Source of source.php

<?php
/*
   The Index software may be freely distributed.
   See license.txt for details.
*/
define('ROOT', './');
$files = array(
        "source.php", // Must be the first one!
        "text.inc",
        "layout.inc",
        "list/random.inc",
        "index.php",
        "item.php",
        "submit.php",
        "changes.php",
        "about.php",
        "counts/count.inc",
        "counts/jump.php",
        "list/list.inc",
        "notes/notes.inc",
        "license.txt"
        );
?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<html>
    <head>
        <title>Source of <?php print $file ?></title>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    </head>
    <body>
        <pre>
<?php
if ($file != "")
{
    $ok = 0;
    reset($files);
    while (list(,$listed) = each($files))
    {
        if ($file == $listed)
        {
            $ok = 1;
        }
    }
    if (!$ok)
    {
        print "$file: Access denied\n\n";
        print "You can only view sources of the Index software. Access to any other file will always be denied.\n";
    }
    else
    {
        $file = ROOT . $file;
        $f = @fopen($file, "r");
        if ($f)
        {
            while (!feof($f))
            {
                $s = fgets($f, 4096);
                $s = htmlentities($s);
                for ($i = 0; $i < count($files); $i++)
                {
                    $s = str_replace($files[$i],
                            "<a href=\"source.php?file=$files[$i]\">$files[$i]</a>", $s);
                }
                print $s;
            }
            fclose($f);
        }
        else
        {
            print "$file: cannot open";
        }
    }
}
else
{
    ?>No file<?php
}
?>
        </pre>
    </body>
</html>