Add pthread_mutex_trylock(3).

libpthread/Makefile

@@ -14,6 +14,7 @@ OBJS=\
 pthread_equal.o \
 pthread_initialize.o \
 pthread_mutex_lock.o \
+pthread_mutex_trylock.o \
 pthread_mutex_unlock.o \
 pthread_self.o \
 

libpthread/include/pthread.h

@@ -210,7 +210,7 @@ int pthread_equal(pthread_t, pthread_t);
 int pthread_mutex_lock(pthread_mutex_t*);
 /* TODO: pthread_mutex_setprioceiling */
 /* TODO: pthread_mutex_timedlock */
-/* TODO: pthread_mutex_trylock */
+int pthread_mutex_trylock(pthread_mutex_t*);
 int pthread_mutex_unlock(pthread_mutex_t*);
 /* TODO: pthread_mutexattr_destroy */
 /* TODO: pthread_mutexattr_getprioceiling */

libpthread/pthread_mutex_trylock.c++

@@ -0,0 +1,43 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013, 2014.
+
+    This file is part of Sortix libpthread.
+
+    Sortix libpthread 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 3 of the License, or (at your
+    option) any later version.
+
+    Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
+
+    pthread_mutex_trylock.c++
+    Attempts to lock a mutex.
+
+*******************************************************************************/
+
+#include <errno.h>
+#include <pthread.h>
+
+static const unsigned long UNLOCKED_VALUE = 0;
+static const unsigned long LOCKED_VALUE = 1;
+
+extern "C" int pthread_mutex_trylock(pthread_mutex_t* mutex)
+{
+	if ( !__sync_bool_compare_and_swap(&mutex->lock, UNLOCKED_VALUE, LOCKED_VALUE) )
+	{
+		if ( mutex->type == PTHREAD_MUTEX_RECURSIVE &&
+		     (pthread_t) mutex->owner == pthread_self() )
+				return mutex->recursion++, 0;
+		return errno = EBUSY;
+	}
+	mutex->owner = (unsigned long) pthread_self();
+	mutex->recursion = 0;
+	return 0;
+}