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XS_RECV(3)		     Crossroads	I/O Manual		    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. 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

Crossroads I/O 1.2.0		  02/28/2021			    XS_RECV(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLE | SEE ALSO | AUTHORS | NOTES

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