
  64   __mach_port_deallocate (__mach_task_self (), newauth);
  65   return err;
  66 }
  67 libc_hidden_def (setegid)