1.\" $OpenBSD: insque.3,v 1.12 2020/04/26 16:36:14 schwarze Exp $ 2.\" Copyright (c) 1993 John Brezak 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. The name of the author may be used to endorse or promote products 14.\" derived from this software without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR `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 AUTHOR 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.\" 29.Dd $Mdocdate: April 26 2020 $ 30.Dt INSQUE 3 31.Os 32.Sh NAME 33.Nm insque , 34.Nm remque 35.Nd legacy doubly linked lists 36.Sh SYNOPSIS 37.In search.h 38.Ft void 39.Fn insque "void *elem" "void *pred" 40.Ft void 41.Fn remque "void *elem" 42.Sh DESCRIPTION 43.Bf -symbolic 44These interfaces have been superseded by the 45.Xr queue 3 46macros and are provided for compatibility with legacy code. 47.Ef 48.Pp 49.Fn insque 50and 51.Fn remque 52manipulate a legacy variety of intrusive doubly linked lists. 53A list can be either circular or linear. 54Each element in the list must be of the following form: 55.Bd -literal -offset indent 56struct qelem { 57 struct qelem *q_forw; 58 struct qelem *q_back; 59 char q_data[]; 60}; 61.Ed 62.Pp 63The first two members of the struct must be pointers of the 64same type that point to the next and previous elements in 65the list, respectively. 66Any subsequent data in the struct is application-dependent. 67.Pp 68The 69.Fn insque 70function inserts 71.Fa elem 72into a list immediately after 73.Fa pred . 74.Pp 75The 76.Fn remque 77function removes 78.Fa elem 79from the list. 80.Pp 81These functions are not atomic. 82.Sh SEE ALSO 83.Xr queue 3 84.Sh STANDARDS 85The 86.Fn insque 87and 88.Fn remque 89functions conform to the X/Open System Interfaces option of the 90.St -p1003.1-2008 91specification. 92.Sh HISTORY 93The 94.Fn insque 95and 96.Fn remque 97functions are derived from the 98.Li insque 99and 100.Li remque 101instructions on the VAX. 102They first appeared in 103.Bx 4.2 . 104