yaz_poll_add(pfd.input_mask, yaz_poll_write);
if (cs->io_pending & CS_WANT_READ)
yaz_poll_add(pfd.input_mask, yaz_poll_read);
yaz_poll_add(pfd.input_mask, yaz_poll_write);
if (cs->io_pending & CS_WANT_READ)
yaz_poll_add(pfd.input_mask, yaz_poll_read);