accept(3N)

NAME
     accept - accept a connection on a socket

SYNOPSIS
     #include <sys/types.h>

     int accept(int s, caddr_t addr, int *addrlen);

DESCRIPTION
     The argument s is a socket that has been created with socket and bound to
     an address with bind, and that is listening for connections after a call
     to listen.  accept extracts the first connection on the queue of pending
     connections, creates a new socket with the 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 non-blocking, accept
     blocks the caller until a connection is present.  If the socket is marked
     as non-blocking and no pending connections are present on the queue,
     accept returns an error as described below.  accept uses the netconfig
     file to determine the STREAMS device file name associated with s.  This
     is the device on which the connect indication will be accepted.  The
     accepted socket, ns, is used to read and write data to and from the
     socket that connected to ns; it is not used to accept more connections.
     The original socket (s) remains open for accepting further connections.

     The argument addr is a result parameter that is filled in with the
     address of the connecting entity as it is known to the communications
     layer.  The exact format of the addr parameter is determined by the
     domain in which the communication occurs.

     addrlen is a value-result parameter.  Initially, it contains the amount
     of space pointed to by addr; on return it contains the length in bytes of
     the address returned.

     accept is used with connection-based socket types, currently with
     SOCK_STREAM.

     It is possible to select a socket for the purpose of an accept by
     selecting it for read.  However, this will only indicate when a connect
     indication is pending; it is still necessary to call accept.

RETURN VALUE
     accept returns -1 on error.  If it succeeds, it returns a non-negative
     integer that is a descriptor for the accepted socket.

ERRORS
     accept will fail if:

     EBADF               The descriptor is invalid.

     ENOTSOCK            The descriptor does not reference a socket.
     EOPNOTSUPP          The referenced socket is not of type SOCK_STREAM.

     EWOULDBLOCK         The socket is marked as non-blocking and no
                         connections are present to be accepted.

     EPROTO              A protocol error has occurred; for example, the
                         STREAMS protocol stack has not been initialized.

     ENODEV              The protocol family and type corresponding to s could
                         not be found in the netconfig file.

     ENOMEM              There was insufficient user memory available to
                         complete the operation.

     ENOSR               There were insufficient STREAMS resources available
                         to complete the operation.

SEE ALSO
     bind(3N), connect(3N), listen(3N), socket(3N), netconfig(4).

NOTES
     The type of address structure passed to accept depends on the address
     family.  UNIX domain sockets (address family AF_UNIX) require a
     socketaddr_un structure as defined in sys/un.h; Internet domain sockets
     (address family AF_INET) require a sockaddr_in structure as defined in
     netinet/in.h.  Other address families may require other structures.  Use
     the structure appropriate to the address family; cast the structure
     address to a generic caddr_t in the call to accept and pass the size of
     the structure in the addrlen argument.