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socketpair(2)
NAME
  socketpair - Creates a pair of connected sockets

SYNOPSIS
  #include <sys/socket.h>
  int socketpair(
	  int domain,
	  int type,
	  int protocol,
	  int socket_vector[2] );

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  socketpair():	 XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  domain    Specifies the communications domain in which the sockets are
	    created. This function does not create sockets in the Internet
	    domain.

  type	    Specifies the communications method that sockets use, for example
	    SOCK_DGRAM or SOCK_STREAM.

  protocol  Specifies an optional identifier used to define the
	    communications protocols used in the transport layer interface.

  socket_vector
	    Specifies a two-integer array used to hold the file descriptors
	    of the socket pair created with the call to this function.

DESCRIPTION
  The socketpair() function creates an unnamed pair of connected sockets in a
  specified domain, of a specified type, under the protocol optionally
  specified by the protocol parameter.	The two sockets are identical. The
  file descriptors used in referencing the created sockets are returned to
  socket_vector[0] and socket_vector[1]. The sys/socket.h include file
  contains definitions for socket domains, types, and protocols.

  Not all protocol families support the socketpair() function.

RETURN VALUES
  Upon successful completion, this function returns a value of 0 (zero).
  Otherwise, -1 is returned and errno is specified to indicate the error.

ERRORS
  If the socketpair() function fails, errno may be set to one of the
  following values:

  [EAFNOSUPPORT]
	    The addresses in the specified address family cannot be used to
	    create this socket pair.

  [EFAULT]  The socket_vector array is not located in a writable part of user
	    address space.

  [EMFILE]  The current process has too many open file descriptors.

  [ENFILE]  No more file descriptors are available for the system.

  [ENOMEM]  The system was unable to allocate kernel memory to increase the
	    process descriptor table.

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

  [EPROTONOSUPPORT]
	    The specified protocol cannot be used in this system.

  [EPROTOTYPE]
	    The socket type is not supported by the protocol.

RELATED INFORMATION
  Functions: socket(2)

  Standards: standards(5)