1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)socketpair.2 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD: src/lib/libc/sys/socketpair.2,v 1.6.2.6 2001/12/14 18:34:01 ru Exp $ 30.\" $DragonFly: src/lib/libc/sys/socketpair.2,v 1.4 2007/07/30 22:11:33 swildner Exp $ 31.\" 32.Dd October 28, 2015 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/types.h 42.In sys/socket.h 43.Ft int 44.Fn socketpair "int d" "int type" "int protocol" "int *sv" 45.Sh DESCRIPTION 46The 47.Fn socketpair 48call creates an unnamed pair of connected sockets in 49the specified domain 50.Fa d , 51of the specified 52.Fa type , 53and using the optionally specified 54.Fa protocol . 55The descriptors used in referencing the new sockets 56are returned in 57.Fa sv Ns [0] 58and 59.Fa sv Ns [1] . 60The two sockets are indistinguishable. 61.Pp 62The 63.Dv SOCK_CLOEXEC 64and 65.Dv SOCK_NONBLOCK 66flags in the 67.Fa type 68argument apply to both descriptors. 69.Sh RETURN VALUES 70.Rv -std socketpair 71.Sh ERRORS 72The call succeeds unless: 73.Bl -tag -width Er 74.It Bq Er EMFILE 75Too many descriptors are in use by this process. 76.It Bq Er EAFNOSUPPORT 77The specified address family is not supported on this machine. 78.It Bq Er EPROTONOSUPPORT 79The specified protocol is not supported on this machine. 80.It Bq Er EOPNOTSUPP 81The specified protocol does not support creation of socket pairs. 82.It Bq Er EFAULT 83The address 84.Fa sv 85does not specify a valid part of the 86process address space. 87.El 88.Sh SEE ALSO 89.Xr pipe 2 , 90.Xr read 2 , 91.Xr socket 2 , 92.Xr write 2 93.Sh HISTORY 94The 95.Fn socketpair 96function call appeared in 97.Bx 4.2 . 98.Sh BUGS 99This call is currently implemented only for the 100.Ux 101domain. 102