NAME

recv, recvfrom - receive a message from a socket

SYNOPSIS

#include <sys/types.h>
#include <sys/socket.h>

size_t recv(int s ,

void *buf ,

size_t len ,

int flags );

size_t recvfrom(int s ,

void *buf ,

size_t len ,

int flags ,

struct sockaddr *from ,

socklen_t *fromlen );

DESCRIPTION

recv() and recvfrom() are used to receive messages from another socket. recv() may be used only on a connected socket (see connect()), while recvfrom() can be used on any socket. s is a socket created with socket().

If from is not a NULL pointer, the source address of the message is filled in. fromlen is a value-result parameter, initialized to the size of the buffer associated with from , and modified on return to indicate the actual size of the address stored there. The length of the message is returned. If a message is too long to fit in the supplied buffer, excess bytes may be discarded depending on the type of socket the message is received from (see socket()).

If no messages are available at the socket, the receive call waits for a message to arrive. Nonblocking sockets are not supported.

The flags parameter is formed by ORing one or more of the following:

MSG_OOB

Read any out-of-band data present on the socket rather than the regular in-band data.

MSG_PEEK

Peek at the data present on the socket; the data is returned, but not consumed, so that a subsequent receive operation will see the same data.

RETURN VALUES

These calls return the number of bytes received, or -1 if an error occurred.

ERRORS

EBADF

s is an invalid file descriptor.

EINTR

The operation was interrupted by delivery of a signal before any data was available to be received.

EIO

An I/O error occurred while reading from or writing to the file system.

ENOMEM

There was insufficient user memory available for the operation to complete.

ENOSR

There were insufficient STREAMS resources available for the operation to complete.

ENOTSOCK

s is not a socket.

ESTALE

A stale NFS file handle exists.

EWOULDBLOCK

The socket is marked non-blocking and the requested operation would block.

SEE ALSO

ioctl(), read(), connect(), getsockopt(), send(), socket()

< Copyright Rowebots Research Inc. and Multiprocessor Toolsmiths Inc. 1987-2008 >