+++ /dev/null
-.\" peter memishian -- meem@gnu.ai.mit.edu
-.\" $Id: insque.3,v 1.2 1996/10/30 21:03:39 meem Exp meem $
-.\" and Copyright (c) 2010, Michael Kerrisk <mtk.manpages@gmail.com>
-.\"
-.\" %%%LICENSE_START(VERBATIM)
-.\" Permission is granted to make and distribute verbatim copies of this
-.\" manual provided the copyright notice and this permission notice are
-.\" preserved on all copies.
-.\"
-.\" Permission is granted to copy and distribute modified versions of this
-.\" manual under the conditions for verbatim copying, provided that the
-.\" entire resulting derived work is distributed under the terms of a
-.\" permission notice identical to this one.
-.\"
-.\" Since the Linux kernel and libraries are constantly changing, this
-.\" manual page may be incorrect or out-of-date. The author(s) assume no
-.\" responsibility for errors or omissions, or for damages resulting from
-.\" the use of the information contained herein. The author(s) may not
-.\" have taken the same level of care in the production of this manual,
-.\" which is licensed free of charge, as they might when working
-.\" professionally.
-.\"
-.\" Formatted or processed versions of this manual, if unaccompanied by
-.\" the source, must acknowledge the copyright and authors of this work.
-.\" %%%LICENSE_END
-.\"
-.\" References consulted:
-.\" Linux libc source code (5.4.7)
-.\" Solaris 2.x, OSF/1, and HP-UX manpages
-.\" Curry's "UNIX Systems Programming for SVR4" (O'Reilly & Associates 1996)
-.\"
-.\" Changed to POSIX, 2003-08-11, aeb+wh
-.\" mtk, 2010-09-09: Noted glibc 2.4 bug, added info on circular
-.\" lists, added example program
-.\"
-.TH INSQUE 3 2014-08-19 "" "Linux Programmer's Manual"
-.SH NAME
-insque, remque \- insert/remove an item from a queue
-.SH SYNOPSIS
-.nf
-.B #include <search.h>
-.sp
-.BI "void insque(void *" elem ", void *" prev );
-
-.BI "void remque(void *" elem );
-.fi
-.sp
-.in -4n
-Feature Test Macro Requirements for glibc (see
-.BR feature_test_macros (7)):
-.in
-.sp
-.ad l
-.BR insque (),
-.BR remque ():
-.RS 4
-_SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
-_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
-.RE
-.ad
-.SH DESCRIPTION
-The
-.BR insque ()
-and
-.BR remque ()
-functions manipulate doubly-linked lists.
-Each element in the list is a structure of
-which the first two elements are a forward and a
-backward pointer.
-The linked list may be linear (i.e., NULL forward pointer at
-the end of the list and NULL backward pointer at the start of the list)
-or circular.
-
-The
-.BR insque ()
-function inserts the element pointed to by \fIelem\fP
-immediately after the element pointed to by \fIprev\fP.
-
-If the list is linear, then the call
-.I "insque(elem, NULL)"
-can be used to insert the initial list element,
-and the call sets the forward and backward pointers of
-.I elem
-to NULL.
-
-If the list is circular,
-the caller should ensure that the forward and backward pointers of the
-first element are initialized to point to that element,
-and the
-.I prev
-argument of the
-.BR insque ()
-call should also point to the element.
-
-The
-.BR remque ()
-function removes the element pointed to by \fIelem\fP from the
-doubly-linked list.
-.SH CONFORMING TO
-POSIX.1-2001.
-.SH NOTES
-Traditionally (e.g., SunOS, Linux libc4 and libc5),
-the arguments of these functions were of type \fIstruct qelem *\fP,
-defined as:
-
-.in +4n
-.nf
-struct qelem {
- struct qelem *q_forw;
- struct qelem *q_back;
- char q_data[1];
-};
-.fi
-.in
-
-This is still what you will get if
-.B _GNU_SOURCE
-is defined before
-including \fI<search.h>\fP.
-
-The location of the prototypes for these functions differs among several
-versions of UNIX.
-The above is the POSIX version.
-Some systems place them in \fI<string.h>\fP.
-.\" Linux libc4 and libc 5 placed them
-.\" in \fI<stdlib.h>\fP.
-.SH BUGS
-In glibc 2.4 and earlier, it was not possible to specify
-.I prev
-as NULL.
-Consequently, to build a linear list, the caller had to build a list
-using an initial call that contained the first two elements of the list,
-with the forward and backward pointers in each element suitably initialized.
-.SH EXAMPLE
-The program below demonstrates the use of
-.BR insque ().
-Here is an example run of the program:
-.in +4n
-.nf
-
-.RB "$ " "./a.out -c a b c"
-Traversing completed list:
- a
- b
- c
-That was a circular list
-.fi
-.in
-.SS Program source
-\&
-.nf
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <search.h>
-
-struct element {
- struct element *forward;
- struct element *backward;
- char *name;
-};
-
-static struct element *
-new_element(void)
-{
- struct element *e;
-
- e = malloc(sizeof(struct element));
- if (e == NULL) {
- fprintf(stderr, "malloc() failed\\n");
- exit(EXIT_FAILURE);
- }
-
- return e;
-}
-
-int
-main(int argc, char *argv[])
-{
- struct element *first, *elem, *prev;
- int circular, opt, errfnd;
-
- /* The "\-c" command\-line option can be used to specify that the
- list is circular */
-
- errfnd = 0;
- circular = 0;
- while ((opt = getopt(argc, argv, "c")) != \-1) {
- switch (opt) {
- case 'c':
- circular = 1;
- break;
- default:
- errfnd = 1;
- break;
- }
- }
-
- if (errfnd || optind >= argc) {
- fprintf(stderr, "Usage: %s [\-c] string...\\n", argv[0]);
- exit(EXIT_FAILURE);
- }
-
- /* Create first element and place it in the linked list */
-
- elem = new_element();
- first = elem;
-
- elem\->name = argv[optind];
-
- if (circular) {
- elem\->forward = elem;
- elem\->backward = elem;
- insque(elem, elem);
- } else {
- insque(elem, NULL);
- }
-
- /* Add remaining command\-line arguments as list elements */
-
- while (++optind < argc) {
- prev = elem;
-
- elem = new_element();
- elem\->name = argv[optind];
- insque(elem, prev);
- }
-
- /* Traverse the list from the start, printing element names */
-
- printf("Traversing completed list:\\n");
- elem = first;
- do {
- printf(" %s\\n", elem\->name);
- elem = elem\->forward;
- } while (elem != NULL && elem != first);
-
- if (elem == first)
- printf("That was a circular list\\n");
-
- exit(EXIT_SUCCESS);
-}
-.fi
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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