test

void BusServer::serve(int fd) {

    auto it = _clients.find(fd);

    if (it == _clients.end()) return;

    char buf[4096];

    Client &c = it->second;

    // what is there, up to one message's worth: the main loop comes back

    // here only every few 100 ms when it has other work

    char buf[65536];

    for (size_t got = 0; got < sysbus::MaxPayload;) {

        ssize_t n = ::read(fd, buf, sizeof(buf));

        if (n < 0 && errno == EINTR) continue;

        if (n < 0 && errno == EAGAIN) {

            if (!got) return;

            break;

        }

        if (n <= 0) {

        if (n < 0 && (errno == EINTR || errno == EAGAIN)) return;

            if (got) break;  // what came before the end still counts

            drop(fd);

            return;

        }

    Client &c = it->second;

        c.decoder.feed(buf, static_cast<size_t>(n));

        got += static_cast<size_t>(n);

    }

    sysbus::Message msg;

    while (c.decoder.next(msg)) {