<?php

$file = @ fopen($file_dir . $file_name,"r");

$filesize=filesize($file_dir.$file_name);

header('Content-Description:File Transfer');

header("Content-Type:application/octet-stream");

header('Content-Transfer-Encoding:binary');

header("Accept-Ranges: bytes");

header('Expires:0');

header('Cache-Control:must-revalidate');

header('Pragma:public');

header("Content-Length:".$filesize);

header("Content-Disposition:attachment;filename=".$file_name);

ob_start();

fseek($file,0);

while (!feof($file)) {

    set_time_limit(0);

    print (fread($file, 1024 * 8));

    ob_flush();

    flush();

}

fclose($file);