Added Session driver with native PHP sessions and original-flavor CI cookie sessions
diff --git a/system/libraries/Session/Session.php b/system/libraries/Session/Session.php
new file mode 100755
index 0000000..7aaf706
--- /dev/null
+++ b/system/libraries/Session/Session.php
@@ -0,0 +1,601 @@
+<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.1.6 or newer
+ *
+ * @package		CodeIgniter
+ * @author		ExpressionEngine Dev Team
+ * @copyright	Copyright (c) 2008 - 2010, EllisLab, Inc.
+ * @license		http://codeigniter.com/user_guide/license.html
+ * @link		http://codeigniter.com
+ * @since		Version 2.0
+ * @filesource
+ */
+
+
+/**
+ * Session Class
+ *
+ * The user interface defined by EllisLabs, now with puggable drivers to manage different storage mechanisms.
+ * By default, the Native PHP session driver will load, but the 'sess_driver' config/param item (see above) can be
+ * used to specify the 'Cookie' driver, or any other you might create.
+ * Once loaded, this driver setup is a drop-in replacement for the former CI_Session library, taking its place as the
+ * 'session' member of the global controller framework (e.g.: $CI->session or $this->session).
+ * In keeping with the CI_Driver methodology, multiple drivers may be loaded, although this might be a bit confusing.
+ * The Session library class keeps track of the most recently loaded driver as "current" to call for driver methods.
+ * Ideally, one driver is loaded and all calls go directly through the main library interface. However, any methods
+ * called through the specific driver will switch the "current" driver to itself before invoking the library method
+ * (which will then call back into the driver for low-level operations). So, alternation between two drivers can be
+ * achieved by specifying which driver to use for each call (e.g.: $this->session->native->set_userdata('foo', 'bar');
+ * $this->session->cookie->userdata('foo'); $this->session->native->unset_userdata('foo');). Notice in the previous
+ * example that the _native_ userdata value 'foo' would be set to 'bar', which would NOT be returned by the call for
+ * the _cookie_ userdata 'foo', nor would the _cookie_ value be unset by the call to unset the _native_ 'foo' value.
+ *
+ * @package		CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author		Darren Hill (DChill)
+ * @link		http://codeigniter.com/user_guide/libraries/sessions.html
+ */
+final class Session extends CI_Driver_Library {
+	public $params = array();
+	private $current = null;
+	private $userdata = array();
+
+	const FLASHDATA_KEY = 'flash';
+	const FLASHDATA_NEW = ':new:';
+	const FLASHDATA_OLD = ':old:';
+	const FLASHDATA_EXP = ':exp:';
+	const EXPIRATION_KEY = '__expirations';
+	const TEMP_EXP_DEF = 300;
+
+	/**
+	 * Session constructor
+	 *
+	 * The constructor loads the configured driver ('sess_driver' in config.php or as a parameter), running
+	 * routines in its constructor, and manages flashdata aging.
+	 *
+	 * @param   array	Configuration parameters
+	 */
+	public function __construct(array $params = array())
+	{
+		log_message('debug', 'Session Class Initialized');
+
+		// Get valid drivers list
+		$CI =& get_instance();
+		$this->valid_drivers = array('Session_Native', 'Session_Cookie');
+		$key = 'sess_valid_drivers';
+		$drivers = (isset($params[$key])) ? $params[$key] : $CI->config->item($key);
+		if ($drivers)
+		{
+			if (!is_array($drivers)) $drivers = array($drivers);
+
+			// Add driver names to valid list
+			foreach ($drivers as $driver)
+			{
+				if (!in_array(strtolower($driver), array_map('strtolower', $this->valid_drivers)))
+				{
+					$this->valid_drivers[] = $driver;
+				}
+			}
+		}
+
+		// Get driver to load
+		$key = 'sess_driver';
+		$driver = (isset($params[$key])) ? $params[$key] : $CI->config->item($key);
+		if (!$driver) $driver = 'Native';
+		if (!in_array('session_'.strtolower($driver), array_map('strtolower', $this->valid_drivers)))
+		{
+			$this->valid_drivers[] = 'Session_'.$driver;
+		}
+
+		// Save a copy of parameters in case drivers need access
+		$this->params = $params;
+
+		// Load driver and get array reference
+		$this->load_driver($driver);
+		$this->userdata =& $this->current->get_userdata();
+
+		// Delete 'old' flashdata (from last request)
+		$this->_flashdata_sweep();
+
+		// Mark all new flashdata as old (data will be deleted before next request)
+		$this->_flashdata_mark();
+
+		// Delete expired tempdata
+		$this->_tempdata_sweep();
+
+		log_message('debug', 'Session routines successfully run');
+	}
+
+	/**
+	 * Loads session storage driver
+	 *
+	 * @param   string	Driver classname
+	 * @return  object	Loaded driver object
+	 */
+	public function load_driver($driver)
+	{
+		// Save reference to most recently loaded driver as library default
+		$this->current = parent::load_driver($driver);
+		return $this->current;
+	}
+
+	/**
+	 * Select default session storage driver
+	 *
+	 * @param   string	Driver classname
+	 * @return  void
+	 */
+	public function select_driver($driver)
+	{
+		// Validate driver name
+		$lowername = strtolower($driver);
+		if (in_array($lowername, array_map('strtolower', $this->valid_drivers)))
+		{
+			// See if regular or lowercase variant is loaded
+			if (class_exists($driver))
+			{
+				$this->current = $this->$driver;
+			}
+			else if (class_exists($lowername))
+			{
+				$this->current = $this->$lowername;
+			}
+			else
+			{
+				$this->load_driver($driver);
+			}
+		}
+	}
+
+	/**
+	 * Destroy the current session
+	 *
+	 * @return  void
+	 */
+	public function sess_destroy()
+	{
+		// Just call destroy on driver
+		$this->current->sess_destroy();
+	}
+
+	/**
+	 * Regenerate the current session
+	 *
+	 * @param   boolean	Destroy session data flag (default: false)
+	 * @return  void
+	 */
+	public function sess_regenerate($destroy = false)
+	{
+		// Just call regenerate on driver
+		$this->current->sess_regenerate($destroy);
+	}
+
+	/**
+	 * Fetch a specific item from the session array
+	 *
+	 * @param   string	Item key
+	 * @return  string	Item value
+	 */
+	public function userdata($item)
+	{
+		// Return value or FALSE if not found
+		return (!isset($this->userdata[$item])) ? FALSE : $this->userdata[$item];
+	}
+
+	/**
+	 * Fetch all session data
+	 *
+	 * @return	array	User data array
+	 */
+	public function all_userdata()
+	{
+		// Return entire array
+		return (!isset($this->userdata)) ? FALSE : $this->userdata;
+	}
+
+	/**
+	 * Add or change data in the "userdata" array
+	 *
+	 * @param   mixed	Item name or array of items
+	 * @param   string	Item value or empty string
+	 * @return  void
+	 */
+	public function set_userdata($newdata = array(), $newval = '')
+	{
+		// Wrap params as array if singular
+		if (is_string($newdata))
+		{
+			$newdata = array($newdata => $newval);
+		}
+
+		// Set each name/value pair
+		if (count($newdata) > 0)
+		{
+			foreach ($newdata as $key => $val)
+			{
+				$this->userdata[$key] = $val;
+			}
+		}
+
+		// Tell driver data changed
+		$this->current->sess_save();
+	}
+
+	/**
+	 * Delete a session variable from the "userdata" array
+	 *
+	 * @param   mixed	Item name or array of item names
+	 * @return  void
+	 */
+	public function unset_userdata($newdata = array())
+	{
+		// Wrap single name as array
+		if (is_string($newdata))
+		{
+			$newdata = array($newdata => '');
+		}
+
+		// Unset each item name
+		if (count($newdata) > 0)
+		{
+			foreach ($newdata as $key => $val)
+			{
+				unset($this->userdata[$key]);
+			}
+		}
+
+		// Tell driver data changed
+		$this->current->sess_save();
+	}
+
+	/**
+	 * Determine if an item exists
+	 *
+	 * @param   string	Item name
+	 * @return  boolean
+	 */
+	public function has_userdata($item)
+	{
+		// Check for item name
+		return isset($this->userdata[$item]);
+	}
+
+	/**
+	 * Add or change flashdata, only available until the next request
+	 *
+	 * @param   mixed	Item name or array of items
+	 * @param   string	Item value or empty string
+	 * @return  void
+	 */
+	public function set_flashdata($newdata = array(), $newval = '')
+	{
+		// Wrap item as array if singular
+		if (is_string($newdata))
+		{
+			$newdata = array($newdata => $newval);
+		}
+
+		// Prepend each key name and set value
+		if (count($newdata) > 0)
+		{
+			foreach ($newdata as $key => $val)
+			{
+				$flashdata_key = self::FLASHDATA_KEY.self::FLASHDATA_NEW.$key;
+				$this->set_userdata($flashdata_key, $val);
+			}
+		}
+	}
+
+	/**
+	 * Keeps existing flashdata available to next request.
+	 *
+	 * @param   string	Item key
+	 * @return  void
+	 */
+	public function keep_flashdata($key)
+	{
+		// 'old' flashdata gets removed.  Here we mark all
+		// flashdata as 'new' to preserve it from _flashdata_sweep()
+		$old_flashdata_key = self::FLASHDATA_KEY.self::FLASHDATA_OLD.$key;
+		$value = $this->userdata($old_flashdata_key);
+
+		$new_flashdata_key = self::FLASHDATA_KEY.self::FLASHDATA_NEW.$key;
+		$this->set_userdata($new_flashdata_key, $value);
+	}
+
+	/**
+	 * Fetch a specific flashdata item from the session array
+	 *
+	 * @param   string	Item key
+	 * @return  string
+	 */
+	public function flashdata($key)
+	{
+		// Prepend key and retrieve value
+		$flashdata_key = self::FLASHDATA_KEY.self::FLASHDATA_OLD.$key;
+		return $this->userdata($flashdata_key);
+	}
+
+	/**
+	 * Add or change tempdata, only available
+	 * until expiration
+	 *
+	 * @param   mixed	Item name or array of items
+	 * @param   string	Item value or empty string
+	 * @param   int		Item lifetime in seconds or 0 for default
+	 * @return  void
+	 */
+	public function set_tempdata($newdata = array(), $newval = '', $expire = 0)
+	{
+		// Set expiration time
+		$expire = time() + ($expire ? $expire : self::TEMP_EXP_DEF);
+
+		// Wrap item as array if singular
+		if (is_string($newdata))
+		{
+			$newdata = array($newdata => $newval);
+		}
+
+		// Get or create expiration list
+		$expirations = $this->userdata(self::EXPIRATION_KEY);
+		if (!$expirations)
+		{
+			$expirations = array();
+		}
+
+		// Prepend each key name and set value
+		if (count($newdata) > 0)
+		{
+			foreach ($newdata as $key => $val)
+			{
+				$tempdata_key = self::FLASHDATA_KEY.self::FLASHDATA_EXP.$key;
+				$expirations[$tempdata_key] = $expire;
+				$this->set_userdata($tempdata_key, $val);
+			}
+		}
+
+		// Update expiration list
+		$this->set_userdata(self::EXPIRATION_KEY, $expirations);
+	}
+
+	/**
+	 * Delete a temporary session variable from the "userdata" array
+	 *
+	 * @param   mixed	Item name or array of item names
+	 * @return  void
+	 */
+	public function unset_tempdata($newdata = array())
+	{
+		// Get expirations list
+		$expirations = $this->userdata(self::EXPIRATION_KEY);
+		if (!$expirations || !count($expirations))
+		{
+			// Nothing to do
+			return;
+		}
+
+		// Wrap single name as array
+		if (is_string($newdata))
+		{
+			$newdata = array($newdata => '');
+		}
+
+		// Prepend each item name and unset
+		if (count($newdata) > 0)
+		{
+			foreach ($newdata as $key => $val)
+			{
+				$tempdata_key = self::FLASHDATA_KEY.self::FLASHDATA_EXP.$key;
+				unset($expirations[$tempdata_key]);
+				$this->unset_userdata($tempdata_key);
+			}
+		}
+
+		// Update expiration list
+		$this->set_userdata(self::EXPIRATION_KEY, $expirations);
+	}
+
+	/**
+	 * Fetch a specific tempdata item from the session array
+	 *
+	 * @param   string	Item key
+	 * @return  string
+	 */
+	public function tempdata($key)
+	{
+		// Prepend key and return value
+		$tempdata_key = self::FLASHDATA_KEY.self::FLASHDATA_EXP.$key;
+		return $this->userdata($tempdata_key);
+	}
+
+	/**
+	 * Identifies flashdata as 'old' for removal
+	 * when _flashdata_sweep() runs.
+	 *
+	 * @access	private
+	 * @return	void
+	 */
+	private function _flashdata_mark()
+	{
+		$userdata = $this->all_userdata();
+		foreach ($userdata as $name => $value)
+		{
+			$parts = explode(self::FLASHDATA_NEW, $name);
+			if (is_array($parts) && count($parts) === 2)
+			{
+				$new_name = self::FLASHDATA_KEY.self::FLASHDATA_OLD.$parts[1];
+				$this->set_userdata($new_name, $value);
+				$this->unset_userdata($name);
+			}
+		}
+	}
+
+	/**
+	 * Removes all flashdata marked as 'old'
+	 *
+	 * @access	private
+	 * @return	void
+	 */
+	private function _flashdata_sweep()
+	{
+		$userdata = $this->all_userdata();
+		foreach ($userdata as $key => $value)
+		{
+			if (strpos($key, self::FLASHDATA_OLD))
+			{
+				$this->unset_userdata($key);
+			}
+		}
+	}
+
+	/**
+	 * Removes all expired tempdata
+	 *
+	 * @access	private
+	 * @return	void
+	 */
+	private function _tempdata_sweep()
+	{
+		// Get expirations list
+		$expirations = $this->userdata(self::EXPIRATION_KEY);
+		if (!$expirations || !count($expirations))
+		{
+			// Nothing to do
+			return;
+		}
+
+		// Unset expired elements
+		$now = time();
+		$userdata = $this->all_userdata();
+		foreach ($userdata as $key => $value)
+		{
+			if (strpos($key, self::FLASHDATA_EXP) && $expirations[$key] < $now)
+			{
+				unset($expirations[$key]);
+				$this->unset_userdata($key);
+			}
+		}
+
+		// Update expiration list
+		$this->set_userdata(self::EXPIRATION_KEY, $expirations);
+	}
+}
+// END Session Class
+
+
+/**
+ * SessionDriver Class
+ *
+ * Extend this class to make a new Session driver.
+ * A Session driver basically manages an array of name/value pairs with some sort of storage mechanism.
+ * To make a new driver, derive from (extend) SessionDriver. Overload the initialize method and read or create
+ * session data. Then implement a save handler to write changed data to storage (sess_save), a destroy handler
+ * to remove deleted data (sess_destroy), and an access handler to expose the data (get_userdata).
+ * Put your driver in the libraries/Session/drivers folder anywhere in the loader paths. This includes the application
+ * directory, the system directory, or any path you add with $CI->load->add_package_path().
+ * Your driver must be named Session_<name>, where <name> is capitalized, and your filename must be Session_<name>.EXT,
+ * preferably also capitalized. (e.g.: Session_Foo in libraries/Session/drivers/Session_Foo.php)
+ * Then specify the driver by setting 'sess_driver' in your config file or as a parameter when loading the Session
+ * object. (e.g.: $config['sess_driver'] = 'foo'; OR $CI->load->driver('session', array('sess_driver' => 'foo')); )
+ * Already provided are the Native driver, which manages the native PHP $_SESSION array, and
+ * the Cookie driver, which manages the data in a browser cookie, with optional extra storage in a database table.
+ *
+ * @package	 CodeIgniter
+ * @subpackage  Libraries
+ * @category	Sessions
+ * @author	  Darren Hill (DChill)
+ */
+abstract class SessionDriver extends CI_Driver {
+	/**
+	 * Decorate
+	 *
+	 * Decorates the child with the parent driver lib's methods and properties
+	 *
+	 * @param	object	Parent library object
+	 * @return	void
+	 */
+	public function decorate($parent)
+	{
+		// Call base class decorate first
+		parent::decorate($parent);
+
+		// Call initialize method now that driver has access to $this->parent
+		$this->initialize();
+	}
+
+	/**
+	 * __call magic method
+	 *
+	 * Handles access to the parent driver library's methods
+	 *
+	 * @param   string	Library method name
+	 * @param   array	Method arguments (default: none)
+	 * @return	mixed
+	 */
+	public function __call($method, $args = array())
+	{
+		// Make sure the parent library uses this driver
+		$this->parent->select_driver(get_class($this));
+		return parent::__call($method, $args);
+	}
+
+	/**
+	 * Initialize driver
+	 *
+	 * @return  void
+	 */
+	protected function initialize()
+	{
+		// Overload this method to implement initialization
+	}
+
+	/**
+	 * Save the session data
+	 *
+	 * Data in the array has changed - perform any storage synchronization necessary
+	 * The child class MUST implement this abstract method!
+	 *
+	 * @return  void
+	 */
+	abstract public function sess_save();
+
+	/**
+	 * Destroy the current session
+	 *
+	 * Clean up storage for this session - it has been terminated
+	 * The child class MUST implement this abstract method!
+	 *
+	 * @return  void
+	 */
+	abstract public function sess_destroy();
+
+	/**
+	 * Regenerate the current session
+	 *
+	 * Regenerate the session id
+	 * The child class MUST implement this abstract method!
+	 *
+	 * @param   boolean	Destroy session data flag (default: false)
+	 * @return  void
+	 */
+	abstract public function sess_regenerate($destroy = false);
+
+	/**
+	 * Get a reference to user data array
+	 *
+	 * Give array access to the main Session object
+	 * The child class MUST implement this abstract method!
+	 *
+	 * @return  array	Reference to userdata
+	 */
+	abstract public function &get_userdata();
+}
+// END SessionDriver Class
+
+
+/* End of file Session.php */
+/* Location: ./system/libraries/Session/Session.php */
+?>