wp need login not sub page free

functions.php

<?php

//every page need login
//not page of /free
//http://myweb.com/free
//http://myweb.com/free/page1
//http://myweb.com/free/page2....

function _nok_force_user_login() {
	global $wp;
	$pagename = isset($wp->query_vars['pagename'])? $wp->query_vars['pagename']:"";
	$isBreak = false;
	if(!empty($pagename)){
		if(substr($pagename, 0, 4) == "free"){
			$isBreak = true;
		}
	}

	if ( !is_page('login') && !is_user_logged_in() && !$isBreak){ 
		auth_redirect(); 
	} 
} 
add_action( 'template_redirect', '_nok_force_user_login' );