wayland: Set compositor when creating MetaWaylandDataSourceXWayland

create_and_send_dnd_offer() sets the compositor of the offer to the one
from the MetaWaylandDataSource. This then later gets used in
display_from_offer() when trying to get the context from the compositor.
meta_wayland_data_source_xwayland_new() however was not setting the
compositor, so this was causing crashes when dragging things from X11
windows on Wayland.

Fixes: 2731f0cda ("wayland: Setup and use ownership chains")
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2723
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2956>

2 files changed, 77 insertions, 9 deletions

diff --git a/src/wayland/meta-wayland-data-source.c b/src/wayland/meta-wayland-data-source.c
index 7a781982b..d4d9520d6 100644
--- a/src/wayland/meta-wayland-data-source.c
+++ b/src/wayland/meta-wayland-data-source.c
@@ -49,6 +49,17 @@ typedef struct _MetaWaylandDataSourcePrivate
   guint drop_performed : 1;
 } MetaWaylandDataSourcePrivate;
 
+enum
+{
+  PROP_0,
+
+  PROP_COMPOSITOR,
+
+  N_PROPS
+};
+
+static GParamSpec *props[N_PROPS] = { 0 };
+
 G_DEFINE_TYPE_WITH_PRIVATE (MetaWaylandDataSource, meta_wayland_data_source,
                             G_TYPE_OBJECT);
 
@@ -146,6 +157,46 @@ meta_wayland_data_source_finalize (GObject *object)
 }
 
 static void
+meta_wayland_data_source_set_property (GObject      *object,
+                                       guint         prop_id,
+                                       const GValue *value,
+                                       GParamSpec   *pspec)
+{
+  MetaWaylandDataSource *source = META_WAYLAND_DATA_SOURCE (object);
+  MetaWaylandDataSourcePrivate *priv =
+    meta_wayland_data_source_get_instance_private (source);
+
+  switch (prop_id)
+    {
+    case PROP_COMPOSITOR:
+      priv->compositor = g_value_get_object (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+meta_wayland_data_source_get_property (GObject    *object,
+                                       guint       prop_id,
+                                       GValue     *value,
+                                       GParamSpec *pspec)
+{
+  MetaWaylandDataSource *source = META_WAYLAND_DATA_SOURCE (object);
+  MetaWaylandDataSourcePrivate *priv =
+    meta_wayland_data_source_get_instance_private (source);
+
+  switch (prop_id)
+    {
+    case PROP_COMPOSITOR:
+      g_value_set_pointer (value, priv->compositor);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
 meta_wayland_data_source_init (MetaWaylandDataSource *source)
 {
   MetaWaylandDataSourcePrivate *priv =
@@ -162,6 +213,8 @@ meta_wayland_data_source_class_init (MetaWaylandDataSourceClass *klass)
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
   object_class->finalize = meta_wayland_data_source_finalize;
+  object_class->set_property = meta_wayland_data_source_set_property;
+  object_class->get_property = meta_wayland_data_source_get_property;
 
   klass->send = meta_wayland_data_source_real_send;
   klass->target = meta_wayland_data_source_real_target;
@@ -169,8 +222,18 @@ meta_wayland_data_source_class_init (MetaWaylandDataSourceClass *klass)
   klass->action = meta_wayland_data_source_real_action;
   klass->drop_performed = meta_wayland_data_source_real_drop_performed;
   klass->drag_finished = meta_wayland_data_source_real_drag_finished;
-}
 
+  props[PROP_COMPOSITOR] =
+    g_param_spec_object ("compositor",
+                         "compositor",
+                         "MetaWaylandCompositor",
+                         META_TYPE_WAYLAND_COMPOSITOR,
+                         G_PARAM_READWRITE |
+                         G_PARAM_CONSTRUCT_ONLY |
+                         G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (object_class, N_PROPS, props);
+}
 
 static void
 data_source_offer (struct wl_client *client,
@@ -245,12 +308,14 @@ MetaWaylandDataSource *
 meta_wayland_data_source_new (MetaWaylandCompositor *compositor,
                               struct wl_resource    *resource)
 {
-  MetaWaylandDataSource *source =
-    g_object_new (META_TYPE_WAYLAND_DATA_SOURCE, NULL);
-  MetaWaylandDataSourcePrivate *priv =
-    meta_wayland_data_source_get_instance_private (source);
+  MetaWaylandDataSource *source;
+  MetaWaylandDataSourcePrivate *priv;
+
+  source = g_object_new (META_TYPE_WAYLAND_DATA_SOURCE,
+                         "compositor", compositor,
+                         NULL);
+  priv = meta_wayland_data_source_get_instance_private (source);
 
-  priv->compositor = compositor;
   meta_wayland_data_source_set_resource (source, resource);
   wl_resource_set_implementation (resource, &data_source_interface,
                                   source, destroy_data_source);
diff --git a/src/wayland/meta-xwayland-dnd.c b/src/wayland/meta-xwayland-dnd.c
index dc10da5bb..314880cdb 100644
--- a/src/wayland/meta-xwayland-dnd.c
+++ b/src/wayland/meta-xwayland-dnd.c
@@ -595,11 +595,14 @@ meta_wayland_data_source_xwayland_class_init (MetaWaylandDataSourceXWaylandClass
 }
 
 static MetaWaylandDataSource *
-meta_wayland_data_source_xwayland_new (MetaXWaylandDnd *dnd)
+meta_wayland_data_source_xwayland_new (MetaXWaylandDnd       *dnd,
+                                       MetaWaylandCompositor *compositor)
 {
   MetaWaylandDataSourceXWayland *source_xwayland;
 
-  source_xwayland = g_object_new (META_TYPE_WAYLAND_DATA_SOURCE_XWAYLAND, NULL);
+  source_xwayland = g_object_new (META_TYPE_WAYLAND_DATA_SOURCE_XWAYLAND,
+                                  "compositor", compositor,
+                                  NULL);
   source_xwayland->dnd = dnd;
 
   return META_WAYLAND_DATA_SOURCE (source_xwayland);
@@ -1032,7 +1035,7 @@ meta_xwayland_dnd_handle_xfixes_selection_notify (MetaWaylandCompositor *composi
   if (event->owner != None && event->owner != x11_display->selection.xwindow &&
       focus && meta_xwayland_is_xwayland_surface (focus))
     {
-      dnd->source = meta_wayland_data_source_xwayland_new (dnd);
+      dnd->source = meta_wayland_data_source_xwayland_new (dnd, compositor);
       meta_wayland_data_device_set_dnd_source (&compositor->seat->data_device,
                                                dnd->source);