Fixed some possible race conditions

When starting the same thread from two different threads, problems
could occur. When calling Kill and Start at the same time, a deadlock
could occur.

Author: j0r1

ChangeLog

@@ -5,6 +5,11 @@
 
 			 	    ---------
 
+ 1.3.3 (?)
+ 	* Fixed race conditions when starting the same thread from
+	  two different threads, or when starting and killing a
+	  thread at the same time. Thanks to Andreas Ringlstetter for
+	  providing the patch.
 
  1.3.2 (March 2017)
 	* CMake tests if pthread_cancel exists (doesn't on Android)

src/pthread/jthread.cpp

@@ -69,10 +69,12 @@ int JThread::Start()
 		mutexinit = true;
 	}
 
+	continuemutex.Lock();
 	runningmutex.Lock();
 	if (running)
 	{
 		runningmutex.Unlock();
+		continuemutex.Unlock();
 		return ERR_JTHREAD_ALREADYRUNNING;
 	}
 	runningmutex.Unlock();
@@ -81,7 +83,6 @@ int JThread::Start()
 	pthread_attr_init(&attr);
 	pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED);
 
-	continuemutex.Lock();
 	status = pthread_create(&threadid,&attr,TheThread,this);	
 	pthread_attr_destroy(&attr);
 	if (status != 0)
@@ -116,17 +117,20 @@ int JThread::Start()
 
 int JThread::Kill()
 {
+	continuemutex.Lock();
 	runningmutex.Lock();			
 	if (!running)
 	{
 		runningmutex.Unlock();
+		continuemutex.Unlock();
 		return ERR_JTHREAD_NOTRUNNING;
 	}
 #ifndef JTHREAD_SKIP_PTHREAD_CANCEL
 	pthread_cancel(threadid);
 #endif // JTHREAD_SKIP_PTHREAD_CANCEL
 	running = false;
 	runningmutex.Unlock();
+	continuemutex.Unlock();
 	return 0;
 }
 

src/win32/jthread.cpp

@@ -40,6 +40,8 @@ JThread::JThread()
 	retval = NULL;
 	mutexinit = false;
 	running = false;
+	threadid = 0;
+	threadhandle = 0;
 }
 
 JThread::~JThread()
@@ -68,15 +70,16 @@ int JThread::Start()
 		}		mutexinit = true;
 	}
 
+	continuemutex.Lock();
 	runningmutex.Lock();
 	if (running)
 	{
 		runningmutex.Unlock();
+		continuemutex.Unlock();
 		return ERR_JTHREAD_ALREADYRUNNING;
 	}
 	runningmutex.Unlock();
 
-	continuemutex.Lock();
 #ifndef _WIN32_WCE
 	threadhandle = (HANDLE)_beginthreadex(NULL,0,TheThread,this,0,&threadid);
 #else
@@ -109,16 +112,20 @@ int JThread::Start()
 
 int JThread::Kill()
 {
+	continuemutex.Lock();
 	runningmutex.Lock();			
 	if (!running)
 	{
 		runningmutex.Unlock();
+		continuemutex.Unlock();
 		return ERR_JTHREAD_NOTRUNNING;
 	}
 	TerminateThread(threadhandle,0);
 	CloseHandle(threadhandle);
+	threadhandle = 0;
 	running = false;
 	runningmutex.Unlock();
+	continuemutex.Unlock();
 	return 0;
 }
 
@@ -174,6 +181,7 @@ DWORD WINAPI JThread::TheThread(void *param)
 	jthread->running = false;
 	jthread->retval = ret;
 	CloseHandle(jthread->threadhandle);
+	jthread->threadhandle = 0;
 	jthread->runningmutex.Unlock();
 	return 0;		
 }