From e02da7d1a729ed168b135baf74ce8f9a501e8414 Mon Sep 17 00:00:00 2001
From: Arjen Hiemstra <ahiemstra@heimr.nl>
Date: Thu, 18 Nov 2021 13:05:30 +0100
Subject: [PATCH 15/55] Client: Delay deletion of QDrag object until after
 we're done with it

In certain cases, most notably when performing drag and drop operations
with touch, the QDrag object gets deleted before data_source_send is
executed. This then tries to access a deleted data_source, crashing the
client.

To avoid this, we indicate we want the QDrag object to stay around and
then delete it in QWaylandDrag::finishDrag, which with data_device v3 is
guaranteed to be called after everyone is done with the data source.

Change-Id: I6a2f5a219f58d1b721a9fec33c57d26d2c522ec9
Reviewed-by: David Edmundson <davidedmundson@kde.org>
(cherry picked from commit 39e3290efa2dd40722fa3322284cae3b01ccedf4)
---
 src/client/qwaylanddnd.cpp | 11 +++++++++++
 src/client/qwaylanddnd_p.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/src/client/qwaylanddnd.cpp b/src/client/qwaylanddnd.cpp
index 97ee5b2e..7c53f5fa 100644
--- a/src/client/qwaylanddnd.cpp
+++ b/src/client/qwaylanddnd.cpp
@@ -80,6 +80,9 @@ void QWaylandDrag::cancel()
     QBasicDrag::cancel();
 
     m_display->currentInputDevice()->dataDevice()->cancelDrag();
+
+    if (drag())
+        drag()->deleteLater();
 }
 
 void QWaylandDrag::move(const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardModifiers mods)
@@ -130,6 +133,14 @@ void QWaylandDrag::finishDrag()
 {
     QKeyEvent event(QEvent::KeyPress, Qt::Key_Escape, Qt::NoModifier);
     eventFilter(shapedPixmapWindow(), &event);
+
+    if (drag())
+        drag()->deleteLater();
+}
+
+bool QWaylandDrag::ownsDragObject() const
+{
+    return true;
 }
 
 }
diff --git a/src/client/qwaylanddnd_p.h b/src/client/qwaylanddnd_p.h
index 747f0190..46f629ac 100644
--- a/src/client/qwaylanddnd_p.h
+++ b/src/client/qwaylanddnd_p.h
@@ -83,6 +83,7 @@ protected:
     void drop(const QPoint &globalPos, Qt::MouseButtons b, Qt::KeyboardModifiers mods) override;
     void endDrag() override;
 
+    bool ownsDragObject() const override;
 
 private:
     QWaylandDisplay *m_display = nullptr;
-- 
2.52.0

