xs_getmsgopt(3) retrieve message option


int xs_getmsgopt (xs_msg_t *message, int option_name, void *option_value, size_t *option_len);


The xs_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 xs_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 xs_getmsgopt() function:


Indicates that there are more message parts to follow after the message. The type of this option is int. 0 means that this is the last message part of a multipart message. 1 means that more message parts will follow.


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



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.


Receiving a multi-part message.

xs_msg_t part;
int more;
size_t more_size = sizeof (more);
while (true) {
    /* Create an empty message to hold the message part */
    int rc = xs_msg_init (&part);
    assert (rc == 0);
    /* Block until a message is available to be received from socket */
    rc = xs_recvmsg (socket, &part, 0);
    assert (rc != -1);
    rc = getmsgopt (&part, XS_MORE, &more, &more_size);
    assert (rc == 0);
    if (more) {
      fprintf (stderr, "more\n");
    else {
      fprintf (stderr, "end\n");
    xs_msg_close (part);


This manual page was written by Chuck Remes <m[blue][email protected]m[][1]>.