View file sys/inc/downloadfile.php

<?php

function DownloadFile($filename, $name, $mimetype = 'application/octet-stream')
{
    $size = filesize($filename);
    $time = date('r', filemtime($filename));
    $fm   = @fopen($filename, 'rb');
    if (!$fm) {
        header("HTTP/1.1 505 Internal server error");
        return;
    }
    $begin = 0;
    $end   = $size - 1;
    if (isset($_SERVER['HTTP_RANGE'])) {
        if (preg_match('/bytes=\h*(\d+)-(\d*)[\D.*]?/i', $_SERVER['HTTP_RANGE'], $matches)) {
            $begin = intval($matches[1]);
            if (!empty($matches[2])) {
                $end = intval($matches[2]);
            }
        }
    }
    if (isset($_SERVER['HTTP_RANGE'])) {
        header('HTTP/1.1 206 Partial Content');
    } else {
        header('HTTP/1.1 200 OK');
    }
    
    header('Connection: close');
    header('Content-Type: ' . $mimetype);
    header('Cache-Control: public, must-revalidate, max-age=0');
    header('Pragma: no-cache');
    header('Accept-Ranges: bytes');
    header('Content-Length:' . (($end - $begin) + 1));
    if (isset($_SERVER['HTTP_RANGE'])) {
        header("Content-Range: bytes $begin-$end/$size");
    }
    header("Content-Disposition: attachment; filename=$name");
    header("Content-Transfer-Encoding: binary");
    header("Last-Modified: $time");
    $cur = $begin;
    fseek($fm, $begin, 0);
    while (!feof($fm) && $cur <= $end && (connection_status() == 0)) {
        print fread($fm, min(1024 * 16, ($end - $cur) + 1));
        $cur += 1024 * 16;
    }
}