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File: class.gzip_encode.php
<?php
/**
 * News: I had once said that when PHP 4.0.5 comes out I will reccomend the built in
 * ob_gzhandler over my code unless you are generating flash or images on the fly.
 *
 * I was wrong. PHP 4.0.5 is out and ob_gzhandler doesn't work for me.
 *
 * Note: This is rather cool: http://leknor.com/code/gziped.php
 * It will calculate the effects of this class on a page.
 * compression level, cpu time, download time, etc
 *
 * Note: this may be better for some sites:
 * http://www.remotecommunications.com/apache/mod_gzip/
 * I've read that the above doesn't work with PHP output.
 *
 * Changes compared to the upstream version:
 *
 * 2007-03-27  Oliver Hader  <oh@inpublica.de>
 *  - Fixed bug #4623: Content encoding with x-gzip not allowed
 *  - Fixed missing comments and line formats (cleaner)
 * 2005-12-09  Peter Niederlag  <peter@niederlag.de>
 *	- Fixed bug #1976: PHP5 type-conversion of string 'true' and boolean
 *
 * $Id: class.gzip_encode.php 2663 2007-11-05 09:22:23Z ingmars $
 *
 * @author	Sandy McArthur, Jr. <leknor@leknor.com>
 */
/**
 * [CLASS/FUNCTION INDEX of SCRIPT]
 *
 *
 *
 *   53: class gzip_encode
 *  193:     function gzip_encode($level = 3, $debug=false, $outputCompressedSizes=false)
 *  268:     function gzip_accepted()
 *  317:     function get_complevel()
 *  342:     function linux_loadavg()
 *  363:     function freebsd_loadavg()
 *
 * TOTAL FUNCTIONS: 5
 * (This index is automatically created/updated by the extension "extdeveval")
 *
 */



/**
 * gzip_encode - a class to gzip encode php output
 *
 * @author		Sandy McArthur, Jr. <Leknor@Leknor.com>
 * @package		TYPO3
 * @subpackage	t3lib
 */
class gzip_encode {
	/**
	 * gzip_encode - a class to gzip encode php output
	 *
	 * By Sandy McArthur, Jr. <Leknor@Leknor.com>
	 *
	 * Copyright 2001 (c) All Rights Reserved, All Responsibility Yours.
	 * One very slight modification 2005 for PHP5 compatibility reasons for TYPO3 port by Peter Niederlag
	 *
	 * This code is released under the GNU LGPL Go read it over here:
	 * http://www.gnu.org/copyleft/lesser.html
	 *
	 * I do make one optional request, I would like an account on or a
	 * copy of where this code is used. If that is not possible then
	 * an email would be cool.
	 *
	 * How to use:
	 * 1. Output buffering has to be turned on. You can do this with ob_start()
	 *    <http://php.net/manual/function.ob-start.php> or in the php config
	 *    file. Nothing bad happens if output buffering isn't turned on, your
	 *    page just won't get compressed.
	 * 2. Include the class file.
	 * 3. At the _very_ end of your script create an instance of the encode
	 *    class.
	 *
	 * eg:
	 *	------------Start of file----------
	 *	|<?php
	 *	| ob_start();
	 *	| include('class.gzip_encode.php');
	 *	|?>
	 *	|<HTML>
	 *	|... the page ...
	 *	|</HTML>
	 *	|<?php
	 *	| new gzip_encode();
	 *	|?>
	 *	-------------End of file-----------
	 *
	 * Things to note:
	 * 1. There is no space before the beginning of the file and the '<?php ' tag
	 * 2. The ob_start() line is optional if output buffering is turned on in
	 *    the main config file.
	 * 3. Turning on and off output buffering just won't work.
	 * 4. There must be nothing after the last '?>' tag at the end of the file.
	 *    Be careful of a space hiding there.
	 * 5. There are better ways to compress served content but I think this is
	 *    the only way to compress php output.
	 * 6. Your auto_prepend_file is a good place for the ob_start() and
	 *    your auto_append_file is a good place for new gzip_encode().
	 * 7. If you put new gzip_encode() in your auto.append file then you can
	 *    call ob_end_flush() in your script to disable compression.
	 *
	 * This was written from scratch from info freely available on the web.
	 *
	 * These site(s) were useful to me:
	 *	http://www.php.net/manual/
	 *	http://www.ietf.org/rfc/rfc2616.txt (Sections: 3.5, 14.3, 14.11)
	 *
	 * Requirments:
	 *	PHP 4.0.1+:	I use the '===' operator, and output buffering, crc32();
	 *	zlib:		Needed for the gzip encoding. (Odds are you have it)
	 *
	 * Benchmarks:
	 *	Take a look at http://Leknor.com/code/gziped.php and feed it a page to
	 *	get an idea of how it will preform on your data or page.
	 *
	 * To Do:
	 * 1. I have reports of no content errors. I can't seem to duplicate this.
	 *    Please visit my discussion boards if you think you may be able to help
	 * 2. The Accept-Encoding isn't handled to spec. Check out 14.3 in RFC 2616
	 *    to see how it should be done.
	 *
	 * Change Log:
	 *	0.66:	Big bug fix. It wouldn't compress when it should.
	 *	0.65:	Fix for PHP-4.0.5 suddenly removing the connection_timeout() function.
	 *	0.62:	Fixed a typo
	 *	0.61:	Detect file types more like described in the magic number files, also
	 *		added detection for gzip and pk zip files.
	 *	0.6:	Detect common file types that shouldn't be compressed, mainly
	 *		for images and swf (Shockwave Flash doesn't really accept gzip)
	 *	0.53:	Made gzip_accepted() method so everyone can detect if a page
	 *		will be gzip'ed with ease.
	 *	0.52:	Detection and graceful handling of improper install/missing libs
	 *	0.51:	Added FreeBSD load average detection.
	 *	0.5:	Passing true as the first parameter will try to calculate the
	 *		compression level from the server's load average. Passing true
	 *		as the second parameter will turn on debugging.
	 *	0.4:	No longer uses a temp file to compress the output. Should speed
	 *		thing up a bit and reduce wear on your hard disk. Also test if
	 *		the http headers have been sent.
	 *	0.31:	Made a small change to the tempnam() line to hopefully be more
	 *		portable.
	 *	0.3:	Added code for the 'x-gzip'. This is untested, I don't know of
	 *		any browser that uses it but the RFC said to look out for it.
	 *	0.2:	Checks for 'gzip' in the Accept-Encoding header
	 *	0.1:	First working version.
	 *
	 * Thanks To (Suggestions and stuff):
	 *	?@boas.anthro.mnsu.edu	http://php.net/manual/function.gzcompress.php
	 *	Kaoslord		<kaoslord@chaos-productions.com>
	 *	Michael R. Gile		<gilem@wsg.net>
	 *	Christian Hamm		<chh@admaster.de>
	 *
	 * The most recent version is available at:
	 *	http://Leknor.com/code/
	 *
	 */

	var $_version = 0.66; // Version of the gzip_encode class

	var $level;		// Compression level
	var $encoding;	// Encoding type
	var $crc;		// crc of the output
	var $size;		// size of the uncompressed content
	var $gzsize;	// size of the compressed content

	/**
	 * gzip_encode constructor - gzip encodes the current output buffer
	 * if the browser supports it.
	 *
	 * Note: all arguments are optionial.
	 *
	 * You can specify one of the following for the first argument:
	 * 	0:	No compression
	 * 	1:	Min compression
	 * 	...	Some compression (integer from 1 to 9)
	 * 	9:	Max compression
	 * 	true:	Determin the compression level from the system load. The
	 * 		higher the load the less the compression.
	 *
	 * You can specify one of the following for the second argument:
	 * 	true:	Don't actully output the compressed form but run as if it
	 * 		had. Used for debugging.
	 *
	 * @param	integer		$level: Define the level of compression between 0 (none) and 9 (best compression)
	 * @param	boolean		$debug: If true, no data will be outputted (default: false)
	 * @param	boolean		$outputCompressedSizes: If true, the original and compressed size appended as HTML (default: false)
	 * @return	void
	 */
	function gzip_encode($level=3, $debug=false, $outputCompressedSizes=false) {
		if (!function_exists('gzcompress')) {
		    trigger_error('gzcompress not found, ' .
			    'zlib needs to be installed for gzip_encode',
			    E_USER_WARNING);
		    return;
		}
		if (!function_exists('crc32')) {
		    trigger_error('crc32() not found, ' .
			    'PHP >= 4.0.1 needed for gzip_encode', E_USER_WARNING);
		    return;
		}
		if (headers_sent()) return;
		if (connection_status() !== 0) return;
		$encoding = $this->gzip_accepted();
		if (!$encoding) return;
		$this->encoding = $encoding;

		if (strtolower($level) == 'true' || $level === true) {
		    $level = $this->get_complevel();
		}
		$this->level = $level;

		$contents = ob_get_contents();
		if ($contents === false) return;

		$gzdata = "\x1f\x8b\x08\x00\x00\x00\x00\x00"; // gzip header

			// By Kasper Skaarhoj, start
		if ($outputCompressedSizes)	{
			$contents.=chr(10)."<!-- Compressed, level ".$level.", original size was ".strlen($contents)." bytes. New size is ".strlen(gzcompress($contents, $level))." bytes -->";
			$size = strlen($contents);	// Must set again!
		}
			// By Kasper Skaarhoj, end

		$size = strlen($contents);
		$crc = crc32($contents);
		$gzdata .= gzcompress($contents, $level);
		$gzdata = substr($gzdata, 0, strlen($gzdata) - 4); // fix crc bug
		$gzdata .= pack("V",$crc) . pack("V", $size);

		$this->size = $size;
		$this->crc = $crc;
		$this->gzsize = strlen($gzdata);

		if ($debug) {
		    return;
		}

		ob_end_clean();
		Header('Content-Encoding: ' . $encoding);
		Header('Content-Length: ' . strlen($gzdata));
		Header('X-Content-Encoded-By: class.gzip_encode '.$this->_version);

		echo $gzdata;
	}


	/**
	 * gzip_accepted() - Test headers for Accept-Encoding: gzip
	 * Returns: if proper headers aren't found: false
	 *          if proper headers are found: 'gzip' or 'x-gzip'
	 *
	 * Tip: using this function you can test if the class will gzip the output
	 *  without actually compressing it yet, eg:
	 *    if (gzip_encode::gzip_accepted()) {
	 *       echo "Page will be gziped";
	 *    }
	 *  note the double colon syntax, I don't know where it is documented but
	 *  somehow it got in my brain.
	 *
	 * @return	mixed		Returns 'gzip' if the client browser accepts gzip encoding, otherwise false
	 */
	function gzip_accepted() {
			// Checks, if the accepted encoding supports gzip or x-gzip.
			// Furthermore a qvalue check is done. "gzip;q=0" means no gzip accepted at all.
		$acceptEncoding = t3lib_div::getIndpEnv('HTTP_ACCEPT_ENCODING');
		if (preg_match('/(^|,\s*)(x-)?gzip(;q=(\d(\.\d+)?))?(,|$)/i', $acceptEncoding, $match) && ($match[4] === '' || $match[4] > 0)) {
			$encoding = 'gzip';
		} else {
			return false;
		}

			// Test file type. I wish I could get HTTP response headers.
		$magic = substr(ob_get_contents(),0,4);
		if (substr($magic,0,2) === '^_') {
		    // gzip data
		    $encoding = false;
		} else if (substr($magic,0,3) === 'GIF') {
		    // gif images
		    $encoding = false;
		} else if (substr($magic,0,2) === "\xFF\xD8") {
		    // jpeg images
		    $encoding = false;
		} else if (substr($magic,0,4) === "\x89PNG") {
		    // png images
		    $encoding = false;
		} else if (substr($magic,0,3) === 'FWS') {
		    // Don't gzip Shockwave Flash files. Flash on windows incorrectly
		    // claims it accepts gzip'd content.
		    $encoding = false;
		} else if (substr($magic,0,2) === 'PK') {
		    // pk zip file
		    $encoding = false;
		}

		return $encoding;
	}

	/**
	 * get_complevel() - The level of compression we should use.
	 *
	 * Returns an int between 0 and 9 inclusive.
	 *
	 * Tip: $gzleve = gzip_encode::get_complevel(); to get the compression level
	 *      that will be used with out actually compressing the output.
	 *
	 * Help: if you use an OS other then linux please send me code to make
	 * this work with your OS - Thanks
	 *
	 * @return	integer		Suggests a level of compression (0..9) for the current situation
	 */
    function get_complevel() {
		$uname = posix_uname();
		switch ($uname['sysname']) {
		    case 'Linux':
				$cl = (1 - $this->linux_loadavg()) * 10;
				$level = (int)max(min(9, $cl), 0);
			break;
		    case 'FreeBSD':
				$cl = (1 - $this->freebsd_loadavg()) * 10;
				$level = (int)max(min(9, $cl), 0);
				break;
			    default:
				$level = 3;
			break;
		}
		return $level;
	}

	/**
	 * linux_loadavg() - Gets the max() system load average from /proc/loadavg
	 *
	 * The max() Load Average will be returned
	 *
	 * @return	float		Returns the current load average
	 */
	function linux_loadavg() {
		$buffer = "0 0 0";
		$f = fopen("/proc/loadavg","rb");
		if (!feof($f)) {
		    $buffer = fgets($f, 1024);
		}
		fclose($f);
		$load = explode(" ",$buffer);
		return max((float)$load[0], (float)$load[1], (float)$load[2]);
	}

	/**
	 * freebsd_loadavg() - Gets the max() system load average from uname(1)
	 *
	 * The max() Load Average will be returned
	 *
	 * I've been told the code below will work on solaris too, anyone wanna
	 * test it?
	 *
	 * @return	float		Returns the current load average
	 */
	function freebsd_loadavg() {
		$buffer= `uptime`;
		$load = array();
		ereg("averag(es|e): ([0-9][.][0-9][0-9]), ([0-9][.][0-9][0-9]), ([0-9][.][0-9][0-9]*)", $buffer, $load);

		return max((float)$load[2], (float)$load[3], (float)$load[4]);
	}
}

?>