Android: Add destruction guard in QAndroidPlatformWindow

To avoid calling functions in QAndroidPlatformWindow during/after
destruction of the object, create a mutex and use lock_guard to
synchronize the destruction of the object and native function calls
originating from Android events.

Task-number: QTBUG-118231
Change-Id: I29818386456c6969ca507d74574b722bf8a19019
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>
(cherry picked from commit 0f20fee)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/plugins/platforms/android/qandroidplatformwindow.cpp

@@ -96,6 +96,7 @@ void QAndroidPlatformWindow::initialize()
 
 QAndroidPlatformWindow::~QAndroidPlatformWindow()
 {
+    const auto guard = destructionGuard();
     if (window()->isTopLevel())
         platformScreen()->removeWindow(this);
 }
@@ -353,6 +354,9 @@ void QAndroidPlatformWindow::setSurface(JNIEnv *env, jobject object, jint window
             continue;
         QAndroidPlatformWindow *platformWindow =
                                 static_cast<QAndroidPlatformWindow *>(window->handle());
+        const auto guard = platformWindow->destructionGuard();
+        if (!platformWindow->m_surfaceCreated)
+            continue;
         if (platformWindow->nativeViewId() == windowId)
             platformWindow->onSurfaceChanged(surface);
     }
@@ -373,6 +377,18 @@ void QAndroidPlatformWindow::windowFocusChanged(JNIEnv *env, jobject object,
     }
 }
 
+/*
+    Due to calls originating from Android, it is possible for native methods to
+    try to manipulate any given instance of QAndroidPlatformWindow when it is
+    already being destroyed. So we use this to guard against that. It is called
+    in the destructor, and should also be called in any function registered to
+    be called from java that may touch an instance of QAndroidPlatformWindow.
+ */
+QMutexLocker<QMutex> QAndroidPlatformWindow::destructionGuard()
+{
+    return QMutexLocker(&m_destructionMutex);
+}
+
 bool QAndroidPlatformWindow::registerNatives(QJniEnvironment &env)
 {
     if (!env.registerNativeMethods(QtJniTypes::Traits<QtJniTypes::QtWindow>::className(),

src/plugins/platforms/android/qandroidplatformwindow.h

@@ -96,12 +96,15 @@ class QAndroidPlatformWindow: public QPlatformWindow
     QWaitCondition m_surfaceWaitCondition;
     bool m_surfaceCreated = false;
     QMutex m_surfaceMutex;
+    QMutex m_destructionMutex;
 
 private:
     static void setSurface(JNIEnv *env, jobject obj, jint windowId, QtJniTypes::Surface surface);
     Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE(setSurface)
     static void windowFocusChanged(JNIEnv *env, jobject object, jboolean focus, jint windowId);
     Q_DECLARE_JNI_NATIVE_METHOD_IN_CURRENT_SCOPE(windowFocusChanged)
+
+    [[nodiscard]] QMutexLocker<QMutex> destructionGuard();
 };
 
 QT_END_NAMESPACE