Allow hostapd to be started without interfaces

If the control interface is enabled, allow hostapd to be started
without any configuration files specific on the command line since
the interfaces can be added dynamically.

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>

hostapd/main.c

@@ -601,7 +601,7 @@ int main(int argc, char *argv[])
 		}
 	}
 
-	if (optind == argc)
+	if (optind == argc && interfaces.global_iface_path == NULL)
 		usage();
 
 	wpa_msg_register_ifname_cb(hostapd_msg_ifname_cb);
@@ -610,11 +610,13 @@ int main(int argc, char *argv[])
 		wpa_debug_open_file(log_file);
 
 	interfaces.count = argc - optind;
-	interfaces.iface = os_calloc(interfaces.count,
-				     sizeof(struct hostapd_iface *));
-	if (interfaces.iface == NULL) {
-		wpa_printf(MSG_ERROR, "malloc failed");
-		return -1;
+	if (interfaces.count) {
+		interfaces.iface = os_calloc(interfaces.count,
+					     sizeof(struct hostapd_iface *));
+		if (interfaces.iface == NULL) {
+			wpa_printf(MSG_ERROR, "malloc failed");
+			return -1;
+		}
 	}
 
 	if (hostapd_global_init(&interfaces, entropy_file))