accept(2)accept(2)Nameaccept - accept a connection on a socket
accept(s, addr, addrlen)
int ns, s;
struct sockaddr *addr;
The system call accepts a connection on a socket. The s argument is a
socket that has been created with the call, bound to an address with
the call and is listening for connections after a call. The system
call 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, ns, for the socket. If no pending connections are
present on the queue, and the socket is not marked as nonblocking,
blocks the caller until a connection is present. If the socket is
marked nonblocking and no pending connections are present on the queue,
returns an error. The accepted socket, ns, cannot be used to accept
more connections. The original socket s remains open.
The addr argument is filled in with the address of the connecting
entity, as known to the communications layer. The exact format of the
addr argument is determined by the domain in which the communication is
occurring. The addrlen argument should initially contain the amount of
space pointed to by addr. On return, the addr argument contains the
actual length in bytes of the address returned. This call is used with
connection-based socket types, currently with SOCK_STREAM.
You can use the system call for the purposes of doing an call by
selecting the socket for reading.
The call returns -1 on error. If the call succeeds, it returns a non‐
negative integer which is a file descriptor for the accepted socket.
The call fails if:
[EBADF] The descriptor is invalid.
[EINTR] The receipt of SIGCHLD signals is enabled and the
process is blocked on the system call. The application
must detect that this situation has occurred and restart
the system call.
[ENOTSOCK] The descriptor references a file, not a socket.
[EOPNOTSUPP] The referenced socket is not of type SOCK_STREAM.
[EFAULT] The addr parameter is not in a writable part of the user
[EWOULDBLOCK] The socket is marked nonblocking and no connections are
present to be accepted.
See Alsobind(2), connect(2), listen(2), select(2), socket(2)accept(2)