hurd/geteuids.c

   1 /* Copyright (C) 1993-2021 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    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <hurd.h>
  19 #include <hurd/id.h>
  20 #include <string.h>
  21
  22 int
  23 geteuids (int n, uid_t *uidset)
  24 {
  25   error_t err;
  26   int nuids;
  27   void *crit;
  28
  29 retry:
  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       if (err == EINTR)
  38         /* Got a signal while inside an RPC of the critical section, retry again */
  39         goto retry;
  40       return __hurd_fail (err);
  41     }
  42
  43   nuids = _hurd_id.gen.nuids;
  44
  45   if (n != 0)
  46     {
  47       /* Copy the uids onto stack storage and then release the idlock.  */
  48       uid_t uids[nuids];
  49       memcpy (uids, _hurd_id.gen.uids, sizeof (uids));
  50       __mutex_unlock (&_hurd_id.lock);
  51       _hurd_critical_section_unlock (crit);
  52
  53       /* Now that the lock is released, we can safely copy the
  54          uid set into the user's array, which might fault.  */
  55       if (nuids > n)
  56         nuids = n;
  57       memcpy (uidset, uids, nuids * sizeof (uid_t));
  58     }
  59   else
  60     {
  61       __mutex_unlock (&_hurd_id.lock);
  62       _hurd_critical_section_unlock (crit);
  63     }
  64
  65   return nuids;
  66 }
  67
  68 /* XXX Remove this alias when we bump the libc soname.  */
  69
  70 #ifdef SHARED
  71 weak_alias (geteuids, __getuids)
  72 #endif