lib/pthread-once.c

   1 /* POSIX once-only control.
   2    Copyright (C) 2019-2020 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program 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
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2019.  */
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include <pthread.h>
  23
  24 #if (defined _WIN32 && ! defined __CYGWIN__) && USE_WINDOWS_THREADS
  25 # include "windows-once.h"
  26 #endif
  27
  28 #if (defined _WIN32 && ! defined __CYGWIN__) && USE_WINDOWS_THREADS
  29 /* Use Windows threads.  */
  30
  31 int
  32 pthread_once (pthread_once_t *once_control, void (*initfunction) (void))
  33 {
  34   glwthread_once (once_control, initfunction);
  35   return 0;
  36 }
  37
  38 #elif HAVE_PTHREAD_H
  39 /* Provide workarounds for POSIX threads.  */
  40
  41 #else
  42 /* Provide a dummy implementation for single-threaded applications.  */
  43
  44 int
  45 pthread_once (pthread_once_t *once_control, void (*initfunction) (void))
  46 {
  47   if (*once_control == 0)
  48     {
  49       *once_control = ~ 0;
  50       initfunction ();
  51     }
  52   return 0;
  53 }
  54
  55 #endif