Unify signal handling under wl_event_loop

Merge our signal handlers into a single function and let Wayland deal
with all the struct sigaction stuff.

ΔSLOC: -3

dwl.c

@@ -260,6 +260,7 @@ static void focusmon(const Arg *arg);
 static void focusstack(const Arg *arg);
 static Client *focustop(Monitor *m);
 static void fullscreennotify(struct wl_listener *listener, void *data);
+static int handlesig(int signo, void *data);
 static void incnmaster(const Arg *arg);
 static void inputdevice(struct wl_listener *listener, void *data);
 static int keybinding(uint32_t mods, xkb_keysym_t sym);
@@ -283,7 +284,6 @@ static void pointerfocus(Client *c, struct wlr_surface *surface,
 		double sx, double sy, uint32_t time);
 static void printstatus(void);
 static void quit(const Arg *arg);
-static void quitsignal(int signo);
 static void rendermon(struct wl_listener *listener, void *data);
 static void requeststartdrag(struct wl_listener *listener, void *data);
 static void resize(Client *c, struct wlr_box geo, int interact);
@@ -297,7 +297,6 @@ static void setmon(Client *c, Monitor *m, uint32_t newtags);
 static void setpsel(struct wl_listener *listener, void *data);
 static void setsel(struct wl_listener *listener, void *data);
 static void setup(void);
-static void sigchld(int unused);
 static void spawn(const Arg *arg);
 static void startdrag(struct wl_listener *listener, void *data);
 static void tag(const Arg *arg);
@@ -327,6 +326,8 @@ static pid_t child_pid = -1;
 static int locked;
 static void *exclusive_focus;
 static struct wl_display *dpy;
+static struct wl_event_loop *eventloop;
+static struct wl_event_source *sighandler[4];
 static struct wlr_backend *backend;
 static struct wlr_scene *scene;
 static struct wlr_scene_tree *layers[NUM_LAYERS];
@@ -652,6 +653,7 @@ checkidleinhibitor(struct wlr_surface *exclude)
 void
 cleanup(void)
 {
+	int i;
 #ifdef XWAYLAND
 	wlr_xwayland_destroy(xwayland);
 #endif
@@ -667,6 +669,8 @@ cleanup(void)
 	wlr_cursor_destroy(cursor);
 	wlr_output_layout_destroy(output_layout);
 	wlr_seat_destroy(seat);
+	for (i = 0; i < LENGTH(sighandler); i++)
+		wl_event_source_remove(sighandler[i]);
 	wl_display_destroy(dpy);
 }
 
@@ -820,8 +824,7 @@ createkeyboard(struct wlr_keyboard *keyboard)
 
 	wlr_seat_set_keyboard(seat, keyboard);
 
-	kb->key_repeat_source = wl_event_loop_add_timer(
-			wl_display_get_event_loop(dpy), keyrepeat, kb);
+	kb->key_repeat_source = wl_event_loop_add_timer(eventloop, keyrepeat, kb);
 
 	/* And add the keyboard to our list of keyboards */
 	wl_list_insert(&keyboards, &kb->link);
@@ -1333,6 +1336,28 @@ fullscreennotify(struct wl_listener *listener, void *data)
 	setfullscreen(c, client_wants_fullscreen(c));
 }
 
+int
+handlesig(int signo, void *data)
+{
+	if (signo == SIGCHLD) {
+#ifdef XWAYLAND
+		siginfo_t in;
+		/* wlroots expects to reap the XWayland process itself, so we
+		 * use WNOWAIT to keep the child waitable until we know it's not
+		 * XWayland.
+		 */
+		while (!waitid(P_ALL, 0, &in, WEXITED|WNOHANG|WNOWAIT) && in.si_pid
+				&& (!xwayland || in.si_pid != xwayland->server->pid))
+			waitpid(in.si_pid, NULL, 0);
+#else
+		while (waitpid(-1, NULL, WNOHANG) > 0);
+#endif
+	} else if (signo == SIGINT || signo == SIGTERM) {
+		quit(NULL);
+	}
+	return 0;
+}
+
 void
 incnmaster(const Arg *arg)
 {
@@ -1875,12 +1900,6 @@ quit(const Arg *arg)
 	wl_display_terminate(dpy);
 }
 
-void
-quitsignal(int signo)
-{
-	quit(NULL);
-}
-
 void
 rendermon(struct wl_listener *listener, void *data)
 {
@@ -1944,8 +1963,6 @@ run(char *startup_cmd)
 {
 	/* Add a Unix socket to the Wayland display. */
 	const char *socket = wl_display_add_socket_auto(dpy);
-	struct sigaction sa = {.sa_flags = SA_RESTART, .sa_handler = SIG_IGN};
-	sigemptyset(&sa.sa_mask);
 	if (!socket)
 		die("startup: display_add_socket_auto");
 	setenv("WAYLAND_DISPLAY", socket, 1);
@@ -1973,8 +1990,6 @@ run(char *startup_cmd)
 		close(piperw[1]);
 		close(piperw[0]);
 	}
-	/* If nobody is reading the status output, don't terminate */
-	sigaction(SIGPIPE, &sa, NULL);
 	printstatus();
 
 	/* At this point the outputs are initialized, choose initial selmon based on
@@ -2127,20 +2142,14 @@ setsel(struct wl_listener *listener, void *data)
 void
 setup(void)
 {
-	int layer;
-
-	/* Set up signal handlers */
-	struct sigaction sa = {.sa_flags = SA_RESTART, .sa_handler = sigchld};
-	sigemptyset(&sa.sa_mask);
-	sigaction(SIGCHLD, &sa, NULL);
-
-	sa.sa_handler = quitsignal;
-	sigaction(SIGINT, &sa, NULL);
-	sigaction(SIGTERM, &sa, NULL);
+	int i, sig[] = {SIGCHLD, SIGINT, SIGTERM, SIGPIPE};
 
 	/* The Wayland display is managed by libwayland. It handles accepting
 	 * clients from the Unix socket, manging Wayland globals, and so on. */
 	dpy = wl_display_create();
+	eventloop = wl_display_get_event_loop(dpy);
+	for (i = 0; i < LENGTH(sighandler); i++)
+		sighandler[i] = wl_event_loop_add_signal(eventloop, sig[i], handlesig, NULL);
 
 	/* The backend is a wlroots feature which abstracts the underlying input and
 	 * output hardware. The autocreate option will choose the most suitable
@@ -2155,8 +2164,8 @@ setup(void)
 
 	/* Initialize the scene graph used to lay out windows */
 	scene = wlr_scene_create();
-	for (layer = 0; layer < NUM_LAYERS; layer++)
-		layers[layer] = wlr_scene_tree_create(&scene->tree);
+	for (i = 0; i < NUM_LAYERS; i++)
+		layers[i] = wlr_scene_tree_create(&scene->tree);
 
 	/* Create a renderer with the default implementation */
 	if (!(drw = wlr_renderer_autocreate(backend)))
@@ -2308,28 +2317,6 @@ setup(void)
 #endif
 }
 
-void
-sigchld(int unused)
-{
-#ifdef XWAYLAND
-	siginfo_t in;
-	/* We should be able to remove this function in favor of a simple
-	 *	struct sigaction sa = {.sa_handler = SIG_IGN};
-	 * 	sigaction(SIGCHLD, &sa, NULL);
-	 * but the Xwayland implementation in wlroots currently prevents us from
-	 * setting our own disposition for SIGCHLD.
-	 */
-	/* WNOWAIT leaves the child in a waitable state, in case this is the
-	 * XWayland process
-	 */
-	while (!waitid(P_ALL, 0, &in, WEXITED|WNOHANG|WNOWAIT) && in.si_pid
-			&& (!xwayland || in.si_pid != xwayland->server->pid))
-		waitpid(in.si_pid, NULL, 0);
-#else
-	while (waitpid(-1, NULL, WNOHANG) > 0);
-#endif
-}
-
 void
 spawn(const Arg *arg)
 {