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diff --git a/pthreads/pthread_rwlock_trywrlock.c b/pthreads/pthread_rwlock_trywrlock.c
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+/*
+ * pthread_rwlock_trywrlock.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 <errno.h>
+#include <limits.h>
+
+#include "pthread.h"
+#include "implement.h"
+
+int
+pthread_rwlock_trywrlock (pthread_rwlock_t * rwlock)
+{
+ int result, result1;
+ 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_trylock (&(rwl->mtxExclusiveAccess))) != 0)
+ {
+ return result;
+ }
+
+ if ((result =
+ pthread_mutex_trylock (&(rwl->mtxSharedAccessCompleted))) != 0)
+ {
+ result1 = pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
+ return ((result1 != 0) ? result1 : result);
+ }
+
+ if (rwl->nExclusiveAccessCount == 0)
+ {
+ if (rwl->nCompletedSharedAccessCount > 0)
+ {
+ rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
+ rwl->nCompletedSharedAccessCount = 0;
+ }
+
+ if (rwl->nSharedAccessCount > 0)
+ {
+ if ((result =
+ pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
+ {
+ (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
+ return result;
+ }
+
+ if ((result =
+ pthread_mutex_unlock (&(rwl->mtxExclusiveAccess))) == 0)
+ {
+ result = EBUSY;
+ }
+ }
+ else
+ {
+ rwl->nExclusiveAccessCount = 1;
+ }
+ }
+ else
+ {
+ result = EBUSY;
+ }
+
+ return result;
+}