<?php
	# for full comments, look in modules/class.gzip_encode.docs

class gzip_encode {
    /*
     * gzip_encode - a class to gzip encode php output
     * By Sandy McArthur, Jr. <hide@address.com>
     *
     * 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.
     */

    var $_version = 0.67; // 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

    function gzip_encode($level = 3, $debug = false) {
	global $HTTP_ACCEPT_ENCODING;
	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 ($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
	$size = strlen($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: ' . $encoding);
	Header('Vary: Accept-Encoding');
	Header('Content-Length: ' . strlen($gzdata));
	Header('X-Content-Encoded-By: class.gzip_encode '.$this->_version);

	echo $gzdata;
    }
   

    function gzip_accepted() {
	global $HTTP_ACCEPT_ENCODING;
	if (strpos($HTTP_ACCEPT_ENCODING, 'gzip') === false) return false;
	if (strpos($HTTP_ACCEPT_ENCODING, 'x-gzip') === false) {
	    $encoding = 'gzip';
	} else {
	    $encoding = 'x-gzip';
	}

	// 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;
    }

    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;
    }

    function linux_loadavg() {
	$buffer = "0 0 0";
	$f = fopen("/proc/loadavg","r");
	if (!feof($f)) {
	    $buffer = fgets($f, 1024);
	}
	fclose($f);
	$load = explode(" ",$buffer);
	return max((float)$load[0], (float)$load[1], (float)$load[2]);
    }

    function freebsd_loadavg() {
	$buffer= `uptime`;
	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]);
    } 
}

?>