sysdeps/mach/hurd/setegid.c

   1 /* Copyright (C) 1993, 1994, 1995, 1997 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 Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    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    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <unistd.h>
  21 #include <hurd.h>
  22 #include <sys/types.h>
  23 #include <hurd/id.h>
  24 #include <string.h>
  25
  26 /* Set the effective user ID of the calling process to GID.  */
  27 int
  28 setegid (gid)
  29      gid_t gid;
  30 {
  31   auth_t newauth;
  32   error_t err;
  33
  34   HURD_CRITICAL_BEGIN;
  35   __mutex_lock (&_hurd_id.lock);
  36   err = _hurd_check_ids ();
  37
  38   if (!err)
  39     {
  40       /* Make a new auth handle which has EGID as the first element in the
  41          list of effective gids.  */
  42
  43       if (_hurd_id.gen.ngids > 0)
  44         {
  45           _hurd_id.gen.gids[0] = gid;
  46           _hurd_id.valid = 0;
  47         }
  48
  49       err = __USEPORT (AUTH, __auth_makeauth
  50                        (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
  51                         _hurd_id.gen.uids, _hurd_id.gen.nuids,
  52                         _hurd_id.aux.uids, _hurd_id.aux.nuids,
  53                         _hurd_id.gen.ngids ? _hurd_id.gen.gids : &gid,
  54                         _hurd_id.gen.ngids ?: 1,
  55                         _hurd_id.aux.gids, _hurd_id.aux.ngids,
  56                         &newauth));
  57     }
  58   __mutex_unlock (&_hurd_id.lock);
  59   HURD_CRITICAL_END;
  60
  61   if (err)
  62     return __hurd_fail (err);
  63
  64   /* Install the new handle and reauthenticate everything.  */
  65   err = __setauth (newauth);
  66   __mach_port_deallocate (__mach_task_self (), newauth);
  67   return err;
  68 }