1.\" $OpenBSD: socketpair.2,v 1.16 2014/08/31 01:42:36 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: August 31 2014 $ 34.Dt SOCKETPAIR 2 35.Os 36.Sh NAME 37.Nm socketpair 38.Nd create a pair of connected sockets 39.Sh SYNOPSIS 40.In 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.Pp 60Any combination of the following flags may additionally be used in the 61.Fa type 62argument: 63.Pp 64.Bl -tag -width "SOCK_NONBLOCKX" -offset indent -compact 65.It SOCK_CLOEXEC 66Set close-on-exec flag on both the new descriptors. 67.It SOCK_NONBLOCK 68Set non-blocking I/O mode on both the new sockets. 69.El 70.Sh RETURN VALUES 71A 0 is returned if the call succeeds, \-1 if it fails. 72.Sh ERRORS 73The call succeeds unless: 74.Bl -tag -width Er 75.It Bq Er EAFNOSUPPORT 76The specified address family is not supported on this machine. 77.It Bq Er EPROTONOSUPPORT 78The specified protocol is not supported on this machine. 79.It Bq Er EOPNOTSUPP 80The specified protocol does not support creation of socket pairs. 81.It Bq Er EPROTOTYPE 82The combination of the specified protocol and type is not supported. 83.It Bq Er EMFILE 84The per-process descriptor table is full. 85.It Bq Er ENFILE 86The system file table is full. 87.It Bq Er ENOBUFS 88Insufficient resources were available in the system 89to perform the operation. 90.It Bq Er EFAULT 91The address 92.Fa sv 93does not specify a valid part of the 94process address space. 95.El 96.Sh SEE ALSO 97.Xr pipe 2 , 98.Xr read 2 , 99.Xr socket 2 , 100.Xr write 2 101.Sh STANDARDS 102The 103.Fn socketpair 104function conforms to 105.St -p1003.1-2008 . 106.Sh HISTORY 107The 108.Fn socketpair 109function call appeared in 110.Bx 4.2 . 111.Sh BUGS 112This call is currently implemented only for the 113.Tn LOCAL 114domain. 115Many operating systems only accept a 116.Ar protocol 117of 118.Dv PF_UNSPEC , 119so that should be used instead of 120.Dv PF_LOCAL 121for maximal portability. 122