xwl: Handle X11 clipboard owners closing more thoroughly

Selection acts as an abstraction around multiple X11Sources, when we get
a new source we asyncronously emit that x11OffersChanged when it
completes.

If the selection is lost, we were just deleting the source, without
notifying other parts.

XwlDataSource is the datasource that SeatInterface knows about. We need
to delete this when the X11 connection is no longer valid. SeatInterface
will update the selection when the XwmlDataSource is deleted if it's the
active selection.

The hook is introduced as updating the selection in Clipboard will cause
Selection to delete m_xSource which gets messy.

BUG: 449909

src/xwayland/clipboard.cpp

@@ -141,6 +141,11 @@ void Clipboard::doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event)
     }
 }
 
+void Clipboard::x11OfferLost()
+{
+    m_selectionSource.reset();
+}
+
 void Clipboard::x11OffersChanged(const QStringList &added, const QStringList &removed)
 {
     m_waitingForTargets = false;

src/xwayland/clipboard.h

@@ -36,6 +36,7 @@ public:
 
 private:
     void doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event) override;
+    void x11OfferLost() override;
     void x11OffersChanged(const QStringList &added, const QStringList &removed) override;
     /**
      * React to Wl selection change.

src/xwayland/dnd.cpp

@@ -113,6 +113,10 @@ void Dnd::doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event)
     m_currentDrag = new XToWlDrag(source, this);
 }
 
+void Dnd::x11OfferLost()
+{
+}
+
 void Dnd::x11OffersChanged(const QStringList &added, const QStringList &removed)
 {
 }

src/xwayland/dnd.h

@@ -45,6 +45,7 @@ public:
     XwlDropHandler *dropHandler() const;
 
     void doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event) override;
+    void x11OfferLost() override;
     void x11OffersChanged(const QStringList &added, const QStringList &removed) override;
     bool handleClientMessage(xcb_client_message_event_t *event) override;
 

src/xwayland/primary.cpp

@@ -144,6 +144,11 @@ void Primary::doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event)
     }
 }
 
+void Primary::x11OfferLost()
+{
+    m_primarySelectionSource.reset();
+}
+
 void Primary::x11OffersChanged(const QStringList &added, const QStringList &removed)
 {
     m_waitingForTargets = false;

src/xwayland/primary.h

@@ -38,6 +38,7 @@ public:
 
 private:
     void doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event) override;
+    void x11OfferLost() override;
     void x11OffersChanged(const QStringList &added, const QStringList &removed) override;
     /**
      * React to Wl selection change.

src/xwayland/selection.cpp

@@ -183,12 +183,14 @@ void Selection::setWlSource(WlSource *source)
 
 void Selection::createX11Source(xcb_xfixes_selection_notify_event_t *event)
 {
-    setWlSource(nullptr);
     if (!event || event->owner == XCB_WINDOW_NONE) {
+        x11OfferLost();
+        setWlSource(nullptr);
         return;
     }
-    m_xSource = new X11Source(this, event);
+    setWlSource(nullptr);
 
+    m_xSource = new X11Source(this, event);
     connect(m_xSource, &X11Source::offersChanged, this, &Selection::x11OffersChanged);
     connect(m_xSource, &X11Source::transferReady, this, &Selection::startTransferToWayland);
 }

src/xwayland/selection.h

@@ -74,6 +74,7 @@ protected:
     void registerXfixes();
 
     virtual void doHandleXfixesNotify(xcb_xfixes_selection_notify_event_t *event) = 0;
+    virtual void x11OfferLost() = 0;
     virtual void x11OffersChanged(const QStringList &added, const QStringList &removed) = 0;
 
     virtual bool handleClientMessage(xcb_client_message_event_t *event)