socketpair

SYNOPSIS
       #include <sys/socket.h>

       int socketpair(int domain, int type, int protocol,
              int socket_vector[2]);


DESCRIPTION
       The  socketpair()  function  shall  create an unbound pair of connected
       sockets in a specified domain, of a specified type, under the  protocol
       optionally specified by the protocol argument. The two sockets shall be
       identical. The file descriptors used in referencing the created sockets
       shall be returned in socket_vector[0] and socket_vector[1].

       The socketpair() function takes the following arguments:

       domain Specifies  the communications domain in which the sockets are to
              be created.

       type   Specifies the type of sockets to be created.

       protocol
              Specifies a particular protocol to be  used  with  the  sockets.
              Specifying a protocol of 0 causes socketpair() to use an unspec-
              ified default protocol  appropriate  for  the  requested  socket
              type.

       socket_vector
              Specifies  a 2-integer array to hold the file descriptors of the
              created socket pair.


       The type argument specifies  the  socket  type,  which  determines  the
       semantics of communications over the socket. The following socket types
       are defined; implementations may specify additional socket types:

       SOCK_STREAM
              Provides  sequenced,  reliable,  bidirectional,  connection-mode
              byte  streams, and may provide a transmission mechanism for out-
              of-band data.

       SOCK_DGRAM
              Provides datagrams, which  are  connectionless-mode,  unreliable
              messages of fixed maximum length.

       SOCK_SEQPACKET
              Provides  sequenced,  reliable,  bidirectional,  connection-mode
              transmission paths for records. A record can be sent  using  one
              or  more  output operations and received using one or more input
              operations, but a single operation never transfers part of  more
              than  one  record. Record boundaries are visible to the receiver
              via the MSG_EOR flag.


ERRORS
       The socketpair() function shall fail if:

       EAFNOSUPPORT

              The  implementation  does not support the specified address fam-
              ily.

       EMFILE No more file descriptors are available for this process.

       ENFILE No more file descriptors are available for the system.

       EOPNOTSUPP
              The specified protocol does not permit creation of socket pairs.

       EPROTONOSUPPORT

              The protocol is not supported by the address family, or the pro-
              tocol is not supported by the implementation.

       EPROTOTYPE
              The socket type is not supported by the protocol.


       The socketpair() function may fail if:

       EACCES The process does not have appropriate privileges.

       ENOBUFS
              Insufficient  resources  were available in the system to perform
              the operation.

       ENOMEM Insufficient memory was available to fulfill the request.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The documentation for specific address families specifies which  proto-
       cols  each address family supports. The documentation for specific pro-
       tocols specifies which socket types each protocol supports.

       The socketpair() function is used primarily with  UNIX  domain  sockets
       and need not be supported for other domains.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                        SOCKETPAIR(P)