backends/native: Seal MetaKeymapNative xkb usage

Don't let the vfuncs (meant to be called from the UI thread) deal with
xkb state itself. Instead store the current state in struct fields, which
is then fetched in vfuncs.

This makes the keymap able to be used from the UI thread, while being
maintained by the input thread. Same caveats apply than
clutter_seat_query_state(), you are asking for the most up-to-date state,
but it still may be changing under your feet.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>

3 files changed, 31 insertions, 18 deletions

diff --git a/src/backends/native/meta-keymap-native.c b/src/backends/native/meta-keymap-native.c
index d19903532..ee56443b5 100644
--- a/src/backends/native/meta-keymap-native.c
+++ b/src/backends/native/meta-keymap-native.c
@@ -36,6 +36,8 @@ struct _MetaKeymapNative
   ClutterKeymap parent_instance;
 
   struct xkb_keymap *keymap;
+  gboolean num_lock;
+  gboolean caps_lock;
 };
 
 G_DEFINE_TYPE (MetaKeymapNative, meta_keymap_native,
@@ -54,31 +56,17 @@ meta_keymap_native_finalize (GObject *object)
 static gboolean
 meta_keymap_native_get_num_lock_state (ClutterKeymap *keymap)
 {
-  struct xkb_state *xkb_state;
-  ClutterSeat *seat;
-
-  seat = clutter_backend_get_default_seat (clutter_get_default_backend ());
-  xkb_state = meta_seat_impl_get_xkb_state (META_SEAT_NATIVE (seat)->impl);
+  MetaKeymapNative *keymap_native = META_KEYMAP_NATIVE (keymap);
 
-  return xkb_state_mod_name_is_active (xkb_state,
-                                       XKB_MOD_NAME_NUM,
-                                       XKB_STATE_MODS_LATCHED |
-                                       XKB_STATE_MODS_LOCKED);
+  return keymap_native->num_lock;
 }
 
 static gboolean
 meta_keymap_native_get_caps_lock_state (ClutterKeymap *keymap)
 {
-  struct xkb_state *xkb_state;
-  ClutterSeat *seat;
-
-  seat = clutter_backend_get_default_seat (clutter_get_default_backend ());
-  xkb_state = meta_seat_impl_get_xkb_state (META_SEAT_NATIVE (seat)->impl);
+  MetaKeymapNative *keymap_native = META_KEYMAP_NATIVE (keymap);
 
-  return xkb_state_mod_name_is_active (xkb_state,
-                                       XKB_MOD_NAME_CAPS,
-                                       XKB_STATE_MODS_LATCHED |
-                                       XKB_STATE_MODS_LOCKED);
+  return keymap_native->caps_lock;
 }
 
 static PangoDirection
@@ -134,3 +122,24 @@ meta_keymap_native_get_keyboard_map (MetaKeymapNative *keymap)
 {
   return keymap->keymap;
 }
+
+void
+meta_keymap_native_update (MetaKeymapNative *keymap)
+{
+  struct xkb_state *xkb_state;
+  ClutterSeat *seat;
+
+  seat = clutter_backend_get_default_seat (clutter_get_default_backend ());
+  xkb_state = meta_seat_impl_get_xkb_state (META_SEAT_NATIVE (seat)->impl);
+
+  keymap->num_lock =
+    xkb_state_mod_name_is_active (xkb_state,
+                                  XKB_MOD_NAME_NUM,
+                                  XKB_STATE_MODS_LATCHED |
+                                  XKB_STATE_MODS_LOCKED);
+  keymap->caps_lock =
+    xkb_state_mod_name_is_active (xkb_state,
+                                  XKB_MOD_NAME_CAPS,
+                                  XKB_STATE_MODS_LATCHED |
+                                  XKB_STATE_MODS_LOCKED);
+}
diff --git a/src/backends/native/meta-keymap-native.h b/src/backends/native/meta-keymap-native.h
index 27364984c..8b276df5d 100644
--- a/src/backends/native/meta-keymap-native.h
+++ b/src/backends/native/meta-keymap-native.h
@@ -32,5 +32,6 @@ G_DECLARE_FINAL_TYPE (MetaKeymapNative, meta_keymap_native,
 void                meta_keymap_native_set_keyboard_map (MetaKeymapNative  *keymap,
                                                          struct xkb_keymap *xkb_keymap);
 struct xkb_keymap * meta_keymap_native_get_keyboard_map (MetaKeymapNative *keymap);
+void                meta_keymap_native_update           (MetaKeymapNative *keymap);
 
 #endif /* META_KEYMAP_NATIVE_H */
diff --git a/src/backends/native/meta-seat-impl.c b/src/backends/native/meta-seat-impl.c
index 323222312..d7cdd8243 100644
--- a/src/backends/native/meta-seat-impl.c
+++ b/src/backends/native/meta-seat-impl.c
@@ -2855,6 +2855,7 @@ meta_seat_impl_update_xkb_state (MetaSeatImpl *seat_impl)
     xkb_keymap_led_get_index (xkb_keymap, XKB_LED_NAME_SCROLL);
 
   meta_seat_impl_sync_leds (seat_impl);
+  meta_keymap_native_update (seat_impl->keymap);
 
   g_rw_lock_writer_unlock (&seat_impl->state_lock);
 }
@@ -2981,6 +2982,7 @@ meta_seat_impl_set_keyboard_layout_index (MetaSeatImpl       *seat_impl,
   locked_mods = xkb_state_serialize_mods (state, XKB_STATE_MODS_LOCKED);
 
   xkb_state_update_mask (state, depressed_mods, latched_mods, locked_mods, 0, 0, idx);
+  meta_keymap_native_update (seat_impl->keymap);
 
   seat_impl->layout_idx = idx;
 
@@ -3046,6 +3048,7 @@ meta_seat_impl_set_keyboard_numlock (MetaSeatImpl *seat_impl,
                          group_mods);
 
   meta_seat_impl_sync_leds (seat_impl);
+  meta_keymap_native_update (seat_impl->keymap);
 
   g_rw_lock_writer_unlock (&seat_impl->state_lock);
 }