accept - Accept a new connection on a socket
struct sockaddr *address,
socklen_t *address_len );
[XNS4.0] The definition of the accept() function in
XNS4.0 uses a size_t data type instead of socklen_t data
type as specified in XNS5.0 (the previous definition).
[Tru64 UNIX] The following definition of the accept()
function does not conform to current standards and is supported
only for compatibility (see standards(5)): int
struct sockaddr *address,
int *address_len );
Interfaces documented on this reference page conform to
industry standards as follows:
accept(): XNS4.0, XNS5.0
Refer to the standards(5) reference page for more information
about industry standards and associated tags.
Specifies a file descriptor for the socket that was created
with the socket() function, has been bound to an
address with the bind() function, and has issued a successful
call to the listen() function. Points to a sockaddr
structure, the format of which is determined by the
domain and by the behavior requested for the socket. The
sockaddr structure is an overlay for a sockaddr_in, sockaddr_un,
sockaddr_in6, or sockaddr_storage structure,
depending on which of the supported address families is
[Tru64 UNIX] If the compile-time option _SOCKADDR_LEN
is defined before the sys/socket.h header
file is included, the sockaddr structure takes
4.4BSD behavior, with a field for specifying the
length of the socket address. Otherwise, the
default 4.3BSD sockaddr structure is used, with the
length of the socket address assumed to be 14 bytes
You can specify NULL to indicate that the address
of the peer is not required.
If _SOCKADDR_LEN is defined, the 4.3BSD sockaddr
structure is defined with the name osockaddr.
Specifies the length of the sockaddr structure
pointed to by the address parameter. If the address
parameter is NULL then this parameter is ignored.
The accept() function extracts the first connection on the
queue of pending connections, creates a new socket with
the same properties as the specified socket, and allocates
a new file descriptor for that socket.
If the listen() queue is empty of connection requests, the
accept() function blocks a calling socket of the blocking
type until a connection is present, or returns an [EWOULDBLOCK]
for sockets marked nonblocking.
The accepted socket cannot itself accept more connections.
The original socket remains open and can accept more connections.
[Tru64 UNIX] When compiled in the X/Open UNIX environment
or the POSIX.1g socket environment, calls to the accept()
function are internally renamed by prepending _E to the
function name. When you are debugging a module that
includes the accept() function and for which
_XOPEN_SOURCE_EXTENDED or _POSIX_PII_SOCKET has been
defined, use _Eaccept to refer to the accept() call. See
standards(5) for further information.
Upon successful completion, the accept() function returns
the nonnegative socket descriptor of the accepted socket.
Additionally, if the address parameter was specified then
it places the address of the peer in the sockaddr structure
pointed to by the address, and sets the address_len
parameter to the length of address. If the accept() function
fails, a value of -1 is returned and errno is set to
indicate the error.
If the accept() function fails, errno may be set to one of
the following values: The socket parameter is not valid.
A connection has been aborted. The address parameter or
address_len parameter is inaccessible or cannot be written.
The accept() function was interrupted by a signal
that was caught before a valid connection arrived. The
socket is not accepting connections. There are too many
open file descriptors. The maximum number of file
descriptors in the system are already open. Insufficient
resources are available in the system to complete the
call. The system was unable to allocate kernel memory to
increase the process descriptor table. The available
STREAMS resources were insufficient for the operation to
complete. The socket parameter refers to a file, not a
socket. The referenced socket cannot accept connections.
A protocol error occurred. The socket is marked nonblocking,
and no connections are present to be accepted.
Functions: bind(2), connect(2), listen(2), socket(2).
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