sysdeps/mach/hurd/getgroups.c

   1 /* Copyright (C) 1993-2014 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 (n, gidset)
  26      int n;
  27      gid_t *gidset;
  28 {
  29   error_t err;
  30   int ngids;
  31   void *crit;
  32
  33   if (n < 0)
  34     return __hurd_fail (EINVAL);
  35
  36   crit = _hurd_critical_section_lock ();
  37   __mutex_lock (&_hurd_id.lock);
  38
  39   if (err = _hurd_check_ids ())
  40     {
  41       __mutex_unlock (&_hurd_id.lock);
  42       _hurd_critical_section_unlock (crit);
  43       return __hurd_fail (err);
  44     }
  45
  46   ngids = _hurd_id.gen.ngids;
  47
  48   if (n != 0)
  49     {
  50       /* Copy the gids onto stack storage and then release the idlock.  */
  51       gid_t gids[ngids];
  52       memcpy (gids, _hurd_id.gen.gids, sizeof (gids));
  53       __mutex_unlock (&_hurd_id.lock);
  54       _hurd_critical_section_unlock (crit);
  55
  56       /* Now that the lock is released, we can safely copy the
  57          group set into the user's array, which might fault.  */
  58       if (ngids > n)
  59         return __hurd_fail (EINVAL);
  60       memcpy (gidset, gids, ngids * sizeof (gid_t));
  61     }
  62   else
  63     {
  64       __mutex_unlock (&_hurd_id.lock);
  65       _hurd_critical_section_unlock (crit);
  66     }
  67
  68   return ngids;
  69 }
  70
  71 weak_alias (__getgroups, getgroups)