Fix crash on startup on Symbian OS

The changes to QThread introduced by commit
9aa4538b219ed759a47e8d1f93c2797bf07b5e2f mean that the QThread constructor
calls into the event dispatcher.
The Symbian event dispatcher owns a QThread, so it crashed when the code
re-entered the partially constructed event dispatcher and used an
uninitialised pointer.

This change delays construction of the QThread until the point of use,
so that the event dispatcher is fully constructed.

Task-number: QTBUG-10029
Reviewed-by: Jason Barron
(cherry picked from commit 2b55d52669beb72396f94e449fdf172735349b3b)

2 files changed, 17 insertions, 6 deletions

diff --git a/src/corelib/kernel/qeventdispatcher_symbian.cpp b/src/corelib/kernel/qeventdispatcher_symbian.cpp
index ca44264..f811361 100644
--- a/src/corelib/kernel/qeventdispatcher_symbian.cpp
+++ b/src/corelib/kernel/qeventdispatcher_symbian.cpp
@@ -632,6 +632,7 @@ void QSocketActiveObject::deleteLater()
 
 QEventDispatcherSymbian::QEventDispatcherSymbian(QObject *parent)
     : QAbstractEventDispatcher(parent),
+      m_selectThread(0),
       m_activeScheduler(0),
       m_wakeUpAO(0),
       m_completeDeferredAOs(0),
@@ -659,11 +660,19 @@ void QEventDispatcherSymbian::startingUp()
     wakeUp();
 }
 
+QSelectThread& QEventDispatcherSymbian::selectThread() {
+    if (!m_selectThread)
+        m_selectThread = new QSelectThread;
+    return *m_selectThread;
+}
+
 void QEventDispatcherSymbian::closingDown()
 {
-    if (m_selectThread.isRunning()) {
-        m_selectThread.stop();
+    if (m_selectThread && m_selectThread->isRunning()) {
+        m_selectThread->stop();
     }
+    delete m_selectThread;
+    m_selectThread = 0;
 
     delete m_completeDeferredAOs;
     delete m_wakeUpAO;
@@ -935,12 +944,13 @@ void QEventDispatcherSymbian::registerSocketNotifier ( QSocketNotifier * notifie
 {
     QSocketActiveObject *socketAO = q_check_ptr(new QSocketActiveObject(this, notifier));
     m_notifiers.insert(notifier, socketAO);
-    m_selectThread.requestSocketEvents(notifier, &socketAO->iStatus);
+    selectThread().requestSocketEvents(notifier, &socketAO->iStatus);
 }
 
 void QEventDispatcherSymbian::unregisterSocketNotifier ( QSocketNotifier * notifier )
 {
-    m_selectThread.cancelSocketEvents(notifier);
+    if (m_selectThread)
+        m_selectThread->cancelSocketEvents(notifier);
     if (m_notifiers.contains(notifier)) {
         QSocketActiveObject *sockObj = *m_notifiers.find(notifier);
         m_deferredSocketEvents.removeAll(sockObj);
@@ -951,7 +961,7 @@ void QEventDispatcherSymbian::unregisterSocketNotifier ( QSocketNotifier * notif
 
 void QEventDispatcherSymbian::reactivateSocketNotifier(QSocketNotifier *notifier)
 {
-    m_selectThread.requestSocketEvents(notifier, &m_notifiers[notifier]->iStatus);
+    selectThread().requestSocketEvents(notifier, &m_notifiers[notifier]->iStatus);
 }
 
 void QEventDispatcherSymbian::registerTimer ( int timerId, int interval, QObject * object )
diff --git a/src/corelib/kernel/qeventdispatcher_symbian_p.h b/src/corelib/kernel/qeventdispatcher_symbian_p.h
index 1ab31cc..5281199 100644
--- a/src/corelib/kernel/qeventdispatcher_symbian_p.h
+++ b/src/corelib/kernel/qeventdispatcher_symbian_p.h
@@ -259,8 +259,9 @@ private:
     bool sendPostedEvents();
     bool sendDeferredSocketEvents();
 
+    QSelectThread& selectThread();
 private:
-    QSelectThread m_selectThread;
+    QSelectThread *m_selectThread;
 
     CQtActiveScheduler *m_activeScheduler;