Create a zip file and download it error - php

Question

I am trying to download some files by creating the zip file on a local-server. The file is downloaded in zip format, but when I try to extract it, it gives me the error:
End-of-central-directory signature not found. Either this file is not
a zip file, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zip file comment will be found
on the last disk(s) of this archive.
This is the code I am using for this:
function download_gallery($id) {
$this->load->library('zip');
$path = '/uploads/post/' . $id;
$this->zip->read_dir($path, FALSE);
$filename = $id . '.zip';
// http headers for zip downloads
header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Cache-Control: public");
header("Content-Description: File Transfer");
header('Content-Type: application/zip'); // mime type
header('Content-Disposition: attachment;filename="' . $filename . '"'); // tell browser what's the file name
header('Cache-Control: max-age=0'); // no cache
header("Content-Transfer-Encoding: binary");
header("Content-Length: " . filesize($path, $filename));
// Download the file to your desktop. Name it "my_backup.zip"
$this->zip->download($filename);
}
I checked the values of all variables which are being passing into the function, and all are fine.
I'm using codeigniter for this by the way.

Answer 1

I see three mistakes.
You never call $this->zip->archive($filename); therefore the zip file doesn't exist at any time.
filesize($path, $filename) is wrong usage of this function. filesize takes only one parameter.
I believe $this->zip->download($filename); already setup the required headers for the download, there is no need to do that yourself.