Directory Listing erzwingen?

<?php
$default="./";
$this_file="./cd.php";
if(isset($save)){
 $fname=str_replace(" ","_",$fname);
 $fname=str_replace("%20","_",$fname);
 header("Cache-control: private");
 header("Content-type: application/force-download");
 header("Content-Length: ".filesize($save));
 header("Content-Disposition: attachment; filename=$fname");
 $fp = fopen($save, 'r');
 fpassthru($fp);
 fclose($fp);
 unset($save);
 exit;
 }
echo "<div align=center>
<font face='Arial' size='2' color='#000000'>
DOCUMENT ROOT: $DOCUMENT_ROOT
<form method=post action=$this_file>";
if(!isset($dir)){
 $dir="$default";
 }
echo "<input type=text size=60 name=dir value='$dir'>
<input type=submit value='get contents'>
</form>
</div>";
$path=$dir;
if(isset($dir)){
if ($dir = @opendir("$dir")) {
 while (($file = readdir($dir)) !== false) {
 if($file!="." && $file!=".."){
 if(is_file("$path/$file")){
 $disk_space=filesize("$path/$file");
 $kb=$disk_space/1024;
 $total_kb = number_format($kb, 2, '.', '');
 $total_kb2="Kb";
 echo "$file - <a href='./$this_file?save=$path/$file&fname=$file'>save</a> - $total_kb$total_kb2<br>\n";
 }
else{
 echo "<a href='./$this_file?dir=$path/$file'>CD></a> $file<br>\n";
 }
 }
}
closedir($dir);
}
}
echo "</font>";
?>