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/*
* pthread_rwlock_wrlock.c
*
* Description:
* This translation unit implements read/write lock 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
*/
#include <limits.h>
#include "pthread.h"
#include "implement.h"
int
pthread_rwlock_wrlock (pthread_rwlock_t * rwlock)
{
int result;
pthread_rwlock_t rwl;
if (rwlock == NULL || *rwlock == NULL)
{
return EINVAL;
}
/*
* We do a quick check to see if we need to do more work
* to initialise a static rwlock. We check
* again inside the guarded section of ptw32_rwlock_check_need_init()
* to avoid race conditions.
*/
if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
{
result = ptw32_rwlock_check_need_init (rwlock);
if (result != 0 && result != EBUSY)
{
return result;
}
}
rwl = *rwlock;
if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
{
return EINVAL;
}
if ((result = pthread_mutex_lock (&(rwl->mtxExclusiveAccess))) != 0)
{
return result;
}
if ((result = pthread_mutex_lock (&(rwl->mtxSharedAccessCompleted))) != 0)
{
(void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
return result;
}
if (rwl->nExclusiveAccessCount == 0)
{
if (rwl->nCompletedSharedAccessCount > 0)
{
rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
rwl->nCompletedSharedAccessCount = 0;
}
if (rwl->nSharedAccessCount > 0)
{
rwl->nCompletedSharedAccessCount = -rwl->nSharedAccessCount;
/*
* This routine may be a cancelation point
* according to POSIX 1003.1j section 18.1.2.
*/
#if defined(_MSC_VER) && _MSC_VER < 1400
#pragma inline_depth(0)
#endif
pthread_cleanup_push (ptw32_rwlock_cancelwrwait, (void *) rwl);
do
{
result = pthread_cond_wait (&(rwl->cndSharedAccessCompleted),
&(rwl->mtxSharedAccessCompleted));
}
while (result == 0 && rwl->nCompletedSharedAccessCount < 0);
pthread_cleanup_pop ((result != 0) ? 1 : 0);
#if defined(_MSC_VER) && _MSC_VER < 1400
#pragma inline_depth()
#endif
if (result == 0)
{
rwl->nSharedAccessCount = 0;
}
}
}
if (result == 0)
{
rwl->nExclusiveAccessCount++;
}
return result;
}
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