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<?php

/**

 * CodeIgniter

 *

 * An open source application development framework for PHP

 *

 * This content is released under the MIT License (MIT)

 *

 * Copyright (c) 2014 - 2018, 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. (https://ellislab.com/)

 * @copyright	Copyright (c) 2014 - 2018, British Columbia Institute of Technology (http://bcit.ca/)

 * @license	http://opensource.org/licenses/MIT	MIT License

 * @link	https://codeigniter.com

 * @since	Version 3.0.0

 * @filesource

*/

defined('BASEPATH') OR exit('No direct script access allowed');

/**

 * CodeIgniter Session Files Driver

 *

 * @package	CodeIgniter

 * @subpackage	Libraries

 * @category	Sessions

 * @author	Andrey Andreev

 * @link	https://codeigniter.com/user_guide/libraries/sessions.html

 */

class CI_Session_files_driver extends CI_Session_driver implements SessionHandlerInterface {

	/**

	 * Save path

	 *

	 * @var	string

	 */

	protected $_save_path;

	/**

	 * File handle

	 *

	 * @var	resource

	 */

	protected $_file_handle;

	/**

	 * File name

	 *

	 * @var	resource

	 */

	protected $_file_path;

	/**

	 * File new flag

	 *

	 * @var	bool

	 */

	protected $_file_new;

	/**

	 * Validate SID regular expression

	 *

	 * @var	string

	 */

	protected $_sid_regexp;

	/**

	 * mbstring.func_overload flag

	 *

	 * @var	bool

	 */

	protected static $func_overload;

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

	/**

	 * Class constructor

	 *

	 * @param	array	$params	Configuration parameters

	 * @return	void

	 */

	public function __construct(&$params)

	{

		parent::__construct($params);

		if (isset($this->_config['save_path']))

		{

			$this->_config['save_path'] = rtrim($this->_config['save_path'], '/\\');

			ini_set('session.save_path', $this->_config['save_path']);

		}

		else

		{

			log_message('debug', 'Session: "sess_save_path" is empty; using "session.save_path" value from php.ini.');

			$this->_config['save_path'] = rtrim(ini_get('session.save_path'), '/\\');

		}

		$this->_sid_regexp = $this->_config['_sid_regexp'];

		isset(self::$func_overload) OR self::$func_overload = (extension_loaded('mbstring') && ini_get('mbstring.func_overload'));

	}

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

	/**

	 * Open

	 *

	 * Sanitizes the save_path directory.

	 *

	 * @param	string	$save_path	Path to session files' directory

	 * @param	string	$name		Session cookie name

	 * @return	bool

	 */

	public function open($save_path, $name)

	{

		if ( ! is_dir($save_path))

		{

			if ( ! mkdir($save_path, 0700, TRUE))

			{

				throw new Exception("Session: Configured save path '".$this->_config['save_path']."' is not a directory, doesn't exist or cannot be created.");

			}

		}

		elseif ( ! is_writable($save_path))

		{

			throw new Exception("Session: Configured save path '".$this->_config['save_path']."' is not writable by the PHP process.");

		}

		$this->_config['save_path'] = $save_path;

		$this->_file_path = $this->_config['save_path'].DIRECTORY_SEPARATOR

			.$name // we'll use the session cookie name as a prefix to avoid collisions

			.($this->_config['match_ip'] ? md5($_SERVER['REMOTE_ADDR']) : '');

		$this->php5_validate_id();

		return $this->_success;

	}

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

	/**

	 * Read

	 *

	 * Reads session data and acquires a lock

	 *

	 * @param	string	$session_id	Session ID

	 * @return	string	Serialized session data

	 */

	public function read($session_id)

	{

		// This might seem weird, but PHP 5.6 introduces session_reset(),

		// which re-reads session data

		if ($this->_file_handle === NULL)

		{

			$this->_file_new = ! file_exists($this->_file_path.$session_id);

			if (($this->_file_handle = fopen($this->_file_path.$session_id, 'c+b')) === FALSE)

			{

				log_message('error', "Session: Unable to open file '".$this->_file_path.$session_id."'.");

				return $this->_failure;

			}

			if (flock($this->_file_handle, LOCK_EX) === FALSE)

			{

				log_message('error', "Session: Unable to obtain lock for file '".$this->_file_path.$session_id."'.");

				fclose($this->_file_handle);

				$this->_file_handle = NULL;

				return $this->_failure;

			}

			// Needed by write() to detect session_regenerate_id() calls

			$this->_session_id = $session_id;

			if ($this->_file_new)

			{

				chmod($this->_file_path.$session_id, 0600);

				$this->_fingerprint = md5('');

				return '';

			}

		}

		// We shouldn't need this, but apparently we do ...

		// See https://github.com/bcit-ci/CodeIgniter/issues/4039

		elseif ($this->_file_handle === FALSE)

		{

			return $this->_failure;

		}

		else

		{

			rewind($this->_file_handle);

		}

		$session_data = '';

		for ($read = 0, $length = filesize($this->_file_path.$session_id); $read < $length; $read += self::strlen($buffer))

		{

			if (($buffer = fread($this->_file_handle, $length - $read)) === FALSE)

			{

				break;

			}

			$session_data .= $buffer;

		}

		$this->_fingerprint = md5($session_data);

		return $session_data;

	}

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

	/**

	 * Write

	 *

	 * Writes (create / update) session data

	 *

	 * @param	string	$session_id	Session ID

	 * @param	string	$session_data	Serialized session data

	 * @return	bool

	 */

	public function write($session_id, $session_data)

	{

		// If the two IDs don't match, we have a session_regenerate_id() call

		// and we need to close the old handle and open a new one

		if ($session_id !== $this->_session_id && ($this->close() === $this->_failure OR $this->read($session_id) === $this->_failure))

		{

			return $this->_failure;

		}

		if ( ! is_resource($this->_file_handle))

		{

			return $this->_failure;

		}

		elseif ($this->_fingerprint === md5($session_data))

		{

			return ( ! $this->_file_new && ! touch($this->_file_path.$session_id))

				? $this->_failure

				: $this->_success;

		}

		if ( ! $this->_file_new)

		{

			ftruncate($this->_file_handle, 0);

			rewind($this->_file_handle);

		}

		if (($length = strlen($session_data)) > 0)

		{

			for ($written = 0; $written < $length; $written += $result)

			{

				if (($result = fwrite($this->_file_handle, substr($session_data, $written))) === FALSE)

				{

					break;

				}

			}

			if ( ! is_int($result))

			{

				$this->_fingerprint = md5(substr($session_data, 0, $written));

				log_message('error', 'Session: Unable to write data.');

				return $this->_failure;

			}

		}

		$this->_fingerprint = md5($session_data);

		return $this->_success;

	}

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

	/**

	 * Close

	 *

	 * Releases locks and closes file descriptor.

	 *

	 * @return	bool

	 */

	public function close()

	{

		if (is_resource($this->_file_handle))

		{

			flock($this->_file_handle, LOCK_UN);

			fclose($this->_file_handle);

			$this->_file_handle = $this->_file_new = $this->_session_id = NULL;

		}

		return $this->_success;

	}

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

	/**

	 * Destroy

	 *

	 * Destroys the current session.

	 *

	 * @param	string	$session_id	Session ID

	 * @return	bool

	 */

	public function destroy($session_id)

	{

		if ($this->close() === $this->_success)

		{

			if (file_exists($this->_file_path.$session_id))

			{

				$this->_cookie_destroy();

				return unlink($this->_file_path.$session_id)

					? $this->_success

					: $this->_failure;

			}

			return $this->_success;

		}

		elseif ($this->_file_path !== NULL)

		{

			clearstatcache();

			if (file_exists($this->_file_path.$session_id))

			{

				$this->_cookie_destroy();

				return unlink($this->_file_path.$session_id)

					? $this->_success

					: $this->_failure;

			}

			return $this->_success;

		}

		return $this->_failure;

	}

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

	/**

	 * Garbage Collector

	 *

	 * Deletes expired sessions

	 *

	 * @param	int 	$maxlifetime	Maximum lifetime of sessions

	 * @return	bool

	 */

	public function gc($maxlifetime)

	{

		if ( ! is_dir($this->_config['save_path']) OR ($directory = opendir($this->_config['save_path'])) === FALSE)

		{

			log_message('debug', "Session: Garbage collector couldn't list files under directory '".$this->_config['save_path']."'.");

			return $this->_failure;

		}

		$ts = time() - $maxlifetime;

		$pattern = ($this->_config['match_ip'] === TRUE)

			? '[0-9a-f]{32}'

			: '';

		$pattern = sprintf(

			'#\A%s'.$pattern.$this->_sid_regexp.'\z#',

			preg_quote($this->_config['cookie_name'])

		);

		while (($file = readdir($directory)) !== FALSE)

		{

			// If the filename doesn't match this pattern, it's either not a session file or is not ours

			if ( ! preg_match($pattern, $file)

				OR ! is_file($this->_config['save_path'].DIRECTORY_SEPARATOR.$file)

				OR ($mtime = filemtime($this->_config['save_path'].DIRECTORY_SEPARATOR.$file)) === FALSE

				OR $mtime > $ts)

			{

				continue;

			}

			unlink($this->_config['save_path'].DIRECTORY_SEPARATOR.$file);

		}

		closedir($directory);

		return $this->_success;

	}

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

	/**

	 * Validate ID

	 *

	 * Checks whether a session ID record exists server-side,

	 * to enforce session.use_strict_mode.

	 *

	 * @param	string	$id

	 * @return	bool

	 */

	public function validateId($id)

	{

		return is_file($this->_file_path.$id);

	}

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

	/**

	 * Byte-safe strlen()

	 *

	 * @param	string	$str

	 * @return	int

	 */

	protected static function strlen($str)

	{

		return (self::$func_overload)

			? mb_strlen($str, '8bit')

			: strlen($str);

	}

}