Extraction of PDF properties

<?php
function get_pdf_prop($file)
{
    $f = fopen($file,'rb');
    if(!$f)
        return false;

    //Read the last 16KB
    fseek($f, -16384, SEEK_END);
    $s = fread($f, 16384);

    //Extract cross-reference table and trailer
    if(!preg_match("/xref[\r\n]+(.*)trailer(.*)startxref/s", $s, $a))
        return false;
    $xref = $a[1];
    $trailer = $a[2];

    //Extract Info object number
    if(!preg_match('/Info ([0-9]+) /', $trailer, $a))
        return false;
    $object_no = $a[1];

    //Extract Info object offset
    $lines = preg_split("/[\r\n]+/", $xref);
    $line = $lines[1 + $object_no];
    $offset = (int)$line;
    if($offset == 0)
        return false;

    //Read Info object
    fseek($f, $offset, SEEK_SET);
    $s = fread($f, 1024);
    fclose($f);

    //Extract properties
    if(!preg_match('/<<(.*)>>/Us', $s, $a))
        return false;
    $n = preg_match_all('|/([a-z]+) ?\((.*)\)|Ui', $a[1], $a);
    $prop = array();
    for($i=0; $i<$n; $i++)
        $prop[$a[1][$i]] = $a[2][$i];
    return $prop;
}
?>