buffer_capacity
r = recv(fd, buffer_current(buf), buffer_capacity(buf), MSG_DONTWAIT);
assert(buffer_capacity(dt_col->inputs[i].buffer) ==
buffer_capacity(dt_col->send_buffer));
int bufsz = buffer_capacity(dt_col->send_buffer);
buffer_set_limit(q->packet, buffer_capacity(q->packet));
if(tcp->msglen > buffer_capacity(tcp->packet)) {
if(tcp->msglen > buffer_capacity(tcp->packet)) {