/*
 * pthread_rwlock_destroy.c
 *
 * Description:
 * This translation unit implements read/write lock primitives.
 *
 * --------------------------------------------------------------------------
 *
 *      Pthreads4w - POSIX Threads Library for Win32
 *      Copyright(C) 1998 John E. Bossom
 *      Copyright(C) 1999-2018, Pthreads4w contributors
 *
 *      Homepage: https://sourceforge.net/projects/pthreads4w/
 *
 *      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:
 *      https://sourceforge.net/p/pthreads4w/wiki/Contributors/
 *
 * This file is part of Pthreads4w.
 *
 *    Pthreads4w is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    Pthreads4w 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 General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with Pthreads4w.  If not, see <http://www.gnu.org/licenses/>. *
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#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
    {
      ptw32_mcs_local_node_t node;
      /*
       * See notes in ptw32_rwlock_check_need_init() above also.
       */
      ptw32_mcs_lock_acquire(&ptw32_rwlock_test_init_lock, &node);

      /*
       * 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;
	}

      ptw32_mcs_lock_release(&node);
    }

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