Downloading large file with php
<p>I have to write a php script to download potentially large files. The file I'm reporting here works fine most of the times. However, if the client's connection is slow the request ends (with status code 200) in the middle of the downloading, but not always at the very same point, and not at the very same time. I tried to overwrite some php.ini variables (see  the first statements) but the problem remains.
I don't know if it's relevant but my hosting server is SiteGround, and for simple static file requests, the download works fine also with slow connections.</p>

<p>I've found <a href="http://stackoverflow.com/questions/4425227/forced-downloading-large-file-with-php">Forced downloading large file with php</a> but I didn't understand mario's answer. I'm new to web programming.</p>

<p>So here's my code.</p>

<pre><code>    &lt;?php
    ini_set('memory_limit','16M');
    ini_set('post_max_size', '30M');
    set_time_limit(0);

    include ('../private/database_connection.php');


    $downloadFolder = '../download/';
    $fileName = $_POST['file'];
    $filePath = $downloadFolder . $fileName;
    if($fileName == NULL)
    {
        exit;
    }
    ob_start();
    session_start();


    if(!isset($_SESSION['Username']))
    {
        // or redirect to login (remembering this download request)
        $_SESSION['previousPage'] = 'download.php?file=' . $fileName;
        header("Location: login.php");
        exit;
    }

    if (file_exists($filePath))
    {               
        header('Content-Description: File Transfer');
        header('Content-Type: application/octet-stream');
        //header('Content-Disposition: attachment; filename='.$fileName);
        header("Content-Disposition: attachment; filename=\"$fileName\"");
        header('Content-Transfer-Encoding: binary');
        header('Expires: 0');
        header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
        //header('Pragma: public');
        header('Content-Length: ' . filesize($filePath));
        ob_clean();
        flush();

        // download
        // 1
//      readfile($filePath);
        // 2
        $file = @fopen($filePath,"rb");
        if ($file) {
          while(!feof($file)) {
            print(fread($file, 1024*8));
            flush();
            if (connection_status()!=0) {
              @fclose($file);
              die();
            }
          }
          @fclose($file);
        }
        exit;
    }
    else
    {
        header('HTTP/1.1 404 File not found');
        exit;
    }
?&gt;
</code></pre>
