apply autostart patch from dwm

https://dwm.suckless.org/patches/cool_autostart/

config.def.h

@@ -93,6 +93,12 @@ LIBINPUT_CONFIG_ACCEL_PROFILE_ADAPTIVE
 static const enum libinput_config_accel_profile accel_profile = LIBINPUT_CONFIG_ACCEL_PROFILE_ADAPTIVE;
 static const double accel_speed = 0.0;
 
+/* Autostart */
+static const char *const autostart[] = {
+        "sh", "-c", "swaybg --image /xap/local/background", NULL,
+        NULL /* terminate */
+};
+
 /* If you want to use the windows key change this to WLR_MODIFIER_LOGO */
 #define MODKEY WLR_MODIFIER_ALT
 #define TAGKEYS(KEY,SKEY,TAG) \

dwl.c

@@ -232,6 +232,7 @@ static void arrange(Monitor *m);
 static void arrangelayer(Monitor *m, struct wl_list *list,
 		struct wlr_box *usable_area, int exclusive);
 static void arrangelayers(Monitor *m);
+static void autostartexec(void);
 static void axisnotify(struct wl_listener *listener, void *data);
 static void buttonpress(struct wl_listener *listener, void *data);
 static void checkconstraintregion(void);
@@ -419,6 +420,9 @@ static Atom netatom[NetLast];
 /* compile-time check if all tags fit into an unsigned int bit array. */
 struct NumTags { char limitexceeded[LENGTH(tags) > 31 ? -1 : 1]; };
 
+static pid_t *autostart_pids;
+static size_t autostart_len;
+
 /* function implementations */
 void
 applybounds(Client *c, struct wlr_box *bbox)
@@ -447,6 +451,29 @@ applybounds(Client *c, struct wlr_box *bbox)
 		c->geom.y = bbox->y;
 }
 
+void
+autostartexec(void) {
+	const char *const *p;
+	size_t i = 0;
+
+	/* count entries */
+	for (p = autostart; *p; autostart_len++, p++)
+		while (*++p);
+
+	autostart_pids = calloc(autostart_len, sizeof(pid_t));
+	for (p = autostart; *p; i++, p++) {
+		if ((autostart_pids[i] = fork()) == 0) {
+			setsid();
+			execvp(*p, (char *const *)p);
+			fprintf(stderr, "dwl: execvp %s\n", *p);
+			perror(" failed");
+			_exit(EXIT_FAILURE);
+		}
+		/* skip arguments */
+		while (*++p);
+	}
+}
+
 void
 applyexclusive(struct wlr_box *usable_area,
 		uint32_t anchor, int32_t exclusive,
@@ -2067,6 +2094,16 @@ printstatus(void)
 void
 quit(const Arg *arg)
 {
+	size_t i;
+
+	/* kill child processes */
+	for (i = 0; i < autostart_len; i++) {
+		if (0 < autostart_pids[i]) {
+			kill(autostart_pids[i], SIGTERM);
+			waitpid(autostart_pids[i], NULL, 0);
+		}
+	}
+
 	wl_display_terminate(dpy);
 }
 
@@ -2162,6 +2199,7 @@ run(char *startup_cmd)
 		die("startup: backend_start");
 
 	/* Now that the socket exists and the backend is started, run the startup command */
+	autostartexec();
 	if (startup_cmd) {
 		int piperw[2];
 		if (pipe(piperw) < 0)
@@ -2551,11 +2589,24 @@ sigchld(int unused)
 	 * setting our own disposition for SIGCHLD.
 	 */
 	pid_t pid;
+
 	if (signal(SIGCHLD, sigchld) == SIG_ERR)
 		die("can't install SIGCHLD handler:");
-	while (0 < (pid = waitpid(-1, NULL, WNOHANG)))
+	while (0 < (pid = waitpid(-1, NULL, WNOHANG))) {
+		pid_t *p, *lim;
 		if (pid == child_pid)
 			child_pid = -1;
+		if (!(p = autostart_pids))
+			continue;
+		lim = &p[autostart_len];
+
+		for (; p < lim; p++) {
+			if (*p == pid) {
+				*p = -1;
+				break;
+			}
+		}
+	}
 }
 
 void