QDBusServer: delay processing of D-Bus messages

We must ensure that QDBusServer's newConnection() signal has been
processed by the application, before starting processing messages on it.

Task-number: QTBUG-55087
Change-Id: I595329b2f98788dbf9f40558b8c230c0c0817ef8
Reviewed-by: Timo Jyrinki <timo.jyrinki@iki.fi>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

4 files changed, 33 insertions, 20 deletions

diff --git a/src/dbus/qdbusconnection.cpp b/src/dbus/qdbusconnection.cpp
index 7cdacc1284..c88cf89897 100644
--- a/src/dbus/qdbusconnection.cpp
+++ b/src/dbus/qdbusconnection.cpp
@@ -68,24 +68,6 @@ static void preventDllUnload();
 
 Q_GLOBAL_STATIC(QDBusConnectionManager, _q_manager)
 
-// can be replaced with a lambda in Qt 5.7
-class QDBusConnectionDispatchEnabler : public QObject
-{
-    Q_OBJECT
-    QDBusConnectionPrivate *con;
-public:
-    QDBusConnectionDispatchEnabler(QDBusConnectionPrivate *con) : con(con) {}
-
-public slots:
-    void execute()
-    {
-        con->setDispatchEnabled(true);
-        if (!con->ref.deref())
-            con->deleteLater();
-        deleteLater();
-    }
-};
-
 struct QDBusConnectionManager::ConnectionRequestData
 {
     enum RequestType {
@@ -1281,8 +1263,6 @@ QByteArray QDBusConnection::localMachineId()
 
 QT_END_NAMESPACE
 
-#include "qdbusconnection.moc"
-
 #ifdef Q_OS_WIN
 #  include <qt_windows.h>
 
diff --git a/src/dbus/qdbusconnection_p.h b/src/dbus/qdbusconnection_p.h
index fff9f29b03..d16cd05058 100644
--- a/src/dbus/qdbusconnection_p.h
+++ b/src/dbus/qdbusconnection_p.h
@@ -375,6 +375,25 @@ extern QDBusMessage qDBusPropertySet(const QDBusConnectionPrivate::ObjectTreeNod
                                      const QDBusMessage &msg);
 extern QDBusMessage qDBusPropertyGetAll(const QDBusConnectionPrivate::ObjectTreeNode &node,
                                         const QDBusMessage &msg);
+
+// can be replaced with a lambda in Qt 5.7
+class QDBusConnectionDispatchEnabler : public QObject
+{
+    Q_OBJECT
+    QDBusConnectionPrivate *con;
+public:
+    QDBusConnectionDispatchEnabler(QDBusConnectionPrivate *con) : con(con) {}
+
+public slots:
+    void execute()
+    {
+        con->setDispatchEnabled(true);
+        if (!con->ref.deref())
+            con->deleteLater();
+        deleteLater();
+    }
+};
+
 #endif // QT_BOOTSTRAPPED
 
 QT_END_NAMESPACE
diff --git a/src/dbus/qdbusintegrator.cpp b/src/dbus/qdbusintegrator.cpp
index 147966b9b0..878a58294c 100644
--- a/src/dbus/qdbusintegrator.cpp
+++ b/src/dbus/qdbusintegrator.cpp
@@ -309,9 +309,21 @@ static void qDBusNewConnection(DBusServer *server, DBusConnection *connection, v
     // setPeer does the error handling for us
     QDBusErrorInternal error;
     newConnection->setPeer(connection, error);
+    newConnection->setDispatchEnabled(false);
 
     // this is a queued connection and will resume in the QDBusServer's thread
     emit serverConnection->newServerConnection(newConnection);
+
+    // we've disabled dispatching of events, so now we post an event to the
+    // QDBusServer's thread in order to enable it after the
+    // QDBusServer::newConnection() signal has been received by the
+    // application's code
+    newConnection->ref.ref();
+    QReadLocker serverLock(&serverConnection->lock);
+    QDBusConnectionDispatchEnabler *o = new QDBusConnectionDispatchEnabler(newConnection);
+    QTimer::singleShot(0, o, SLOT(execute()));
+    if (serverConnection->serverObject)
+        o->moveToThread(serverConnection->serverObject->thread());
 }
 
 void QDBusConnectionPrivate::_q_newConnection(QDBusConnectionPrivate *newConnection)
diff --git a/src/dbus/qdbusserver.cpp b/src/dbus/qdbusserver.cpp
index babb270da0..39d08b4e63 100644
--- a/src/dbus/qdbusserver.cpp
+++ b/src/dbus/qdbusserver.cpp
@@ -97,6 +97,7 @@ QDBusServer::QDBusServer(QObject *parent)
 */
 QDBusServer::~QDBusServer()
 {
+    QWriteLocker locker(&d->lock);
     if (QDBusConnectionManager::instance()) {
         QMutexLocker locker(&QDBusConnectionManager::instance()->mutex);
         Q_FOREACH (const QString &name, d->serverConnectionNames) {
@@ -104,6 +105,7 @@ QDBusServer::~QDBusServer()
         }
         d->serverConnectionNames.clear();
     }
+    d->serverObject = nullptr;
     d->ref.store(0);
     d->deleteLater();
 }