recv(3XNET) X/Open Networking Services Library Functions recv(3XNET)NAMErecv - receive a message from a connected socket
SYNOPSIS
cc [ flag ... ] file ... -lxnet [ library ... ]
#include <sys/socket.h>
ssize_t recv(int socket, void *buffer, size_t length, int flags);
DESCRIPTION
The recv() function receives a message from a connection-mode or con‐
nectionless-mode socket. It is normally used with connected sockets
because it does not permit the application to retrieve the source
address of received data. The function takes the following arguments:
socket Specifies the socket file descriptor.
buffer Points to a buffer where the message should be stored.
length Specifies the length in bytes of the buffer pointed to
by the buffer argument.
flags Specifies the type of message reception. Values of
this argument are formed by logically OR'ing zero or
more of the following values:
MSG_PEEK Peeks at an incoming message.
The data is treated as unread
and the next recv() or similar
function will still return this
data.
MSG_OOB Requests out-of-band data. The
significance and semantics of
out-of-band data are protocol-
specific.
MSG_WAITALL Requests that the function
block until the full amount of
data requested can be returned.
The function may return a
smaller amount of data if a
signal is caught, if the con‐
nection is terminated, if
MSG_PEEK was specified, or if
an error is pending for the
socket.
The recv() function returns the length of the message written to the
buffer pointed to by the buffer argument. For message-based sockets
such as SOCK_DGRAM and SOCK_SEQPACKET, the entire message must be read
in a single operation. If a message is too long to fit in the supplied
buffer, and MSG_PEEK is not set in the flags argument, the excess bytes
are discarded. For stream-based sockets such as SOCK_STREAM, message
boundaries are ignored. In this case, data is returned to the user as
soon as it becomes available, and no data is discarded.
If the MSG_WAITALL flag is not set, data will be returned only up to
the end of the first message.
If no messages are available at the socket and O_NONBLOCK is not set on
the socket's file descriptor, recv() blocks until a message arrives.
If no messages are available at the socket and O_NONBLOCK is set on the
socket's file descriptor, recv() fails and sets errno to EAGAIN or
EWOULDBLOCK.
USAGE
The recv() function is identical to recvfrom(3XNET) with a zero
address_len argument, and to read() if no flags are used.
The select(3C) and poll(2) functions can be used to determine when data
is available to be received.
RETURN VALUES
Upon successful completion, recv() returns the length of the message in
bytes. If no messages are available to be received and the peer has
performed an orderly shutdown, recv() returns 0. Otherwise, -1 is
returned and errno is set to indicate the error.
ERRORS
The recv() function will fail if:
EAGAIN The socket's file descriptor is marked O_NON‐
EWOULDBLOCK BLOCK and no data is waiting to be received; or
MSG_OOB is set and no out-of-band data is
available and either the socket's file descrip‐
tor is marked O_NONBLOCK or the socket does not
support blocking to await out-of-band data.
EBADF The socket argument is not a valid file
descriptor.
ECONNRESET A connection was forcibly closed by a peer.
EFAULT The buffer parameter can not be accessed or
written.
EINTR The recv() function was interrupted by a signal
that was caught, before any data was available.
EINVAL The MSG_OOB flag is set and no out-of-band data
is available.
ENOTCONN A receive is attempted on a connection-mode
socket that is not connected.
ENOTSOCK The socket argument does not refer to a socket.
EOPNOTSUPP The specified flags are not supported for this
socket type or protocol.
ETIMEDOUT The connection timed out during connection
establishment, or due to a transmission timeout
on active connection.
The recv() function may fail if:
EIO An I/O error occurred while reading from or
writing to the file system.
ENOBUFS Insufficient resources were available in the
system to perform the operation.
ENOMEM Insufficient memory was available to fulfill
the request.
ENOSR There were insufficient STREAMS resources
available for the operation to complete.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOpoll(2), recvmsg(3XNET), recvfrom(3XNET), select(3C), send(3XNET),
sendmsg(3XNET), sendto(3XNET), shutdown(3XNET), socket(3XNET),
attributes(5), standards(5)SunOS 5.10 10 Jun 2002 recv(3XNET)
