Note: I think this bug may be related to #17885, but I am using Apache 1.3.20, not Apache2.

Any script outputting a zipfile intermittently generates corrupt output. I can't work out what factors influence when it does and when it doesn't.

I have tried everything from:

readfile("test.zip");

to 

$fp = fopen("test.zip", "rb");
$data = fread($fp, 100000);  //the zip is < 100kb
fclose($fp);
$md5 = md5($data);
for($i=0; $i < strlen($data); $i += 100)
{
	echo substr($data, $i, min(100, strlen($data)-$i));
}
$fp = fopen("logfile", "a");
fwrite($fp, "served $filename: $md5\n");
fclose($fp);

The above script logs the md5 hash of the data read in. The value logged does not change whether or not the output was corrupt, suggesting that the bug is in the output not the file reading.

I am not able to test on different OSs or apache versions, but the problem IS new since php4.1.2.
My configure line is: --with-apxs --with-zip --with-zlib --with-sybase=/usr/local/freetds
I've temporarily moved my zip-reading code to a bit of cgi perl which is working fine.