#define BARF(fmt, ...)		do { fprintf(stderr, fmt "\n", ##__VA_ARGS__); exit(EXIT_FAILURE); } while (0)
#define EBARF(fmt, ...)		BARF(fmt ": %s", ##__VA_ARGS__, strerror(errno))

	if (!socket) {
		perror("startup: display_add_socket_auto");
		wlr_backend_destroy(backend);
		exit(EXIT_FAILURE);
	}

	if (!socket)
		BARF("startup: display_add_socket_auto");

	if (!wlr_backend_start(backend)) {
		perror("startup: backend_start");
		wlr_backend_destroy(backend);
		wl_display_destroy(dpy);
		exit(EXIT_FAILURE);
	}

	if (!wlr_backend_start(backend))
		BARF("startup: backend_start");

		if (startup_pid < 0) {
			perror("startup: fork");
			wl_display_destroy(dpy);
			exit(EXIT_FAILURE);
		}

		if (startup_pid < 0)
			EBARF("startup: fork");

			perror("startup: execl");
			wl_display_destroy(dpy);
			exit(EXIT_FAILURE);

			EBARF("startup: execl");

	if (signal(SIGCHLD, sigchld) == SIG_ERR) {
		perror("can't install SIGCHLD handler");
		exit(EXIT_FAILURE);
	}

	if (signal(SIGCHLD, sigchld) == SIG_ERR)
		EBARF("can't install SIGCHLD handler");

		fprintf(stderr, "dwl: execvp %s", ((char **)arg->v)[0]);
		perror(" failed");
		exit(EXIT_FAILURE);

		EBARF("dwl: execvp %s failed", ((char **)arg->v)[0]);

	if (!getenv("XDG_RUNTIME_DIR")) {
		fprintf(stderr, "XDG_RUNTIME_DIR must be set\n");
		exit(EXIT_FAILURE);
	}

	if (!getenv("XDG_RUNTIME_DIR"))
		BARF("XDG_RUNTIME_DIR must be set");