Random file I found on desktop...

directory.php

<?php
/**
 * Template Name: Directory Listing
*/
$dr = realpath(dirname($_SERVER['SCRIPT_FILENAME']));
$document_root = realpath($_SERVER['DOCUMENT_ROOT']);

function relpath($path = null) {
	global $dr, $document_root;
	if ($path == null || ! strstr(($path = realpath($path)),$document_root) || ! strstr($path,$dr)) return ".";
	
	return str_replace($dr . "/", "",$path);
}

$names = scandir($dir_name = relpath($_GET['dir']));
if(count($names)):
?><ul><?php
foreach($names as $file) {
	
	$truefile = relpath($dir_name . "/" . $file);
	
	echo "<!--\n";
		echo "file: " . $file . "\n";
		echo "truefile: " . $truefile . "\n";
		echo "relative path: " . relpath($truefile) . "\n";
		echo "realpath: " . ($path = realpath($truefile)). "\n";
		echo "Script Root: " . $dr . "\n";
		echo "-->\n";
		
	if(is_dir($truefile)) {				
		echo "<!-- Is dir!! -->\n";
		if ($file != "." && $truefile != ".") {
			?><li><a href="?dir=<?php echo (($file == "..") ? $file : $truefile); ?>"><?php echo $file; ?></a></li><?php 
		}
		else echo "<!-- condition check failed $truefile, $file -->\n";
	}
	else {
		if(realpath($file) != realpath($_SERVER['SCRIPT_FILENAME'])):
			?><li><a href="<?php echo $truefile; ?>"><?php echo $file; ?></a></li><?php
		endif;
	}
}
?></ul><?php
endif;
?>