1 /* Licensed under BSD-MIT - see LICENSE file for details */
4 //#define CCAN_LIST_DEBUG 1
7 #include <ccan/str/str.h>
8 #include <ccan/container_of/container_of.h>
9 #include <ccan/check_type/check_type.h>
12 * struct list_node - an entry in a doubly-linked list
13 * @next: next entry (self if empty)
14 * @prev: previous entry (self if empty)
16 * This is used as an entry in a linked list.
20 * // Linked list of all us children.
21 * struct list_node list;
26 struct list_node *next, *prev;
30 * struct list_head - the head of a doubly-linked list
31 * @h: the list_head (containing next and prev pointers)
33 * This is used as the head of a linked list.
37 * struct list_head children;
38 * unsigned int num_children;
47 * list_check - check head of a list for consistency
49 * @abortstr: the location to print on aborting, or NULL.
51 * Because list_nodes have redundant information, consistency checking between
52 * the back and forward links can be done. This is useful as a debugging check.
53 * If @abortstr is non-NULL, that will be printed in a diagnostic if the list
54 * is inconsistent, and the function will abort.
56 * Returns the list head if the list is consistent, NULL if not (it
57 * can never return NULL if @abortstr is set).
59 * See also: list_check_node()
62 * static void dump_parent(struct parent *p)
66 * printf("%s (%u children):\n", p->name, p->num_children);
67 * list_check(&p->children, "bad child list");
68 * list_for_each(&p->children, c, list)
69 * printf(" -> %s\n", c->name);
72 struct list_head *list_check(const struct list_head *h, const char *abortstr);
75 * list_check_node - check node of a list for consistency
77 * @abortstr: the location to print on aborting, or NULL.
79 * Check consistency of the list node is in (it must be in one).
81 * See also: list_check()
84 * static void dump_child(const struct child *c)
86 * list_check_node(&c->list, "bad child list");
87 * printf("%s\n", c->name);
90 struct list_node *list_check_node(const struct list_node *n,
91 const char *abortstr);
93 #define LIST_LOC __FILE__ ":" stringify(__LINE__)
94 #ifdef CCAN_LIST_DEBUG
95 #define list_debug(h, loc) list_check((h), loc)
96 #define list_debug_node(n, loc) list_check_node((n), loc)
98 #define list_debug(h, loc) (h)
99 #define list_debug_node(n, loc) (n)
103 * LIST_HEAD_INIT - initializer for an empty list_head
104 * @name: the name of the list.
106 * Explicit initializer for an empty list.
109 * LIST_HEAD, list_head_init()
112 * static struct list_head my_list = LIST_HEAD_INIT(my_list);
114 #define LIST_HEAD_INIT(name) { { &name.n, &name.n } }
117 * LIST_HEAD - define and initialize an empty list_head
118 * @name: the name of the list.
120 * The LIST_HEAD macro defines a list_head and initializes it to an empty
121 * list. It can be prepended by "static" to define a static list_head.
124 * LIST_HEAD_INIT, list_head_init()
127 * static LIST_HEAD(my_global_list);
129 #define LIST_HEAD(name) \
130 struct list_head name = LIST_HEAD_INIT(name)
133 * list_head_init - initialize a list_head
134 * @h: the list_head to set to the empty list
138 * struct parent *parent = malloc(sizeof(*parent));
140 * list_head_init(&parent->children);
141 * parent->num_children = 0;
143 static inline void list_head_init(struct list_head *h)
145 h->n.next = h->n.prev = &h->n;
149 * list_node_init - initialize a list_node
150 * @n: the list_node to link to itself.
152 * You don't need to use this normally! But it lets you list_del(@n)
155 static inline void list_node_init(struct list_node *n)
157 n->next = n->prev = n;
161 * list_add_after - add an entry after an existing node in a linked list
162 * @h: the list_head to add the node to (for debugging)
163 * @p: the existing list_node to add the node after
164 * @n: the new list_node to add to the list.
166 * The existing list_node must already be a member of the list.
167 * The new list_node does not need to be initialized; it will be overwritten.
170 * struct child c1, c2, c3;
173 * list_add_tail(&h, &c1.list);
174 * list_add_tail(&h, &c3.list);
175 * list_add_after(&h, &c1.list, &c2.list);
177 #define list_add_after(h, p, n) list_add_after_(h, p, n, LIST_LOC)
178 static inline void list_add_after_(struct list_head *h,
181 const char *abortstr)
187 (void)list_debug(h, abortstr);
191 * list_add - add an entry at the start of a linked list.
192 * @h: the list_head to add the node to
193 * @n: the list_node to add to the list.
195 * The list_node does not need to be initialized; it will be overwritten.
197 * struct child *child = malloc(sizeof(*child));
199 * child->name = "marvin";
200 * list_add(&parent->children, &child->list);
201 * parent->num_children++;
203 #define list_add(h, n) list_add_(h, n, LIST_LOC)
204 static inline void list_add_(struct list_head *h,
206 const char *abortstr)
208 list_add_after_(h, &h->n, n, abortstr);
212 * list_add_before - add an entry before an existing node in a linked list
213 * @h: the list_head to add the node to (for debugging)
214 * @p: the existing list_node to add the node before
215 * @n: the new list_node to add to the list.
217 * The existing list_node must already be a member of the list.
218 * The new list_node does not need to be initialized; it will be overwritten.
221 * list_head_init(&h);
222 * list_add_tail(&h, &c1.list);
223 * list_add_tail(&h, &c3.list);
224 * list_add_before(&h, &c3.list, &c2.list);
226 #define list_add_before(h, p, n) list_add_before_(h, p, n, LIST_LOC)
227 static inline void list_add_before_(struct list_head *h,
230 const char *abortstr)
236 (void)list_debug(h, abortstr);
240 * list_add_tail - add an entry at the end of a linked list.
241 * @h: the list_head to add the node to
242 * @n: the list_node to add to the list.
244 * The list_node does not need to be initialized; it will be overwritten.
246 * list_add_tail(&parent->children, &child->list);
247 * parent->num_children++;
249 #define list_add_tail(h, n) list_add_tail_(h, n, LIST_LOC)
250 static inline void list_add_tail_(struct list_head *h,
252 const char *abortstr)
254 list_add_before_(h, &h->n, n, abortstr);
258 * list_empty - is a list empty?
261 * If the list is empty, returns true.
264 * assert(list_empty(&parent->children) == (parent->num_children == 0));
266 #define list_empty(h) list_empty_(h, LIST_LOC)
267 static inline bool list_empty_(const struct list_head *h, const char* abortstr)
269 (void)list_debug(h, abortstr);
270 return h->n.next == &h->n;
274 * list_empty_nodebug - is a list empty (and don't perform debug checks)?
277 * If the list is empty, returns true.
278 * This differs from list_empty() in that if CCAN_LIST_DEBUG is set it
279 * will NOT perform debug checks. Only use this function if you REALLY
280 * know what you're doing.
283 * assert(list_empty_nodebug(&parent->children) == (parent->num_children == 0));
285 #ifndef CCAN_LIST_DEBUG
286 #define list_empty_nodebug(h) list_empty(h)
288 static inline bool list_empty_nodebug(const struct list_head *h)
290 return h->n.next == &h->n;
295 * list_del - delete an entry from an (unknown) linked list.
296 * @n: the list_node to delete from the list.
298 * Note that this leaves @n in an undefined state; it can be added to
299 * another list, but not deleted again.
302 * list_del_from(), list_del_init()
305 * list_del(&child->list);
306 * parent->num_children--;
308 #define list_del(n) list_del_(n, LIST_LOC)
309 static inline void list_del_(struct list_node *n, const char* abortstr)
311 (void)list_debug_node(n, abortstr);
312 n->next->prev = n->prev;
313 n->prev->next = n->next;
314 #ifdef CCAN_LIST_DEBUG
315 /* Catch use-after-del. */
316 n->next = n->prev = NULL;
321 * list_del_init - delete a node, and reset it so it can be deleted again.
322 * @n: the list_node to be deleted.
324 * list_del(@n) or list_del_init() again after this will be safe,
325 * which can be useful in some cases.
328 * list_del_from(), list_del()
331 * list_del_init(&child->list);
332 * parent->num_children--;
334 #define list_del_init(n) list_del_init_(n, LIST_LOC)
335 static inline void list_del_init_(struct list_node *n, const char *abortstr)
337 list_del_(n, abortstr);
342 * list_del_from - delete an entry from a known linked list.
343 * @h: the list_head the node is in.
344 * @n: the list_node to delete from the list.
346 * This explicitly indicates which list a node is expected to be in,
347 * which is better documentation and can catch more bugs.
349 * See also: list_del()
352 * list_del_from(&parent->children, &child->list);
353 * parent->num_children--;
355 static inline void list_del_from(struct list_head *h, struct list_node *n)
357 #ifdef CCAN_LIST_DEBUG
359 /* Thorough check: make sure it was in list! */
361 for (i = h->n.next; i != n; i = i->next)
364 #endif /* CCAN_LIST_DEBUG */
366 /* Quick test that catches a surprising number of bugs. */
367 assert(!list_empty(h));
372 * list_entry - convert a list_node back into the structure containing it.
374 * @type: the type of the entry
375 * @member: the list_node member of the type
378 * // First list entry is children.next; convert back to child.
379 * child = list_entry(parent->children.n.next, struct child, list);
382 * list_top(), list_for_each()
384 #define list_entry(n, type, member) container_of(n, type, member)
387 * list_top - get the first entry in a list
389 * @type: the type of the entry
390 * @member: the list_node member of the type
392 * If the list is empty, returns NULL.
395 * struct child *first;
396 * first = list_top(&parent->children, struct child, list);
398 * printf("Empty list!\n");
400 #define list_top(h, type, member) \
401 ((type *)list_top_((h), list_off_(type, member)))
403 static inline const void *list_top_(const struct list_head *h, size_t off)
407 return (const char *)h->n.next - off;
411 * list_pop - remove the first entry in a list
413 * @type: the type of the entry
414 * @member: the list_node member of the type
416 * If the list is empty, returns NULL.
420 * one = list_pop(&parent->children, struct child, list);
422 * printf("Empty list!\n");
424 #define list_pop(h, type, member) \
425 ((type *)list_pop_((h), list_off_(type, member)))
427 static inline const void *list_pop_(const struct list_head *h, size_t off)
435 return (const char *)n - off;
439 * list_tail - get the last entry in a list
441 * @type: the type of the entry
442 * @member: the list_node member of the type
444 * If the list is empty, returns NULL.
447 * struct child *last;
448 * last = list_tail(&parent->children, struct child, list);
450 * printf("Empty list!\n");
452 #define list_tail(h, type, member) \
453 ((type *)list_tail_((h), list_off_(type, member)))
455 static inline const void *list_tail_(const struct list_head *h, size_t off)
459 return (const char *)h->n.prev - off;
463 * list_for_each - iterate through a list.
464 * @h: the list_head (warning: evaluated multiple times!)
465 * @i: the structure containing the list_node
466 * @member: the list_node member of the structure
468 * This is a convenient wrapper to iterate @i over the entire list. It's
469 * a for loop, so you can break and continue as normal.
472 * list_for_each(&parent->children, child, list)
473 * printf("Name: %s\n", child->name);
475 #define list_for_each(h, i, member) \
476 list_for_each_off(h, i, list_off_var_(i, member))
479 * list_for_each_rev - iterate through a list backwards.
481 * @i: the structure containing the list_node
482 * @member: the list_node member of the structure
484 * This is a convenient wrapper to iterate @i over the entire list. It's
485 * a for loop, so you can break and continue as normal.
488 * list_for_each_rev(&parent->children, child, list)
489 * printf("Name: %s\n", child->name);
491 #define list_for_each_rev(h, i, member) \
492 for (i = container_of_var(list_debug(h, LIST_LOC)->n.prev, i, member); \
493 &i->member != &(h)->n; \
494 i = container_of_var(i->member.prev, i, member))
497 * list_for_each_safe - iterate through a list, maybe during deletion
499 * @i: the structure containing the list_node
500 * @nxt: the structure containing the list_node
501 * @member: the list_node member of the structure
503 * This is a convenient wrapper to iterate @i over the entire list. It's
504 * a for loop, so you can break and continue as normal. The extra variable
505 * @nxt is used to hold the next element, so you can delete @i from the list.
508 * struct child *next;
509 * list_for_each_safe(&parent->children, child, next, list) {
510 * list_del(&child->list);
511 * parent->num_children--;
514 #define list_for_each_safe(h, i, nxt, member) \
515 list_for_each_safe_off(h, i, nxt, list_off_var_(i, member))
518 * list_next - get the next entry in a list
520 * @i: a pointer to an entry in the list.
521 * @member: the list_node member of the structure
523 * If @i was the last entry in the list, returns NULL.
526 * struct child *second;
527 * second = list_next(&parent->children, first, list);
529 * printf("No second child!\n");
531 #define list_next(h, i, member) \
532 ((list_typeof(i))list_entry_or_null(list_debug(h, \
533 __FILE__ ":" stringify(__LINE__)), \
535 list_off_var_((i), member)))
538 * list_prev - get the previous entry in a list
540 * @i: a pointer to an entry in the list.
541 * @member: the list_node member of the structure
543 * If @i was the first entry in the list, returns NULL.
546 * first = list_prev(&parent->children, second, list);
548 * printf("Can't go back to first child?!\n");
550 #define list_prev(h, i, member) \
551 ((list_typeof(i))list_entry_or_null(list_debug(h, \
552 __FILE__ ":" stringify(__LINE__)), \
554 list_off_var_((i), member)))
557 * list_append_list - empty one list onto the end of another.
558 * @to: the list to append into
559 * @from: the list to empty.
561 * This takes the entire contents of @from and moves it to the end of
562 * @to. After this @from will be empty.
565 * struct list_head adopter;
567 * list_append_list(&adopter, &parent->children);
568 * assert(list_empty(&parent->children));
569 * parent->num_children = 0;
571 #define list_append_list(t, f) list_append_list_(t, f, \
572 __FILE__ ":" stringify(__LINE__))
573 static inline void list_append_list_(struct list_head *to,
574 struct list_head *from,
575 const char *abortstr)
577 struct list_node *from_tail = list_debug(from, abortstr)->n.prev;
578 struct list_node *to_tail = list_debug(to, abortstr)->n.prev;
580 /* Sew in head and entire list. */
581 to->n.prev = from_tail;
582 from_tail->next = &to->n;
583 to_tail->next = &from->n;
584 from->n.prev = to_tail;
586 /* Now remove head. */
588 list_head_init(from);
592 * list_prepend_list - empty one list into the start of another.
593 * @to: the list to prepend into
594 * @from: the list to empty.
596 * This takes the entire contents of @from and moves it to the start
597 * of @to. After this @from will be empty.
600 * list_prepend_list(&adopter, &parent->children);
601 * assert(list_empty(&parent->children));
602 * parent->num_children = 0;
604 #define list_prepend_list(t, f) list_prepend_list_(t, f, LIST_LOC)
605 static inline void list_prepend_list_(struct list_head *to,
606 struct list_head *from,
607 const char *abortstr)
609 struct list_node *from_tail = list_debug(from, abortstr)->n.prev;
610 struct list_node *to_head = list_debug(to, abortstr)->n.next;
612 /* Sew in head and entire list. */
613 to->n.next = &from->n;
614 from->n.prev = &to->n;
615 to_head->prev = from_tail;
616 from_tail->next = to_head;
618 /* Now remove head. */
620 list_head_init(from);
624 * list_for_each_off - iterate through a list of memory regions.
626 * @i: the pointer to a memory region wich contains list node data.
627 * @off: offset(relative to @i) at which list node data resides.
629 * This is a low-level wrapper to iterate @i over the entire list, used to
630 * implement all oher, more high-level, for-each constructs. It's a for loop,
631 * so you can break and continue as normal.
633 * WARNING! Being the low-level macro that it is, this wrapper doesn't know
634 * nor care about the type of @i. The only assumtion made is that @i points
635 * to a chunk of memory that at some @offset, relative to @i, contains a
636 * properly filled `struct node_list' which in turn contains pointers to
637 * memory chunks and it's turtles all the way down. Whith all that in mind
638 * remember that given the wrong pointer/offset couple this macro will
639 * happilly churn all you memory untill SEGFAULT stops it, in other words
642 * It is worth mentioning that one of legitimate use-cases for that wrapper
643 * is operation on opaque types with known offset for `struct list_node'
644 * member(preferably 0), because it allows you not to disclose the type of
648 * list_for_each_off(&parent->children, child,
649 * offsetof(struct child, list))
650 * printf("Name: %s\n", child->name);
652 #define list_for_each_off(h, i, off) \
653 for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.next, \
655 list_node_from_off_((void *)i, (off)) != &(h)->n; \
656 i = list_node_to_off_(list_node_from_off_((void *)i, (off))->next, \
660 * list_for_each_safe_off - iterate through a list of memory regions, maybe
663 * @i: the pointer to a memory region wich contains list node data.
664 * @nxt: the structure containing the list_node
665 * @off: offset(relative to @i) at which list node data resides.
667 * For details see `list_for_each_off' and `list_for_each_safe'
671 * list_for_each_safe_off(&parent->children, child,
672 * next, offsetof(struct child, list))
673 * printf("Name: %s\n", child->name);
675 #define list_for_each_safe_off(h, i, nxt, off) \
676 for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.next, \
678 nxt = list_node_to_off_(list_node_from_off_(i, (off))->next, \
680 list_node_from_off_(i, (off)) != &(h)->n; \
682 nxt = list_node_to_off_(list_node_from_off_(i, (off))->next, \
686 /* Other -off variants. */
687 #define list_entry_off(n, type, off) \
688 ((type *)list_node_from_off_((n), (off)))
690 #define list_head_off(h, type, off) \
691 ((type *)list_head_off((h), (off)))
693 #define list_tail_off(h, type, off) \
694 ((type *)list_tail_((h), (off)))
696 #define list_add_off(h, n, off) \
697 list_add((h), list_node_from_off_((n), (off)))
699 #define list_del_off(n, off) \
700 list_del(list_node_from_off_((n), (off)))
702 #define list_del_from_off(h, n, off) \
703 list_del_from(h, list_node_from_off_((n), (off)))
705 /* Offset helper functions so we only single-evaluate. */
706 static inline void *list_node_to_off_(struct list_node *node, size_t off)
708 return (void *)((char *)node - off);
710 static inline struct list_node *list_node_from_off_(void *ptr, size_t off)
712 return (struct list_node *)((char *)ptr + off);
715 /* Get the offset of the member, but make sure it's a list_node. */
716 #define list_off_(type, member) \
717 (container_off(type, member) + \
718 check_type(((type *)0)->member, struct list_node))
720 #define list_off_var_(var, member) \
721 (container_off_var(var, member) + \
722 check_type(var->member, struct list_node))
725 #define list_typeof(var) typeof(var)
727 #define list_typeof(var) void *
730 /* Returns member, or NULL if at end of list. */
731 static inline void *list_entry_or_null(const struct list_head *h,
732 const struct list_node *n,
737 return (char *)n - off;
739 #endif /* CCAN_LIST_H */