initctl: fix runlevel and start/stop/restart segfault regression

Introduced in e2f6ac0.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/initctl.c

@@ -143,10 +143,9 @@ static int do_runlevel(char *arg)
 	struct init_request rq = {
 		.magic = INIT_MAGIC,
 		.cmd = INIT_CMD_RUNLVL,
-		.runlevel = (int)arg[0],
 	};
 
-	if (!rq.runlevel) {
+	if (!arg) {
 		int prevlevel = 0;
 		int runlevel;
 		char prev;
@@ -165,6 +164,9 @@ static int do_runlevel(char *arg)
 		return 0;
 	}
 
+	/* set runlevel */
+	rq.runlevel = (int)arg[0];
+
 	return client_send(&rq, sizeof(rq));
 }
 
@@ -195,6 +197,13 @@ static int do_startstop(int cmd, char *arg)
 		.cmd   = INIT_CMD_SVC_QUERY
 	};
 
+	if (!arg || !arg[0])
+		errx(1, "missing argument to %s", (cmd == INIT_CMD_START_SVC
+						   ? "start"
+						   : (cmd == INIT_CMD_STOP_SVC
+						      ? "stop"
+						      : "restart")));
+
 	strlcpy(rq.data, arg, sizeof(rq.data));
 	if (client_send(&rq, sizeof(rq))) {
 		fprintf(stderr, "No such job(s) or service(s): %s\n\n", rq.data);