nptl/pthread_once.c

   1 /* Copyright (C) 2002-2013 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include "pthreadP.h"
  20 #include <lowlevellock.h>
  21
  22
  23
  24 static int once_lock = LLL_LOCK_INITIALIZER;
  25
  26
  27 int
  28 __pthread_once (once_control, init_routine)
  29      pthread_once_t *once_control;
  30      void (*init_routine) (void);
  31 {
  32   /* XXX Depending on whether the LOCK_IN_ONCE_T is defined use a
  33      global lock variable or one which is part of the pthread_once_t
  34      object.  */
  35   if (*once_control == PTHREAD_ONCE_INIT)
  36     {
  37       lll_lock (once_lock, LLL_PRIVATE);
  38
  39       /* XXX This implementation is not complete.  It doesn't take
  40          cancelation and fork into account.  */
  41       if (*once_control == PTHREAD_ONCE_INIT)
  42         {
  43           init_routine ();
  44
  45           *once_control = !PTHREAD_ONCE_INIT;
  46         }
  47
  48       lll_unlock (once_lock, LLL_PRIVATE);
  49     }
  50
  51   return 0;
  52 }
  53 strong_alias (__pthread_once, pthread_once)
  54 hidden_def (__pthread_once)