NAME

       xs_recv - receive a message part from a socket

SYNOPSIS

       int xs_recv (void *socket, void *buf, size_t len, int flags);

DESCRIPTION

       The xs_recv() function shall receive a message from the socket referenced by the socket
       argument and store it in the buffer referenced by the buf argument. Any bytes exceeding
       the length specified by the len argument shall be truncated. If there are no messages
       available on the specified socket the xs_recv() function shall block until the request can
       be satisfied. The flags argument is a combination of the flags defined below:

       XS_DONTWAIT
           Specifies that the operation should be performed in non-blocking mode. If there are no
           messages available on the specified socket, the xs_recv() function shall fail with
           errno set to EAGAIN.

   Multi-part messages
       A Crossroads message is composed of 1 or more message parts. Crossroads ensures atomic
       delivery of messages; peers shall receive either all message parts of a message or none at
       all. The total number of message parts is unlimited except by available memory.

       An application that processes multipart messages must use the XS_RCVMORE xs_getsockopt(3)
       option on the socket after calling xs_recv() to determine if there are further parts to
       receive.

RETURN VALUE

       The xs_recv() function shall return the number of bytes in the received message if
       successful. Note that the value can exceed the value of the len parameter, in this case
       the message was truncated. If not successful the function shall return -1 and set errno to
       one of the values defined below.

ERRORS

       EAGAIN
           Non-blocking mode was requested and no messages are available at the moment.

       ENOTSUP
           The xs_recv() operation is not supported by this socket type.

       EFSM
           The xs_recv() operation cannot be performed on this socket at the moment due to the
           socket not being in the appropriate state. This error may occur with socket types that
           switch between several states, such as XS_REP. See the messaging patterns section of
           xs_socket(3) for more information.

       ETERM
           The context associated with the specified socket was terminated.

       ENOTSOCK
           The provided socket was invalid.

       EINTR
           The operation was interrupted by delivery of a signal before a message was available.

       ETIMEDOUT
           Survey has timed out. (Applicable only to XS_SURVEYOR socket.)

EXAMPLE

       Receiving a message from a socket.

           char buf [256];
           nbytes = xs_recv (socket, buf, 256, 0);
           assert (nbytes != -1);

SEE ALSO

       Applications that wish to use zero-copy messaging must use xs_recvmsg(3) instead of
       xs_recv().

       xs_sendmsg(3) xs_getsockopt(3) xs_socket(7) xs(7)

AUTHORS

       This man page was written by Martin Sustrik <sustrik@250bpm.com[1]>, Martin Lucina
       <martin@lucina.net[2]> and Pieter Hintjens <ph@imatix.com[3]>.

NOTES

        1. sustrik@250bpm.com
           mailto:sustrik@250bpm.com

        2. martin@lucina.net
           mailto:martin@lucina.net

        3. ph@imatix.com
           mailto:ph@imatix.com