hurd/getuids.c

   1 /* Copyright (C) 1993, 1994 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 <hurd.h>
  20 #include <hurd/id.h>
  21 #include <string.h>
  22
  23 int
  24 __getuids (int n, uid_t *uidset)
  25 {
  26   error_t err;
  27   int nuids;
  28   void *crit;
  29
  30   crit = _hurd_critical_section_lock ();
  31   __mutex_lock (&_hurd_id.lock);
  32
  33   if (err = _hurd_check_ids ())
  34     {
  35       __mutex_unlock (&_hurd_id.lock);
  36       _hurd_critical_section_unlock (crit);
  37       return __hurd_fail (err);
  38     }
  39
  40   nuids = _hurd_id.gen.nuids;
  41
  42   if (n != 0)
  43     {
  44       /* Copy the uids onto stack storage and then release the idlock.  */
  45       uid_t uids[nuids];
  46       memcpy (uids, _hurd_id.gen.uids, sizeof (uids));
  47       __mutex_unlock (&_hurd_id.lock);
  48       _hurd_critical_section_unlock (crit);
  49
  50       /* Now that the lock is released, we can safely copy the
  51          uid set into the user's array, which might fault.  */
  52       if (nuids > n)
  53         nuids = n;
  54       memcpy (uidset, uids, nuids * sizeof (uid_t));
  55     }
  56   else
  57     {
  58       __mutex_unlock (&_hurd_id.lock);
  59       _hurd_critical_section_unlock (crit);
  60     }
  61
  62   return nuids;
  63 }