Problem: zmq_msg_send doc incorrect for large messages.

[evoskuil]

Documentation for zmq_msg_send states:

"Return value

The zmq_msg_send() function shall return number of bytes in the message if successful. Otherwise it shall return -1 and set errno to one of the values defined below."

However due to the implementation:

s_sendmsg (zmq::socket_base_t *s_, zmq_msg_t *msg_, int flags_)
{
    size_t sz = zmq_msg_size (msg_);
    int rc = s_->send ((zmq::msg_t *) msg_, flags_);
    if (unlikely (rc < 0))
        return -1;

    size_t max_msgsz = INT_MAX;
    return (int) (sz < max_msgsz? sz: max_msgsz);
}

the documentation is incorrect for any message of size that exceeds INT_MAX. Either the documentation should be changed to indicate that the return is set to INT_MAX in the case of success for such messages, or the implementation should be changed to limit message size accordingly. Otherwise behavior in these cases is ambiguous to the API caller.

[bluca]

The documentation should be fixed I think, the problem if I remember correctly is that the value would just be truncated if higher than INT_MAX given the API returns an int.
I sincerely hope nobody ever has to send 2 gigabytes of data in a single message though :-)

[bluca]

Fixed by #3266

[akropp]

The documentation should be fixed I think, the problem if I remember correctly is that the value would just be truncated if higher than INT_MAX given the API returns an int. I sincerely hope nobody ever has to send 2 gigabytes of data in a single message though :-)

Actually, I just tried to send more than 2gb of data and hit the assertion in zmq.hpp that checks whether the return value from zmq_msg_recv matches the size of the message received.