Description:
------------
The `zlib.inflate` filter silently fails in some circumstances.

The attached test case creates highly compressed files, then reads them in chunks of 4 KiB with two chained `zlib.inflate` filters. When the original data is larger than 25 MB, something breaks and I have no idea what or why.


Test script:
---------------
ini_set('display_startup_errors', 1);
ini_set('display_errors', 1);
error_reporting(-1);
 
/* Create a doubly-gzipped file, then read it back using zlib filters
 * and report how many KiB were decompressed. */
function create_and_read($f, $kb)
{
    system("dd count=$kb bs=1024 </dev/zero 2>/dev/null | gzip | gzip >| $f");
 
    $in = fopen($f, 'rb');
    $out = 0;
    $args = array('window' => 30);
    stream_filter_prepend($in, 'zlib.inflate', STREAM_FILTER_READ, $args);
    stream_filter_prepend($in, 'zlib.inflate', STREAM_FILTER_READ, $args);
    while (!feof($in))
        $out += strlen(fread($in, 4096));
 
    unlink($f);
 
    print "in: $kb KiB\tout: " . $out / 1024 . " KiB\n";
}
 
foreach (array(10, 100, 10000, 24800, 24801, 100000) as $kb)
    create_and_read('/tmp/x', $kb);

Expected result:
----------------
in: 10 KiB      out: 10 KiB
in: 100 KiB     out: 100 KiB
in: 10000 KiB   out: 10000 KiB
in: 24800 KiB   out: 24800 KiB
in: 24801 KiB   out: 24801 KiB
in: 100000 KiB  out: 100000 KiB

Actual result:
--------------
in: 10 KiB      out: 10 KiB
in: 100 KiB     out: 100 KiB
in: 10000 KiB   out: 10000 KiB
in: 24800 KiB   out: 24800 KiB
in: 24801 KiB   out: 0 KiB
in: 100000 KiB  out: 0 KiB