Session expiry in CodeIgniter

Though the CodeIgniter 2.1.0 has included a new feature in Session class to define the session expiry on browser with the help of a configuration in the config.

$config['sess_expire_on_close'] = TRUE; 

it is not available there in CodeIgniter 1.7.2 and for some reason the session doesn’t expire automatically on browser close in this version. Though the ideal way would of course be to upgrade the version to CodeIgniter 2.1.0 still for people like me for whom an immediate upgrade in their live projects is not possible the following could work as a quick fix.

1. Add a variable to the Session class in CodeIgniter\system\libraries\Session.php as below:

var $sess_expire_on_close = FALSE; 

2. In that same Session class, in the function declared as _set_cookie($cookie_data = NULL) update the below mentioned lines

setcookie(
    $this->sess_cookie_name,
    $cookie_data,
    $expire,
    $this->cookie_path,
    $this->cookie_domain); 

to

$expire =($this->sess_expire_on_close===TRUE)?0:$this->sess_expiration+time();
  setcookie(
      $this->sess_cookie_name,
      $cookie_data,
      $expire,
      $this->cookie_path,
      $this->cookie_domain); 

3. Again in the Session class in the constructor CI_Session change

 foreach (array('sess_encrypt_cookie', 'sess_use_database', 'sess_table_name',   

  'sess_expiration', 'sess_match_ip', 'sess_match_useragent', 'sess_cookie_name', 

  'cookie_path', 'cookie_domain', 'sess_time_to_update', 'time_reference', 

  'cookie_prefix', 'encryption_key') as $key)

 {
 $this->$key =(isset($params[$key]))?$params[$key]:$this->CI->config->item($key);
 } 

   to

  foreach(array('sess_encrypt_cookie', 'sess_use_database', 'sess_table_name',

 'sess_expiration', 'sess_match_ip', 'sess_match_useragent', 'sess_cookie_name',

 'cookie_path', 'cookie_domain', 'sess_time_to_update', 'time_reference', 

'cookie_prefix', 'encryption_key' , 'sess_expire_on_close' ) as $key)
 {
  $this->$key=(isset($params[$key]))?$params[$key]:$this->CI->config->item($key);
 } 

4. Now in Config.php in add the following line

 $config['sess_expire_on_close'] = TRUE;

These four steps should do the trick in CodeIgniter 1.7.2 and the sessions should be expiring on browser close automatically by now.