system/libraries/Session/Session_driver.php

<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.2.4 or newer
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
 * @copyright	Copyright (c) 2014, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	http://codeigniter.com
 * @since	Version 3.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * CodeIgniter Session Driver Class
 *
 * @package	CodeIgniter
 * @subpackage	Libraries
 * @category	Sessions
 * @author	Andrey Andreev
 * @link	http://codeigniter.com/user_guide/libraries/sessions.html
 */
abstract class CI_Session_driver implements SessionHandlerInterface {

	protected $_config;

	/**
	 * Data fingerprint
	 *
	 * @var	bool
	 */
	protected $_fingerprint;

	/**
	 * Lock placeholder
	 *
	 * @var	mixed
	 */
	protected $_lock = FALSE;

	/**
	 * Read session ID
	 *
	 * Used to detect session_regenerate_id() calls because PHP only calls
	 * write() after regenerating the ID.
	 *
	 * @var	string
	 */
	protected $_session_id;

	// ------------------------------------------------------------------------

	/**
	 * Class constructor
	 *
	 * @param	array	$params	Configuration parameters
	 * @return	void
	 */
	public function __construct(&$params)
	{
		$this->_config =& $params;
	}

	// ------------------------------------------------------------------------

	protected function _cookie_destroy()
	{
		return setcookie(
			$this->_config['cookie_name'],
			NULL,
			1,
			$this->_config['cookie_path'],
			$this->_config['cookie_domain'],
			$this->_config['cookie_secure'],
			TRUE
		);
	}

	// ------------------------------------------------------------------------

	/**
	 * Get lock
	 *
	 * A default locking mechanism via semaphores, if ext/sysvsem is available.
	 *
	 * Drivers will usually override this and only fallback to it if no other
	 * locking mechanism is available.
	 *
	 * @param	string	$session_id
	 * @return	bool
	 */
	protected function _get_lock($session_id)
	{
		if ( ! extension_loaded('sysvsem'))
		{
			$this->_lock = TRUE;
			return TRUE;
		}

		if (($this->_lock = sem_get($session_id.($this->_config['match_ip'] ? '_'.$_SERVER['REMOTE_ADDR'] : ''), 1, 0644)) === FALSE)
		{
			return FALSE;
		}

		if ( ! sem_acquire($this->_lock))
		{
			sem_remove($this->_lock);
			$this->_lock = FALSE;
			return FALSE;
		}

		return TRUE;
	}

	// ------------------------------------------------------------------------

	/**
	 * Release lock
	 *
	 * @return	bool
	 */
	protected function _release_lock()
	{
		if (extension_loaded('sysvsem') && $this->_lock)
		{
			sem_release($this->_lock);
			sem_remove($this->_lock);
			$this->_lock = FALSE;
		}

		return TRUE;
	}

}

/* End of file Session_driver.php */
/* Location: ./system/libraries/Session/Session_driver.php */