Downloading large files reliably in PHP

Question

I have a php script on a server to send files to recipents: they get a unique link and then they can download large files. Sometimes there is a problem with the transfer and the file is corrupted or never finishes. I am wondering if there is a better way to send large files

Code:

$f = fopen(DOWNLOAD_DIR.$database[$_REQUEST['fid']]['filePath'], 'r');
while(!feof($f)){
    print fgets($f, 1024);
}
fclose($f);

I have seen functions such as

http_send_file
http_send_data

But I am not sure if they will work.

What is the best way to solve this problem?

Regards
erwing

Answer 1

I have used the following snippet found in the comments of the php manual entry for readfile:

function _readfileChunked($filename, $retbytes=true) {
    $chunksize = 1*(1024*1024); // how many bytes per chunk
    $buffer = '';
    $cnt =0;
    // $handle = fopen($filename, 'rb');
    $handle = fopen($filename, 'rb');
    if ($handle === false) {
        return false;
    }
    while (!feof($handle)) {
        $buffer = fread($handle, $chunksize);
        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;
}