sysdeps/mach/hurd/setgid.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 96 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
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <errno.h>
  21 #include <unistd.h>
  22 #include <sys/types.h>
  23 #include <hurd.h>
  24 #include <hurd/id.h>
  25 #include <string.h>
  26
  27 /* Set the group ID of the calling process to UID.
  28    If the calling process is the super-user, the real
  29    and effective group IDs, and the saved set-group-ID to UID;
  30    if not, the effective group ID is set to GID.  */
  31 int
  32 DEFUN(__setgid, (gid), gid_t gid)
  33 {
  34   auth_t newauth;
  35   error_t err;
  36
  37   HURD_CRITICAL_BEGIN;
  38   __mutex_lock (&_hurd_id.lock);
  39   err = _hurd_check_ids ();
  40
  41   if (!err)
  42     {
  43       /* Make a new auth handle which has GID as the real gid,
  44          and as the first element in the list of effective gids.  */
  45
  46       gid_t *newgen, *newaux, auxbuf[2];
  47       size_t ngen, naux;
  48
  49       if (_hurd_id.gen.ngids == 0)
  50         {
  51           /* No effective gids now.  The new set will be just GID.  */
  52           newgen = &gid;
  53           ngen = 1;
  54         }
  55       else
  56         {
  57           _hurd_id.gen.gids[0] = gid;
  58           _hurd_id.valid = 0;
  59           newgen = _hurd_id.gen.gids;
  60           ngen = _hurd_id.gen.ngids;
  61         }
  62
  63       newaux = _hurd_id.aux.gids;
  64       naux = _hurd_id.aux.ngids;
  65       if (_hurd_id.gen.nuids > 0 && _hurd_id.gen.uids[0] == 0)
  66         {
  67           /* We are root; set the real and saved IDs too.  */
  68           _hurd_id.valid = 0;
  69           if (_hurd_id.aux.ngids < 2)
  70             {
  71               newaux = auxbuf;
  72               naux = 2;
  73             }
  74           newaux[0] = newaux[1] = gid;
  75         }
  76
  77       err = __USEPORT (AUTH, __auth_makeauth
  78                        (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
  79                         _hurd_id.gen.uids, _hurd_id.gen.nuids,
  80                         _hurd_id.aux.uids, _hurd_id.aux.nuids,
  81                         newgen, ngen, newaux, naux,
  82                         &newauth));
  83     }
  84   __mutex_unlock (&_hurd_id.lock);
  85   HURD_CRITICAL_END;
  86
  87   if (err)
  88     return __hurd_fail (err);
  89
  90   /* Install the new handle and reauthenticate everything.  */
  91   err = __setauth (newauth);
  92   __mach_port_deallocate (__mach_task_self (), newauth);
  93   return err;
  94 }
  95
  96 weak_alias (__setgid, setgid)