backend: introduce wlr_backend_finish

This new functions cleans up the common backend state. While this
currently only emits the destroy signal, this will also clean up
the renderer and allocator in upcoming patches.

backend/backend.c

@@ -18,6 +18,7 @@
 #include <wlr/util/log.h>
 #include "backend/backend.h"
 #include "backend/multi.h"
+#include "util/signal.h"
 
 #if WLR_HAS_X11_BACKEND
 #include <wlr/backend/x11.h>
@@ -32,6 +33,10 @@ void wlr_backend_init(struct wlr_backend *backend,
 	wl_signal_init(&backend->events.new_output);
 }
 
+void wlr_backend_finish(struct wlr_backend *backend) {
+	wlr_signal_emit_safe(&backend->events.destroy, backend);
+}
+
 bool wlr_backend_start(struct wlr_backend *backend) {
 	if (backend->impl->start) {
 		return backend->impl->start(backend);

backend/drm/backend.c

@@ -41,7 +41,7 @@ static void backend_destroy(struct wlr_backend *backend) {
 		destroy_drm_connector(conn);
 	}
 
-	wlr_signal_emit_safe(&backend->events.destroy, backend);
+	wlr_backend_finish(backend);
 
 	struct wlr_drm_fb *fb, *fb_tmp;
 	wl_list_for_each_safe(fb, fb_tmp, &drm->fbs, link) {

backend/headless/backend.c

@@ -67,7 +67,7 @@ static void backend_destroy(struct wlr_backend *wlr_backend) {
 		wlr_input_device_destroy(&input_device->wlr_input_device);
 	}
 
-	wlr_signal_emit_safe(&wlr_backend->events.destroy, backend);
+	wlr_backend_finish(wlr_backend);
 
 	free(backend->format);
 

backend/libinput/backend.c

@@ -150,7 +150,7 @@ static void backend_destroy(struct wlr_backend *wlr_backend) {
 		free(wlr_devices);
 	}
 
-	wlr_signal_emit_safe(&wlr_backend->events.destroy, wlr_backend);
+	wlr_backend_finish(wlr_backend);
 
 	wl_list_remove(&backend->display_destroy.link);
 	wl_list_remove(&backend->session_destroy.link);

backend/multi/backend.c

@@ -58,7 +58,7 @@ static void multi_backend_destroy(struct wlr_backend *wlr_backend) {
 	}
 
 	// Destroy this backend only after removing all sub-backends
-	wlr_signal_emit_safe(&wlr_backend->events.destroy, backend);
+	wlr_backend_finish(wlr_backend);
 	free(backend);
 }
 

backend/noop/backend.c

@@ -37,7 +37,7 @@ static void backend_destroy(struct wlr_backend *wlr_backend) {
 		wlr_output_destroy(&output->wlr_output);
 	}
 
-	wlr_signal_emit_safe(&wlr_backend->events.destroy, backend);
+	wlr_backend_finish(wlr_backend);
 
 	wl_list_remove(&backend->display_destroy.link);
 

backend/wayland/backend.c

@@ -309,7 +309,7 @@ static void backend_destroy(struct wlr_backend *backend) {
 		wlr_input_device_destroy(input_device);
 	}
 
-	wlr_signal_emit_safe(&wl->backend.events.destroy, &wl->backend);
+	wlr_backend_finish(backend);
 
 	wl_list_remove(&wl->local_display_destroy.link);
 

backend/x11/backend.c

@@ -191,7 +191,7 @@ static void backend_destroy(struct wlr_backend *backend) {
 
 	wlr_input_device_destroy(&x11->keyboard_dev);
 
-	wlr_signal_emit_safe(&backend->events.destroy, backend);
+	wlr_backend_finish(backend);
 
 	if (x11->event_source) {
 		wl_event_source_remove(x11->event_source);

include/wlr/backend/interface.h

@@ -29,5 +29,9 @@ struct wlr_backend_impl {
  */
 void wlr_backend_init(struct wlr_backend *backend,
 		const struct wlr_backend_impl *impl);
+/**
+ * Emit the destroy event and clean up common backend state.
+ */
+void wlr_backend_finish(struct wlr_backend *backend);
 
 #endif