XS_RECV(3) Crossroads I/O Manual XS_RECV(3)NAMExs_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 02/17/2016 XS_RECV(3)
