Description:
------------
Hello,

when zlib.output_compression is enabled and the script stop without any contents (case of a 304 page), after all PHP sends contents.
So, if the client use keep-alive, the next request could be "corrupted".

I use php as an Apache 2 module. I reproduced it under PHP 4.4.X too.


Note : if I disable "zlib.output_compression" and use "ob_start( 'gz_handler' )" there is not this problem.

Reproduce code:
---------------
A minimal 304 page :
<?php
header( 'Date: '.gmdate('D, d M Y H:i:s').' GMT' );

header( 'Not Modified', true, 304 );
exit;
?>

A minimal client simulation :
<?php
$sk = fsockopen( 'your-domain.tld', 80 );

$headers = array(
    'GET /test_304.php HTTP/1.1',
    'Host: your-domain.tld',
    'Accept-Encoding: gzip,deflate',
    'Keep-Alive: 300',
    'Connection: keep-alive',
    'If-Modified-Since: Tue, 21 Aug 2007 13:00:54 GMT',
    );

function sock_send( &$sk, $line )
{
    echo '> ', $line, PHP_EOL;
    fputs( $sk, $line . "\r\n" );
}

function sock_gets( &$sk )
{
    $line = fgets( $sk, 4096 );
    echo '< ', rtrim($line), PHP_EOL;
    return $line;
}

for( $i = 1; $i <=2 ; $i++ )
{
    echo "Sending request ", $i, PHP_EOL;

    foreach( $headers as $h )
        sock_send( $sk, $h );
    sock_send( $sk, '' );

    echo "Reading headers only (no contents should be send)", PHP_EOL;

    while( !feof( $sk ) )
    {
        $line = trim(sock_gets( $sk ));
        if( $line === '' )
        {
            break;
        }
    }
}

fclose( $sk );
?>


Expected result:
----------------
Response headers for the second request should be the same as the first.

In my example :
< HTTP/1.1 304 Not Modified
< Date: Tue, 21 Aug 2007 14:45:40 GMT
< Server: Apache/2.2.3 (Debian) PHP/4.4.4-8+etch4
< Connection: Keep-Alive
< Keep-Alive: timeout=60, max=100
< Vary: Accept-Encoding


Actual result:
--------------
Actually there is some "chars" (I suppose the end of compressed data, like checksum ?)
< &#9660;      &#9829;&#9787;     &#9829;         HTTP/1.1 304 Not Modified
< Date: Tue, 21 Aug 2007 14:45:40 GMT
< Server: Apache/2.2.3 (Debian) PHP/4.4.4-8+etch4
< Connection: Keep-Alive
< Keep-Alive: timeout=60, max=99
< Vary: Accept-Encoding
<