The accept() function shall extract the first connection on the queue of
pending connections, create a new socket with the same socket type protocol
and address family as the specified socket, and allocate a new file descriptor
for that socket.
The accept() function takes the following arguments:
Specifies a socket that was created with socket(),
has been bound to an address with bind(), and has issued a
successful call to listen().
Either a null pointer, or a pointer to a sockaddr
structure where the address of the connecting socket shall be
Points to a socklen_t structure which on input
specifies the length of the supplied sockaddr structure, and on
output specifies the length of the stored address.
If address is not a null pointer, the address of the peer for the
accepted connection shall be stored in the sockaddr structure pointed
to by address, and the length of this address shall be stored in the
object pointed to by address_len.
If the actual length of the address is greater than the length of the supplied
sockaddr structure, the stored address shall be truncated.
If the protocol permits connections by unbound clients, and the peer is not
bound, then the value stored in the object pointed to by address is
If the listen queue is empty of connection requests and O_NONBLOCK is not set on
the file descriptor for the socket, accept() shall block until a
connection is present. If the listen() queue is empty of connection
requests and O_NONBLOCK is set on the file descriptor for the socket,
accept() shall fail and set errno to [EAGAIN] or [EWOULDBLOCK].
The accepted socket cannot itself accept more connections. The original socket
remains open and can accept more connections.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html