Description:
------------
The constant PSFS_ERR_FATAL used to indicate an error condition in a user stream filter has no effect on the return value of relevant stream functions, and there is no alternative way to detect these errors.

Test script:
---------------
<?php

class FatalFilter extends php_user_filter
{
    function filter($in, $out, &$consumed, $closing)
    {
        $bucket = stream_bucket_make_writeable($in);

        return PSFS_ERR_FATAL;
    }
}

stream_filter_register('fatal', 'FatalFilter');

$stream = fopen('php://memory', 'wb');
stream_filter_append($stream, 'fatal');
var_dump(fwrite($stream, 'foobar'));
fclose($stream);


Expected result:
----------------
bool(false)

Actual result:
--------------
int(0)