Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
ACCEPT(2)		  FreeBSD System Calls Manual		     ACCEPT(2)

NAME
     accept -- accept a	connection on a	socket

LIBRARY
     Standard C	Library	(libc, -lc)

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

     int
     accept(int	s, struct sockaddr *addr, socklen_t *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).	 The accept() call extracts the	first connection request on
     the queue of pending connections, creates a new socket with the same
     properties	as 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 may not be used to accept more	connections.  The
     original socket s remains open.

     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.

     For certain protocols which require an explicit confirmation, such	as ISO
     or	DATAKIT, accept() can be thought of as merely dequeueing the next con-
     nection request and not implying confirmation.  Confirmation can be
     implied by	a normal read or write on the new file descriptor, and rejec-
     tion can be implied by closing the	new socket.

     One can obtain user connection request data without confirming the	con-
     nection by	issuing	a recvmsg(2) call with an msg_iovlen of	0 and a	non-
     zero msg_controllen, or by	issuing	a getsockopt(2)	request.  Similarly,
     one can provide user connection rejection information by issuing a
     sendmsg(2)	call providing only the	control	information, or	by calling
     setsockopt(2).

RETURN VALUES
     The call returns -1 on error.  If it succeeds, it returns a non-negative
     integer that is a descriptor for the accepted socket.

ERRORS
     The accept() will fail if:

     [EBADF]		The descriptor is invalid.

     [EINTR]		The accept() operation was interrupted.

     [EMFILE]		The per-process	descriptor table is full.

     [ENFILE]		The system file	table is full.

     [ENOTSOCK]		The descriptor references a file, not a	socket.

     [EINVAL]		listen(2) has not been called on the socket descrip-
			tor.

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

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

     [ECONNABORTED]	A connection arrived, but it was closed	while waiting
			on the listen queue.

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

HISTORY
     The accept() function appeared in 4.2BSD.

FreeBSD	9.3		       December	11, 1993		   FreeBSD 9.3

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

Want to link to this manual page? Use this URL:
<http://www.freebsd.org/cgi/man.cgi?query=accept&sektion=2&manpath=FreeBSD+4.5-RELEASE>

home | help