136 lines
3.9 KiB
C
136 lines
3.9 KiB
C
/*
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* ptw32_semwait.c
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*
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* Description:
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* This translation unit implements mutual exclusion (mutex) primitives.
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*
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* --------------------------------------------------------------------------
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*
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* Pthreads-win32 - POSIX Threads Library for Win32
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* Copyright(C) 1998 John E. Bossom
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* Copyright(C) 1999,2005 Pthreads-win32 contributors
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*
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* Contact Email: rpj@callisto.canberra.edu.au
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*
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* The current list of contributors is contained
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* in the file CONTRIBUTORS included with the source
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* code distribution. The list can also be seen at the
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* following World Wide Web location:
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* http://sources.redhat.com/pthreads-win32/contributors.html
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library in the file COPYING.LIB;
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* if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#if !defined(_UWIN)
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/*# include <process.h> */
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#endif
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#include "pthread.h"
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#include "implement.h"
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int
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ptw32_semwait (sem_t * sem)
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/*
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* ------------------------------------------------------
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* DESCRIPTION
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* This function waits on a POSIX semaphore. If the
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* semaphore value is greater than zero, it decreases
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* its value by one. If the semaphore value is zero, then
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* the calling thread (or process) is blocked until it can
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* successfully decrease the value.
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*
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* Unlike sem_wait(), this routine is non-cancelable.
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*
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* RESULTS
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* 0 successfully decreased semaphore,
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* -1 failed, error in errno.
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* ERRNO
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* EINVAL 'sem' is not a valid semaphore,
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* ENOSYS semaphores are not supported,
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* EINTR the function was interrupted by a signal,
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* EDEADLK a deadlock condition was detected.
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*
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* ------------------------------------------------------
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*/
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{
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int result = 0;
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sem_t s = *sem;
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if (s == NULL)
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{
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result = EINVAL;
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}
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else
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{
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if ((result = pthread_mutex_lock (&s->lock)) == 0)
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{
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int v;
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/* See sem_destroy.c
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*/
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if (*sem == NULL)
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{
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(void) pthread_mutex_unlock (&s->lock);
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errno = EINVAL;
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return -1;
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}
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v = --s->value;
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(void) pthread_mutex_unlock (&s->lock);
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if (v < 0)
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{
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/* Must wait */
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if (WaitForSingleObject (s->sem, INFINITE) == WAIT_OBJECT_0)
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{
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#if defined(NEED_SEM)
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if (pthread_mutex_lock (&s->lock) == 0)
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{
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if (*sem == NULL)
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{
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(void) pthread_mutex_unlock (&s->lock);
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errno = EINVAL;
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return -1;
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}
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if (s->leftToUnblock > 0)
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{
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--s->leftToUnblock;
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SetEvent(s->sem);
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}
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(void) pthread_mutex_unlock (&s->lock);
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}
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#endif
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return 0;
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}
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}
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else
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{
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return 0;
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}
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}
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}
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if (result != 0)
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{
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errno = result;
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return -1;
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}
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return 0;
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} /* ptw32_semwait */
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