system/core/Common.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 4.3.2 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 1.0
 * @filesource
 */

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

/**
 * Common Functions
 *
 * Loads the base classes and executes the request.
 *
 * @package		CodeIgniter
 * @subpackage	codeigniter
 * @category	Common Functions
 * @author		ExpressionEngine Dev Team
 * @link		http://codeigniter.com/user_guide/
 */

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

/**
* Determines if the current version of PHP is greater then the supplied value
*
* Since there are a few places where we conditionally test for PHP > 5
* we'll set a static variable.
*
* @access	public
* @param	string
* @return	bool	TRUE if the current version is $version or higher
*/
	function is_php($version = '5.0.0')
	{
		static $_is_php;
		$version = (string)$version;
	
		if ( ! isset($_is_php[$version]))
		{
			$_is_php[$version] = (version_compare(PHP_VERSION, $version) < 0) ? FALSE : TRUE;
		}

		return $_is_php[$version];
	}

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

/**
 * Tests for file writability
 *
 * is_writable() returns TRUE on Windows servers when you really can't write to 
 * the file, based on the read-only attribute.  is_writable() is also unreliable
 * on Unix servers if safe_mode is on.
 *
 * @access	private
 * @return	void
 */	
	function is_really_writable($file)
	{
		// If we're on a Unix server with safe_mode off we call is_writable
		if (DIRECTORY_SEPARATOR == '/' AND @ini_get("safe_mode") == FALSE)
		{
			return is_writable($file);
		}

		// For windows servers and safe_mode "on" installations we'll actually
		// write a file then read it.  Bah...
		if (is_dir($file))
		{
			$file = rtrim($file, '/').'/'.md5(mt_rand(1,100).mt_rand(1,100));

			if (($fp = @fopen($file, FOPEN_WRITE_CREATE)) === FALSE)
			{
				return FALSE;
			}

			fclose($fp);
			@chmod($file, DIR_WRITE_MODE);
			@unlink($file);
			return TRUE;
		}
		elseif (($fp = @fopen($file, FOPEN_WRITE_CREATE)) === FALSE)
		{
			return FALSE;
		}

		fclose($fp);
		return TRUE;
	}

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

/**
* Class registry
*
* This function acts as a singleton.  If the requested class does not
* exist it is instantiated and set to a static variable.  If it has
* previously been instantiated the variable is returned.
*
* @access	public
* @param	string	the class name being requested
* @param	string	the directory where the class should be found
* @param	string	the class name prefix
* @return	object
*/
	function &load_class($class, $directory = 'libraries', $prefix = 'CI_')
	{
		static $_classes = array();
		
		// Does the class exist?  If so, we're done...
		if (isset($_classes[$class]))
		{
			return $_classes[$class];
		}

		$name = FALSE;

		// Look for the class first in the native system/libraries folder
		// thenin the local application/libraries folder
		foreach (array(BASEPATH, APPPATH) as $path)
		{ 
			if (file_exists($path.$directory.'/'.$class.EXT))
			{
				$name = $prefix.$class;
		
				if (class_exists($name) === FALSE)
				{
					require($path.$directory.'/'.$class.EXT);
				}
		
				break;
			}
		}

		// Is the request a class extension?  If so we load it too
		if (file_exists(APPPATH.$directory.'/'.config_item('subclass_prefix').$class.EXT))
		{	
			$name = config_item('subclass_prefix').$class;
	
			if (class_exists($name) === FALSE)
			{
				require(APPPATH.$directory.'/'.config_item('subclass_prefix').$class.EXT);
			}
		}

		// Did we find the class?
		if ($name === FALSE)
		{
			// Note: We use exit() rather then show_error() in order to avoid a 
			// self-referencing loop with the Excptions class 
			exit('Unable to locate the specified class: '.$class.EXT);
		}

		// Keep track of what we just loaded
		is_loaded($class);

		$_classes[$class] =& instantiate_class(new $name());
		return $_classes[$class];
	}

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

/**
 * Instantiate Class
 *
 * Returns a new class object by reference, used by load_class() and the DB class.
 * Required to retain PHP 4 compatibility and also not make PHP 5.3 cry.
 *
 * Use: $obj =& instantiate_class(new Foo());
 * 
 * @access	public
 * @param	object
 * @return	object
 */
	function &instantiate_class(&$class_object)
	{
		return $class_object;
	}

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

/**
* Keeps track of which libraries have been loaded.  This function is
* called by the load_class() function above
*
* @access	public
* @return	array
*/
	function is_loaded($class = '')
	{
		static $_is_loaded = array();

		if ($class != '')
		{
			$_is_loaded[strtolower($class)] = $class;
		}

		return $_is_loaded;
	}

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

/**
* Loads the main config.php file
*
* This function lets us grab the config file even if the Config class
* hasn't been instantiated yet
*
* @access	private
* @return	array
*/
	function &get_config($replace = array())
	{
		static $_config;
	
		if (isset($_config))
		{
			return $_config[0];
		}	

		// Fetch the config file
		if ( ! file_exists(APPPATH.'config/config'.EXT))
		{
			exit('The configuration file does not exist.');
		}
		else
		{
			require(APPPATH.'config/config'.EXT);
		}

		// Does the $config array exist in the file?
		if ( ! isset($config) OR ! is_array($config))
		{
			exit('Your config file does not appear to be formatted correctly.');
		}

		// Are any values being dynamically replaced?
		if (count($replace) > 0)
		{
			foreach ($replace as $key => $val)
			{
				if (isset($config[$key]))
				{
					$config[$key] = $val;
				}
			}
		}
	
		return $_config[0] =& $config;
	}

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

/**
* Returns the specified config item
*
* @access	public
* @return	mixed
*/
	function config_item($item)
	{
		static $_config_item = array();
	
		if ( ! isset($_config_item[$item]))
		{
			$config =& get_config();
	
			if ( ! isset($config[$item]))
			{
				return FALSE;
			}
			$_config_item[$item] = $config[$item];
		}
	
		return $_config_item[$item];
	}

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

/**
* Error Handler
*
* This function lets us invoke the exception class and
* display errors using the standard error template located
* in application/errors/errors.php
* This function will send the error page directly to the
* browser and exit.
*
* @access	public
* @return	void
*/
	function show_error($message, $status_code = 500, $heading = 'An Error Was Encountered')
	{
		$_error =& load_class('Exceptions', 'core');
		echo $_error->show_error($heading, $message, 'error_general', $status_code);
		exit;
	}

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

/**
* 404 Page Handler
*
* This function is similar to the show_error() function above
* However, instead of the standard error template it displays
* 404 errors.
*
* @access	public
* @return	void
*/
	function show_404($page = '', $log_error = TRUE)
	{
		$_error =& load_class('Exceptions', 'core');
		$_error->show_404($page, $log_error);
		exit;
	}

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

/**
* Error Logging Interface
*
* We use this as a simple mechanism to access the logging
* class and send messages to be logged.
*
* @access	public
* @return	void
*/
	function log_message($level = 'error', $message, $php_error = FALSE)
	{
		static $_log;

		if (config_item('log_threshold') == 0)
		{
			return;
		}
	
		$_log =& load_class('Log');
		$_log->write_log($level, $message, $php_error);
	}

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

/**
 * Set HTTP Status Header
 *
 * @access	public
 * @param	int 	the status code
 * @param	string	
 * @return	void
 */	
	function set_status_header($code = 200, $text = '')
	{
		$stati = array(
							200	=> 'OK',
							201	=> 'Created',
							202	=> 'Accepted',
							203	=> 'Non-Authoritative Information',
							204	=> 'No Content',
							205	=> 'Reset Content',
							206	=> 'Partial Content',

							300	=> 'Multiple Choices',
							301	=> 'Moved Permanently',
							302	=> 'Found',
							304	=> 'Not Modified',
							305	=> 'Use Proxy',
							307	=> 'Temporary Redirect',

							400	=> 'Bad Request',
							401	=> 'Unauthorized',
							403	=> 'Forbidden',
							404	=> 'Not Found',
							405	=> 'Method Not Allowed',
							406	=> 'Not Acceptable',
							407	=> 'Proxy Authentication Required',
							408	=> 'Request Timeout',
							409	=> 'Conflict',
							410	=> 'Gone',
							411	=> 'Length Required',
							412	=> 'Precondition Failed',
							413	=> 'Request Entity Too Large',
							414	=> 'Request-URI Too Long',
							415	=> 'Unsupported Media Type',
							416	=> 'Requested Range Not Satisfiable',
							417	=> 'Expectation Failed',

							500	=> 'Internal Server Error',
							501	=> 'Not Implemented',
							502	=> 'Bad Gateway',
							503	=> 'Service Unavailable',
							504	=> 'Gateway Timeout',
							505	=> 'HTTP Version Not Supported'
						);

		if ($code == '' OR ! is_numeric($code))
		{
			show_error('Status codes must be numeric', 500);
		}

		if (isset($stati[$code]) AND $text == '')
		{				
			$text = $stati[$code];
		}
	
		if ($text == '')
		{
			show_error('No status text available.  Please check your status code number or supply your own message text.', 500);
		}
	
		$server_protocol = (isset($_SERVER['SERVER_PROTOCOL'])) ? $_SERVER['SERVER_PROTOCOL'] : FALSE;

		if (substr(php_sapi_name(), 0, 3) == 'cgi')
		{
			header("Status: {$code} {$text}", TRUE);
		}
		elseif ($server_protocol == 'HTTP/1.1' OR $server_protocol == 'HTTP/1.0')
		{
			header($server_protocol." {$code} {$text}", TRUE, $code);
		}
		else
		{
			header("HTTP/1.1 {$code} {$text}", TRUE, $code);
		}
	}
	
// --------------------------------------------------------------------

/**
* Exception Handler
*
* This is the custom exception handler that is declaired at the top
* of Codeigniter.php.  The main reason we use this is to permit
* PHP errors to be logged in our own log files since the user may
* not have access to server logs. Since this function
* effectively intercepts PHP errors, however, we also need
* to display errors based on the current error_reporting level.
* We do that with the use of a PHP error template.
*
* @access	private
* @return	void
*/
	function _exception_handler($severity, $message, $filepath, $line)
	{	
		 // We don't bother with "strict" notices since they tend to fill up
		 // the log file with excess information that isn't normally very helpful.
		 // For example, if you are running PHP 5 and you use version 4 style 
		 // class functions (without prefixes like "public", "private", etc.) 
		 // you'll get notices telling you that these have been deprecated.
		if ($severity == E_STRICT)
		{
			return;
		}
	
		$_error =& load_class('Exceptions', 'core');
	
		// Should we display the error? We'll get the current error_reporting 
		// level and add its bits with the severity bits to find out.
		if (($severity & error_reporting()) == $severity)
		{
			$_error->show_php_error($severity, $message, $filepath, $line);
		}

		// Should we log the error?  No?  We're done...
		if (config_item('log_threshold') == 0)
		{
			return;
		}
	
		$_error->log_exception($severity, $message, $filepath, $line);
	}

	// --------------------------------------------------------------------
	
	/**
	 * Remove Invisible Characters
	 *
	 * This prevents sandwiching null characters
	 * between ascii characters, like Java\0script.
	 *
	 * @access	public
	 * @param	string
	 * @return	string
	 */
	function remove_invisible_characters($str)
	{
		static $non_displayables;
		
		if ( ! isset($non_displayables))
		{
			// every control character except newline (dec 10), carriage return (dec 13), and horizontal tab (dec 09),
			$non_displayables = array(
										'/%0[0-8bcef]/',			// url encoded 00-08, 11, 12, 14, 15
										'/%1[0-9a-f]/',				// url encoded 16-31
										'/[\x00-\x08]/',			// 00-08
										'/\x0b/', '/\x0c/',			// 11, 12
										'/[\x0e-\x1f]/'				// 14-31
									);
		}

		do
		{
			$cleaned = $str;
			$str = preg_replace($non_displayables, '', $str);
		}
		while ($cleaned != $str);

		return $str;
	}


/* End of file Common.php */
/* Location: ./system/core/Common.php */