Yeah, it's duplication. But this way it's also separation and we can't
accidentally use the wrong struct.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Plenty of duplication there from the normal filter.c, but that also makes it
less likely to break if we adjust the other one.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>