io_buffer_head
head = io_buffer_head(&cur_comm);
io_buffer_head(&cur_resp));
memmove(io->data, io_buffer_head(io), io->len);
nwritten = write(fd, io_buffer_head(&cur_resp), cur_resp.len);
debug("-> %.*s\n", (int)cur_resp.len, io_buffer_head(&cur_resp));