1.\" $NetBSD: socketpair.2,v 1.19 2004/05/13 10:20:58 wiz Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)socketpair.2 8.1 (Berkeley) 6/4/93 31.\" 32.Dd August 18, 2002 33.Dt SOCKETPAIR 2 34.Os 35.Sh NAME 36.Nm socketpair 37.Nd create a pair of connected sockets 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In sys/socket.h 42.Ft int 43.Fn socketpair "int d" "int type" "int protocol" "int *sv" 44.Sh DESCRIPTION 45The 46.Fn socketpair 47call creates an unnamed pair of connected sockets in 48the specified domain 49.Fa d , 50of the specified 51.Fa type , 52and using the optionally specified 53.Fa protocol . 54The descriptors used in referencing the new sockets 55are returned in 56.Fa sv Ns [0] 57and 58.Fa sv Ns [1] . 59The two sockets are indistinguishable. 60.Sh RETURN VALUES 61A 0 is returned if the call succeeds, \-1 if it fails. 62.Sh ERRORS 63The call succeeds unless: 64.Bl -tag -width Er 65.It Bq Er EMFILE 66Too many descriptors are in use by this process. 67.It Bq Er ENFILE 68The system file table is full. 69.It Bq Er EAFNOSUPPORT 70The specified address family is not supported on this machine. 71.It Bq Er EPROTONOSUPPORT 72The specified protocol is not supported on this machine. 73.It Bq Er EOPNOTSUPP 74The specified protocol does not support creation of socket pairs. 75.It Bq Er EFAULT 76The address 77.Fa sv 78does not specify a valid part of the 79process address space. 80.El 81.Sh SEE ALSO 82.Xr pipe 2 , 83.Xr read 2 , 84.Xr write 2 85.Sh HISTORY 86The 87.Fn socketpair 88function call appeared in 89.Bx 4.2 . 90.Sh BUGS 91This call is currently implemented only for the 92.Tn LOCAL 93domain. 94Many operating systems only accept a 95.Ar protocol 96of 97.Ev PF_UNSPEC , 98so that should be used instead of 99.Ev PF_LOCAL 100for maximal portability. 101