nptl/pthread_once.c

   1 /* Copyright (C) 2002, 2007 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include "pthreadP.h"
  21 #include <lowlevellock.h>
  22
  23
  24
  25 static int once_lock = LLL_LOCK_INITIALIZER;
  26
  27
  28 int
  29 __pthread_once (once_control, init_routine)
  30      pthread_once_t *once_control;
  31      void (*init_routine) (void);
  32 {
  33   /* XXX Depending on whether the LOCK_IN_ONCE_T is defined use a
  34      global lock variable or one which is part of the pthread_once_t
  35      object.  */
  36   if (*once_control == PTHREAD_ONCE_INIT)
  37     {
  38       lll_lock (once_lock, LLL_PRIVATE);
  39
  40       /* XXX This implementation is not complete.  It doesn't take
  41          cancelation and fork into account.  */
  42       if (*once_control == PTHREAD_ONCE_INIT)
  43         {
  44           init_routine ();
  45
  46           *once_control = !PTHREAD_ONCE_INIT;
  47         }
  48
  49       lll_unlock (once_lock, LLL_PRIVATE);
  50     }
  51
  52   return 0;
  53 }
  54 strong_alias (__pthread_once, pthread_once)