Client: Add safer fromObject function to scanner

Makes the scanner produce generated static functions such as

QtWaylandClient::wl_surface *wl_surface::fromObject(struct ::wl_surface *object);

Which casts from the wayland-scanner generated types, such as struct ::wl_surface *,
to types types generated by qtwaylandscanner, but performs a check to see if
the listener is set to the wrapper class first (at least for interfaces with events).

This lets us easily fix crashes in a couple of places where we receive events
with wayland objects that we didn't create.

Also adds nullptr checks whenever we use the fromWlSurface() and fromWlOutput()
functions to handle failed conversions.

Task-number: QTBUG-73801
Fixes: QTBUG-74085
Change-Id: I9f33c31c7d1a939ccb3ebbbcb0eb67af10037237
Reviewed-by: Jaroslaw Kubik <jarek@froglogic.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 13 insertions, 4 deletions

diff --git a/src/client/qwaylandinputdevice.cpp b/src/client/qwaylandinputdevice.cpp
index daad6f15..8231dd9c 100644
--- a/src/client/qwaylandinputdevice.cpp
+++ b/src/client/qwaylandinputdevice.cpp
@@ -555,6 +555,9 @@ void QWaylandInputDevice::Pointer::pointer_enter(uint32_t serial, struct wl_surf
 
     QWaylandWindow *window = QWaylandWindow::fromWlSurface(surface);
 
+    if (!window)
+        return; // Ignore foreign surfaces
+
     if (mFocus) {
         qCWarning(lcQpaWayland) << "The compositor sent a wl_pointer.enter event before sending a"
                                 << "leave event first, this is not allowed by the wayland protocol"
@@ -596,10 +599,12 @@ void QWaylandInputDevice::Pointer::pointer_leave(uint32_t time, struct wl_surfac
     if (!surface)
         return;
 
-    if (!QWaylandWindow::mouseGrab()) {
-        QWaylandWindow *window = QWaylandWindow::fromWlSurface(surface);
+    auto *window = QWaylandWindow::fromWlSurface(surface);
+    if (!window)
+        return; // Ignore foreign surfaces
+
+    if (!QWaylandWindow::mouseGrab())
         setFrameEvent(new LeaveEvent(window, mSurfacePos, mGlobalPos));
-    }
 
     invalidateFocus();
     mButtons = Qt::NoButton;
@@ -1264,9 +1269,13 @@ void QWaylandInputDevice::Touch::touch_down(uint32_t serial,
     if (!surface)
         return;
 
+    auto *window = QWaylandWindow::fromWlSurface(surface);
+    if (!window)
+        return; // Ignore foreign surfaces
+
     mParent->mTime = time;
     mParent->mSerial = serial;
-    mFocus = QWaylandWindow::fromWlSurface(surface);
+    mFocus = window;
     mParent->mQDisplay->setLastInputDevice(mParent, serial, mFocus);
     mParent->handleTouchPoint(id, wl_fixed_to_double(x), wl_fixed_to_double(y), Qt::TouchPointPressed);
 }