sysdeps/mach/hurd/getgroups.c

   1 /* Copyright (C) 1993-2018 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 <hurd/id.h>
  22 #include <string.h>
  23
  24 int
  25 __getgroups (int n, gid_t *gidset)
  26 {
  27   error_t err;
  28   int ngids;
  29   void *crit;
  30
  31   if (n < 0)
  32     return __hurd_fail (EINVAL);
  33
  34   crit = _hurd_critical_section_lock ();
  35   __mutex_lock (&_hurd_id.lock);
  36
  37   if (err = _hurd_check_ids ())
  38     {
  39       __mutex_unlock (&_hurd_id.lock);
  40       _hurd_critical_section_unlock (crit);
  41       return __hurd_fail (err);
  42     }
  43
  44   ngids = _hurd_id.gen.ngids;
  45
  46   if (n != 0)
  47     {
  48       /* Copy the gids onto stack storage and then release the idlock.  */
  49       gid_t gids[ngids];
  50       memcpy (gids, _hurd_id.gen.gids, sizeof (gids));
  51       __mutex_unlock (&_hurd_id.lock);
  52       _hurd_critical_section_unlock (crit);
  53
  54       /* Now that the lock is released, we can safely copy the
  55          group set into the user's array, which might fault.  */
  56       if (ngids > n)
  57         return __hurd_fail (EINVAL);
  58       memcpy (gidset, gids, ngids * sizeof (gid_t));
  59     }
  60   else
  61     {
  62       __mutex_unlock (&_hurd_id.lock);
  63       _hurd_critical_section_unlock (crit);
  64     }
  65
  66   return ngids;
  67 }
  68
  69 weak_alias (__getgroups, getgroups)