/* * ptw32_semwait.c * * Description: * This translation unit implements mutual exclusion (mutex) primitives. * * -------------------------------------------------------------------------- * * 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 */ #ifndef _UWIN //# include <process.h> #endif #include "pthread.h" #include "implement.h" int ptw32_semwait (sem_t * sem) /* * ------------------------------------------------------ * DESCRIPTION * This function waits on a POSIX 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. * * Unlike sem_wait(), this routine is non-cancelable. * * 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; if (s == NULL) { result = EINVAL; } else { if ((result = pthread_mutex_lock (&s->lock)) == 0) { int v = --s->value; (void) pthread_mutex_unlock (&s->lock); if (v < 0) { /* Must wait */ if (WaitForSingleObject (s->sem, INFINITE) == WAIT_OBJECT_0) { #ifdef NEED_SEM if (pthread_mutex_lock (&s->lock) == 0) { if (s->leftToUnblock > 0) { --s->leftToUnblock; SetEvent(s->sem); } (void) pthread_mutex_unlock (&s->lock); } #endif return 0; } } else { return 0; } } } if (result != 0) { errno = result; return -1; } return 0; } /* ptw32_semwait */