209 lines
8.9 KiB
C
209 lines
8.9 KiB
C
/*
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* list.h : list manipulation macros and structures.
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* Copyright 2002-2010 Willy Tarreau <w@1wt.eu>
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*
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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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/* dual linked lists :
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* Start = (struct list *) pointer to the next elem's prev list entry
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* For each element :
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* - prev = pointer to previous element's next (or start). Cannot be NULL
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* - next = pointer to next element's prev. NULL = end.
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*
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*/
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/* adds an element at the beginning of a dual-linked list ; returns the element */
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#define DLIST_ADD(lh, el) ({ typeof(el) __ret = (el); __ret->n = (void *)(lh); __ret->p = (void *)&(lh); if (likely(__ret->n != NULL)) __ret->n->p = __ret; (lh) = (typeof(lh))&__ret->n; __ret; })
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/* removes an element from a dual-linked list and returns it */
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#define DLIST_DEL(el) ({ typeof(el) __ret = (el); if (likely(__ret->n != NULL)) __ret->n->p = __ret->p; __ret->p->n = __ret->n; __ret; })
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/*
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* iterates through a list of items of type "<struct_type>" which are
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* linked via a "struct list" member named <struct_member>. The head of the
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* list is stored at a location designed by <list_head>, which should be a
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* "struct list *". A variable <end_item> of type "<struct_type>" will
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* be used as temporary end of list pointer. It can be derived from <list_head>
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* since this one is only used before. <list_head> will be modified except for
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* foreach_dlist_item_cst which is slightly slower.
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* Major difference between FOREACH_ITEM is that it stops at NULL.
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* Example: foreach_dlist_item(cur_node, args, struct node *, list) { ... };
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* foreach_dlist_item_cst(cur_node, &node->args, struct node *, list) { ... };
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*/
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#define foreach_dlist_item_cst(iterator, list_head, struct_type, struct_member) \
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for ((iterator) = LIST_ELEM(&(list_head), struct_type, struct_member.n); \
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((iterator)->struct_member.n != NULL) && \
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(((iterator) = LIST_ELEM((iterator)->struct_member.n, struct_type, struct_member.n)), 1);\
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)
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#define foreach_dlist_item(iterator, var_list_head, struct_type, struct_member) \
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while ((var_list_head != NULL) && \
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((var_list_head=((iterator)=LIST_ELEM(var_list_head, struct_type, struct_member.n))->struct_member.n), 1))
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/*
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* Like foreach_dlist_item, except that this one only operates on the head of
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* the list. It's to the inner instructions to iterate the list head. If not,
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* this will be an endless loop.
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*/
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#define while_dlist_item(iterator, var_list_head, struct_type, struct_member) \
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while ((var_list_head != NULL) && \
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(((iterator)=LIST_ELEM(var_list_head, struct_type, struct_member.n)),1))
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/****** circular lists ********/
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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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* DEPRECATED !!! Use list_for_each_entry() below instead !
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*
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* iterates through a list of items of type "<struct_type>" which are
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* linked via a "struct list" member named <struct_member>. The head of the
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* list is stored at a location designed by <list_head>, which should be a
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* "struct list *". A variable <end_item> of type "<struct_type>" will
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* be used as temporary end of list pointer. It can be derived from <list_head>
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* since this one is only used before.
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* Example: FOREACH_ITEM(cur_node, &node->args, node, struct node *, neigh) { ... };
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*/
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#define FOREACH_ITEM(iterator, list_head, end_item, struct_type, struct_member) \
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iterator = end_item = LIST_ELEM(list_head, struct_type, struct_member); \
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while (((iterator) = LIST_ELEM((iterator)->struct_member.n, \
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struct_type, struct_member)) != (end_item))
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/*
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* DEPRECATED !!! Use list_for_each_entry_safe() below instead !
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*
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* idem except that this one is safe against deletion, but it needs a backup
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* pointer of the element after the iterator.
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* Example: FOREACH_ITEM_SAFE(cur_node, backup, &node->args, node, struct node *, neigh) { ... };
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*/
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#define FOREACH_ITEM_SAFE(iterator, backup, list_head, end_item, struct_type, struct_member) \
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end_item = LIST_ELEM(list_head, struct_type, struct_member); \
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iterator = LIST_ELEM((end_item)->struct_member.n, struct_type, struct_member); \
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if ((iterator) != (end_item)) \
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backup = LIST_ELEM((iterator)->struct_member.n, struct_type, struct_member); \
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for ( ; (iterator) != (end_item); (iterator) = (backup), \
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backup = LIST_ELEM((iterator)->struct_member.n, struct_type, struct_member))
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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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