1.\" $OpenBSD: socketpair.2,v 1.14 2011/11/06 12:07:42 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. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)socketpair.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: November 6 2011 $ 34.Dt SOCKETPAIR 2 35.Os 36.Sh NAME 37.Nm socketpair 38.Nd create a pair of connected sockets 39.Sh SYNOPSIS 40.Fd #include <sys/types.h> 41.Fd #include <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 EAFNOSUPPORT 68The specified address family is not supported on this machine. 69.It Bq Er EPROTONOSUPPORT 70The specified protocol is not supported on this machine. 71.It Bq Er EOPNOTSUPP 72The specified protocol does not support creation of socket pairs. 73.It Bq Er EFAULT 74The address 75.Fa sv 76does not specify a valid part of the 77process address space. 78.It Bq Er ENFILE 79The system file table is full. 80.El 81.Sh SEE ALSO 82.Xr pipe 2 , 83.Xr read 2 , 84.Xr write 2 85.Sh STANDARDS 86The 87.Fn socketpair 88function conforms to 89.St -xpg4.2 . 90.Sh HISTORY 91The 92.Fn socketpair 93function call appeared in 94.Bx 4.2 . 95.Sh BUGS 96This call is currently implemented only for the 97.Tn LOCAL 98domain. 99Many operating systems only accept a 100.Ar protocol 101of 102.Dv PF_UNSPEC , 103so that should be used instead of 104.Dv PF_LOCAL 105for maximal portability. 106