/*
 * pthread_rwlock_destroy.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) 1999,2003 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 <errno.h>
#include <limits.h>

#include "pthread.h"
#include "implement.h"

int
pthread_rwlock_destroy(pthread_rwlock_t *rwlock)
{
    pthread_rwlock_t rwl;
    int result = 0, result1 = 0, result2 = 0;

    if (rwlock == NULL || *rwlock == NULL)
      {
	return EINVAL;
      }

    if (*rwlock != PTHREAD_RWLOCK_INITIALIZER)
      {
	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;
	  }

	/*
	 * Check whether any threads own/wait for the lock (wait for ex.access);
	 * report "BUSY" if so.
	 */
	if (rwl->nExclusiveAccessCount > 0
	    || rwl->nSharedAccessCount > rwl->nCompletedSharedAccessCount)
	  {
	    result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted));
	    result1 = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
	    result2 = EBUSY;
	  }
	else 
	  {
	    rwl->nMagic = 0;

	    if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0)
	      {
		pthread_mutex_unlock(&rwl->mtxExclusiveAccess);
		return result;
	      }

	    if ((result = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess))) != 0)
	      {
		return result;
	      }

	    *rwlock = NULL; /* Invalidate rwlock before anything else */
	    result = pthread_cond_destroy(&(rwl->cndSharedAccessCompleted));
	    result1 = pthread_mutex_destroy(&(rwl->mtxSharedAccessCompleted));
	    result2 = pthread_mutex_destroy(&(rwl->mtxExclusiveAccess));
	    (void) free(rwl);
	  }
      }
    else
      {
	/*
	 * See notes in ptw32_rwlock_check_need_init() above also.
	 */
	EnterCriticalSection(&ptw32_rwlock_test_init_lock);

	/*
	 * Check again.
	 */
	if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
	  {
	    /*
	     * This is all we need to do to destroy a statically
	     * initialised rwlock that has not yet been used (initialised).
	     * If we get to here, another thread
	     * waiting to initialise this rwlock will get an EINVAL.
	     */
	    *rwlock = NULL;
	  }
	else
	  {
	    /*
	     * The rwlock has been initialised while we were waiting
	     * so assume it's in use.
	     */
	    result = EBUSY;
	  }

	LeaveCriticalSection(&ptw32_rwlock_test_init_lock);
      }

    return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
}
