Merge pull request #1124 from roscaviktor/async-terminate-crash

Fix MQTTAsync_terminate() to re-check the number of handles after re-acquisition of mqttasync_mutex

src/MQTTAsync.c

@@ -629,15 +629,14 @@ int MQTTAsync_connect(MQTTAsync handle, const MQTTAsync_connectOptions* options)
 	m->connect.context = options->context;
 	m->connectTimeout = options->connectTimeout;
 
-	MQTTAsync_tostop = 0;
-
 	/* don't lock async mutex if we are being called from a callback */
 	thread_id = Thread_getid();
 	if (thread_id != sendThread_id && thread_id != receiveThread_id)
 	{
 		MQTTAsync_lock_mutex(mqttasync_mutex);
 		locked = 1;
 	}
+	MQTTAsync_tostop = 0;
 	if (sendThread_state != STARTING && sendThread_state != RUNNING)
 	{
 		sendThread_state = STARTING;

src/MQTTAsyncUtils.c

@@ -198,7 +198,9 @@ void MQTTAsync_terminate(void)
 {
 	FUNC_ENTRY;
 	MQTTAsync_stop();
-	if (global_initialized)
+
+	/* don't destroy global data if a new client was created while waiting for background threads to terminate */
+	if (global_initialized && bstate->clients->count == 0)
 	{
 		ListElement* elem = NULL;
 		ListFree(bstate->clients);
@@ -2309,7 +2311,7 @@ static void MQTTAsync_stop(void)
 		{
 			int count = 0;
 			MQTTAsync_tostop = 1;
-			while ((sendThread_state != STOPPED || receiveThread_state != STOPPED) && ++count < 100)
+			while ((sendThread_state != STOPPED || receiveThread_state != STOPPED) && MQTTAsync_tostop != 0 && ++count < 100)
 			{
 				MQTTAsync_unlock_mutex(mqttasync_mutex);
 				Log(TRACE_MIN, -1, "sleeping");