From f75e53af60e715030f942c70db8b04cf5cf300c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Gr=C3=A4=C3=9Flin?= <mgraesslin@kde.org>
Date: Tue, 10 Nov 2015 13:54:26 +0100
Subject: [PATCH] [wayland] Ensure to not call into x11 on Compositor tear-down

During Compositor tear down Xwayland is already destroyed. Thus it
doesn't make sense to try to delete the support properties: either
it freezes in xcb or it crashes because the connection is null.

At the same time we also ensure that the connection internally is
reset to null. Note: the one in kwinglobals.h caches and could cause
use-after-free errors. Any tear-down code must be migrated to
kwinApp()->x11Connection().
---
 autotests/wayland/kwin_wayland_test.cpp | 1 +
 composite.cpp                           | 8 +++++---
 main_wayland.cpp                        | 1 +
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/autotests/wayland/kwin_wayland_test.cpp b/autotests/wayland/kwin_wayland_test.cpp
index 676bedc72c..88facd1faf 100644
--- a/autotests/wayland/kwin_wayland_test.cpp
+++ b/autotests/wayland/kwin_wayland_test.cpp
@@ -56,6 +56,7 @@ WaylandTestApplication::~WaylandTestApplication()
         Xcb::setInputFocus(XCB_INPUT_FOCUS_POINTER_ROOT);
         destroyAtoms();
         xcb_disconnect(x11Connection());
+        setX11Connection(nullptr);
     }
     if (m_xwaylandProcess) {
         m_xwaylandProcess->terminate();
diff --git a/composite.cpp b/composite.cpp
index 2ed44ceaf4..77d66d4ae5 100644
--- a/composite.cpp
+++ b/composite.cpp
@@ -443,9 +443,11 @@ void Compositor::deleteUnusedSupportProperties()
         m_unusedSupportPropertyTimer.start();
         return;
     }
-    foreach (const xcb_atom_t &atom, m_unusedSupportProperties) {
-        // remove property from root window
-        xcb_delete_property(connection(), rootWindow(), atom);
+    if (kwinApp()->x11Connection()) {
+        foreach (const xcb_atom_t &atom, m_unusedSupportProperties) {
+            // remove property from root window
+            xcb_delete_property(connection(), rootWindow(), atom);
+        }
     }
 }
 
diff --git a/main_wayland.cpp b/main_wayland.cpp
index 946598f44f..41fc7e5158 100644
--- a/main_wayland.cpp
+++ b/main_wayland.cpp
@@ -80,6 +80,7 @@ ApplicationWayland::~ApplicationWayland()
         Xcb::setInputFocus(XCB_INPUT_FOCUS_POINTER_ROOT);
         destroyAtoms();
         xcb_disconnect(x11Connection());
+        setX11Connection(nullptr);
     }
     if (m_xwaylandProcess) {
         m_xwaylandProcess->terminate();