fix dbus service registration/invocation

REVIEW: 108016

dbusinterface.cpp

@@ -20,6 +20,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 // own
 #include "dbusinterface.h"
+
 // kwin
 // TODO: remove together with deprecated methods
 #include "client.h"
@@ -28,6 +29,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "kwinadaptor.h"
 #include "workspace.h"
 
+// Qt
+#include <QDBusServiceWatcher>
+
 namespace KWin
 {
 
@@ -38,7 +42,10 @@ DBusInterface::DBusInterface(QObject *parent)
 
     QDBusConnection dbus = QDBusConnection::sessionBus();
     dbus.registerObject("/KWin", this);
-    dbus.registerService("org.kde.KWin");
+    if (!dbus.registerService("org.kde.KWin")) {
+        QDBusServiceWatcher *dog = new QDBusServiceWatcher("org.kde.KWin", dbus, QDBusServiceWatcher::WatchForUnregistration, this);
+        connect (dog, SIGNAL(serviceUnregistered(const QString&)), SLOT(becomeKWinService(const QString&)));
+    }
     connect(Compositor::self(), SIGNAL(compositingToggled(bool)), SIGNAL(compositingToggled(bool)));
     dbus.connect(QString(), "/KWin", "org.kde.KWin", "reloadConfig",
                  Workspace::self(), SLOT(slotReloadConfig()));
@@ -46,8 +53,20 @@ DBusInterface::DBusInterface(QObject *parent)
                  Compositor::self(), SLOT(slotReinitialize()));
 }
 
+void DBusInterface::becomeKWinService(const QString &service)
+{
+    // TODO: this watchdog exists to make really safe that we at some point get the service
+    // but it's probably no longer needed since we explicitly unregister the service with the deconstructor
+    if (service == "org.kde.KWin" && QDBusConnection::sessionBus().registerService("org.kde.KWin") && sender()) {
+        sender()->deleteLater(); // bye doggy :'(
+    }
+}
+
 DBusInterface::~DBusInterface()
 {
+    QDBusConnection::sessionBus().unregisterService("org.kde.KWin"); // this is the long standing legal service
+    // KApplication automatically also grabs org.kde.kwin, so it's often been used externally - ensure to free it as well
+    QDBusConnection::sessionBus().unregisterService("org.kde.kwin");
 }
 
 void DBusInterface::circulateDesktopApplications()

dbusinterface.h

@@ -147,6 +147,8 @@ Q_SIGNALS: // SIGNALS
      * @deprecated
      **/
     void compositingToggled(bool active);
+private Q_SLOTS:
+    void becomeKWinService(const QString &service);
 };
 
 } // namespace

kcmkwin/kwincompositing/main.cpp

@@ -196,7 +196,7 @@ void KWinCompositingConfig::showConfirmDialog(bool reinitCompositing)
     bool revert = false;
     // Feel free to extend this to support several kwin instances (multihead) if you
     // think it makes sense.
-    OrgKdeKWinInterface kwin("org.kde.kwin", "/KWin", QDBusConnection::sessionBus());
+    OrgKdeKWinInterface kwin("org.kde.KWin", "/KWin", QDBusConnection::sessionBus());
     if (reinitCompositing ? !kwin.compositingActive().value() : !kwin.waitForCompositingSetup().value()) {
         KMessageBox::sorry(this, i18n(
                                "Failed to activate desktop effects using the given "
@@ -399,7 +399,7 @@ void KWinCompositingConfig::updateStatusUI(bool compositingIsPossible)
         ui.rearmGlSupport->hide();
     }
     else {
-        OrgKdeKWinInterface kwin("org.kde.kwin", "/KWin", QDBusConnection::sessionBus());
+        OrgKdeKWinInterface kwin("org.kde.KWin", "/KWin", QDBusConnection::sessionBus());
         ui.compositingOptionsContainer->hide();
         QString text = i18n("Desktop effects are not available on this system due to the following technical issues:");
         text += "<hr>";
@@ -416,7 +416,7 @@ void KWinCompositingConfig::load()
 {
     initEffectSelector();
     mKWinConfig->reparseConfiguration();
-    QDBusMessage msg = QDBusMessage::createMethodCall("org.kde.kwin", "/KWin", "org.kde.KWin", "compositingPossible");
+    QDBusMessage msg = QDBusMessage::createMethodCall("org.kde.KWin", "/KWin", "org.kde.KWin", "compositingPossible");
     QDBusConnection::sessionBus().callWithCallback(msg, this, SLOT(updateStatusUI(bool)));
 
     // Copy Plugins group to temp config file
@@ -527,7 +527,7 @@ bool KWinCompositingConfig::saveAdvancedTab()
 
 void KWinCompositingConfig::save()
 {
-    OrgKdeKWinInterface kwin("org.kde.kwin", "/KWin", QDBusConnection::sessionBus());
+    OrgKdeKWinInterface kwin("org.kde.KWin", "/KWin", QDBusConnection::sessionBus());
     if (ui.compositingType->currentIndex() == OPENGL_INDEX &&
         kwin.openGLIsBroken() && !ui.rearmGlSupport->isVisible())
     {
@@ -595,7 +595,7 @@ void KWinCompositingConfig::checkLoadedEffects()
 {
     // check for effects not supported by Backend or hardware
     // such effects are enabled but not returned by DBus method loadedEffects
-    OrgKdeKWinInterface kwin("org.kde.kwin", "/KWin", QDBusConnection::sessionBus());
+    OrgKdeKWinInterface kwin("org.kde.KWin", "/KWin", QDBusConnection::sessionBus());
     KConfigGroup effectConfig = KConfigGroup(mKWinConfig, "Compositing");
     bool enabledAfter = effectConfig.readEntry("Enabled", true);
 
@@ -626,7 +626,7 @@ void KWinCompositingConfig::checkLoadedEffects()
 void KWinCompositingConfig::showDetailedEffectLoadingInformation()
 {
     QStringList disabledEffects = m_showDetailedErrors->data().toStringList();
-    OrgKdeKWinInterface kwin("org.kde.kwin", "/KWin", QDBusConnection::sessionBus());
+    OrgKdeKWinInterface kwin("org.kde.KWin", "/KWin", QDBusConnection::sessionBus());
     QDBusPendingReply< QString > pendingCompositingType = kwin.compositingType();
     QString compositingType = pendingCompositingType.isError() ? "none" : pendingCompositingType.value();
     KServiceTypeTrader* trader = KServiceTypeTrader::self();