Description:
------------
deflate_add can grossly overestimate memory needed for the output buffer. This is more likely with highly compressable data. The allocations are roughly equal to the total bytes processed by deflate_add and can cause PHP to run out of memory.

Test script:
---------------
$deflator = deflate_init(ZLIB_ENCODING_RAW);

$bytes = str_repeat("*", 65536);
// if you use random bytes this usually can run forever
// because they are not very compressable
//$bytes = openssl_random_pseudo_bytes(65536);

// this crashes after about 500 iterations if PHP is
// configured for 64M
for ($i = 0; $i < 100000; $i++) {
    echo "$i\n";
    $output = deflate_add(
        $deflator,
        $bytes,
        ZLIB_SYNC_FLUSH
    );
}