1.\" $OpenBSD: socketpair.2,v 1.15 2013/04/08 19:49:55 guenther 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: April 8 2013 $ 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/socket.h> 41.Ft int 42.Fn socketpair "int d" "int type" "int protocol" "int sv[2]" 43.Sh DESCRIPTION 44The 45.Fn socketpair 46call creates an unnamed pair of connected sockets in 47the specified domain 48.Fa d , 49of the specified 50.Fa type , 51and using the optionally specified 52.Fa protocol . 53The descriptors used in referencing the new sockets 54are returned in 55.Fa sv Ns [0] 56and 57.Fa sv Ns [1] . 58The two sockets are indistinguishable. 59.Sh RETURN VALUES 60A 0 is returned if the call succeeds, \-1 if it fails. 61.Sh ERRORS 62The call succeeds unless: 63.Bl -tag -width Er 64.It Bq Er EAFNOSUPPORT 65The specified address family is not supported on this machine. 66.It Bq Er EPROTONOSUPPORT 67The specified protocol is not supported on this machine. 68.It Bq Er EOPNOTSUPP 69The specified protocol does not support creation of socket pairs. 70.It Bq Er EPROTOTYPE 71The combination of the specified protocol and type is not supported. 72.It Bq Er EMFILE 73The per-process descriptor table is full. 74.It Bq Er ENFILE 75The system file table is full. 76.It Bq Er ENOBUFS 77Insufficient resources were available in the system 78to perform the operation. 79.It Bq Er EFAULT 80The address 81.Fa sv 82does not specify a valid part of the 83process address space. 84.El 85.Sh SEE ALSO 86.Xr pipe 2 , 87.Xr read 2 , 88.Xr socket 2 , 89.Xr write 2 90.Sh STANDARDS 91The 92.Fn socketpair 93function conforms to 94.St -p1003.1-2008 . 95.Sh HISTORY 96The 97.Fn socketpair 98function call appeared in 99.Bx 4.2 . 100.Sh BUGS 101This call is currently implemented only for the 102.Tn LOCAL 103domain. 104Many operating systems only accept a 105.Ar protocol 106of 107.Dv PF_UNSPEC , 108so that should be used instead of 109.Dv PF_LOCAL 110for maximal portability. 111