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 - add an entry at the start of a linked list.
162 * @h: the list_head to add the node to
163 * @n: the list_node to add to the list.
165 * The list_node does not need to be initialized; it will be overwritten.
167 * struct child *child = malloc(sizeof(*child));
169 * child->name = "marvin";
170 * list_add(&parent->children, &child->list);
171 * parent->num_children++;
173 #define list_add(h, n) list_add_(h, n, LIST_LOC)
174 static inline void list_add_(struct list_head *h,
176 const char *abortstr)
182 (void)list_debug(h, abortstr);
186 * list_add_tail - add an entry at the end of a linked list.
187 * @h: the list_head to add the node to
188 * @n: the list_node to add to the list.
190 * The list_node does not need to be initialized; it will be overwritten.
192 * list_add_tail(&parent->children, &child->list);
193 * parent->num_children++;
195 #define list_add_tail(h, n) list_add_tail_(h, n, LIST_LOC)
196 static inline void list_add_tail_(struct list_head *h,
198 const char *abortstr)
204 (void)list_debug(h, abortstr);
208 * list_empty - is a list empty?
211 * If the list is empty, returns true.
214 * assert(list_empty(&parent->children) == (parent->num_children == 0));
216 #define list_empty(h) list_empty_(h, LIST_LOC)
217 static inline bool list_empty_(const struct list_head *h, const char* abortstr)
219 (void)list_debug(h, abortstr);
220 return h->n.next == &h->n;
224 * list_empty_nodebug - is a list empty (and don't perform debug checks)?
227 * If the list is empty, returns true.
228 * This differs from list_empty() in that if CCAN_LIST_DEBUG is set it
229 * will NOT perform debug checks. Only use this function if you REALLY
230 * know what you're doing.
233 * assert(list_empty_nodebug(&parent->children) == (parent->num_children == 0));
235 #ifndef CCAN_LIST_DEBUG
236 #define list_empty_nodebug(h) list_empty(h)
238 static inline bool list_empty_nodebug(const struct list_head *h)
240 return h->n.next == &h->n;
245 * list_del - delete an entry from an (unknown) linked list.
246 * @n: the list_node to delete from the list.
248 * Note that this leaves @n in an undefined state; it can be added to
249 * another list, but not deleted again.
252 * list_del_from(), list_del_init()
255 * list_del(&child->list);
256 * parent->num_children--;
258 #define list_del(n) list_del_(n, LIST_LOC)
259 static inline void list_del_(struct list_node *n, const char* abortstr)
261 (void)list_debug_node(n, abortstr);
262 n->next->prev = n->prev;
263 n->prev->next = n->next;
264 #ifdef CCAN_LIST_DEBUG
265 /* Catch use-after-del. */
266 n->next = n->prev = NULL;
271 * list_del_init - delete a node, and reset it so it can be deleted again.
272 * @n: the list_node to be deleted.
274 * list_del(@n) or list_del_init() again after this will be safe,
275 * which can be useful in some cases.
278 * list_del_from(), list_del()
281 * list_del_init(&child->list);
282 * parent->num_children--;
284 #define list_del_init(n) list_del_init_(n, LIST_LOC)
285 static inline void list_del_init_(struct list_node *n, const char *abortstr)
287 list_del_(n, abortstr);
292 * list_del_from - delete an entry from a known linked list.
293 * @h: the list_head the node is in.
294 * @n: the list_node to delete from the list.
296 * This explicitly indicates which list a node is expected to be in,
297 * which is better documentation and can catch more bugs.
299 * See also: list_del()
302 * list_del_from(&parent->children, &child->list);
303 * parent->num_children--;
305 static inline void list_del_from(struct list_head *h, struct list_node *n)
307 #ifdef CCAN_LIST_DEBUG
309 /* Thorough check: make sure it was in list! */
311 for (i = h->n.next; i != n; i = i->next)
314 #endif /* CCAN_LIST_DEBUG */
316 /* Quick test that catches a surprising number of bugs. */
317 assert(!list_empty(h));
322 * list_entry - convert a list_node back into the structure containing it.
324 * @type: the type of the entry
325 * @member: the list_node member of the type
328 * // First list entry is children.next; convert back to child.
329 * child = list_entry(parent->children.n.next, struct child, list);
332 * list_top(), list_for_each()
334 #define list_entry(n, type, member) container_of(n, type, member)
337 * list_top - get the first entry in a list
339 * @type: the type of the entry
340 * @member: the list_node member of the type
342 * If the list is empty, returns NULL.
345 * struct child *first;
346 * first = list_top(&parent->children, struct child, list);
348 * printf("Empty list!\n");
350 #define list_top(h, type, member) \
351 ((type *)list_top_((h), list_off_(type, member)))
353 static inline const void *list_top_(const struct list_head *h, size_t off)
357 return (const char *)h->n.next - off;
361 * list_pop - remove the first entry in a list
363 * @type: the type of the entry
364 * @member: the list_node member of the type
366 * If the list is empty, returns NULL.
370 * one = list_pop(&parent->children, struct child, list);
372 * printf("Empty list!\n");
374 #define list_pop(h, type, member) \
375 ((type *)list_pop_((h), list_off_(type, member)))
377 static inline const void *list_pop_(const struct list_head *h, size_t off)
385 return (const char *)n - off;
389 * list_tail - get the last entry in a list
391 * @type: the type of the entry
392 * @member: the list_node member of the type
394 * If the list is empty, returns NULL.
397 * struct child *last;
398 * last = list_tail(&parent->children, struct child, list);
400 * printf("Empty list!\n");
402 #define list_tail(h, type, member) \
403 ((type *)list_tail_((h), list_off_(type, member)))
405 static inline const void *list_tail_(const struct list_head *h, size_t off)
409 return (const char *)h->n.prev - off;
413 * list_for_each - iterate through a list.
414 * @h: the list_head (warning: evaluated multiple times!)
415 * @i: the structure containing the list_node
416 * @member: the list_node member of the structure
418 * This is a convenient wrapper to iterate @i over the entire list. It's
419 * a for loop, so you can break and continue as normal.
422 * list_for_each(&parent->children, child, list)
423 * printf("Name: %s\n", child->name);
425 #define list_for_each(h, i, member) \
426 list_for_each_off(h, i, list_off_var_(i, member))
429 * list_for_each_rev - iterate through a list backwards.
431 * @i: the structure containing the list_node
432 * @member: the list_node member of the structure
434 * This is a convenient wrapper to iterate @i over the entire list. It's
435 * a for loop, so you can break and continue as normal.
438 * list_for_each_rev(&parent->children, child, list)
439 * printf("Name: %s\n", child->name);
441 #define list_for_each_rev(h, i, member) \
442 for (i = container_of_var(list_debug(h, LIST_LOC)->n.prev, i, member); \
443 &i->member != &(h)->n; \
444 i = container_of_var(i->member.prev, i, member))
447 * list_for_each_safe - iterate through a list, maybe during deletion
449 * @i: the structure containing the list_node
450 * @nxt: the structure containing the list_node
451 * @member: the list_node member of the structure
453 * This is a convenient wrapper to iterate @i over the entire list. It's
454 * a for loop, so you can break and continue as normal. The extra variable
455 * @nxt is used to hold the next element, so you can delete @i from the list.
458 * struct child *next;
459 * list_for_each_safe(&parent->children, child, next, list) {
460 * list_del(&child->list);
461 * parent->num_children--;
464 #define list_for_each_safe(h, i, nxt, member) \
465 list_for_each_safe_off(h, i, nxt, list_off_var_(i, member))
468 * list_next - get the next entry in a list
470 * @i: a pointer to an entry in the list.
471 * @member: the list_node member of the structure
473 * If @i was the last entry in the list, returns NULL.
476 * struct child *second;
477 * second = list_next(&parent->children, first, list);
479 * printf("No second child!\n");
481 #define list_next(h, i, member) \
482 ((list_typeof(i))list_entry_or_null(list_debug(h, \
483 __FILE__ ":" stringify(__LINE__)), \
485 list_off_var_((i), member)))
488 * list_prev - get the previous entry in a list
490 * @i: a pointer to an entry in the list.
491 * @member: the list_node member of the structure
493 * If @i was the first entry in the list, returns NULL.
496 * first = list_prev(&parent->children, second, list);
498 * printf("Can't go back to first child?!\n");
500 #define list_prev(h, i, member) \
501 ((list_typeof(i))list_entry_or_null(list_debug(h, \
502 __FILE__ ":" stringify(__LINE__)), \
504 list_off_var_((i), member)))
507 * list_append_list - empty one list onto the end of another.
508 * @to: the list to append into
509 * @from: the list to empty.
511 * This takes the entire contents of @from and moves it to the end of
512 * @to. After this @from will be empty.
515 * struct list_head adopter;
517 * list_append_list(&adopter, &parent->children);
518 * assert(list_empty(&parent->children));
519 * parent->num_children = 0;
521 #define list_append_list(t, f) list_append_list_(t, f, \
522 __FILE__ ":" stringify(__LINE__))
523 static inline void list_append_list_(struct list_head *to,
524 struct list_head *from,
525 const char *abortstr)
527 struct list_node *from_tail = list_debug(from, abortstr)->n.prev;
528 struct list_node *to_tail = list_debug(to, abortstr)->n.prev;
530 /* Sew in head and entire list. */
531 to->n.prev = from_tail;
532 from_tail->next = &to->n;
533 to_tail->next = &from->n;
534 from->n.prev = to_tail;
536 /* Now remove head. */
538 list_head_init(from);
542 * list_prepend_list - empty one list into the start of another.
543 * @to: the list to prepend into
544 * @from: the list to empty.
546 * This takes the entire contents of @from and moves it to the start
547 * of @to. After this @from will be empty.
550 * list_prepend_list(&adopter, &parent->children);
551 * assert(list_empty(&parent->children));
552 * parent->num_children = 0;
554 #define list_prepend_list(t, f) list_prepend_list_(t, f, LIST_LOC)
555 static inline void list_prepend_list_(struct list_head *to,
556 struct list_head *from,
557 const char *abortstr)
559 struct list_node *from_tail = list_debug(from, abortstr)->n.prev;
560 struct list_node *to_head = list_debug(to, abortstr)->n.next;
562 /* Sew in head and entire list. */
563 to->n.next = &from->n;
564 from->n.prev = &to->n;
565 to_head->prev = from_tail;
566 from_tail->next = to_head;
568 /* Now remove head. */
570 list_head_init(from);
574 * list_for_each_off - iterate through a list of memory regions.
576 * @i: the pointer to a memory region wich contains list node data.
577 * @off: offset(relative to @i) at which list node data resides.
579 * This is a low-level wrapper to iterate @i over the entire list, used to
580 * implement all oher, more high-level, for-each constructs. It's a for loop,
581 * so you can break and continue as normal.
583 * WARNING! Being the low-level macro that it is, this wrapper doesn't know
584 * nor care about the type of @i. The only assumtion made is that @i points
585 * to a chunk of memory that at some @offset, relative to @i, contains a
586 * properly filled `struct node_list' which in turn contains pointers to
587 * memory chunks and it's turtles all the way down. Whith all that in mind
588 * remember that given the wrong pointer/offset couple this macro will
589 * happilly churn all you memory untill SEGFAULT stops it, in other words
592 * It is worth mentioning that one of legitimate use-cases for that wrapper
593 * is operation on opaque types with known offset for `struct list_node'
594 * member(preferably 0), because it allows you not to disclose the type of
598 * list_for_each_off(&parent->children, child,
599 * offsetof(struct child, list))
600 * printf("Name: %s\n", child->name);
602 #define list_for_each_off(h, i, off) \
603 for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.next, \
605 list_node_from_off_((void *)i, (off)) != &(h)->n; \
606 i = list_node_to_off_(list_node_from_off_((void *)i, (off))->next, \
610 * list_for_each_safe_off - iterate through a list of memory regions, maybe
613 * @i: the pointer to a memory region wich contains list node data.
614 * @nxt: the structure containing the list_node
615 * @off: offset(relative to @i) at which list node data resides.
617 * For details see `list_for_each_off' and `list_for_each_safe'
621 * list_for_each_safe_off(&parent->children, child,
622 * next, offsetof(struct child, list))
623 * printf("Name: %s\n", child->name);
625 #define list_for_each_safe_off(h, i, nxt, off) \
626 for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.next, \
628 nxt = list_node_to_off_(list_node_from_off_(i, (off))->next, \
630 list_node_from_off_(i, (off)) != &(h)->n; \
632 nxt = list_node_to_off_(list_node_from_off_(i, (off))->next, \
636 /* Other -off variants. */
637 #define list_entry_off(n, type, off) \
638 ((type *)list_node_from_off_((n), (off)))
640 #define list_head_off(h, type, off) \
641 ((type *)list_head_off((h), (off)))
643 #define list_tail_off(h, type, off) \
644 ((type *)list_tail_((h), (off)))
646 #define list_add_off(h, n, off) \
647 list_add((h), list_node_from_off_((n), (off)))
649 #define list_del_off(n, off) \
650 list_del(list_node_from_off_((n), (off)))
652 #define list_del_from_off(h, n, off) \
653 list_del_from(h, list_node_from_off_((n), (off)))
655 /* Offset helper functions so we only single-evaluate. */
656 static inline void *list_node_to_off_(struct list_node *node, size_t off)
658 return (void *)((char *)node - off);
660 static inline struct list_node *list_node_from_off_(void *ptr, size_t off)
662 return (struct list_node *)((char *)ptr + off);
665 /* Get the offset of the member, but make sure it's a list_node. */
666 #define list_off_(type, member) \
667 (container_off(type, member) + \
668 check_type(((type *)0)->member, struct list_node))
670 #define list_off_var_(var, member) \
671 (container_off_var(var, member) + \
672 check_type(var->member, struct list_node))
675 #define list_typeof(var) typeof(var)
677 #define list_typeof(var) void *
680 /* Returns member, or NULL if at end of list. */
681 static inline void *list_entry_or_null(const struct list_head *h,
682 const struct list_node *n,
687 return (char *)n - off;
689 #endif /* CCAN_LIST_H */