| /* |
| * ------------------------------------------------------------- |
| * |
| * Module: sem_wait.c |
| * |
| * Purpose: |
| * Semaphores aren't actually part of the PThreads standard. |
| * They are defined by the POSIX Standard: |
| * |
| * POSIX 1003.1b-1993 (POSIX.1b) |
| * |
| * ------------------------------------------------------------- |
| * |
| * -------------------------------------------------------------------------- |
| * |
| * Pthreads-win32 - POSIX Threads Library for Win32 |
| * Copyright(C) 1998 John E. Bossom |
| * Copyright(C) 1999,2005 Pthreads-win32 contributors |
| * |
| * Contact Email: rpj@callisto.canberra.edu.au |
| * |
| * The current list of contributors is contained |
| * in the file CONTRIBUTORS included with the source |
| * code distribution. The list can also be seen at the |
| * following World Wide Web location: |
| * http://sources.redhat.com/pthreads-win32/contributors.html |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with this library in the file COPYING.LIB; |
| * if not, write to the Free Software Foundation, Inc., |
| * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA |
| */ |
| |
| #include "pthread.h" |
| #include "semaphore.h" |
| #include "implement.h" |
| |
| |
| static void PTW32_CDECL |
| ptw32_sem_wait_cleanup(void * sem) |
| { |
| sem_t s = (sem_t) sem; |
| |
| if (pthread_mutex_lock (&s->lock) == 0) |
| { |
| /* |
| * If sema is destroyed do nothing, otherwise:- |
| * If the sema is posted between us being cancelled and us locking |
| * the sema again above then we need to consume that post but cancel |
| * anyway. If we don't get the semaphore we indicate that we're no |
| * longer waiting. |
| */ |
| if (*((sem_t *)sem) != NULL && !(WaitForSingleObject(s->sem, 0) == WAIT_OBJECT_0)) |
| { |
| ++s->value; |
| #if defined(NEED_SEM) |
| if (s->value > 0) |
| { |
| s->leftToUnblock = 0; |
| } |
| #else |
| /* |
| * Don't release the W32 sema, it doesn't need adjustment |
| * because it doesn't record the number of waiters. |
| */ |
| #endif /* NEED_SEM */ |
| } |
| (void) pthread_mutex_unlock (&s->lock); |
| } |
| } |
| |
| int |
| sem_wait (sem_t * sem) |
| /* |
| * ------------------------------------------------------ |
| * DOCPUBLIC |
| * This function waits on a semaphore. |
| * |
| * PARAMETERS |
| * sem |
| * pointer to an instance of sem_t |
| * |
| * DESCRIPTION |
| * This function waits on a semaphore. If the |
| * semaphore value is greater than zero, it decreases |
| * its value by one. If the semaphore value is zero, then |
| * the calling thread (or process) is blocked until it can |
| * successfully decrease the value or until interrupted by |
| * a signal. |
| * |
| * RESULTS |
| * 0 successfully decreased semaphore, |
| * -1 failed, error in errno |
| * ERRNO |
| * EINVAL 'sem' is not a valid semaphore, |
| * ENOSYS semaphores are not supported, |
| * EINTR the function was interrupted by a signal, |
| * EDEADLK a deadlock condition was detected. |
| * |
| * ------------------------------------------------------ |
| */ |
| { |
| int result = 0; |
| sem_t s = *sem; |
| |
| pthread_testcancel(); |
| |
| if (s == NULL) |
| { |
| result = EINVAL; |
| } |
| else |
| { |
| if ((result = pthread_mutex_lock (&s->lock)) == 0) |
| { |
| int v; |
| |
| /* See sem_destroy.c |
| */ |
| if (*sem == NULL) |
| { |
| (void) pthread_mutex_unlock (&s->lock); |
| errno = EINVAL; |
| return -1; |
| } |
| |
| v = --s->value; |
| (void) pthread_mutex_unlock (&s->lock); |
| |
| if (v < 0) |
| { |
| #if defined(_MSC_VER) && _MSC_VER < 1400 |
| #pragma inline_depth(0) |
| #endif |
| /* Must wait */ |
| pthread_cleanup_push(ptw32_sem_wait_cleanup, (void *) s); |
| result = pthreadCancelableWait (s->sem); |
| /* Cleanup if we're canceled or on any other error */ |
| pthread_cleanup_pop(result); |
| #if defined(_MSC_VER) && _MSC_VER < 1400 |
| #pragma inline_depth() |
| #endif |
| } |
| #if defined(NEED_SEM) |
| |
| if (!result && pthread_mutex_lock (&s->lock) == 0) |
| { |
| if (*sem == NULL) |
| { |
| (void) pthread_mutex_unlock (&s->lock); |
| errno = EINVAL; |
| return -1; |
| } |
| |
| if (s->leftToUnblock > 0) |
| { |
| --s->leftToUnblock; |
| SetEvent(s->sem); |
| } |
| (void) pthread_mutex_unlock (&s->lock); |
| } |
| |
| #endif /* NEED_SEM */ |
| |
| } |
| |
| } |
| |
| if (result != 0) |
| { |
| errno = result; |
| return -1; |
| } |
| |
| return 0; |
| |
| } /* sem_wait */ |