prestashop - php make directory with write permission not working -

in php want make directory write permission(0777). php code looks this

public function getcontent()   {     global $cookie;     $uploaddir = (dirname(__file__).'/storename');     $tmpname = $uploaddir.'/';     if(file_exists($uploaddir)){       echo 'file exists';     }     else {       mkdir($uploaddir,0777);     }   } 

but here getting error warning: mkdir(): permission denied on line 10 . . can kindly tell me why error coming out here? using lamp server.

you use is_writable() function check before if parent directory writable