how to detect a successful file download?

[mark_nsx]

Hi there,

Im working on a script which facilitates file download off of a server (.zip files)
and I would like to know how to detect a successful download..
This is the approach I have tried so far but failed (tried comparing the return value of fpassthru with the stored file size of the file to be downloaded)... Any ideas? thanks!

[code]
// Set headers
header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Content-Type: application/force-download");
header("Content-Disposition: attachment; filename=$file_name");
header("Content-Description: File Transfer");

// Read file to download
$fp = fopen("$file_url", "r");
$res = fpassthru($fp);

// Successful download
if ($res == $file_size) {
// Update product download date/# of downloads
$order->updateOrderHistory($order_ID, $prod_ID);
}

// Close file pointer
fclose($fp);
[/code]