Back to index

glibc  2.9
setgid.c
Go to the documentation of this file.
00001 /* Copyright (C) 1991, 92, 93, 94, 95, 96, 97 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 <sys/types.h>
00022 #include <hurd.h>
00023 #include <hurd/id.h>
00024 #include <string.h>
00025 
00026 /* Set the group ID of the calling process to UID.
00027    If the calling process is the super-user, the real
00028    and effective group IDs, and the saved set-group-ID to UID;
00029    if not, the effective group ID is set to GID.  */
00030 int
00031 __setgid (gid)
00032      gid_t gid;
00033 {
00034   auth_t newauth;
00035   error_t err;
00036 
00037   HURD_CRITICAL_BEGIN;
00038   __mutex_lock (&_hurd_id.lock);
00039   err = _hurd_check_ids ();
00040 
00041   if (!err)
00042     {
00043       /* Make a new auth handle which has GID as the real gid,
00044         and as the first element in the list of effective gids.  */
00045 
00046       gid_t *newgen, *newaux, auxbuf[2];
00047       size_t ngen, naux;
00048 
00049       if (_hurd_id.gen.ngids == 0)
00050        {
00051          /* No effective gids now.  The new set will be just GID.  */
00052          newgen = &gid;
00053          ngen = 1;
00054        }
00055       else
00056        {
00057          _hurd_id.gen.gids[0] = gid;
00058          _hurd_id.valid = 0;
00059          newgen = _hurd_id.gen.gids;
00060          ngen = _hurd_id.gen.ngids;
00061        }
00062 
00063       newaux = _hurd_id.aux.gids;
00064       naux = _hurd_id.aux.ngids;
00065       if (_hurd_id.gen.nuids > 0 && _hurd_id.gen.uids[0] == 0)
00066        {
00067          /* We are root; set the real and saved IDs too.  */
00068          _hurd_id.valid = 0;
00069          if (_hurd_id.aux.ngids < 2)
00070            {
00071              newaux = auxbuf;
00072              naux = 2;
00073            }
00074          newaux[0] = newaux[1] = gid;
00075        }
00076 
00077       err = __USEPORT (AUTH, __auth_makeauth
00078                      (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
00079                      _hurd_id.gen.uids, _hurd_id.gen.nuids,
00080                      _hurd_id.aux.uids, _hurd_id.aux.nuids,
00081                      newgen, ngen, newaux, naux,
00082                      &newauth));
00083     }
00084   __mutex_unlock (&_hurd_id.lock);
00085   HURD_CRITICAL_END;
00086 
00087   if (err)
00088     return __hurd_fail (err);
00089 
00090   /* Install the new handle and reauthenticate everything.  */
00091   err = __setauth (newauth);
00092   __mach_port_deallocate (__mach_task_self (), newauth);
00093   return err;
00094 }
00095 
00096 weak_alias (__setgid, setgid)