layers: ignore destroyed layers

Fixes: #2858

src/debug.c

@@ -124,6 +124,9 @@ get_special(struct server *server, struct wlr_scene_node *node)
 				return "output->layer_popup_tree";
 			}
 			for (int i = 0; i < 4; i++) {
+				if (!output->layer_tree[i]) {
+					continue;
+				}
 				if (node == &output->layer_tree[i]->node) {
 					return get_layer_name(i);
 				}

src/desktop.c

@@ -215,7 +215,9 @@ desktop_update_top_layer_visibility(struct server *server)
 		if (!output_is_usable(output)) {
 			continue;
 		}
-		wlr_scene_node_set_enabled(&output->layer_tree[top]->node, true);
+		if (output->layer_tree[top]) {
+			wlr_scene_node_set_enabled(&output->layer_tree[top]->node, true);
+		}
 	}
 
 	/*
@@ -231,8 +233,10 @@ desktop_update_top_layer_visibility(struct server *server)
 			continue;
 		}
 		if (view->fullscreen && !(view->outputs & outputs_covered)) {
-			wlr_scene_node_set_enabled(
+			if (output->layer_tree[top]) {
-				&view->output->layer_tree[top]->node, false);
+				wlr_scene_node_set_enabled(
+					&view->output->layer_tree[top]->node, false);
+			}
 		}
 		outputs_covered |= view->outputs;
 	}

src/layers.c

@@ -43,6 +43,8 @@ static void
 arrange_one_layer(const struct wlr_box *full_area, struct wlr_box *usable_area,
 		struct wlr_scene_tree *tree, bool exclusive)
 {
+	assert(tree);
+
 	struct wlr_scene_node *node;
 	wl_list_for_each(node, &tree->children, link) {
 		/*
@@ -90,6 +92,10 @@ layers_arrange(struct output *output)
 
 	for (int i = ARRAY_SIZE(output->layer_tree) - 1; i >= 0; i--) {
 		struct wlr_scene_tree *layer = output->layer_tree[i];
+		if (!layer) {
+			/* Might happen on output destroy */
+			continue;
+		}
 
 		/*
 		 * Process exclusive-zone clients before non-exclusive-zone
@@ -110,6 +116,10 @@ layers_arrange(struct output *output)
 
 	for (size_t i = 0; i < ARRAY_SIZE(output->layer_tree); i++) {
 		struct wlr_scene_tree *layer = output->layer_tree[i];
+		if (!layer) {
+			/* Might happen on output destroy */
+			continue;
+		}
 		arrange_one_layer(&full_area, &usable_area, layer, /* exclusive */ false);
 
 		/* Set node position to account for output layout change */
@@ -156,6 +166,10 @@ try_to_focus_next_layer_or_toplevel(struct server *server)
 	enum zwlr_layer_shell_v1_layer top = ZWLR_LAYER_SHELL_V1_LAYER_TOP;
 	for (size_t i = overlay; i >= top; i--) {
 		struct wlr_scene_tree *tree = output->layer_tree[i];
+		if (!tree) {
+			/* Might happen on output destroy */
+			continue;
+		}
 		struct wlr_scene_node *node;
 		/*
 		 * In wlr_scene.c they were added at end of list so we
@@ -270,8 +284,11 @@ handle_surface_commit(struct wl_listener *listener, void *data)
 
 	/* Process layer change */
 	if (committed & WLR_LAYER_SURFACE_V1_STATE_LAYER) {
-		wlr_scene_node_reparent(&layer->scene_layer_surface->tree->node,
+		if (output->layer_tree[layer_surface->current.layer]) {
-			output->layer_tree[layer_surface->current.layer]);
+			/* Might happen on output destroy */
+			wlr_scene_node_reparent(&layer->scene_layer_surface->tree->node,
+				output->layer_tree[layer_surface->current.layer]);
+		}
 	}
 	/* Process keyboard-interactivity change */
 	if (committed & WLR_LAYER_SURFACE_V1_STATE_KEYBOARD_INTERACTIVITY) {
@@ -597,6 +614,11 @@ handle_new_layer_surface(struct wl_listener *listener, void *data)
 
 	struct wlr_scene_tree *selected_layer =
 		output->layer_tree[layer_surface->current.layer];
+	if (!selected_layer) {
+		wlr_layer_surface_v1_destroy(layer_surface);
+		wlr_log(WLR_ERROR, "Targeted output by layer surface destroyed");
+		return;
+	}
 
 	surface->scene_layer_surface = wlr_scene_layer_surface_v1_create(
 		selected_layer, layer_surface);

src/output.c

@@ -175,6 +175,7 @@ output_destroy_notify(struct wl_listener *listener, void *data)
 
 	for (size_t i = 0; i < ARRAY_SIZE(output->layer_tree); i++) {
 		wlr_scene_node_destroy(&output->layer_tree[i]->node);
+		output->layer_tree[i] = NULL;
 	}
 	wlr_scene_node_destroy(&output->layer_popup_tree->node);
 	wlr_scene_node_destroy(&output->osd_tree->node);