system/core/Output.php - code-igniter-v3-giggi - Gitiles

 <?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 1.0.0
  * @filesource
  */
 defined('BASEPATH') OR exit('No direct script access allowed');

 /**
  * Output Class
  *
  * Responsible for sending final output to the browser.
  *
  * @package		CodeIgniter
  * @subpackage	Libraries
  * @category	Output
  * @author		EllisLab Dev Team
  * @link		https://codeigniter.com/user_guide/libraries/output.html
  */
 class CI_Output {

 	/**
 	 * Final output string
 	 *
 	 * @var	string
 	 */
 	public $final_output;

 	/**
 	 * Cache expiration time
 	 *
 	 * @var	int
 	 */
 	public $cache_expiration = 0;

 	/**
 	 * List of server headers
 	 *
 	 * @var	array
 	 */
 	public $headers = array();

 	/**
 	 * List of mime types
 	 *
 	 * @var	array
 	 */
 	public $mimes =	array();

 	/**
 	 * Mime-type for the current page
 	 *
 	 * @var	string
 	 */
 	protected $mime_type = 'text/html';

 	/**
 	 * Enable Profiler flag
 	 *
 	 * @var	bool
 	 */
 	public $enable_profiler = FALSE;

 	/**
 	 * php.ini zlib.output_compression flag
 	 *
 	 * @var	bool
 	 */
 	protected $_zlib_oc = FALSE;

 	/**
 	 * CI output compression flag
 	 *
 	 * @var	bool
 	 */
 	protected $_compress_output = FALSE;

 	/**
 	 * List of profiler sections
 	 *
 	 * @var	array
 	 */
 	protected $_profiler_sections =	array();

 	/**
 	 * Parse markers flag
 	 *
 	 * Whether or not to parse variables like {elapsed_time} and {memory_usage}.
 	 *
 	 * @var	bool
 	 */
 	public $parse_exec_vars = TRUE;

 	/**
 	 * mbstring.func_overload flag
 	 *
 	 * @var	bool
 	 */
 	protected static $func_overload;

 	/**
 	 * Class constructor
 	 *
 	 * Determines whether zLib output compression will be used.
 	 *
 	 * @return	void
 	 */
 	public function __construct()
 	{
 		$this->_zlib_oc = (bool) ini_get('zlib.output_compression');
 		$this->_compress_output = (
 			$this->_zlib_oc === FALSE
 			&& config_item('compress_output') === TRUE
 			&& extension_loaded('zlib')
 		);

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

 		// Get mime types for later
 		$this->mimes =& get_mimes();

 		log_message('info', 'Output Class Initialized');
 	}

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

 	/**
 	 * Get Output
 	 *
 	 * Returns the current output string.
 	 *
 	 * @return	string
 	 */
 	public function get_output()
 	{
 		return $this->final_output;
 	}

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

 	/**
 	 * Set Output
 	 *
 	 * Sets the output string.
 	 *
 	 * @param	string	$output	Output data
 	 * @return	CI_Output
 	 */
 	public function set_output($output)
 	{
 		$this->final_output = $output;
 		return $this;
 	}

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

 	/**
 	 * Append Output
 	 *
 	 * Appends data onto the output string.
 	 *
 	 * @param	string	$output	Data to append
 	 * @return	CI_Output
 	 */
 	public function append_output($output)
 	{
 		$this->final_output .= $output;
 		return $this;
 	}

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

 	/**
 	 * Set Header
 	 *
 	 * Lets you set a server header which will be sent with the final output.
 	 *
 	 * Note: If a file is cached, headers will not be sent.
 	 * @todo	We need to figure out how to permit headers to be cached.
 	 *
 	 * @param	string	$header		Header
 	 * @param	bool	$replace	Whether to replace the old header value, if already set
 	 * @return	CI_Output
 	 */
 	public function set_header($header, $replace = TRUE)
 	{
 		// If zlib.output_compression is enabled it will compress the output,
 		// but it will not modify the content-length header to compensate for
 		// the reduction, causing the browser to hang waiting for more data.
 		// We'll just skip content-length in those cases.
 		if ($this->_zlib_oc && strncasecmp($header, 'content-length', 14) === 0)
 		{
 			return $this;
 		}

 		$this->headers[] = array($header, $replace);
 		return $this;
 	}

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

 	/**
 	 * Set Content-Type Header
 	 *
 	 * @param	string	$mime_type	Extension of the file we're outputting
 	 * @param	string	$charset	Character set (default: NULL)
 	 * @return	CI_Output
 	 */
 	public function set_content_type($mime_type, $charset = NULL)
 	{
 		if (strpos($mime_type, '/') === FALSE)
 		{
 			$extension = ltrim($mime_type, '.');

 			// Is this extension supported?
 			if (isset($this->mimes[$extension]))
 			{
 				$mime_type =& $this->mimes[$extension];

 				if (is_array($mime_type))
 				{
 					$mime_type = current($mime_type);
 				}
 			}
 		}

 		$this->mime_type = $mime_type;

 		if (empty($charset))
 		{
 			$charset = config_item('charset');
 		}

 		$header = 'Content-Type: '.$mime_type
 			.(empty($charset) ? '' : '; charset='.$charset);

 		$this->headers[] = array($header, TRUE);
 		return $this;
 	}

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

 	/**
 	 * Get Current Content-Type Header
 	 *
 	 * @return	string	'text/html', if not already set
 	 */
 	public function get_content_type()
 	{
 		for ($i = 0, $c = count($this->headers); $i < $c; $i++)
 		{
 			if (sscanf($this->headers[$i][0], 'Content-Type: %[^;]', $content_type) === 1)
 			{
 				return $content_type;
 			}
 		}

 		return 'text/html';
 	}

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

 	/**
 	 * Get Header
 	 *
 	 * @param	string	$header
 	 * @return	string
 	 */
 	public function get_header($header)
 	{
 		// Combine headers already sent with our batched headers
 		$headers = array_merge(
 			// We only need [x][0] from our multi-dimensional array
 			array_map('array_shift', $this->headers),
 			headers_list()
 		);

 		if (empty($headers) OR empty($header))
 		{
 			return NULL;
 		}

 		// Count backwards, in order to get the last matching header
 		for ($c = count($headers) - 1; $c > -1; $c--)
 		{
 			if (strncasecmp($header, $headers[$c], $l = self::strlen($header)) === 0)
 			{
 				return trim(self::substr($headers[$c], $l+1));
 			}
 		}

 		return NULL;
 	}

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

 	/**
 	 * Set HTTP Status Header
 	 *
 	 * As of version 1.7.2, this is an alias for common function
 	 * set_status_header().
 	 *
 	 * @param	int	$code	Status code (default: 200)
 	 * @param	string	$text	Optional message
 	 * @return	CI_Output
 	 */
 	public function set_status_header($code = 200, $text = '')
 	{
 		set_status_header($code, $text);
 		return $this;
 	}

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

 	/**
 	 * Enable/disable Profiler
 	 *
 	 * @param	bool	$val	TRUE to enable or FALSE to disable
 	 * @return	CI_Output
 	 */
 	public function enable_profiler($val = TRUE)
 	{
 		$this->enable_profiler = is_bool($val) ? $val : TRUE;
 		return $this;
 	}

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

 	/**
 	 * Set Profiler Sections
 	 *
 	 * Allows override of default/config settings for
 	 * Profiler section display.
 	 *
 	 * @param	array	$sections	Profiler sections
 	 * @return	CI_Output
 	 */
 	public function set_profiler_sections($sections)
 	{
 		if (isset($sections['query_toggle_count']))
 		{
 			$this->_profiler_sections['query_toggle_count'] = (int) $sections['query_toggle_count'];
 			unset($sections['query_toggle_count']);
 		}

 		foreach ($sections as $section => $enable)
 		{
 			$this->_profiler_sections[$section] = ($enable !== FALSE);
 		}

 		return $this;
 	}

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

 	/**
 	 * Set Cache
 	 *
 	 * @param	int	$time	Cache expiration time in minutes
 	 * @return	CI_Output
 	 */
 	public function cache($time)
 	{
 		$this->cache_expiration = is_numeric($time) ? $time : 0;
 		return $this;
 	}

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

 	/**
 	 * Display Output
 	 *
 	 * Processes and sends finalized output data to the browser along
 	 * with any server headers and profile data. It also stops benchmark
 	 * timers so the page rendering speed and memory usage can be shown.
 	 *
 	 * Note: All "view" data is automatically put into $this->final_output
 	 *	 by controller class.
 	 *
 	 * @uses	CI_Output::$final_output
 	 * @param	string	$output	Output data override
 	 * @return	void
 	 */
 	public function _display($output = '')
 	{
 		// Note:  We use load_class() because we can't use $CI =& get_instance()
 		// since this function is sometimes called by the caching mechanism,
 		// which happens before the CI super object is available.
 		$BM =& load_class('Benchmark', 'core');
 		$CFG =& load_class('Config', 'core');

 		// Grab the super object if we can.
 		if (class_exists('CI_Controller', FALSE))
 		{
 			$CI =& get_instance();
 		}

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

 		// Set the output data
 		if ($output === '')
 		{
 			$output =& $this->final_output;
 		}

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

 		// Do we need to write a cache file? Only if the controller does not have its
 		// own _output() method and we are not dealing with a cache file, which we
 		// can determine by the existence of the $CI object above
 		if ($this->cache_expiration > 0 && isset($CI) && ! method_exists($CI, '_output'))
 		{
 			$this->_write_cache($output);
 		}

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

 		// Parse out the elapsed time and memory usage,
 		// then swap the pseudo-variables with the data

 		$elapsed = $BM->elapsed_time('total_execution_time_start', 'total_execution_time_end');

 		if ($this->parse_exec_vars === TRUE)
 		{
 			$memory	= round(memory_get_usage() / 1024 / 1024, 2).'MB';
 			$output = str_replace(array('{elapsed_time}', '{memory_usage}'), array($elapsed, $memory), $output);
 		}

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

 		// Is compression requested?
 		if (isset($CI) // This means that we're not serving a cache file, if we were, it would already be compressed
 			&& $this->_compress_output === TRUE
 			&& isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
 		{
 			ob_start('ob_gzhandler');
 		}

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

 		// Are there any server headers to send?
 		if (count($this->headers) > 0)
 		{
 			foreach ($this->headers as $header)
 			{
 				@header($header[0], $header[1]);
 			}
 		}

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

 		// Does the $CI object exist?
 		// If not we know we are dealing with a cache file so we'll
 		// simply echo out the data and exit.
 		if ( ! isset($CI))
 		{
 			if ($this->_compress_output === TRUE)
 			{
 				if (isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
 				{
 					header('Content-Encoding: gzip');
 					header('Content-Length: '.self::strlen($output));
 				}
 				else
 				{
 					// User agent doesn't support gzip compression,
 					// so we'll have to decompress our cache
 					$output = gzinflate(self::substr($output, 10, -8));
 				}
 			}

 			echo $output;
 			log_message('info', 'Final output sent to browser');
 			log_message('debug', 'Total execution time: '.$elapsed);
 			return;
 		}

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

 		// Do we need to generate profile data?
 		// If so, load the Profile class and run it.
 		if ($this->enable_profiler === TRUE)
 		{
 			$CI->load->library('profiler');
 			if ( ! empty($this->_profiler_sections))
 			{
 				$CI->profiler->set_sections($this->_profiler_sections);
 			}

 			// If the output data contains closing </body> and </html> tags
 			// we will remove them and add them back after we insert the profile data
 			$output = preg_replace('|</body>.*?</html>|is', '', $output, -1, $count).$CI->profiler->run();
 			if ($count > 0)
 			{
 				$output .= '</body></html>';
 			}
 		}

 		// Does the controller contain a function named _output()?
 		// If so send the output there.  Otherwise, echo it.
 		if (method_exists($CI, '_output'))
 		{
 			$CI->_output($output);
 		}
 		else
 		{
 			echo $output; // Send it to the browser!
 		}

 		log_message('info', 'Final output sent to browser');
 		log_message('debug', 'Total execution time: '.$elapsed);
 	}

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

 	/**
 	 * Write Cache
 	 *
 	 * @param	string	$output	Output data to cache
 	 * @return	void
 	 */
 	public function _write_cache($output)
 	{
 		$CI =& get_instance();
 		$path = $CI->config->item('cache_path');
 		$cache_path = ($path === '') ? APPPATH.'cache/' : $path;

 		if ( ! is_dir($cache_path) OR ! is_really_writable($cache_path))
 		{
 			log_message('error', 'Unable to write cache file: '.$cache_path);
 			return;
 		}

 		$uri = $CI->config->item('base_url')
 			.$CI->config->item('index_page')
 			.$CI->uri->uri_string();

 		if (($cache_query_string = $CI->config->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
 		{
 			if (is_array($cache_query_string))
 			{
 				$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
 			}
 			else
 			{
 				$uri .= '?'.$_SERVER['QUERY_STRING'];
 			}
 		}

 		$cache_path .= md5($uri);

 		if ( ! $fp = @fopen($cache_path, 'w+b'))
 		{
 			log_message('error', 'Unable to write cache file: '.$cache_path);
 			return;
 		}

 		if ( ! flock($fp, LOCK_EX))
 		{
 			log_message('error', 'Unable to secure a file lock for file at: '.$cache_path);
 			fclose($fp);
 			return;
 		}

 		// If output compression is enabled, compress the cache
 		// itself, so that we don't have to do that each time
 		// we're serving it
 		if ($this->_compress_output === TRUE)
 		{
 			$output = gzencode($output);

 			if ($this->get_header('content-type') === NULL)
 			{
 				$this->set_content_type($this->mime_type);
 			}
 		}

 		$expire = time() + ($this->cache_expiration * 60);

 		// Put together our serialized info.
 		$cache_info = serialize(array(
 			'expire'	=> $expire,
 			'headers'	=> $this->headers
 		));

 		$output = $cache_info.'ENDCI--->'.$output;

 		for ($written = 0, $length = self::strlen($output); $written < $length; $written += $result)
 		{
 			if (($result = fwrite($fp, self::substr($output, $written))) === FALSE)
 			{
 				break;
 			}
 		}

 		flock($fp, LOCK_UN);
 		fclose($fp);

 		if ( ! is_int($result))
 		{
 			@unlink($cache_path);
 			log_message('error', 'Unable to write the complete cache content at: '.$cache_path);
 			return;
 		}

 		chmod($cache_path, 0640);
 		log_message('debug', 'Cache file written: '.$cache_path);

 		// Send HTTP cache-control headers to browser to match file cache settings.
 		$this->set_cache_header($_SERVER['REQUEST_TIME'], $expire);
 	}

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

 	/**
 	 * Update/serve cached output
 	 *
 	 * @uses	CI_Config
 	 * @uses	CI_URI
 	 *
 	 * @param	object	&$CFG	CI_Config class instance
 	 * @param	object	&$URI	CI_URI class instance
 	 * @return	bool	TRUE on success or FALSE on failure
 	 */
 	public function _display_cache(&$CFG, &$URI)
 	{
 		$cache_path = ($CFG->item('cache_path') === '') ? APPPATH.'cache/' : $CFG->item('cache_path');

 		// Build the file path. The file name is an MD5 hash of the full URI
 		$uri = $CFG->item('base_url').$CFG->item('index_page').$URI->uri_string;

 		if (($cache_query_string = $CFG->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
 		{
 			if (is_array($cache_query_string))
 			{
 				$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
 			}
 			else
 			{
 				$uri .= '?'.$_SERVER['QUERY_STRING'];
 			}
 		}

 		$filepath = $cache_path.md5($uri);

 		if ( ! file_exists($filepath) OR ! $fp = @fopen($filepath, 'rb'))
 		{
 			return FALSE;
 		}

 		flock($fp, LOCK_SH);

 		$cache = (filesize($filepath) > 0) ? fread($fp, filesize($filepath)) : '';

 		flock($fp, LOCK_UN);
 		fclose($fp);

 		// Look for embedded serialized file info.
 		if ( ! preg_match('/^(.*)ENDCI--->/', $cache, $match))
 		{
 			return FALSE;
 		}

 		$cache_info = unserialize($match[1]);
 		$expire = $cache_info['expire'];

 		$last_modified = filemtime($filepath);

 		// Has the file expired?
 		if ($_SERVER['REQUEST_TIME'] >= $expire && is_really_writable($cache_path))
 		{
 			// If so we'll delete it.
 			@unlink($filepath);
 			log_message('debug', 'Cache file has expired. File deleted.');
 			return FALSE;
 		}

 		// Send the HTTP cache control headers
 		$this->set_cache_header($last_modified, $expire);

 		// Add headers from cache file.
 		foreach ($cache_info['headers'] as $header)
 		{
 			$this->set_header($header[0], $header[1]);
 		}

 		// Display the cache
 		$this->_display(self::substr($cache, self::strlen($match[0])));
 		log_message('debug', 'Cache file is current. Sending it to browser.');
 		return TRUE;
 	}

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

 	/**
 	 * Delete cache
 	 *
 	 * @param	string	$uri	URI string
 	 * @return	bool
 	 */
 	public function delete_cache($uri = '')
 	{
 		$CI =& get_instance();
 		$cache_path = $CI->config->item('cache_path');
 		if ($cache_path === '')
 		{
 			$cache_path = APPPATH.'cache/';
 		}

 		if ( ! is_dir($cache_path))
 		{
 			log_message('error', 'Unable to find cache path: '.$cache_path);
 			return FALSE;
 		}

 		if (empty($uri))
 		{
 			$uri = $CI->uri->uri_string();

 			if (($cache_query_string = $CI->config->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
 			{
 				if (is_array($cache_query_string))
 				{
 					$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
 				}
 				else
 				{
 					$uri .= '?'.$_SERVER['QUERY_STRING'];
 				}
 			}
 		}

 		$cache_path .= md5($CI->config->item('base_url').$CI->config->item('index_page').ltrim($uri, '/'));

 		if ( ! @unlink($cache_path))
 		{
 			log_message('error', 'Unable to delete cache file for '.$uri);
 			return FALSE;
 		}

 		return TRUE;
 	}

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

 	/**
 	 * Set Cache Header
 	 *
 	 * Set the HTTP headers to match the server-side file cache settings
 	 * in order to reduce bandwidth.
 	 *
 	 * @param	int	$last_modified	Timestamp of when the page was last modified
 	 * @param	int	$expiration	Timestamp of when should the requested page expire from cache
 	 * @return	void
 	 */
 	public function set_cache_header($last_modified, $expiration)
 	{
 		$max_age = $expiration - $_SERVER['REQUEST_TIME'];

 		if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && $last_modified <= strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']))
 		{
 			$this->set_status_header(304);
 			exit;
 		}

 		header('Pragma: public');
 		header('Cache-Control: max-age='.$max_age.', public');
 		header('Expires: '.gmdate('D, d M Y H:i:s', $expiration).' GMT');
 		header('Last-modified: '.gmdate('D, d M Y H:i:s', $last_modified).' GMT');
 	}

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

 	/**
 	 * Byte-safe strlen()
 	 *
 	 * @param	string	$str
 	 * @return	int
 	 */
 	protected static function strlen($str)
 	{
 		return (self::$func_overload)
 			? mb_strlen($str, '8bit')
 			: strlen($str);
 	}

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

 	/**
 	 * Byte-safe substr()
 	 *
 	 * @param	string	$str
 	 * @param	int	$start
 	 * @param	int	$length
 	 * @return	string
 	 */
 	protected static function substr($str, $start, $length = NULL)
 	{
 		if (self::$func_overload)
 		{
 			// mb_substr($str, $start, null, '8bit') returns an empty
 			// string on PHP 5.3
 			isset($length) OR $length = ($start >= 0 ? self::strlen($str) - $start : -$start);
 			return mb_substr($str, $start, $length, '8bit');
 		}

 		return isset($length)
 			? substr($str, $start, $length)
 			: substr($str, $start);
 	}
 }
	<?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 1.0.0
	* @filesource
	*/
	defined('BASEPATH') OR exit('No direct script access allowed');

	/**
	* Output Class
	*
	* Responsible for sending final output to the browser.
	*
	* @package CodeIgniter
	* @subpackage Libraries
	* @category Output
	* @author EllisLab Dev Team
	* @link https://codeigniter.com/user_guide/libraries/output.html
	*/
	class CI_Output {

	/**
	* Final output string
	*
	* @var string
	*/
	public $final_output;

	/**
	* Cache expiration time
	*
	* @var int
	*/
	public $cache_expiration = 0;

	/**
	* List of server headers
	*
	* @var array
	*/
	public $headers = array();

	/**
	* List of mime types
	*
	* @var array
	*/
	public $mimes = array();

	/**
	* Mime-type for the current page
	*
	* @var string
	*/
	protected $mime_type = 'text/html';

	/**
	* Enable Profiler flag
	*
	* @var bool
	*/
	public $enable_profiler = FALSE;

	/**
	* php.ini zlib.output_compression flag
	*
	* @var bool
	*/
	protected $_zlib_oc = FALSE;

	/**
	* CI output compression flag
	*
	* @var bool
	*/
	protected $_compress_output = FALSE;

	/**
	* List of profiler sections
	*
	* @var array
	*/
	protected $_profiler_sections = array();

	/**
	* Parse markers flag
	*
	* Whether or not to parse variables like {elapsed_time} and {memory_usage}.
	*
	* @var bool
	*/
	public $parse_exec_vars = TRUE;

	/**
	* mbstring.func_overload flag
	*
	* @var bool
	*/
	protected static $func_overload;

	/**
	* Class constructor
	*
	* Determines whether zLib output compression will be used.
	*
	* @return void
	*/
	public function __construct()
	{
	$this->_zlib_oc = (bool) ini_get('zlib.output_compression');
	$this->_compress_output = (
	$this->_zlib_oc === FALSE
	&& config_item('compress_output') === TRUE
	&& extension_loaded('zlib')
	);

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

	// Get mime types for later
	$this->mimes =& get_mimes();

	log_message('info', 'Output Class Initialized');
	}

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

	/**
	* Get Output
	*
	* Returns the current output string.
	*
	* @return string
	*/
	public function get_output()
	{
	return $this->final_output;
	}

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

	/**
	* Set Output
	*
	* Sets the output string.
	*
	* @param string $output Output data
	* @return CI_Output
	*/
	public function set_output($output)
	{
	$this->final_output = $output;
	return $this;
	}

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

	/**
	* Append Output
	*
	* Appends data onto the output string.
	*
	* @param string $output Data to append
	* @return CI_Output
	*/
	public function append_output($output)
	{
	$this->final_output .= $output;
	return $this;
	}

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

	/**
	* Set Header
	*
	* Lets you set a server header which will be sent with the final output.
	*
	* Note: If a file is cached, headers will not be sent.
	* @todo We need to figure out how to permit headers to be cached.
	*
	* @param string $header Header
	* @param bool $replace Whether to replace the old header value, if already set
	* @return CI_Output
	*/
	public function set_header($header, $replace = TRUE)
	{
	// If zlib.output_compression is enabled it will compress the output,
	// but it will not modify the content-length header to compensate for
	// the reduction, causing the browser to hang waiting for more data.
	// We'll just skip content-length in those cases.
	if ($this->_zlib_oc && strncasecmp($header, 'content-length', 14) === 0)
	{
	return $this;
	}

	$this->headers[] = array($header, $replace);
	return $this;
	}

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

	/**
	* Set Content-Type Header
	*
	* @param string $mime_type Extension of the file we're outputting
	* @param string $charset Character set (default: NULL)
	* @return CI_Output
	*/
	public function set_content_type($mime_type, $charset = NULL)
	{
	if (strpos($mime_type, '/') === FALSE)
	{
	$extension = ltrim($mime_type, '.');

	// Is this extension supported?
	if (isset($this->mimes[$extension]))
	{
	$mime_type =& $this->mimes[$extension];

	if (is_array($mime_type))
	{
	$mime_type = current($mime_type);
	}
	}
	}

	$this->mime_type = $mime_type;

	if (empty($charset))
	{
	$charset = config_item('charset');
	}

	$header = 'Content-Type: '.$mime_type
	.(empty($charset) ? '' : '; charset='.$charset);

	$this->headers[] = array($header, TRUE);
	return $this;
	}

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

	/**
	* Get Current Content-Type Header
	*
	* @return string 'text/html', if not already set
	*/
	public function get_content_type()
	{
	for ($i = 0, $c = count($this->headers); $i < $c; $i++)
	{
	if (sscanf($this->headers[$i][0], 'Content-Type: %[^;]', $content_type) === 1)
	{
	return $content_type;
	}
	}

	return 'text/html';
	}

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

	/**
	* Get Header
	*
	* @param string $header
	* @return string
	*/
	public function get_header($header)
	{
	// Combine headers already sent with our batched headers
	$headers = array_merge(
	// We only need [x][0] from our multi-dimensional array
	array_map('array_shift', $this->headers),
	headers_list()
	);

	if (empty($headers) OR empty($header))
	{
	return NULL;
	}

	// Count backwards, in order to get the last matching header
	for ($c = count($headers) - 1; $c > -1; $c--)
	{
	if (strncasecmp($header, $headers[$c], $l = self::strlen($header)) === 0)
	{
	return trim(self::substr($headers[$c], $l+1));
	}
	}

	return NULL;
	}

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

	/**
	* Set HTTP Status Header
	*
	* As of version 1.7.2, this is an alias for common function
	* set_status_header().
	*
	* @param int $code Status code (default: 200)
	* @param string $text Optional message
	* @return CI_Output
	*/
	public function set_status_header($code = 200, $text = '')
	{
	set_status_header($code, $text);
	return $this;
	}

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

	/**
	* Enable/disable Profiler
	*
	* @param bool $val TRUE to enable or FALSE to disable
	* @return CI_Output
	*/
	public function enable_profiler($val = TRUE)
	{
	$this->enable_profiler = is_bool($val) ? $val : TRUE;
	return $this;
	}

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

	/**
	* Set Profiler Sections
	*
	* Allows override of default/config settings for
	* Profiler section display.
	*
	* @param array $sections Profiler sections
	* @return CI_Output
	*/
	public function set_profiler_sections($sections)
	{
	if (isset($sections['query_toggle_count']))
	{
	$this->_profiler_sections['query_toggle_count'] = (int) $sections['query_toggle_count'];
	unset($sections['query_toggle_count']);
	}

	foreach ($sections as $section => $enable)
	{
	$this->_profiler_sections[$section] = ($enable !== FALSE);
	}

	return $this;
	}

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

	/**
	* Set Cache
	*
	* @param int $time Cache expiration time in minutes
	* @return CI_Output
	*/
	public function cache($time)
	{
	$this->cache_expiration = is_numeric($time) ? $time : 0;
	return $this;
	}

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

	/**
	* Display Output
	*
	* Processes and sends finalized output data to the browser along
	* with any server headers and profile data. It also stops benchmark
	* timers so the page rendering speed and memory usage can be shown.
	*
	* Note: All "view" data is automatically put into $this->final_output
	* by controller class.
	*
	* @uses CI_Output::$final_output
	* @param string $output Output data override
	* @return void
	*/
	public function _display($output = '')
	{
	// Note: We use load_class() because we can't use $CI =& get_instance()
	// since this function is sometimes called by the caching mechanism,
	// which happens before the CI super object is available.
	$BM =& load_class('Benchmark', 'core');
	$CFG =& load_class('Config', 'core');

	// Grab the super object if we can.
	if (class_exists('CI_Controller', FALSE))
	{
	$CI =& get_instance();
	}

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

	// Set the output data
	if ($output === '')
	{
	$output =& $this->final_output;
	}

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

	// Do we need to write a cache file? Only if the controller does not have its
	// own _output() method and we are not dealing with a cache file, which we
	// can determine by the existence of the $CI object above
	if ($this->cache_expiration > 0 && isset($CI) && ! method_exists($CI, '_output'))
	{
	$this->_write_cache($output);
	}

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

	// Parse out the elapsed time and memory usage,
	// then swap the pseudo-variables with the data

	$elapsed = $BM->elapsed_time('total_execution_time_start', 'total_execution_time_end');

	if ($this->parse_exec_vars === TRUE)
	{
	$memory = round(memory_get_usage() / 1024 / 1024, 2).'MB';
	$output = str_replace(array('{elapsed_time}', '{memory_usage}'), array($elapsed, $memory), $output);
	}

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

	// Is compression requested?
	if (isset($CI) // This means that we're not serving a cache file, if we were, it would already be compressed
	&& $this->_compress_output === TRUE
	&& isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
	{
	ob_start('ob_gzhandler');
	}

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

	// Are there any server headers to send?
	if (count($this->headers) > 0)
	{
	foreach ($this->headers as $header)
	{
	@header($header[0], $header[1]);
	}
	}

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

	// Does the $CI object exist?
	// If not we know we are dealing with a cache file so we'll
	// simply echo out the data and exit.
	if ( ! isset($CI))
	{
	if ($this->_compress_output === TRUE)
	{
	if (isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
	{
	header('Content-Encoding: gzip');
	header('Content-Length: '.self::strlen($output));
	}
	else
	{
	// User agent doesn't support gzip compression,
	// so we'll have to decompress our cache
	$output = gzinflate(self::substr($output, 10, -8));
	}
	}

	echo $output;
	log_message('info', 'Final output sent to browser');
	log_message('debug', 'Total execution time: '.$elapsed);
	return;
	}

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

	// Do we need to generate profile data?
	// If so, load the Profile class and run it.
	if ($this->enable_profiler === TRUE)
	{
	$CI->load->library('profiler');
	if ( ! empty($this->_profiler_sections))
	{
	$CI->profiler->set_sections($this->_profiler_sections);
	}

	// If the output data contains closing </body> and </html> tags
	// we will remove them and add them back after we insert the profile data
	$output = preg_replace('\|</body>.*?</html>\|is', '', $output, -1, $count).$CI->profiler->run();
	if ($count > 0)
	{
	$output .= '</body></html>';
	}
	}

	// Does the controller contain a function named _output()?
	// If so send the output there. Otherwise, echo it.
	if (method_exists($CI, '_output'))
	{
	$CI->_output($output);
	}
	else
	{
	echo $output; // Send it to the browser!
	}

	log_message('info', 'Final output sent to browser');
	log_message('debug', 'Total execution time: '.$elapsed);
	}

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

	/**
	* Write Cache
	*
	* @param string $output Output data to cache
	* @return void
	*/
	public function _write_cache($output)
	{
	$CI =& get_instance();
	$path = $CI->config->item('cache_path');
	$cache_path = ($path === '') ? APPPATH.'cache/' : $path;

	if ( ! is_dir($cache_path) OR ! is_really_writable($cache_path))
	{
	log_message('error', 'Unable to write cache file: '.$cache_path);
	return;
	}

	$uri = $CI->config->item('base_url')
	.$CI->config->item('index_page')
	.$CI->uri->uri_string();

	if (($cache_query_string = $CI->config->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
	{
	if (is_array($cache_query_string))
	{
	$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
	}
	else
	{
	$uri .= '?'.$_SERVER['QUERY_STRING'];
	}
	}

	$cache_path .= md5($uri);

	if ( ! $fp = @fopen($cache_path, 'w+b'))
	{
	log_message('error', 'Unable to write cache file: '.$cache_path);
	return;
	}

	if ( ! flock($fp, LOCK_EX))
	{
	log_message('error', 'Unable to secure a file lock for file at: '.$cache_path);
	fclose($fp);
	return;
	}

	// If output compression is enabled, compress the cache
	// itself, so that we don't have to do that each time
	// we're serving it
	if ($this->_compress_output === TRUE)
	{
	$output = gzencode($output);

	if ($this->get_header('content-type') === NULL)
	{
	$this->set_content_type($this->mime_type);
	}
	}

	$expire = time() + ($this->cache_expiration * 60);

	// Put together our serialized info.
	$cache_info = serialize(array(
	'expire' => $expire,
	'headers' => $this->headers
	));

	$output = $cache_info.'ENDCI--->'.$output;

	for ($written = 0, $length = self::strlen($output); $written < $length; $written += $result)
	{
	if (($result = fwrite($fp, self::substr($output, $written))) === FALSE)
	{
	break;
	}
	}

	flock($fp, LOCK_UN);
	fclose($fp);

	if ( ! is_int($result))
	{
	@unlink($cache_path);
	log_message('error', 'Unable to write the complete cache content at: '.$cache_path);
	return;
	}

	chmod($cache_path, 0640);
	log_message('debug', 'Cache file written: '.$cache_path);

	// Send HTTP cache-control headers to browser to match file cache settings.
	$this->set_cache_header($_SERVER['REQUEST_TIME'], $expire);
	}

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

	/**
	* Update/serve cached output
	*
	* @uses CI_Config
	* @uses CI_URI
	*
	* @param object &$CFG CI_Config class instance
	* @param object &$URI CI_URI class instance
	* @return bool TRUE on success or FALSE on failure
	*/
	public function _display_cache(&$CFG, &$URI)
	{
	$cache_path = ($CFG->item('cache_path') === '') ? APPPATH.'cache/' : $CFG->item('cache_path');

	// Build the file path. The file name is an MD5 hash of the full URI
	$uri = $CFG->item('base_url').$CFG->item('index_page').$URI->uri_string;

	if (($cache_query_string = $CFG->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
	{
	if (is_array($cache_query_string))
	{
	$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
	}
	else
	{
	$uri .= '?'.$_SERVER['QUERY_STRING'];
	}
	}

	$filepath = $cache_path.md5($uri);

	if ( ! file_exists($filepath) OR ! $fp = @fopen($filepath, 'rb'))
	{
	return FALSE;
	}

	flock($fp, LOCK_SH);

	$cache = (filesize($filepath) > 0) ? fread($fp, filesize($filepath)) : '';

	flock($fp, LOCK_UN);
	fclose($fp);

	// Look for embedded serialized file info.
	if ( ! preg_match('/^(.*)ENDCI--->/', $cache, $match))
	{
	return FALSE;
	}

	$cache_info = unserialize($match[1]);
	$expire = $cache_info['expire'];

	$last_modified = filemtime($filepath);

	// Has the file expired?
	if ($_SERVER['REQUEST_TIME'] >= $expire && is_really_writable($cache_path))
	{
	// If so we'll delete it.
	@unlink($filepath);
	log_message('debug', 'Cache file has expired. File deleted.');
	return FALSE;
	}

	// Send the HTTP cache control headers
	$this->set_cache_header($last_modified, $expire);

	// Add headers from cache file.
	foreach ($cache_info['headers'] as $header)
	{
	$this->set_header($header[0], $header[1]);
	}

	// Display the cache
	$this->_display(self::substr($cache, self::strlen($match[0])));
	log_message('debug', 'Cache file is current. Sending it to browser.');
	return TRUE;
	}

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

	/**
	* Delete cache
	*
	* @param string $uri URI string
	* @return bool
	*/
	public function delete_cache($uri = '')
	{
	$CI =& get_instance();
	$cache_path = $CI->config->item('cache_path');
	if ($cache_path === '')
	{
	$cache_path = APPPATH.'cache/';
	}

	if ( ! is_dir($cache_path))
	{
	log_message('error', 'Unable to find cache path: '.$cache_path);
	return FALSE;
	}

	if (empty($uri))
	{
	$uri = $CI->uri->uri_string();

	if (($cache_query_string = $CI->config->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
	{
	if (is_array($cache_query_string))
	{
	$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
	}
	else
	{
	$uri .= '?'.$_SERVER['QUERY_STRING'];
	}
	}
	}

	$cache_path .= md5($CI->config->item('base_url').$CI->config->item('index_page').ltrim($uri, '/'));

	if ( ! @unlink($cache_path))
	{
	log_message('error', 'Unable to delete cache file for '.$uri);
	return FALSE;
	}

	return TRUE;
	}

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

	/**
	* Set Cache Header
	*
	* Set the HTTP headers to match the server-side file cache settings
	* in order to reduce bandwidth.
	*
	* @param int $last_modified Timestamp of when the page was last modified
	* @param int $expiration Timestamp of when should the requested page expire from cache
	* @return void
	*/
	public function set_cache_header($last_modified, $expiration)
	{
	$max_age = $expiration - $_SERVER['REQUEST_TIME'];

	if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && $last_modified <= strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']))
	{
	$this->set_status_header(304);
	exit;
	}

	header('Pragma: public');
	header('Cache-Control: max-age='.$max_age.', public');
	header('Expires: '.gmdate('D, d M Y H:i:s', $expiration).' GMT');
	header('Last-modified: '.gmdate('D, d M Y H:i:s', $last_modified).' GMT');
	}

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

	/**
	* Byte-safe strlen()
	*
	* @param string $str
	* @return int
	*/
	protected static function strlen($str)
	{
	return (self::$func_overload)
	? mb_strlen($str, '8bit')
	: strlen($str);
	}

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

	/**
	* Byte-safe substr()
	*
	* @param string $str
	* @param int $start
	* @param int $length
	* @return string
	*/
	protected static function substr($str, $start, $length = NULL)
	{
	if (self::$func_overload)
	{
	// mb_substr($str, $start, null, '8bit') returns an empty
	// string on PHP 5.3
	isset($length) OR $length = ($start >= 0 ? self::strlen($str) - $start : -$start);
	return mb_substr($str, $start, $length, '8bit');
	}

	return isset($length)
	? substr($str, $start, $length)
	: substr($str, $start);
	}
	}