accept(SSC)                    6 January 1993                    accept(SSC)


 Name

    accept - accept a connection on a socket

 Syntax


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

    int accept(s, (addr, addrlen)
    int s;
    struct sockaddr *addr;
    int addrlen;


 Description

    accept accepts a connection on a socket.  The argument s is a socket
    which has been created with socket(SSC), bound to an address with
    bind(SSC), and is listening for connections after a listen(SSC).  accept
    extracts the first connection on the queue of pending connections, cre-
    ates a new socket with the same properties of 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, ns, may not be
    used to accept more connections.  The original socket s remains open.

    The argument addr is a result parameter which 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 "communica-
    tions domain". (See protocols(SFF) for more information.)  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 SOCKSTREAM.

 Return value

    The call returns -1 on error.  If it succeeds it returns a non-negative
    integer which is a descriptor for the accepted socket (ns, described
    above).

 Errors

    The accept will fail if:

    [EBADF]             The descriptor is invalid.

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

    [EOPNOTSUPP]        The referenced socket is not of type SOCKSTREAM.

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

 See also

    Intro(SSC), bind(SSC), connect(SSC), listen(SSC), socket(SSC) and
    intro(ADMP).