downloading large zip files to the browser in php, chunking - php

Question

I am trying to download large zip files (800MB to 1GB) containing audio files to the browser. As I have seen so far, chunking seems to be the most popular approach, but I am having zero luck. The code I have been working with is
$filename = $_SERVER['DOCUMENT_ROOT'] . $filepath;
$download_rate = 5000;
$progress = 0;
if (file_exists($filename)) {
header('Cache-control: private');
header('Content-Type: application/octet-stream');
header('Content-Length: '.filesize($filename));
header('Content-Disposition: filename='.basename($filename));
flush();
$file = fopen($filename, "r");
while(!feof($file)) {
// send the current file part to the browser
print fread($file, round($download_rate * 1024));
// flush the content to the browser
flush();
// sleep one second
sleep(1);
}
fclose($file);
} else echo 'File does not exist!';
This works for a wide variety of file types and sizes up to a certain point -- I have no problem downloading typical PDFs, etc. But the browser just spins and spins when I try to download large zip files, and eventually dies (around 2 minutes). I am really needing some help here. I've tried a number of code variants for chucking, but something always seems to die and I'm not sure what I'm doing wrong. Perhaps there's a better approach to chunking?

Answer 1

Consider change change for readfile will not present any memory issues, your lost download rate and progress show in browser. your limit download rate in .httaccess.
$filename = $_SERVER['DOCUMENT_ROOT'] . $filepath;
if (file_exists($filename)) {
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="'.basename($filename).'"');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header('Content-Length: '.filesize($filename));
readfile($filename);
} else echo 'File does not exist!';
https://www.php.net/manual/en/function.readfile.php