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_add - add an entry at the start of a linked list.
150 * @h: the list_head to add the node to
151 * @n: the list_node to add to the list.
153 * The list_node does not need to be initialized; it will be overwritten.
155 * struct child *child = malloc(sizeof(*child));
157 * child->name = "marvin";
158 * list_add(&parent->children, &child->list);
159 * parent->num_children++;
161 #define list_add(h, n) list_add_(h, n, LIST_LOC)
162 static inline void list_add_(struct list_head *h,
164 const char *abortstr)
170 (void)list_debug(h, abortstr);
174 * list_add_tail - add an entry at the end of a linked list.
175 * @h: the list_head to add the node to
176 * @n: the list_node to add to the list.
178 * The list_node does not need to be initialized; it will be overwritten.
180 * list_add_tail(&parent->children, &child->list);
181 * parent->num_children++;
183 #define list_add_tail(h, n) list_add_tail_(h, n, LIST_LOC)
184 static inline void list_add_tail_(struct list_head *h,
186 const char *abortstr)
192 (void)list_debug(h, abortstr);
196 * list_empty - is a list empty?
199 * If the list is empty, returns true.
202 * assert(list_empty(&parent->children) == (parent->num_children == 0));
204 #define list_empty(h) list_empty_(h, LIST_LOC)
205 static inline bool list_empty_(const struct list_head *h, const char* abortstr)
207 (void)list_debug(h, abortstr);
208 return h->n.next == &h->n;
212 * list_empty_nodebug - is a list empty (and don't perform debug checks)?
215 * If the list is empty, returns true.
216 * This differs from list_empty() in that if CCAN_LIST_DEBUG is set it
217 * will NOT perform debug checks. Only use this function if you REALLY
218 * know what you're doing.
221 * assert(list_empty_nodebug(&parent->children) == (parent->num_children == 0));
223 #ifndef CCAN_LIST_DEBUG
224 #define list_empty_nodebug(h) list_empty(h)
226 static inline bool list_empty_nodebug(const struct list_head *h)
228 return h->n.next == &h->n;
233 * list_del - delete an entry from an (unknown) linked list.
234 * @n: the list_node to delete from the list.
236 * Note that this leaves @n in an undefined state; it can be added to
237 * another list, but not deleted again.
243 * list_del(&child->list);
244 * parent->num_children--;
246 #define list_del(n) list_del_(n, LIST_LOC)
247 static inline void list_del_(struct list_node *n, const char* abortstr)
249 (void)list_debug_node(n, abortstr);
250 n->next->prev = n->prev;
251 n->prev->next = n->next;
252 #ifdef CCAN_LIST_DEBUG
253 /* Catch use-after-del. */
254 n->next = n->prev = NULL;
259 * list_del_from - delete an entry from a known linked list.
260 * @h: the list_head the node is in.
261 * @n: the list_node to delete from the list.
263 * This explicitly indicates which list a node is expected to be in,
264 * which is better documentation and can catch more bugs.
266 * See also: list_del()
269 * list_del_from(&parent->children, &child->list);
270 * parent->num_children--;
272 static inline void list_del_from(struct list_head *h, struct list_node *n)
274 #ifdef CCAN_LIST_DEBUG
276 /* Thorough check: make sure it was in list! */
278 for (i = h->n.next; i != n; i = i->next)
281 #endif /* CCAN_LIST_DEBUG */
283 /* Quick test that catches a surprising number of bugs. */
284 assert(!list_empty(h));
289 * list_entry - convert a list_node back into the structure containing it.
291 * @type: the type of the entry
292 * @member: the list_node member of the type
295 * // First list entry is children.next; convert back to child.
296 * child = list_entry(parent->children.n.next, struct child, list);
299 * list_top(), list_for_each()
301 #define list_entry(n, type, member) container_of(n, type, member)
304 * list_top - get the first entry in a list
306 * @type: the type of the entry
307 * @member: the list_node member of the type
309 * If the list is empty, returns NULL.
312 * struct child *first;
313 * first = list_top(&parent->children, struct child, list);
315 * printf("Empty list!\n");
317 #define list_top(h, type, member) \
318 ((type *)list_top_((h), list_off_(type, member)))
320 static inline const void *list_top_(const struct list_head *h, size_t off)
324 return (const char *)h->n.next - off;
328 * list_pop - remove the first entry in a list
330 * @type: the type of the entry
331 * @member: the list_node member of the type
333 * If the list is empty, returns NULL.
337 * one = list_pop(&parent->children, struct child, list);
339 * printf("Empty list!\n");
341 #define list_pop(h, type, member) \
342 ((type *)list_pop_((h), list_off_(type, member)))
344 static inline const void *list_pop_(const struct list_head *h, size_t off)
352 return (const char *)n - off;
356 * list_tail - get the last entry in a list
358 * @type: the type of the entry
359 * @member: the list_node member of the type
361 * If the list is empty, returns NULL.
364 * struct child *last;
365 * last = list_tail(&parent->children, struct child, list);
367 * printf("Empty list!\n");
369 #define list_tail(h, type, member) \
370 ((type *)list_tail_((h), list_off_(type, member)))
372 static inline const void *list_tail_(const struct list_head *h, size_t off)
376 return (const char *)h->n.prev - off;
380 * list_for_each - iterate through a list.
381 * @h: the list_head (warning: evaluated multiple times!)
382 * @i: the structure containing the list_node
383 * @member: the list_node member of the structure
385 * This is a convenient wrapper to iterate @i over the entire list. It's
386 * a for loop, so you can break and continue as normal.
389 * list_for_each(&parent->children, child, list)
390 * printf("Name: %s\n", child->name);
392 #define list_for_each(h, i, member) \
393 list_for_each_off(h, i, list_off_var_(i, member))
396 * list_for_each_rev - iterate through a list backwards.
398 * @i: the structure containing the list_node
399 * @member: the list_node member of the structure
401 * This is a convenient wrapper to iterate @i over the entire list. It's
402 * a for loop, so you can break and continue as normal.
405 * list_for_each_rev(&parent->children, child, list)
406 * printf("Name: %s\n", child->name);
408 #define list_for_each_rev(h, i, member) \
409 for (i = container_of_var(list_debug(h, LIST_LOC)->n.prev, i, member); \
410 &i->member != &(h)->n; \
411 i = container_of_var(i->member.prev, i, member))
414 * list_for_each_safe - iterate through a list, maybe during deletion
416 * @i: the structure containing the list_node
417 * @nxt: the structure containing the list_node
418 * @member: the list_node member of the structure
420 * This is a convenient wrapper to iterate @i over the entire list. It's
421 * a for loop, so you can break and continue as normal. The extra variable
422 * @nxt is used to hold the next element, so you can delete @i from the list.
425 * struct child *next;
426 * list_for_each_safe(&parent->children, child, next, list) {
427 * list_del(&child->list);
428 * parent->num_children--;
431 #define list_for_each_safe(h, i, nxt, member) \
432 list_for_each_safe_off(h, i, nxt, list_off_var_(i, member))
435 * list_next - get the next entry in a list
437 * @i: a pointer to an entry in the list.
438 * @member: the list_node member of the structure
440 * If @i was the last entry in the list, returns NULL.
443 * struct child *second;
444 * second = list_next(&parent->children, first, list);
446 * printf("No second child!\n");
448 #define list_next(h, i, member) \
449 ((list_typeof(i))list_entry_or_null(list_debug(h, \
450 __FILE__ ":" stringify(__LINE__)), \
452 list_off_var_((i), member)))
455 * list_prev - get the previous entry in a list
457 * @i: a pointer to an entry in the list.
458 * @member: the list_node member of the structure
460 * If @i was the first entry in the list, returns NULL.
463 * first = list_prev(&parent->children, second, list);
465 * printf("Can't go back to first child?!\n");
467 #define list_prev(h, i, member) \
468 ((list_typeof(i))list_entry_or_null(list_debug(h, \
469 __FILE__ ":" stringify(__LINE__)), \
471 list_off_var_((i), member)))
474 * list_append_list - empty one list onto the end of another.
475 * @to: the list to append into
476 * @from: the list to empty.
478 * This takes the entire contents of @from and moves it to the end of
479 * @to. After this @from will be empty.
482 * struct list_head adopter;
484 * list_append_list(&adopter, &parent->children);
485 * assert(list_empty(&parent->children));
486 * parent->num_children = 0;
488 #define list_append_list(t, f) list_append_list_(t, f, \
489 __FILE__ ":" stringify(__LINE__))
490 static inline void list_append_list_(struct list_head *to,
491 struct list_head *from,
492 const char *abortstr)
494 struct list_node *from_tail = list_debug(from, abortstr)->n.prev;
495 struct list_node *to_tail = list_debug(to, abortstr)->n.prev;
497 /* Sew in head and entire list. */
498 to->n.prev = from_tail;
499 from_tail->next = &to->n;
500 to_tail->next = &from->n;
501 from->n.prev = to_tail;
503 /* Now remove head. */
505 list_head_init(from);
509 * list_prepend_list - empty one list into the start of another.
510 * @to: the list to prepend into
511 * @from: the list to empty.
513 * This takes the entire contents of @from and moves it to the start
514 * of @to. After this @from will be empty.
517 * list_prepend_list(&adopter, &parent->children);
518 * assert(list_empty(&parent->children));
519 * parent->num_children = 0;
521 #define list_prepend_list(t, f) list_prepend_list_(t, f, LIST_LOC)
522 static inline void list_prepend_list_(struct list_head *to,
523 struct list_head *from,
524 const char *abortstr)
526 struct list_node *from_tail = list_debug(from, abortstr)->n.prev;
527 struct list_node *to_head = list_debug(to, abortstr)->n.next;
529 /* Sew in head and entire list. */
530 to->n.next = &from->n;
531 from->n.prev = &to->n;
532 to_head->prev = from_tail;
533 from_tail->next = to_head;
535 /* Now remove head. */
537 list_head_init(from);
541 * list_for_each_off - iterate through a list of memory regions.
543 * @i: the pointer to a memory region wich contains list node data.
544 * @off: offset(relative to @i) at which list node data resides.
546 * This is a low-level wrapper to iterate @i over the entire list, used to
547 * implement all oher, more high-level, for-each constructs. It's a for loop,
548 * so you can break and continue as normal.
550 * WARNING! Being the low-level macro that it is, this wrapper doesn't know
551 * nor care about the type of @i. The only assumtion made is that @i points
552 * to a chunk of memory that at some @offset, relative to @i, contains a
553 * properly filled `struct node_list' which in turn contains pointers to
554 * memory chunks and it's turtles all the way down. Whith all that in mind
555 * remember that given the wrong pointer/offset couple this macro will
556 * happilly churn all you memory untill SEGFAULT stops it, in other words
559 * It is worth mentioning that one of legitimate use-cases for that wrapper
560 * is operation on opaque types with known offset for `struct list_node'
561 * member(preferably 0), because it allows you not to disclose the type of
565 * list_for_each_off(&parent->children, child,
566 * offsetof(struct child, list))
567 * printf("Name: %s\n", child->name);
569 #define list_for_each_off(h, i, off) \
570 for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.next, \
572 list_node_from_off_((void *)i, (off)) != &(h)->n; \
573 i = list_node_to_off_(list_node_from_off_((void *)i, (off))->next, \
577 * list_for_each_safe_off - iterate through a list of memory regions, maybe
580 * @i: the pointer to a memory region wich contains list node data.
581 * @nxt: the structure containing the list_node
582 * @off: offset(relative to @i) at which list node data resides.
584 * For details see `list_for_each_off' and `list_for_each_safe'
588 * list_for_each_safe_off(&parent->children, child,
589 * next, offsetof(struct child, list))
590 * printf("Name: %s\n", child->name);
592 #define list_for_each_safe_off(h, i, nxt, off) \
593 for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.next, \
595 nxt = list_node_to_off_(list_node_from_off_(i, (off))->next, \
597 list_node_from_off_(i, (off)) != &(h)->n; \
599 nxt = list_node_to_off_(list_node_from_off_(i, (off))->next, \
603 /* Other -off variants. */
604 #define list_entry_off(n, type, off) \
605 ((type *)list_node_from_off_((n), (off)))
607 #define list_head_off(h, type, off) \
608 ((type *)list_head_off((h), (off)))
610 #define list_tail_off(h, type, off) \
611 ((type *)list_tail_((h), (off)))
613 #define list_add_off(h, n, off) \
614 list_add((h), list_node_from_off_((n), (off)))
616 #define list_del_off(n, off) \
617 list_del(list_node_from_off_((n), (off)))
619 #define list_del_from_off(h, n, off) \
620 list_del_from(h, list_node_from_off_((n), (off)))
622 /* Offset helper functions so we only single-evaluate. */
623 static inline void *list_node_to_off_(struct list_node *node, size_t off)
625 return (void *)((char *)node - off);
627 static inline struct list_node *list_node_from_off_(void *ptr, size_t off)
629 return (struct list_node *)((char *)ptr + off);
632 /* Get the offset of the member, but make sure it's a list_node. */
633 #define list_off_(type, member) \
634 (container_off(type, member) + \
635 check_type(((type *)0)->member, struct list_node))
637 #define list_off_var_(var, member) \
638 (container_off_var(var, member) + \
639 check_type(var->member, struct list_node))
642 #define list_typeof(var) typeof(var)
644 #define list_typeof(var) void *
647 /* Returns member, or NULL if at end of list. */
648 static inline void *list_entry_or_null(const struct list_head *h,
649 const struct list_node *n,
654 return (char *)n - off;
656 #endif /* CCAN_LIST_H */