(libc.info.gz) Socket Pairs

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 16.8.3 Socket Pairs
 -------------------
 
 A "socket pair" consists of a pair of connected (but unnamed) sockets.
 It is very similar to a pipe and is used in much the same way.  Socket
 pairs are created with the `socketpair' function, declared in
 `sys/socket.h'.  A socket pair is much like a pipe; the main difference
 is that the socket pair is bidirectional, whereas the pipe has one
 input-only end and one output-only end ( Pipes and FIFOs).
 
  -- Function: int socketpair (int NAMESPACE, int STYLE, int PROTOCOL,
           int FILEDES[2])
      This function creates a socket pair, returning the file
      descriptors in `FILEDES[0]' and `FILEDES[1]'.  The socket pair is
      a full-duplex communications channel, so that both reading and
      writing may be performed at either end.
 
      The NAMESPACE, STYLE and PROTOCOL arguments are interpreted as for
      the `socket' function.  STYLE should be one of the communication
      styles listed in  Communication Styles.  The NAMESPACE
      Local Namespace::); PROTOCOL specifies the communications
      protocol, but zero is the only meaningful value.
 
      If STYLE specifies a connectionless communication style, then the
      two sockets you get are not _connected_, strictly speaking, but
      each of them knows the other as the default destination address,
      so they can send packets to each other.
 
      The `socketpair' function returns `0' on success and `-1' on
      failure.  The following `errno' error conditions are defined for
      this function:
 
     `EMFILE'
           The process has too many file descriptors open.
 
     `EAFNOSUPPORT'
           The specified namespace is not supported.
 
     `EPROTONOSUPPORT'
           The specified protocol is not supported.
 
     `EOPNOTSUPP'
           The specified protocol does not support the creation of
           socket pairs.
 

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(libc.info.gz) Closing a Socket

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