ansaurus

Question

PHP File Serving Script: Unreliable Downloads?

Answer 1

+2 A:

Content-Encoding: gzip

Hmm. Presumably PHP's zlib.output_compression is doing that. (Doesn't look like Apache's mod_deflate.)

Try turning it off and seeing if it's that that's forcing chunked encoding. You don't want to compress the download of a filetype like WMV which is already highly compressed.

However, chunked encoding would only explain the lack of size report. The download should still work. Is it possible you're being hit by a timeout (eg. PHP's set_time_limit, or Apache Timeout)?

bobince 2010-04-11 14:03:17

I agree that the two are probably related. I'm trying to sort out the cause.zlib.output_compression is already set to Off in php.ini

JGB146 2010-04-11 16:30:33

Answer 2

+2 A:

It's your GZIP compression. When you specify a content length but turn compression on, it gums everything up. It's happened to me a few times: try turning it off in your script.

Generally you'd turn it on with:

ob_start("ob_gzhandler");

...so just comment that line out. If that's not in your code, chances are there's a setting in either your php.ini file somewhere or your apache.conf/conf.d.

Hope this helps!

mattbasta 2010-04-11 14:05:50

That line isn't in the code anywhere, so I'm digging through php.ini. If you happen to know what I should be looking for, that would be quite helpful!

JGB146 2010-04-11 16:17:22

Try looking for this: `zlib_output_compression`. It should be set to Off.

mattbasta 2010-04-11 16:41:34

My bad: `zlib.output_compression = Off` and `zlib.output_handler = Off`

mattbasta 2010-04-11 16:42:24

zlib.output_compression was already set to off. The other value was commented out by default, and my reading says that it should only be used when output_compression is turned on.

JGB146 2010-04-11 17:12:06

I went ahead and starting digging into other places in the apache config. Ultimately, I uncovered a setting that can be added to .htaccess for the specified directory to prevent compression on apache's end as well:SetEnvIfNoCase Request_URI \.php$ no-gzip dont-vary

JGB146 2010-04-11 17:12:33

Answer 3

A:

If it is the script then have you tried using a substitute function for the readfile() function that reads and outputs a bit at a time? The reasoning behind this could be that a memory limit is reached somewhere and it fails.

From http://php.net/manual/en/function.readfile.php :

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

Also, try to flush the output as often as you can.

zaf 2010-04-11 14:08:05

ansaurus

tags:

views:

answers:

PHP File Serving Script: Unreliable Downloads?

related questions