Check cast instance refcount before attaching

src/core/main.c

@@ -78,14 +78,14 @@ int main(int argc, char *argv[]) {
 		logprint(ERROR, "dbus: failed to connect to user bus: %s", strerror(-ret));
 		goto error;
 	}
-	logprint(TRACE, "dbus: connected");
+	logprint(DEBUG, "dbus: connected");
 
 	struct wl_display *wl_display = wl_display_connect(NULL);
 	if (!wl_display) {
 		logprint(ERROR, "wayland: failed to connect to display");
 		goto error;
 	}
-	logprint(TRACE, "wlroots: wl_display connected");
+	logprint(DEBUG, "wlroots: wl_display connected");
 
 	pw_init(NULL, NULL);
 	struct pw_loop *pw_loop = pw_loop_new(NULL);
@@ -93,7 +93,7 @@ int main(int argc, char *argv[]) {
 		logprint(ERROR, "pipewire: failed to create loop");
 		goto error;
 	}
-	logprint(TRACE, "pipewire: pw_loop created");
+	logprint(DEBUG, "pipewire: pw_loop created");
 
 	struct xdpw_state state = {
 		.bus = bus,

src/core/session.c

@@ -57,7 +57,7 @@ struct xdpw_session *xdpw_session_create(struct xdpw_state *state, sd_bus *bus,
 }
 
 void xdpw_session_destroy(struct xdpw_session *sess) {
-	logprint(TRACE, "dbus: destroying session");
+	logprint(DEBUG, "dbus: destroying session %p", sess);
 	if (!sess) {
 		return;
 	}
@@ -65,7 +65,8 @@ void xdpw_session_destroy(struct xdpw_session *sess) {
 	if (cast) {
 		assert(cast->refcount > 0);
 		--cast->refcount;
-		logprint(INFO, "xdpw: screencast instance %p has %d references", cast, cast->refcount);
+		logprint(DEBUG, "xdpw: screencast instance %p now has %d references",
+			cast, cast->refcount);
 		if (cast->refcount < 1) {
 			cast->quit = true;
 		}

src/screencast/pipewire_screencast.c

@@ -161,7 +161,7 @@ void xdpw_pwr_stream_init(struct xdpw_screencast_instance *cast) {
 	/* make an event to signal frame ready */
 	cast->event =
 		pw_loop_add_event(state->pw_loop, pwr_on_event, cast);
-	logprint(TRACE, "pipewire: registered event %p", cast->event);
+	logprint(DEBUG, "pipewire: registered event %p", cast->event);
 
 	params[0] = spa_pod_builder_add_object(&b,
 		SPA_TYPE_OBJECT_Format, SPA_PARAM_EnumFormat,
@@ -194,7 +194,7 @@ void xdpw_pwr_stream_init(struct xdpw_screencast_instance *cast) {
 int xdpw_pwr_core_connect(struct xdpw_state *state) {
 	struct xdpw_screencast_context *ctx = &state->screencast;
 
-	logprint(TRACE, "pipewire: establishing connection to core");
+	logprint(DEBUG, "pipewire: establishing connection to core");
 
 	if (!ctx->pwr_context) {
 		ctx->pwr_context = pw_context_new(state->pw_loop, NULL, 0);
@@ -215,7 +215,7 @@ int xdpw_pwr_core_connect(struct xdpw_state *state) {
 }
 
 void xdpw_pwr_stream_destroy(struct xdpw_screencast_instance *cast) {
-	logprint(TRACE, "pipewire: destroying stream");
+	logprint(DEBUG, "pipewire: destroying stream");
 	pw_stream_flush(cast->stream, false);
 	pw_stream_disconnect(cast->stream);
 	pw_stream_destroy(cast->stream);

src/screencast/screencast.c

@@ -34,8 +34,8 @@ void xdpw_screencast_instance_init(struct xdpw_screencast_context *ctx,
 }
 
 void xdpw_screencast_instance_destroy(struct xdpw_screencast_instance *cast) {
-	assert(cast->refcount == 0);
-	logprint(TRACE, "xdpw: destroying cast instance");
+	assert(cast->refcount == 0); // Fails assert if called by screencast_finish
+	logprint(DEBUG, "xdpw: destroying cast instance");
 	wl_list_remove(&cast->link);
 	xdpw_pwr_stream_destroy(cast);
 	free(cast);
@@ -71,9 +71,17 @@ int setup_outputs(struct xdpw_screencast_context *ctx, struct xdpw_session *sess
 			cast->with_cursor ? "with" : "without");
 
 		if (cast->target_output->id == out->id && cast->with_cursor == with_cursor) {
+			if (cast->refcount == 0) {
+				logprint(DEBUG,
+					"xdpw: matching cast instance found, "
+					"but is already scheduled for destruction, skipping");
+			}
+			else {
 				sess->screencast_instance = cast;
 				++cast->refcount;
-			logprint(INFO, "xdpw: screencast instance %p has %d references", cast, cast->refcount);
+			}
+			logprint(INFO, "xdpw: screencast instance %p now has %d references",
+				cast, cast->refcount);
 		}
 	}
 
@@ -270,7 +278,7 @@ static int method_screencast_select_sources(sd_bus_message *msg, void *data,
 	ret = -1;
 	wl_list_for_each_reverse_safe(sess, tmp_s, &state->xdpw_sessions, link) {
 		if (strcmp(sess->session_handle, session_handle) == 0) {
-				logprint(TRACE, "dbus: select sources: found matching session %s", sess->session_handle);
+				logprint(DEBUG, "dbus: select sources: found matching session %s", sess->session_handle);
 				ret = setup_outputs(ctx, sess, cursor_embedded);
 		}
 	}
@@ -296,7 +304,7 @@ static int method_screencast_select_sources(sd_bus_message *msg, void *data,
 error:
 	wl_list_for_each_reverse_safe(sess, tmp_s, &state->xdpw_sessions, link) {
 		if (strcmp(sess->session_handle, session_handle) == 0) {
-				logprint(TRACE, "dbus: select sources error: destroying matching session %s", sess->session_handle);
+				logprint(DEBUG, "dbus: select sources error: destroying matching session %s", sess->session_handle);
 				xdpw_session_destroy(sess);
 		}
 	}
@@ -366,7 +374,7 @@ static int method_screencast_start(sd_bus_message *msg, void *data,
 	struct xdpw_session *sess, *tmp_s;
 	wl_list_for_each_reverse_safe(sess, tmp_s, &state->xdpw_sessions, link) {
 		if (strcmp(sess->session_handle, session_handle) == 0) {
-				logprint(TRACE, "dbus: start: found matching session %s", sess->session_handle);
+				logprint(DEBUG, "dbus: start: found matching session %s", sess->session_handle);
 				cast = sess->screencast_instance;
 		}
 	}
@@ -453,6 +461,7 @@ int xdpw_screencast_init(struct xdpw_state *state, const char *output_name, cons
 		screencast_vtable, state);
 
 end:
+	// TODO: clean up pipewire
 	xdpw_wlr_screencopy_finish(&state->screencast);
 	return err;
 }

src/screencast/wlr_screencast.c

@@ -32,6 +32,9 @@ void xdpw_wlr_frame_free(struct xdpw_screencast_instance *cast) {
 	logprint(TRACE, "wlroots: frame destroyed");
 
 	if (cast->quit || cast->err) {
+		// TODO: revisit the exit condition (remove quit?)
+		// and clean up sessions that still exist if err
+		// is the cause of the instance_destroy call
 		xdpw_screencast_instance_destroy(cast);
 		return ;
 	}
@@ -342,14 +345,14 @@ int xdpw_wlr_screencopy_init(struct xdpw_state *state) {
 	wl_display_dispatch(state->wl_display);
 	wl_display_roundtrip(state->wl_display);
 
-	logprint(TRACE, "wayland: registry listeners run");
+	logprint(DEBUG, "wayland: registry listeners run");
 
 	wlr_init_xdg_outputs(ctx);
 
 	wl_display_dispatch(state->wl_display);
 	wl_display_roundtrip(state->wl_display);
 
-	logprint(TRACE, "wayland: xdg output listeners run");
+	logprint(DEBUG, "wayland: xdg output listeners run");
 
 	// make sure our wlroots supports shm protocol
 	if (!ctx->shm) {