download - Streaming a large file using PHP

Question

I have a 200MB file that I want to give to a user via download. However, since we want the user to only download this file once, we are doing this:

echo file_get_contents('http://some.secret.location.com/secretfolder/the_file.tar.gz');

to force a download. However, this means that the whole file has to be loaded in memory, which usually doesn't work. How can we stream this file to them, at some kb per chunk?

Answer 1

Try something like this (source http://teddy.fr/2007/11/28/how-serve-big-files-through-php/):

<?php
define('CHUNK_SIZE', 1024*1024); // Size (in bytes) of tiles chunk

// Read a file and display its content chunk by chunk
function readfile_chunked($filename, $retbytes = TRUE) {
    $buffer = '';
    $cnt    = 0;
    $handle = fopen($filename, 'rb');

    if ($handle === false) {
        return false;
    }

    while (!feof($handle)) {
        $buffer = fread($handle, CHUNK_SIZE);
        echo $buffer;
        ob_flush();
        flush();

        if ($retbytes) {
            $cnt += strlen($buffer);
        }
    }

    $status = fclose($handle);

    if ($retbytes && $status) {
        return $cnt; // return num. bytes delivered like readfile() does.
    }

    return $status;
}

// Here goes your code for checking that the user is logged in
// ...
// ...

if ($logged_in) {
    $filename = 'path/to/your/file';
    $mimetype = 'mime/type';
    header('Content-Type: '.$mimetype );
    readfile_chunked($filename);

} else {
    echo 'Tabatha says you haven't paid.';
}
?>