Fix handle leak in symbian QTimer implementation

The timer handle was only being closed when a timer was cancelled,
which resulted in a leak for one shot timers that have completed normally.

Instead the timer is now closed in a destructor (closing null handles is
safe, so it doesn't matter if the handle was never created - e.g. in the
case of a zero timer)
Also added a handle check before creating a timer to prevent a leak in
case the start function is called twice in the backend.

Task-number: QTBUG-16380
Reviewed-by: mread
(cherry picked from commit 2b1b617664bfc78f6e95e53dc0f9749bd1f2d27a)

2 files changed, 42 insertions, 2 deletions

diff --git a/src/corelib/kernel/qeventdispatcher_symbian.cpp b/src/corelib/kernel/qeventdispatcher_symbian.cpp
index bb9bd01..99c4087 100644
--- a/src/corelib/kernel/qeventdispatcher_symbian.cpp
+++ b/src/corelib/kernel/qeventdispatcher_symbian.cpp
@@ -217,13 +217,13 @@ QTimerActiveObject::QTimerActiveObject(QEventDispatcherSymbian *dispatcher, Symb
 QTimerActiveObject::~QTimerActiveObject()
 {
     Cancel();
+    m_rTimer.Close(); //close of null handle is safe
 }
 
 void QTimerActiveObject::DoCancel()
 {
     if (m_timerInfo->interval > 0) {
         m_rTimer.Cancel();
-        m_rTimer.Close();
     } else {
         if (iStatus.Int() == KRequestPending) {
             TRequestStatus *status = &iStatus;
@@ -302,7 +302,9 @@ void QTimerActiveObject::Start()
     CActiveScheduler::Add(this);
     m_timerInfo->msLeft = m_timerInfo->interval;
     if (m_timerInfo->interval > 0) {
-        m_rTimer.CreateLocal();
+        if (!m_rTimer.Handle()) {
+            qt_symbian_throwIfError(m_rTimer.CreateLocal());
+        }
         StartTimer();
     } else {
         iStatus = KRequestPending;
diff --git a/tests/auto/qtimer/tst_qtimer.cpp b/tests/auto/qtimer/tst_qtimer.cpp
index 102308e..e964728 100644
--- a/tests/auto/qtimer/tst_qtimer.cpp
+++ b/tests/auto/qtimer/tst_qtimer.cpp
@@ -90,6 +90,9 @@ private slots:
 
     void QTBUG13633_dontBlockEvents();
     void postedEventsShouldNotStarveTimers();
+#ifdef Q_OS_SYMBIAN
+    void handleLeaks();
+#endif
 };
 
 class TimerHelper : public QObject
@@ -750,5 +753,40 @@ void tst_QTimer::postedEventsShouldNotStarveTimers()
     QVERIFY(timerHelper.count > 5);
 }
 
+#ifdef Q_OS_SYMBIAN
+void tst_QTimer::handleLeaks()
+{
+    const int timercount = 5;
+    int processhandles_start;
+    int threadhandles_start;
+    RThread().HandleCount(processhandles_start, threadhandles_start);
+    {
+    TimerHelper timerHelper;
+    QList<QTimer*> timers;
+    for (int i=0;i<timercount;i++) {
+        QTimer* timer = new QTimer;
+        timers.append(timer);
+        connect(timer, SIGNAL(timeout()), &timerHelper, SLOT(timeout()));
+        timer->setSingleShot(true);
+        timer->start(i); //test both zero and normal timeouts
+    }
+    int processhandles_mid;
+    int threadhandles_mid;
+    RThread().HandleCount(processhandles_mid, threadhandles_mid);
+    qDebug() << threadhandles_mid - threadhandles_start << "new thread owned handles";
+    QTest::qWait(100);
+    QCOMPARE(timerHelper.count, timercount);
+    qDeleteAll(timers);
+    }
+    int processhandles_end;
+    int threadhandles_end;
+    RThread().HandleCount(processhandles_end, threadhandles_end);
+    QCOMPARE(threadhandles_end, threadhandles_start); //RTimer::CreateLocal creates a thread owned handle
+    //Can not verify process handles because QObject::connect may create up to 2 mutexes
+    //from a QMutexPool (4 process owned handles with open C imp.)
+    //QCOMPARE(processhandles_end, processhandles_start);
+}
+#endif
+
 QTEST_MAIN(tst_QTimer)
 #include "tst_qtimer.moc"