[gtk/event-source-device: 3/3] events: Enforce that source device must be a slave

[Matthias Clasen <matthiasc src gnome org>]

commit 391472870fdc86bead198b5a845a1c4f3e8e57c7
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue May 19 15:59:15 2020 -0400

    events: Enforce that source device must be a slave
    
    We were allowing backends too much leeway to create
    nonsense events. Enforce that the device is NULL or
    a master device, and the source device is NULL or a
    slave device.

 gdk/gdkevents.c | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/gdk/gdkevents.c b/gdk/gdkevents.c
index 5495d5e6ca..a89adcbb2f 100644
--- a/gdk/gdkevents.c
+++ b/gdk/gdkevents.c
@@ -416,6 +416,11 @@ gdk_event_alloc (GdkEventType event_type,
   g_assert (event_type >= GDK_DELETE && event_type < GDK_EVENT_LAST);
   g_assert (gdk_event_types[event_type] != G_TYPE_INVALID);
 
+  g_assert (device == NULL ||
+            gdk_device_get_device_type (device) == GDK_DEVICE_TYPE_MASTER);
+  g_assert (source_device == NULL ||
+            gdk_device_get_device_type (source_device) == GDK_DEVICE_TYPE_SLAVE);
+
   GdkEvent *event = (GdkEvent *) g_type_create_instance (gdk_event_types[event_type]);
 
   GDK_NOTE (EVENTS, {