Appearance of user id when downloading to the file

There's this code which I have

function pushfile(&$file) {
    header_remove();
  if (isset($file["type"])) header('Content-Type: '.$file["type"]);
  if (isset($file["name"])) header('Content-Disposition: attachment; filename="'.$file["name"].'"');
  print $file["name"];
  header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
  header("Pragma: ");
  echo $file["content"];
  exit;

$h=fopen($filename,"r");
        $content = fread($h, filesize($filename));
        fclose($h);
        $file["type"] = "application/";  //
        $file["name"] = $real_filename;
        $file["content"] = $content."*".$context['user']['id'];
        pushfile($file);

This ID number was well placed into the downloaded file, but it disappeared after converting it (e.g. from pdf to epub). Is there a good solution for that?