listen

Purpose

     Listens for connections on a socket.

Library

     Sockets Library (libsock.a)

Syntax

     int listen (s, backlog)
     int s, backlog;

Description

     To  accept  connections,  create a  socket  with  socket,
     specify a  backlog for incoming connections  with listen,
     and accept  the connections with accept.  The listen sub-
     routine applies only to sockets of type SOCK_STREAM.

     The backlog parameter defines  the maximum length for the
     queue of  pending connections.   If a  connection request
     arrives with the queue full, the client receives an error
     with an indication of ECONNREFUSED.

Return Value

     Upon successful completion, a value of 0 is returned.  If
     the listen routine fails, a  value of -1 is returned, and
     errno is set to indicate the error.

Diagnostics

     The subroutine fails if one  or more of the following are
     true:

     EBADF             The s parameter is not valid.

     ENOTSOCK          The s parameter refers to a file, not a
                       socket.

     EOPNOTSUPP        The  referenced socket  is not  of type
                       that supports listen.

Related Information

     In this book:  "accept," "connect," and "socket."