wayland/layershell: ensure bridge is nulled on layer destruction

Fixes rare race condition crashes.

Author: outfoxxed

src/wayland/wlr_layershell/surface.cpp

@@ -173,7 +173,10 @@ LayerSurface::LayerSurface(LayerShellIntegration* shell, QtWaylandClient::QWayla
 	this->bridge->surface = this;
 }
 
-LayerSurface::~LayerSurface() { this->destroy(); }
+LayerSurface::~LayerSurface() {
+	delete this->bridge;
+	this->destroy();
+}
 
 void LayerSurface::zwlr_layer_surface_v1_configure(quint32 serial, quint32 width, quint32 height) {
 	this->ack_configure(serial);

src/wayland/wlr_layershell/wlr_layershell.cpp

@@ -34,7 +34,8 @@ ProxiedWindow* WlrLayershell::retrieveWindow(QObject* oldInstance) {
 	auto* window = old == nullptr ? nullptr : old->disownWindow();
 
 	if (window != nullptr) {
-		this->bridge = LayerSurfaceBridge::init(window, this->computeState());
+		this->connectBridge(LayerSurfaceBridge::init(window, this->computeState()));
+
 		if (this->bridge) {
 			return window;
 		} else {
@@ -48,7 +49,7 @@ ProxiedWindow* WlrLayershell::retrieveWindow(QObject* oldInstance) {
 ProxiedWindow* WlrLayershell::createQQuickWindow() {
 	auto* window = this->ProxyWindowBase::createQQuickWindow();
 
-	this->bridge = LayerSurfaceBridge::init(window, this->computeState());
+	this->connectBridge(LayerSurfaceBridge::init(window, this->computeState()));
 	if (!this->bridge) {
 		qWarning() << "Could not attach Layershell extension to new QQuickWindow. Layer will not "
 		              "behave correctly.";
@@ -72,6 +73,30 @@ void WlrLayershell::connectWindow() {
 	this->updateAutoExclusion();
 }
 
+ProxiedWindow* WlrLayershell::disownWindow(bool keepItemOwnership) {
+	auto* window = this->ProxyWindowBase::disownWindow(keepItemOwnership);
+
+	if (this->bridge) {
+		this->connectBridge(nullptr);
+	}
+
+	return window;
+}
+
+void WlrLayershell::connectBridge(LayerSurfaceBridge* bridge) {
+	if (this->bridge) {
+		QObject::disconnect(this->bridge, nullptr, this, nullptr);
+	}
+
+	this->bridge = bridge;
+
+	if (bridge) {
+		QObject::connect(this->bridge, &QObject::destroyed, this, &WlrLayershell::onBridgeDestroyed);
+	}
+}
+
+void WlrLayershell::onBridgeDestroyed() { this->bridge = nullptr; }
+
 bool WlrLayershell::deleteOnInvisible() const {
 	// Qt windows behave weirdly when geometry is modified and setVisible(false)
 	// is subsequently called in the same frame.

src/wayland/wlr_layershell/wlr_layershell.hpp

@@ -122,6 +122,7 @@ class WlrLayershell: public ProxyWindowBase {
 	ProxiedWindow* retrieveWindow(QObject* oldInstance) override;
 	ProxiedWindow* createQQuickWindow() override;
 	void connectWindow() override;
+	ProxiedWindow* disownWindow(bool keepItemOwnership = false) override;
 	[[nodiscard]] bool deleteOnInvisible() const override;
 
 	void onPolished() override;
@@ -175,10 +176,12 @@ class WlrLayershell: public ProxyWindowBase {
 
 private slots:
 	void updateAutoExclusion();
+	void onBridgeDestroyed();
 
 private:
 	[[nodiscard]] LayerSurfaceState computeState() const;
 
+	void connectBridge(LayerSurfaceBridge* bridge);
 	void onStateChanged();
 
 	bool compositorPicksScreen = true;