ACCEPT(2)

NAME
accept - accept a connection on a socket

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

int accept(s, addr, addrlen)
int s;
struct sockaddr *addr;
int *addrlen;

DESCRIPTION

The argument s is a socket that has been created with socket(2), bound to an address with bind(2), and is listening for connections after a listen(2). accept() extracts the first connection on the queue of pending connections, creates a new socket with the same properties of s and allocates a new file descriptor for the socket. If no pending connections are present on the queue, and the socket is not marked as non-blocking, accept() blocks the caller until a connection is present. If the socket is marked non-blocking and no pending connections are present on the queue, accept() returns an error as described below. The accepted socket is used to read and write data to and from the socket which connected to this one; it is not used to accept more connections. The original socket s remains open for accepting further connections.

The argument addr is a result parameter that is filled in with the address of the connecting entity, as known to the communications layer. The exact format of the addr parameter is determined by the domain in which the communication is occurring. The addrlen is a value-result parameter; it should initially contain the amount of space pointed to by addr; on return it will contain the actual length (in bytes) of the address returned. This call is used with connection-based socket types, currently with SOCK_STREAM.

It is possible to select(2) a socket for the purposes of doing an accept() by selecting it for read.

RETURN VALUES

accept() returns a non-negative descriptor for the accepted socket on success. On failure, it returns -1 and sets errno to indicate the error.

ERRORS

EBADF
    The descriptor is invalid.

EFAULT
    The addr parameter is not in a writable part of the user address space.

ENOTSOCK
    The descriptor references a file, not a socket.

EOPNOTSUPP
    The referenced socket is not of type SOCK_STREAM.

EWOULDBLOCK
    The socket is marked non-blocking and no connections are present to be accepted.

SEE ALSO
bind(2), connect(2), listen(2), select(2), socket(2)