PHP Configuration problem

Virtualsetworks

I'm not really sure what field this problem falls under, but my closest bet would be php configuration. Here's the problem, I have an ecommerce platform from SumEffect called Digishop that is php based. The downloading feature allowing customers to download products is causing an error which means my customers can't get their products. SumEffect support has washed their hands of the problem saying that the problem is mine. Without remonstrating me regarding whether I'm suited to run a server could someone take a look at this code and error message and make an enlighted guess as to what things I might try to fix it?

Server 2008 R2
IIS 7.5
PhP 5.3.6

Here's the Code

<?php

$path = 'C:/Documents/Virtualsetworks/files/VSPHD1080S164.zip';
$downloadFile = basename($path);
$filesize = filesize($path);

header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="' . $downloadFile . '"');
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');

if($filesize){
	header('Content-Length: ' . $filesize);
}

header('Content-Encoding: chunked'); //This is passed so in case the default encoding of the server uses compression a progress bar will display.


$handle = fopen($path, 'rb');
$chunksize = 1024;
$length = 0;
ob_start();

while($line = fread($handle, $chunksize)){
	echo $line;
	ob_end_flush();
	ob_flush();
	flush();
	ob_start();
}

fclose($handle);
ob_end_clean();

?>

Here's the error on the client side:
"F:\E\temp\VSPHD1080S164(13).zip.part could not be saved, because the source file could not be read.
Try again later, or contact the server administrator."

My clients get this too, it's not just me.

It usually reads between 9 and 10 megs of the file and then stops, waits a bit, and then throws that message. Sometimes it reads 0 bytes, or just a few bytes, but mostly it goes to 9.3MB. PHP.ini memory_limit is 128Mb, max-execution time is 1200. The folder has all the correct security permissions. The files in question are between 100-500Mb.

Any help would be appreciated

sneakyimp

It's possible that the script is either running out of memory or time. Downloading a 100-500Mb file is never easy. You might try disabling the time limit at the top of your script:

set_time_limit(0);

You might also try increasing the memory_limit. If that doesn't fix the problem, you'll need to start examining other possibilities.

You should probably check to make sure that fopen works -- it probably isn't returning an error but it's good practice to check anyway.

If the problem isn't solved, try writing a file at certain points in your code to see where it might be failing. You might also set error_reporting to be more revealing to see if any errors or exceptions are being thrown.

Virtualsetworks

Well, it's failing at 9 MB and 1-30 seconds, I'm not sure it's memory or time with 128MB and 1200 second limits, but there could be a limit somewhere else I'm unaware of because I'm not familiar with php.
How would I check if fopen is working?
I'm not sure how I'd go about writing files at different stages in that script, would that be the same as downloading?
Thanks

bradgrafelman

Have you checked your Apache error logs for any clues?

Also, is PHP's error_reporting directive set to E_ALL and are you logging all PHP errors?

Virtualsetworks

I'm not running Apache, but I've been through the IIS logs to see if anything stands out. I've change the PHP reporting from Production Machine to Developement machine and I get the error:
[06-Jul-2011 13:25:35] PHP Fatal error: Class 'Util' not found in C:\Documents\Virtualset\secure\downloadtest.php on line 5 when I run the below code.
I'm not sure if this is the problem though because the main code doesn't seem to throw that error.

Virtualsetworks

It's funny, I'm still having this problem and when I google it now, this page comes up.
So, I've been able to improve the problem by using this code instead:

header("Pragma: public"); // required
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Cache-Control: private",false); // required for certain browsers
header("Content-Type:application/zip");
header("Content-Disposition: attachment; filename=\"".basename($filename)."\";" );
header("Content-Transfer-Encoding: binary");
header("Content-Length: ".filesize($filename));
readfile("$filename");

But... customers still get the same error sometimes. I can't duplicate it using this code (it works for me 100% of the time) but it's essentially the same error from the above code which I can duplicate.
I'd almost say it's not code related at all except the code causes a behavioral difference in the problem: the fp almost always fails at the same spot 9.5mb, the code in this post completes most of the time but fails sometimes on some machines, both with the same error. I've read about people having this problem with gzip on, but I've turned off compression in the web.config file, in the code, and in the ini
Does not seem related to browser, os, or filesize
PHP.ini
zlib.output_compression = Off
max_execution_time = 1200
max_input_time = 60
memory_limit = 256M
IIS 7.5 Windows 2008 R2

Any help appreciated