PHP force download, not sending full binary files - php

Question

I'm creating a protected file download system for an e-commerce website. I am using PHP to authenticate that a user is logged in and owns the product before it is downloaded. I am using the example provided by the PHP.net manual but have run into an error serving both PDF and PNG files.
It has worked at one point, during development. Now that we've gone live, it seems to have broke... Fortunately the website is not running full-force at the moment so it's not a huge issue right now.
What is happening:
You visit the download URL. You are verified as an owner of the product, and the download starts. Everything appears to be normal, reviewing the headers everything looks OK. The header states the content length is "229542" (224.16kb), which looks OK.
The problem:
When the download completes, the file size is only 222 bytes. There are no errors displayed, and no PHP errors/warnings/notices are being sent in the file or browser. It's as if PHP is being terminated, but without any warnings. Even if I turn debugging on, I don't see any warnings.
The source file looks like this (in Notepad++, it's a PDF so it's binary)
When downloaded, it looks like this (Only 7 lines, compared to 2554)
My guess:
I am fairly certain the issue is header related. Maybe caused by a plugin? This shows up in Chrome's networking console:
Response Headers:
Below are the response headers. The "Connection: close" concerns me. I am not sending that header. I'm guessing it is sent by the exit command.
Access-Control-Allow-Origin:*
Cache-Control:must-revalidate, post-check=0, pre-check=0
Connection:close
Content-Description:File Transfer
Content-Disposition:attachment; filename="workbook.pdf"
Content-Length:229542
Content-Transfer-Encoding:binary
Content-Type:application/pdf
Date:Tue, 03 Sep 2013 21:16:14 GMT
Expires:0
Pragma:public
Server:Apache
X-Powered-By:PleskLin
I have also tried:
Turning on PHP debugging to get some sort of error/warning, but I don't get anything useful in browser or in the downloaded file source.
Outputting to the browser, rather than streaming. The file is still cut short, I would expect a PDF would try to display in the browser's PDF reader - but it doesn't even try. Just a white page with a bunch of unknown symbols.
Using +rb read mode, using fopen( $file['file'], 'rb' ); echo fread( $fh, filesize( $file['file'] ) ); fclose( $fh );
Using ignore_user_abort(true) and set_time_limit(0) to no effect (also tried set_time_limit(10000) just for in case, still nothing)
Sending a .txt file. This worked. I tried with a simple 5-byte text file, and again with an 86.3kb file. Both appear to have come out the same as they went in. So it must be related to binary files...
/* --- This is what the $file variable looks like:
$file = array(
[file] => /var/www/vhosts/my-website/uploads/workbook.pdf
[type] => application/pdf
[filesize] => 229542
[filename] => workbook.pdf
[upload_date] => 1377278303
);
*/
// Stream the file to the user
if (file_exists($file['file'])) {
header_remove(); // Remove any previously set header
header('Content-Description: File Transfer');
header('Content-Type: ' . $file['type']);
header('Content-Disposition: attachment; filename="'.$filename.'"');
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: ' . $filesize);
ob_clean();
flush();
readfile($file['file']);
exit;
}

Answer 1

I know this is an older thread but I have the solution for everyone here.
You have a script somewhere in your application that's compressing spaces or other characters.
ob_start("sanitize_output");
That was the problem in one scenario I noticed. If you turn off the buffer reduction script (called "sanitize_output" above) then your .pdf will show up normally. That extra 2kb's you noticed that were trimmed was probably from spacing or cutting out unneeded characters.

Answer 2

Try this code: Just give $file a relative path to the file and check it.
<?php
// your file to download
$file = path/to/the/file;
header("Expires: 0");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
$ext = pathinfo($file, PATHINFO_EXTENSION);
$basename = pathinfo($file, PATHINFO_BASENAME);
header("Content-type: application/".$ext);
// tell file size
header('Content-length: '.filesize($file));
// set file name
header("Content-Disposition: attachment; filename=\"$basename\"");
readfile($file);
// Exit script. So that no useless data is output-ed.
exit;
?>
Let php calculate the file size and date and other stuff. It is quiet possible that an error can occur while feeding it via an array.
Also in this code I have used pathinfo so as to automatically set the Content-type and file name.

Answer 3

I would like to contribute for someone that was lost with this solution.
What worked for me, has said above by #Kalob Taulien was insert these lines that turn off a compactation algorith builtin that was corrupting my files on download by the script, here is:
#ob_end_clean();
if(ini_get('zlib.output_compression'))
ini_set('zlib.output_compression', 'Off');
After insert that before fpassthru($file) function, the downloads worked well.