Display a pdf without revealing the path

<?php
$file = "reports/".urldecode($_REQUEST['dir'])."/".urldecode($_REQUEST['rep']);
$len = filesize($file);
header("Cache-Control: no-store, maxage=1, must-revalidate"); // HTTP/1.1
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: public"); // HTTP/1.0
header("Content-type: application/pdf");
header("Content-Length: $len");
header("Content-Disposition: inline; filename=file1.pdf");
header("Content-Transfer-Encoding: binary\n");
readfile($file);
?>