ZMQ_GETMSGOPT(3)

NAME
zmq_getmsgopt - retrieve message option

SYNOPSIS

int zmq_getmsgopt (zmq_msg_t *message, int option_name, void *option_value, size_t *option_len);

DESCRIPTION

The zmq_getmsgopt() function shall retrieve the value for the option specified by the option_name argument for the message pointed to by the message argument, and store it in the buffer pointed to by the option_value argument. The option_len argument is the size in bytes of the buffer pointed to by option_value; upon successful completion zmq_getsockopt() shall modify the option_len argument to indicate the actual size of the option value stored in the buffer.

The following options can be retrieved with the zmq_getmsgopt() function:

ZMQ_MORE
    Indicates that there are more message parts to follow after the message.

RETURN VALUE

The zmq_getmsgopt() function shall return zero if successful. Otherwise it shall return -1 and set errno to one of the values defined below.

ERRORS

EINVAL
    The requested option option_name is unknown, or the requested option_size or option_value is invalid, or the size of the buffer pointed to by option_value, as specified by option_len, is insufficient for storing the option value.

EXAMPLE

Receiving a multi-part message.

    zmq_msg_t part;
    int more;
    size_t more_size = sizeof (more);
    while (true) {
        /* Create an empty 0MQ message to hold the message part */
        int rc = zmq_msg_init (&part);
        assert (rc == 0);
        /* Block until a message is available to be received from socket */
        rc = zmq_recvmsg (socket, &part, 0);
        assert (rc != -1);
        rc = getmsgopt (&part, ZMQ_MORE, &more, &more_size);
        assert (rc == 0);
        if (more) {
          fprintf (stderr, "more\n");
        }
        else {
          fprintf (stderr, "end\n");
          break;
        }
        zmq_msg_close (part);
    }

SEE ALSO

zmq_msg_data(3) zmq_msg_init(3) zmq_msg_init_size(3) zmq_msg_init_data(3) zmq_msg_close(3) zmq(7)

AUTHORS

The 0MQ documentation was written by Chuck Remes <cremes@mac.com[1]>.

NOTES

1.  cremes@mac.com
    mailto:cremes@mac.com