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.Dd February 10, 2018 29.Dt SOCKETPAIR 2 30.Os 31.Sh NAME 32.Nm socketpair 33.Nd create a pair of connected sockets 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In sys/types.h 38.In sys/socket.h 39.Ft int 40.Fn socketpair "int domain" "int type" "int protocol" "int *sv" 41.Sh DESCRIPTION 42The 43.Fn socketpair 44system call creates an unnamed pair of connected sockets in 45the specified communications 46.Fa domain , 47of the specified 48.Fa type , 49and using the optionally specified 50.Fa protocol . 51The descriptors used in referencing the new sockets 52are returned in 53.Fa sv Ns [0] 54and 55.Fa sv Ns [1] . 56The two sockets are indistinguishable. 57.Pp 58The 59.Dv SOCK_CLOEXEC 60and 61.Dv SOCK_NONBLOCK 62flags in the 63.Fa type 64argument apply to both descriptors. 65.Sh RETURN VALUES 66.Rv -std socketpair 67.Sh ERRORS 68The call succeeds unless: 69.Bl -tag -width Er 70.It Bq Er EMFILE 71Too many descriptors are in use by this process. 72.It Bq Er EAFNOSUPPORT 73The specified address family is not supported on this machine. 74.It Bq Er EPROTONOSUPPORT 75The specified protocol is not supported on this machine. 76.It Bq Er EOPNOTSUPP 77The specified protocol does not support creation of socket pairs. 78.It Bq Er EFAULT 79The address 80.Fa sv 81does not specify a valid part of the 82process address space. 83.El 84.Sh SEE ALSO 85.Xr pipe 2 , 86.Xr read 2 , 87.Xr socket 2 , 88.Xr write 2 89.Sh STANDARDS 90The 91.Fn socketpair 92system call conforms to 93.St -p1003.1-2001 94and 95.St -p1003.1-2008 . 96.Sh HISTORY 97The 98.Fn socketpair 99system call appeared in 100.Bx 4.2 . 101.Sh BUGS 102This call is currently implemented only for the 103.Ux 104domain. 105