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xs_recv(3)
==========
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. Each message
part is an independent 'xs_msg_t' in its own right. Crossroads ensure 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_
linkxs:xs_getsockopt[3] option after calling _xs_recv()_ to determine if
there are further parts to receive.
RETURN VALUE
------------
The _xs_recv()_ function shall return number of bytes in the message
if successful. Note that the value can exceed the value of the 'len' parameter
in 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 linkxs: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.
EXAMPLE
-------
.Receiving a message from a socket
----
char buf [256];
nbytes = xs_recv (socket, buf, 256, 0);
assert (nbytes != -1);
----
SEE ALSO
--------
linkxs:xs_recvmsg[3]
linkxs:xs_send[3]
linkxs:xs_sendmsg[3]
linkxs:xs_getsockopt[3]
linkxs:xs_socket[7]
linkxs:xs[7]
AUTHORS
-------
+This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
+Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
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