File download in php, memory limit problem?

Question

A client of mine decided to move the website from a somewhat nice server to a... lets call it lesser nice server.

The problem is, there's a file with 40MBs to be downloaded and the memory limit on the server is 32. To make it even more difficult for me, they don't allow fopen...

Also, if i reduce the file size to 20MB it works fine.

So, my question is, what can i do - besides reducing the file size - to make this work?

Thank you

EDIT:`

        $fsize = filesize($file_path);
        $path_parts = pathinfo($file_path);
        $ext = strtolower($path_parts["extension"]);


        switch ($ext) {
            case "pdf": $ctype = "application/pdf";
                break;
            case "exe": $ctype = "application/octet-stream";
                break;
            case "zip": $ctype = "application/zip";
                break;
            case "doc": $ctype = "application/msword";
                break;
            case "xls": $ctype = "application/vnd.ms-excel";
                break;
            case "ppt": $ctype = "application/vnd.ms-powerpoint";
                break;
            case "gif": $ctype = "image/gif";
                break;
            case "png": $ctype = "image/png";
                break;
            case "jpeg":
            case "jpg": $ctype = "image/jpg";
                break;
            default: $ctype = "application/force-download";
        }

        header("Pragma: public"); // required
        header("Expires: 0");
        header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
        header("Cache-Control: private", false); // required for certain browsers
        header("Content-Type: $ctype");
        header("Content-Disposition: attachment; filename=\"" . basename($file_path) . "\";");
        header("Content-Transfer-Encoding: binary");
        header("Content-Length: " . $fsize);
        ob_clean();
        flush();
        readfile($file_path);`

The code i saw on php.net

// If it's a large file, readfile might not be able to do it in one go, so:
$chunksize = 1 * (1024 * 1024); // how many bytes per chunk
if ($size > $chunksize) {
  $handle = fopen($realpath, 'rb');
  $buffer = '';
  while (!feof($handle)) {
    $buffer = fread($handle, $chunksize);
    echo $buffer;
    ob_flush();
    flush();
  }
  fclose($handle);
} else {
  readfile($realpath);
}

Answer 1

Use readfile() instead. It'll stream the file in small chunks and handle all the background work to keep memory usage minimal.