cakephp - How to know webroot in core.php -

i'm using cakephp 2.3.1.

our server has independent applications in 1 server. want change session.cookie_path setting following cookbook :

configure::write('session', array(     'defaults' => 'php',     'ini' => array(         'session.cookie_path' => '/app/dir'     ) )); 

i change this. here problem. need set session.cookie_path value webroot dynamically (without string literal value such '/app/dir').

i've tried use $this->webroot following this q&a, of course not work because there no controller in file app/config/core.php.

any ideas?

i realized php variable available : $_server['request_uri']. solve problem.

$requesturi = $_server['request_uri']; $webroot = preg_replace('/(^\/[^\/]+\/).*$/', '$1', $requesturi); //echo $webroot; configure::write('session', array(     'defaults' => 'cake',     'ini' => array(         'session.cookie_path' => $webroot   // looks '/app/'     ) )); 

but solution not have reusability enough : not work apps located in deeper directories such /apps/app1/.

i'm still awaiting better solution.