osx man page for socketpair

SOCKETPAIR(2)						      BSD System Calls Manual						     SOCKETPAIR(2)

NAME
     socketpair -- create a pair of connected sockets

SYNOPSIS
     #include <sys/socket.h>

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

DESCRIPTION
     The socketpair() call creates an unnamed pair of connected sockets in the specified domain domain, of the specified type, and using the
     optionally specified protocol.  The descriptors used in referencing the new sockets are returned in socket_vector[0] and socket_vector[1].
     The two sockets are indistinguishable.

RETURN VALUES
     The socketpair() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indi-
     cate the error.

ERRORS
     The call succeeds unless:

     [EAFNOSUPPORT]	The specified address family is not supported on this machine.

     [EFAULT]		The address socket_vector does not specify a valid part of the process address space.

     [EMFILE]		No more file descriptors are available for this process.

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

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

     [ENOMEM]		Insufficient memory was available to fulfill the request.

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

     [EPROTONOSUPPORT]	The specified protocol is not supported on this machine.

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

     [EACCES]		The process does not have appropriate privileges to create a socket of the specified type and/or protocol.

LEGACY SYNOPSIS
     #include <sys/types.h>
     #include <sys/socket.h>

     The include file <sys/types.h> is necessary.

SEE ALSO
     socket(2), read(2), write(2), compat(5)

BUGS
     This call is currently implemented only for the UNIX domain.

HISTORY
     The socketpair() function call appeared in 4.2BSD.

4.2 Berkeley Distribution					   June 4, 1993 					 4.2 Berkeley Distribution