145 lines
5.6 KiB
C
145 lines
5.6 KiB
C
/*
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* include/common/mini-clist.h
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* Circular list manipulation macros and structures.
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*
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* Copyright (C) 2002-2014 Willy Tarreau - w@1wt.eu
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation, version 2.1
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* exclusively.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _COMMON_MINI_CLIST_H
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#define _COMMON_MINI_CLIST_H
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#include <common/config.h>
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/* these are circular or bidirectionnal lists only. Each list pointer points to
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* another list pointer in a structure, and not the structure itself. The
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* pointer to the next element MUST be the first one so that the list is easily
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* cast as a single linked list or pointer.
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*/
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struct list {
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struct list *n; /* next */
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struct list *p; /* prev */
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};
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/* a back-ref is a pointer to a target list entry. It is used to detect when an
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* element being deleted is currently being tracked by another user. The best
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* example is a user dumping the session table. The table does not fit in the
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* output buffer so we have to set a mark on a session and go on later. But if
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* that marked session gets deleted, we don't want the user's pointer to go in
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* the wild. So we can simply link this user's request to the list of this
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* session's users, and put a pointer to the list element in ref, that will be
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* used as the mark for next iteration.
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*/
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struct bref {
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struct list users;
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struct list *ref; /* pointer to the target's list entry */
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};
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/* a word list is a generic list with a pointer to a string in each element. */
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struct wordlist {
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struct list list;
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char *s;
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};
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/* this is the same as above with an additional pointer to a condition. */
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struct cond_wordlist {
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struct list list;
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void *cond;
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char *s;
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};
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/* First undefine some macros which happen to also be defined on OpenBSD,
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* in sys/queue.h, used by sys/event.h
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*/
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#undef LIST_HEAD
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#undef LIST_INIT
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#undef LIST_NEXT
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/* ILH = Initialized List Head : used to prevent gcc from moving an empty
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* list to BSS. Some older version tend to trim all the array and cause
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* corruption.
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*/
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#define ILH { .n = (struct list *)1, .p = (struct list *)2 }
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#define LIST_HEAD(a) ((void *)(&(a)))
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#define LIST_INIT(l) ((l)->n = (l)->p = (l))
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#define LIST_HEAD_INIT(l) { &l, &l }
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/* adds an element at the beginning of a list ; returns the element */
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#define LIST_ADD(lh, el) ({ (el)->n = (lh)->n; (el)->n->p = (lh)->n = (el); (el)->p = (lh); (el); })
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/* adds an element at the end of a list ; returns the element */
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#define LIST_ADDQ(lh, el) ({ (el)->p = (lh)->p; (el)->p->n = (lh)->p = (el); (el)->n = (lh); (el); })
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/* removes an element from a list and returns it */
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#define LIST_DEL(el) ({ typeof(el) __ret = (el); (el)->n->p = (el)->p; (el)->p->n = (el)->n; (__ret); })
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/* returns a pointer of type <pt> to a structure containing a list head called
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* <el> at address <lh>. Note that <lh> can be the result of a function or macro
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* since it's used only once.
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* Example: LIST_ELEM(cur_node->args.next, struct node *, args)
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*/
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#define LIST_ELEM(lh, pt, el) ((pt)(((void *)(lh)) - ((void *)&((pt)NULL)->el)))
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/* checks if the list head <lh> is empty or not */
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#define LIST_ISEMPTY(lh) ((lh)->n == (lh))
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/* returns a pointer of type <pt> to a structure following the element
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* which contains list head <lh>, which is known as element <el> in
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* struct pt.
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* Example: LIST_NEXT(args, struct node *, list)
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*/
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#define LIST_NEXT(lh, pt, el) (LIST_ELEM((lh)->n, pt, el))
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/* returns a pointer of type <pt> to a structure preceeding the element
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* which contains list head <lh>, which is known as element <el> in
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* struct pt.
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*/
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#define LIST_PREV(lh, pt, el) (LIST_ELEM((lh)->p, pt, el))
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/*
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* Simpler FOREACH_ITEM macro inspired from Linux sources.
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* Iterates <item> through a list of items of type "typeof(*item)" which are
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* linked via a "struct list" member named <member>. A pointer to the head of
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* the list is passed in <list_head>. No temporary variable is needed. Note
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* that <item> must not be modified during the loop.
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* Example: list_for_each_entry(cur_acl, known_acl, list) { ... };
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*/
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#define list_for_each_entry(item, list_head, member) \
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for (item = LIST_ELEM((list_head)->n, typeof(item), member); \
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&item->member != (list_head); \
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item = LIST_ELEM(item->member.n, typeof(item), member))
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/*
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* Simpler FOREACH_ITEM_SAFE macro inspired from Linux sources.
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* Iterates <item> through a list of items of type "typeof(*item)" which are
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* linked via a "struct list" member named <member>. A pointer to the head of
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* the list is passed in <list_head>. A temporary variable <back> of same type
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* as <item> is needed so that <item> may safely be deleted if needed.
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* Example: list_for_each_entry_safe(cur_acl, tmp, known_acl, list) { ... };
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*/
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#define list_for_each_entry_safe(item, back, list_head, member) \
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for (item = LIST_ELEM((list_head)->n, typeof(item), member), \
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back = LIST_ELEM(item->member.n, typeof(item), member); \
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&item->member != (list_head); \
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item = back, back = LIST_ELEM(back->member.n, typeof(back), member))
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#endif /* _COMMON_MINI_CLIST_H */
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