gui: Fix crash when wayland display goes away

The WaylandUtils class had to be rewritten to not cache the seat or
display as they can change.

The crash is resolved with a hack that removes the registry proxy
immediately after it's been used.

src/gui/wayland/waylandidletimer.cpp

@@ -52,13 +52,13 @@ public:
 };
 
 WaylandIdleTimer::WaylandIdleTimer()
-    : m_supported{WaylandUtils::hasInterface("ext_idle_notifier_v1")}
+    : wl_utils(new WaylandUtils), m_supported(wl_utils->hasInterface("ext_idle_notifier_v1"))
 {
     if (m_supported) {
         auto seat = WaylandUtils::seat();
         m_notifier.reset(new WaylandIdleNotifier());
 #ifdef USE_WAYLAND_INPUT_IDLE_NOTIFY
-        if (WaylandUtils::hasInterface("ext_idle_notifier_v1", 2)) {
+        if (wl_utils->hasInterface("ext_idle_notifier_v1", 2)) {
             m_notification.reset(new WaylandIdleNotification(m_notifier->get_input_idle_notification(0, seat)));
         } else {
             m_notification.reset(new WaylandIdleNotification(m_notifier->get_idle_notification(0, seat)));
@@ -88,4 +88,6 @@ bool WaylandIdleTimer::isSupported() const
 {
     return m_supported;
 }
+
 #endif
+

src/gui/wayland/waylandidletimer.h

@@ -3,6 +3,7 @@
 
 #ifdef USE_WAYLAND_IDLE_NOTIFY
 #include "idletimer.h"
+#include "waylandutils.h"
 
 #include <QScopedPointer>
 
@@ -17,6 +18,7 @@ public:
     bool isSupported() const override;
 
 private:
+    QScopedPointer<WaylandUtils> wl_utils;
     bool m_supported;
     QScopedPointer<WaylandIdleNotifier> m_notifier;
     QScopedPointer<WaylandIdleNotification> m_notification;

src/gui/wayland/waylandutils.cpp

@@ -3,7 +3,6 @@
 #include <QGuiApplication>
 
 #ifdef USE_WAYLAND
-#include <QGuiApplication>
 #if QT_VERSION < QT_VERSION_CHECK(6, 5 ,0)
 #include <qpa/qplatformnativeinterface.h>
 #endif
@@ -11,17 +10,9 @@
 #include <wayland-client-protocol.h>
 #include <wayland-client.h>
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 3 ,0)
-#include <qapplicationstatic.h>
-#else
-#include <QGlobalStatic>
-#endif
 #endif
 
-namespace WaylandUtils
-{
-
-bool isWayland()
+bool WaylandUtils::isWayland()
 {
     if (qGuiApp->platformName() == "wayland") {
         return true;
@@ -39,51 +30,29 @@ bool isWayland()
 }
 
 #ifdef USE_WAYLAND
-struct RegistryData {
-    QString interfaceName;
-    quint32 version;
-};
 
-class WaylandUtilsHelper {
-public:
-    wl_display* m_display = nullptr;
-    wl_registry* m_registry = nullptr;
-    wl_seat *m_seat = nullptr;
-
-    QList<RegistryData> m_registerData;
-
-    WaylandUtilsHelper()
+WaylandUtils::WaylandUtils()
 {
+    wl_display* m_display = nullptr;
 #if QT_VERSION < QT_VERSION_CHECK(6, 5 ,0)
     QPlatformNativeInterface* nativeInterface = qGuiApp->platformNativeInterface();
-        if (!nativeInterface) {
+    if (!nativeInterface)
         return;
-        }
 
     m_display = static_cast<wl_display *>(nativeInterface->nativeResourceForIntegration("wl_display"));
-        if (!m_display) {
-            return;
-        }
-
-        m_seat = static_cast<wl_seat *>(nativeInterface->nativeResourceForIntegration("m_seat"));
-        if (!m_seat) {
-            m_display = nullptr;
-            return;
-        }
 #else
     auto nativeInterface = qGuiApp->nativeInterface<QNativeInterface::QWaylandApplication>();
-        if (!nativeInterface) {
+    if (!nativeInterface)
         return;
-        }
 
     m_display = nativeInterface->display();
-        m_seat = nativeInterface->seat();
 #endif
+    if (!m_display)
+        return;
 
-        m_registry = wl_display_get_registry(m_display);
-        if (!m_registry) {
+    wl_registry* m_registry = wl_display_get_registry(m_display);
+    if (!m_registry)
         return;
-        }
 
     auto global_handler = [](void* data_ptr, wl_registry*, uint32_t name, const char* interface, uint32_t version) {
         auto registerData = static_cast<QList<RegistryData>*>(data_ptr);
@@ -101,34 +70,39 @@ public:
 
     wl_display_dispatch(m_display);
     wl_display_roundtrip(m_display);
+
+    // HACK: Destroy the registry proxy to indirectly remove the listener
+    // This way we avoid crashing when the display disappears/changes
+    wl_proxy_destroy(reinterpret_cast<wl_proxy*>(m_registry));
 }
-};
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 3 ,0)
-Q_APPLICATION_STATIC(WaylandUtilsHelper, g_helper,)
+wl_seat* WaylandUtils::seat() {
+#if QT_VERSION < QT_VERSION_CHECK(6, 5 ,0)
+    QPlatformNativeInterface* nativeInterface = qGuiApp->platformNativeInterface();
+    if (!nativeInterface)
+        return nullptr;
+
+    wl_seat* s = static_cast<wl_seat*>(nativeInterface->nativeResourceForIntegration("m_seat"));
 #else
-Q_GLOBAL_STATIC(WaylandUtilsHelper, g_helper)
-#endif
+    auto nativeInterface = qGuiApp->nativeInterface<QNativeInterface::QWaylandApplication>();
+    if (!nativeInterface)
+        return nullptr;
 
-bool hasInterface(const QString &name, quint32 version)
+    wl_seat* s = nativeInterface->seat();
+#endif
+    return s;
+}
+
+bool WaylandUtils::hasInterface(const QString &name, quint32 version)
 {
-    auto it = std::find_if(g_helper->m_registerData.constBegin(), g_helper->m_registerData.constEnd(), [&name, &version](const RegistryData& data){
+    auto it = std::find_if(m_registerData.constBegin(), m_registerData.constEnd(), [&name, &version](const RegistryData& data){
         const bool matched = data.interfaceName == name;
         if (version == 0) {
             return matched;
         }
         return matched && data.version == version;
     });
-    return it != g_helper->m_registerData.constEnd();
+    return it != m_registerData.constEnd();
 }
 
-wl_display *display() {
-    return g_helper->m_display;
-}
-
-wl_seat *seat() {
-    return g_helper->m_seat;
-}
 #endif
-
-} // WaylandUtils

src/gui/wayland/waylandutils.h

@@ -6,20 +6,29 @@
 #ifdef USE_WAYLAND
 class wl_display;
 class wl_seat;
+#include <QList>
 #endif
 
-namespace WaylandUtils
+class WaylandUtils
 {
 
-bool isWayland();
+public:
+    static bool isWayland();
 
 #ifdef USE_WAYLAND
+    WaylandUtils();
+    static wl_seat* seat();
+
     bool hasInterface(const QString& name, quint32 version = 0);
 
-wl_display *display();
-wl_seat *seat();
+private:
+    struct RegistryData {
+        QString interfaceName;
+        quint32 version;
+    };
+    QList<RegistryData> m_registerData;
 #endif
 
-} // WaylandUtils
+}; // WaylandUtils
 
 #endif // WAYLANDUTILS_HPP