Do not delete window decorations before next update

When window decorations are turned on/off, a timing issue might happen
with accessing deleted decorations.
A boolean value, mWindowDecorationEnabled, will be used instead of
mWindowDecoration.

Pick-to: 6.3 6.2
Fixes: QTBUG-59627
Change-Id: I5514a408d89340fdbf481721ea2dc4bf62078852
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

3 files changed, 34 insertions, 26 deletions

diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index 29e6ef671..e1c645e15 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -327,7 +327,7 @@ void QWaylandWindow::setWindowTitle(const QString &title)
         mShellSurface->setTitle(truncated.toString());
     }
 
-    if (mWindowDecoration && window()->isVisible())
+    if (mWindowDecorationEnabled && window()->isVisible())
         mWindowDecoration->update();
 }
 
@@ -335,7 +335,7 @@ void QWaylandWindow::setWindowIcon(const QIcon &icon)
 {
     mWindowIcon = icon;
 
-    if (mWindowDecoration && window()->isVisible())
+    if (mWindowDecorationEnabled && window()->isVisible())
         mWindowDecoration->update();
 }
 
@@ -369,7 +369,7 @@ void QWaylandWindow::setGeometry(const QRect &rect)
     setGeometry_helper(rect);
 
     if (window()->isVisible() && rect.isValid()) {
-        if (mWindowDecoration)
+        if (mWindowDecorationEnabled)
             mWindowDecoration->update();
 
         if (mResizeAfterSwap && windowType() == Egl && mSentInitialResize)
@@ -429,7 +429,7 @@ void QWaylandWindow::resizeFromApplyConfigure(const QSize &sizeWithMargins, cons
     // 2) Following resizeFromApplyConfigure() calls should have sizeWithMargins equal to
     //    windowContentGeometry() which excludes shadows, therefore in this case we have to
     //    exclude them too in order not to accidentally apply smaller size to the window.
-    if (mWindowDecoration && (sizeWithMargins != surfaceSize()))
+    if (mWindowDecorationEnabled && (sizeWithMargins != surfaceSize()))
         margins = mWindowDecoration->margins(QWaylandAbstractDecoration::ShadowsExcluded);
 
     int widthWithoutMargins = qMax(sizeWithMargins.width() - (margins.left() + margins.right()), 1);
@@ -751,7 +751,7 @@ bool QWaylandWindow::waitForFrameSync(int timeout)
 
 QMargins QWaylandWindow::frameMargins() const
 {
-    if (mWindowDecoration)
+    if (mWindowDecorationEnabled)
         return mWindowDecoration->margins();
     else if (mShellSurface)
         return mShellSurface->serverSideFrameMargins();
@@ -761,7 +761,7 @@ QMargins QWaylandWindow::frameMargins() const
 
 QMargins QWaylandWindow::clientSideMargins() const
 {
-    return mWindowDecoration ? mWindowDecoration->margins() : QMargins{};
+    return mWindowDecorationEnabled ? mWindowDecoration->margins() : QMargins{};
 }
 
 /*!
@@ -780,7 +780,7 @@ QRect QWaylandWindow::windowContentGeometry() const
 {
     QMargins shadowMargins;
 
-    if (mWindowDecoration)
+    if (mWindowDecorationEnabled)
         shadowMargins = mWindowDecoration->margins(QWaylandAbstractDecoration::ShadowsOnly);
 
     return QRect(QPoint(shadowMargins.left(), shadowMargins.top()), surfaceSize().shrunkBy(shadowMargins));
@@ -904,9 +904,14 @@ bool QWaylandWindow::createDecoration()
     if (!mShellSurface || !mShellSurface->wantsDecorations())
         decoration = false;
 
-    bool hadDecoration = mWindowDecoration;
+    bool hadDecoration = mWindowDecorationEnabled;
     if (decoration && !decorationPluginFailed) {
-        if (!mWindowDecoration) {
+        if (!mWindowDecorationEnabled) {
+            if (mWindowDecoration) {
+                delete mWindowDecoration;
+                mWindowDecoration = nullptr;
+            }
+
             QStringList decorations = QWaylandDecorationFactory::keys();
             if (decorations.empty()) {
                 qWarning() << "No decoration plugins available. Running with no decorations.";
@@ -935,13 +940,13 @@ bool QWaylandWindow::createDecoration()
                 return false;
             }
             mWindowDecoration->setWaylandWindow(this);
+            mWindowDecorationEnabled = true;
         }
     } else {
-        delete mWindowDecoration;
-        mWindowDecoration = nullptr;
+        mWindowDecorationEnabled = false;
     }
 
-    if (hadDecoration != (bool)mWindowDecoration) {
+    if (hadDecoration != mWindowDecorationEnabled) {
         for (QWaylandSubSurface *subsurf : qAsConst(mChildren)) {
             QPoint pos = subsurf->window()->geometry().topLeft();
             QMargins m = frameMargins();
@@ -962,7 +967,7 @@ bool QWaylandWindow::createDecoration()
 
 QWaylandAbstractDecoration *QWaylandWindow::decoration() const
 {
-    return mWindowDecoration;
+    return mWindowDecorationEnabled ? mWindowDecoration : nullptr;
 }
 
 static QWaylandWindow *closestShellSurfaceWindow(QWindow *window)
@@ -993,7 +998,7 @@ QWaylandWindow *QWaylandWindow::transientParent() const
 void QWaylandWindow::handleMouse(QWaylandInputDevice *inputDevice, const QWaylandPointerEvent &e)
 {
     if (e.type == QEvent::Leave) {
-        if (mWindowDecoration) {
+        if (mWindowDecorationEnabled) {
             if (mMouseEventsInContentArea)
                 QWindowSystemInterface::handleLeaveEvent(window());
         } else {
@@ -1005,7 +1010,7 @@ void QWaylandWindow::handleMouse(QWaylandInputDevice *inputDevice, const QWaylan
         return;
     }
 
-    if (mWindowDecoration) {
+    if (mWindowDecorationEnabled) {
         handleMouseEventWithDecoration(inputDevice, e);
     } else {
         switch (e.type) {
@@ -1045,7 +1050,7 @@ void QWaylandWindow::handleSwipeGesture(QWaylandInputDevice *inputDevice,
             if (mGestureState != GestureNotActive)
                 qCWarning(lcQpaWaylandInput) << "Unexpected GestureStarted while already active";
 
-            if (mWindowDecoration && !mMouseEventsInContentArea) {
+            if (mWindowDecorationEnabled && !mMouseEventsInContentArea) {
                 // whole gesture sequence will be ignored
                 mGestureState = GestureActiveInDecoration;
                 return;
@@ -1100,7 +1105,7 @@ void QWaylandWindow::handlePinchGesture(QWaylandInputDevice *inputDevice,
             if (mGestureState != GestureNotActive)
                 qCWarning(lcQpaWaylandInput) << "Unexpected GestureStarted while already active";
 
-            if (mWindowDecoration && !mMouseEventsInContentArea) {
+            if (mWindowDecorationEnabled && !mMouseEventsInContentArea) {
                 // whole gesture sequence will be ignored
                 mGestureState = GestureActiveInDecoration;
                 return;
@@ -1165,7 +1170,7 @@ void QWaylandWindow::handlePinchGesture(QWaylandInputDevice *inputDevice,
 
 bool QWaylandWindow::touchDragDecoration(QWaylandInputDevice *inputDevice, const QPointF &local, const QPointF &global, QEventPoint::State state, Qt::KeyboardModifiers mods)
 {
-    if (!mWindowDecoration)
+    if (!mWindowDecorationEnabled)
         return false;
     return mWindowDecoration->handleTouch(inputDevice, local, global, state, mods);
 }
diff --git a/src/client/qwaylandwindow_p.h b/src/client/qwaylandwindow_p.h
index 6eb8053bf..70d878f44 100644
--- a/src/client/qwaylandwindow_p.h
+++ b/src/client/qwaylandwindow_p.h
@@ -257,6 +257,7 @@ protected:
     QList<QWaylandSubSurface *> mChildren;
 
     QWaylandAbstractDecoration *mWindowDecoration = nullptr;
+    bool mWindowDecorationEnabled = false;
     bool mMouseEventsInContentArea = false;
     Qt::MouseButtons mMousePressedInContentArea = Qt::NoButton;
 
diff --git a/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp b/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp
index e9b290a76..d8efeb4a2 100644
--- a/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp
+++ b/src/hardwareintegration/client/wayland-egl/qwaylandglcontext.cpp
@@ -199,14 +199,16 @@ public:
         glViewport(0, 0, surfaceSize.width() * scale, surfaceSize.height() * scale);
 
         //Draw Decoration
-        m_blitProgram->setAttributeBuffer(0, GL_FLOAT, m_inverseSquareVerticesOffset, 2);
-        QImage decorationImage = window->decoration()->contentImage();
-        cache->bindTexture(m_context->context(), decorationImage);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, m_textureWrap);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, m_textureWrap);
-        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+        if (auto *decoration = window->decoration()) {
+            m_blitProgram->setAttributeBuffer(0, GL_FLOAT, m_inverseSquareVerticesOffset, 2);
+            QImage decorationImage = decoration->contentImage();
+            cache->bindTexture(m_context->context(), decorationImage);
+            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, m_textureWrap);
+            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, m_textureWrap);
+            glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+        }
 
         //Draw Content
         m_blitProgram->setAttributeBuffer(0, GL_FLOAT, m_squareVerticesOffset, 2);