4.1cBSD/usr/man/man2/accept.2

.TH ACCEPT 2 2/12/83
.SH NAME
accept \- accept a connection on a socket
.SH SYNOPSIS
.ft B
.nf
#include <sys/socket.h>
.PP
.ft B
ns = accept(s, addr, addrlen)
int ns, s;
struct sockaddr *addr;
int *addrlen;
.fi
.SH DESCRIPTION
The argument
.I s
is a socket which has been created with
.IR socket (2),
bound to an address with
.IR bind (2)
and is listening for connections after a
.IR listen (2).
The first queued connection
is extracted from the queue with
.I accept.
.PP
The argument
.I addr
is a result indicating the address of the entity which
connected, as known to the communications layer.
The exact format of the
.I addr
parameter is determined by the domain in which the communication
is occurring.
The 
.I addrlen
is a value-result parameter; it should initially contain the
amount of space pointed to by
.IR 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.
.PP
It is possible to
.IR select (2)
a socket for the purposes of doing an
.I accept
by selecting it for read.
.SH "RETURN VALUE
The call returns \-1 on error.  If it succeeds it returns a non-negative
descriptor.
.SH ERRORS
The \fIaccept\fP will fail if:
.TP 20
[EBADF]
The descriptor is invalid.
.TP 20
[ENOTSOCK]
The descriptor references a file, not a socket.
.TP 20
[EOPNOTSUPP]
The referenced socket is not of type SOCK_STREAM.
.TP 20
[EFAULT]
The \fIaddr\fP parameter is not in a writeable part of the
user address space.
.SH SEE ALSO
bind(2), connect(2), listen(2), select(2), socket(2)