1.\" $OpenBSD: socketpair.2,v 1.10 1999/07/06 18:21:04 deraadt Exp $ 2.\" $NetBSD: socketpair.2,v 1.5 1995/02/27 12:38:00 cgd Exp $ 3.\" 4.\" Copyright (c) 1983, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)socketpair.2 8.1 (Berkeley) 6/4/93 36.\" 37.Dd June 4, 1993 38.Dt SOCKETPAIR 2 39.Os 40.Sh NAME 41.Nm socketpair 42.Nd create a pair of connected sockets 43.Sh SYNOPSIS 44.Fd #include <sys/types.h> 45.Fd #include <sys/socket.h> 46.Ft int 47.Fn socketpair "int d" "int type" "int protocol" "int *sv" 48.Sh DESCRIPTION 49The 50.Fn socketpair 51call creates an unnamed pair of connected sockets in 52the specified domain 53.Fa d , 54of the specified 55.Fa type , 56and using the optionally specified 57.Fa protocol . 58The descriptors used in referencing the new sockets 59are returned in 60.Fa sv Ns [0] 61and 62.Fa sv Ns [1] . 63The two sockets are indistinguishable. 64.Sh RETURN VALUES 65A 0 is returned if the call succeeds, \-1 if it fails. 66.Sh ERRORS 67The call succeeds unless: 68.Bl -tag -width Er 69.It Bq Er EMFILE 70Too many descriptors are in use by this process. 71.It Bq Er EAFNOSUPPORT 72The specified address family is not supported on this machine. 73.It Bq Er EPROTONOSUPPORT 74The specified protocol is not supported on this machine. 75.It Bq Er EOPNOTSUPP 76The specified protocol does not support creation of socket pairs. 77.It Bq Er EFAULT 78The address 79.Fa sv 80does not specify a valid part of the 81process address space. 82.It Bq Er ENFILE 83The system file table is full. 84.El 85.Sh SEE ALSO 86.Xr pipe 2 , 87.Xr read 2 , 88.Xr write 2 89.Sh BUGS 90This call is currently implemented only for the 91.Tn LOCAL 92domain. 93Many operating systems only accept a 94.Ar protocol 95of 96.Ev PF_UNSPEC , 97so that should be used instead of 98.Ev PF_LOCAL 99for maximal portability. 100.Sh STANDARDS 101The 102.Fn socketpair 103function conforms to 104.St -xpg4.2 . 105.Sh HISTORY 106The 107.Fn socketpair 108function call appeared in 109.Bx 4.2 . 110