Now to report receive queue size for AF_UNIX sockets

netstat -a reports Recv-Q (amount of unread data pending for a reading application) for AF_INET sockets, but not AF_UNIX sockets (at least not for SOCK_DGRAM).

Does anybody know a way to obtain this information for AF_UNIX sockets from outside of the process itself?

I don't actually need the amount, just an indication whether there is any unread data pending for the application.