util: add wlr_output_destroy_safe

This adds a generic helper to destory transient globals.

See [1]. This patch depends on [2] and [3].

[1]: https://gitlab.freedesktop.org/wayland/wayland/issues/10
[2]: https://gitlab.freedesktop.org/wayland/wayland/merge_requests/28
[3]: https://gitlab.freedesktop.org/wayland/wayland/merge_requests/30

1 files changed, 43 insertions, 0 deletions

diff --git a/util/global.c b/util/global.c
new file mode 100644
index 00000000..a0d84ed3
--- /dev/null
+++ b/util/global.c
@@ -0,0 +1,43 @@
+#include <stdlib.h>
+#include "util/global.h"
+
+struct destroy_global_data {
+	struct wl_global *global;
+	struct wl_event_source *event_source;
+};
+
+static int destroy_global(void *_data) {
+	struct destroy_global_data *data = _data;
+	wl_global_destroy(data->global);
+	wl_event_source_remove(data->event_source);
+	free(data);
+	return 0;
+}
+
+void wlr_global_destroy_safe(struct wl_global *global,
+		struct wl_display *display) {
+	// Don't destroy the global immediately. If the global has been created
+	// recently, clients might try to bind to it after we've destroyed it.
+	// Instead, remove the global so that clients stop seeing it and wait an
+	// arbitrary amount of time before destroying the global as a workaround.
+	// See: https://gitlab.freedesktop.org/wayland/wayland/issues/10
+
+	wl_global_remove(global);
+	wl_global_set_user_data(global, NULL); // safety net
+
+	struct wl_event_loop *event_loop = wl_display_get_event_loop(display);
+	struct destroy_global_data *data = calloc(1, sizeof(*data));
+	if (data == NULL) {
+		wl_global_destroy(global);
+		return;
+	}
+	data->global = global;
+	data->event_source =
+		wl_event_loop_add_timer(event_loop, destroy_global, data);
+	if (data->event_source == NULL) {
+		free(data);
+		wl_global_destroy(global);
+		return;
+	}
+	wl_event_source_timer_update(data->event_source, 5000);
+}