| /* Licensed under BSD-MIT - see LICENSE file for details */ |
| #ifndef CCAN_LIST_H |
| #define CCAN_LIST_H |
| #include <stdbool.h> |
| #include <assert.h> |
| #include <ccan/container_of/container_of.h> |
| #include <ccan/check_type/check_type.h> |
| |
| /** |
| * struct list_node - an entry in a doubly-linked list |
| * @next: next entry (self if empty) |
| * @prev: previous entry (self if empty) |
| * |
| * This is used as an entry in a linked list. |
| * Example: |
| * struct child { |
| * const char *name; |
| * // Linked list of all us children. |
| * struct list_node list; |
| * }; |
| */ |
| struct list_node |
| { |
| struct list_node *next, *prev; |
| }; |
| |
| /** |
| * struct list_head - the head of a doubly-linked list |
| * @h: the list_head (containing next and prev pointers) |
| * |
| * This is used as the head of a linked list. |
| * Example: |
| * struct parent { |
| * const char *name; |
| * struct list_head children; |
| * unsigned int num_children; |
| * }; |
| */ |
| struct list_head |
| { |
| struct list_node n; |
| }; |
| |
| /** |
| * list_check - check head of a list for consistency |
| * @h: the list_head |
| * @abortstr: the location to print on aborting, or NULL. |
| * |
| * Because list_nodes have redundant information, consistency checking between |
| * the back and forward links can be done. This is useful as a debugging check. |
| * If @abortstr is non-NULL, that will be printed in a diagnostic if the list |
| * is inconsistent, and the function will abort. |
| * |
| * Returns the list head if the list is consistent, NULL if not (it |
| * can never return NULL if @abortstr is set). |
| * |
| * See also: list_check_node() |
| * |
| * Example: |
| * static void dump_parent(struct parent *p) |
| * { |
| * struct child *c; |
| * |
| * printf("%s (%u children):\n", p->name, p->num_children); |
| * list_check(&p->children, "bad child list"); |
| * list_for_each(&p->children, c, list) |
| * printf(" -> %s\n", c->name); |
| * } |
| */ |
| struct list_head *list_check(const struct list_head *h, const char *abortstr); |
| |
| /** |
| * list_check_node - check node of a list for consistency |
| * @n: the list_node |
| * @abortstr: the location to print on aborting, or NULL. |
| * |
| * Check consistency of the list node is in (it must be in one). |
| * |
| * See also: list_check() |
| * |
| * Example: |
| * static void dump_child(const struct child *c) |
| * { |
| * list_check_node(&c->list, "bad child list"); |
| * printf("%s\n", c->name); |
| * } |
| */ |
| struct list_node *list_check_node(const struct list_node *n, |
| const char *abortstr); |
| |
| #ifdef CCAN_LIST_DEBUG |
| #define list_debug(h) list_check((h), __func__) |
| #define list_debug_node(n) list_check_node((n), __func__) |
| #else |
| #define list_debug(h) (h) |
| #define list_debug_node(n) (n) |
| #endif |
| |
| /** |
| * LIST_HEAD_INIT - initializer for an empty list_head |
| * @name: the name of the list. |
| * |
| * Explicit initializer for an empty list. |
| * |
| * See also: |
| * LIST_HEAD, list_head_init() |
| * |
| * Example: |
| * static struct list_head my_list = LIST_HEAD_INIT(my_list); |
| */ |
| #define LIST_HEAD_INIT(name) { { &name.n, &name.n } } |
| |
| /** |
| * LIST_HEAD - define and initialize an empty list_head |
| * @name: the name of the list. |
| * |
| * The LIST_HEAD macro defines a list_head and initializes it to an empty |
| * list. It can be prepended by "static" to define a static list_head. |
| * |
| * See also: |
| * LIST_HEAD_INIT, list_head_init() |
| * |
| * Example: |
| * static LIST_HEAD(my_global_list); |
| */ |
| #define LIST_HEAD(name) \ |
| struct list_head name = LIST_HEAD_INIT(name) |
| |
| /** |
| * list_head_init - initialize a list_head |
| * @h: the list_head to set to the empty list |
| * |
| * Example: |
| * ... |
| * struct parent *parent = malloc(sizeof(*parent)); |
| * |
| * list_head_init(&parent->children); |
| * parent->num_children = 0; |
| */ |
| static inline void list_head_init(struct list_head *h) |
| { |
| h->n.next = h->n.prev = &h->n; |
| } |
| |
| /** |
| * list_add - add an entry at the start of a linked list. |
| * @h: the list_head to add the node to |
| * @n: the list_node to add to the list. |
| * |
| * The list_node does not need to be initialized; it will be overwritten. |
| * Example: |
| * struct child *child = malloc(sizeof(*child)); |
| * |
| * child->name = "marvin"; |
| * list_add(&parent->children, &child->list); |
| * parent->num_children++; |
| */ |
| static inline void list_add(struct list_head *h, struct list_node *n) |
| { |
| n->next = h->n.next; |
| n->prev = &h->n; |
| h->n.next->prev = n; |
| h->n.next = n; |
| (void)list_debug(h); |
| } |
| |
| /** |
| * list_add_before - add an entry before another entry. |
| * @h: the list_head to add the node to (we use it for debug purposes, can be NULL) |
| * @n: the list_node to add to the list. |
| * @p: the list_node of the other entry |
| * |
| * The list_node does not need to be initialized; it will be overwritten. |
| */ |
| static inline void list_add_before(struct list_head *h, struct list_node *n, |
| struct list_node *p) |
| { |
| n->next = p; |
| n->prev = p->prev; |
| p->prev = n; |
| n->prev->next = n; |
| if (h) |
| (void)list_debug(h); |
| } |
| |
| /** |
| * list_add_tail - add an entry at the end of a linked list. |
| * @h: the list_head to add the node to |
| * @n: the list_node to add to the list. |
| * |
| * The list_node does not need to be initialized; it will be overwritten. |
| * Example: |
| * list_add_tail(&parent->children, &child->list); |
| * parent->num_children++; |
| */ |
| static inline void list_add_tail(struct list_head *h, struct list_node *n) |
| { |
| n->next = &h->n; |
| n->prev = h->n.prev; |
| h->n.prev->next = n; |
| h->n.prev = n; |
| (void)list_debug(h); |
| } |
| |
| /** |
| * list_empty - is a list empty? |
| * @h: the list_head |
| * |
| * If the list is empty, returns true. |
| * |
| * Example: |
| * assert(list_empty(&parent->children) == (parent->num_children == 0)); |
| */ |
| static inline bool list_empty(const struct list_head *h) |
| { |
| (void)list_debug(h); |
| return h->n.next == &h->n; |
| } |
| |
| /** |
| * list_empty_nocheck - is a list empty? |
| * @h: the list_head |
| * |
| * If the list is empty, returns true. This doesn't perform any |
| * debug check for list consistency, so it can be called without |
| * locks, racing with the list being modified. This is ok for |
| * checks where an incorrect result is not an issue (optimized |
| * bail out path for example). |
| */ |
| static inline bool list_empty_nocheck(const struct list_head *h) |
| { |
| return h->n.next == &h->n; |
| } |
| |
| /** |
| * list_del - delete an entry from an (unknown) linked list. |
| * @n: the list_node to delete from the list. |
| * |
| * Note that this leaves @n in an undefined state; it can be added to |
| * another list, but not deleted again. |
| * |
| * See also: |
| * list_del_from() |
| * |
| * Example: |
| * list_del(&child->list); |
| * parent->num_children--; |
| */ |
| static inline void list_del(struct list_node *n) |
| { |
| (void)list_debug_node(n); |
| n->next->prev = n->prev; |
| n->prev->next = n->next; |
| #ifdef CCAN_LIST_DEBUG |
| /* Catch use-after-del. */ |
| n->next = n->prev = NULL; |
| #endif |
| } |
| |
| /** |
| * list_del_from - delete an entry from a known linked list. |
| * @h: the list_head the node is in. |
| * @n: the list_node to delete from the list. |
| * |
| * This explicitly indicates which list a node is expected to be in, |
| * which is better documentation and can catch more bugs. |
| * |
| * See also: list_del() |
| * |
| * Example: |
| * list_del_from(&parent->children, &child->list); |
| * parent->num_children--; |
| */ |
| static inline void list_del_from(struct list_head *h, struct list_node *n) |
| { |
| #ifdef CCAN_LIST_DEBUG |
| { |
| /* Thorough check: make sure it was in list! */ |
| struct list_node *i; |
| for (i = h->n.next; i != n; i = i->next) |
| assert(i != &h->n); |
| } |
| #endif /* CCAN_LIST_DEBUG */ |
| |
| /* Quick test that catches a surprising number of bugs. */ |
| assert(!list_empty(h)); |
| list_del(n); |
| } |
| |
| /** |
| * list_entry - convert a list_node back into the structure containing it. |
| * @n: the list_node |
| * @type: the type of the entry |
| * @member: the list_node member of the type |
| * |
| * Example: |
| * // First list entry is children.next; convert back to child. |
| * child = list_entry(parent->children.n.next, struct child, list); |
| * |
| * See Also: |
| * list_top(), list_for_each() |
| */ |
| #define list_entry(n, type, member) container_of(n, type, member) |
| |
| /** |
| * list_top - get the first entry in a list |
| * @h: the list_head |
| * @type: the type of the entry |
| * @member: the list_node member of the type |
| * |
| * If the list is empty, returns NULL. |
| * |
| * Example: |
| * struct child *first; |
| * first = list_top(&parent->children, struct child, list); |
| * if (!first) |
| * printf("Empty list!\n"); |
| */ |
| #define list_top(h, type, member) \ |
| ((type *)list_top_((h), list_off_(type, member))) |
| |
| static inline const void *list_top_(const struct list_head *h, size_t off) |
| { |
| if (list_empty(h)) |
| return NULL; |
| return (const char *)h->n.next - off; |
| } |
| |
| /** |
| * list_pop - get the first entry in a list and dequeue it |
| * @h: the list_head |
| * @type: the type of the entry |
| * @member: the list_node member of the type |
| */ |
| #define list_pop(h, type, member) \ |
| ((type *)list_pop_((h), list_off_(type, member))) |
| static inline const void *list_pop_(struct list_head *h, size_t off) |
| { |
| struct list_node *n; |
| |
| if (list_empty(h)) |
| return NULL; |
| n = h->n.next; |
| list_del(n); |
| return (const char *)n - off; |
| } |
| |
| /** |
| * list_tail - get the last entry in a list |
| * @h: the list_head |
| * @type: the type of the entry |
| * @member: the list_node member of the type |
| * |
| * If the list is empty, returns NULL. |
| * |
| * Example: |
| * struct child *last; |
| * last = list_tail(&parent->children, struct child, list); |
| * if (!last) |
| * printf("Empty list!\n"); |
| */ |
| #define list_tail(h, type, member) \ |
| ((type *)list_tail_((h), list_off_(type, member))) |
| |
| static inline const void *list_tail_(const struct list_head *h, size_t off) |
| { |
| if (list_empty(h)) |
| return NULL; |
| return (const char *)h->n.prev - off; |
| } |
| |
| /** |
| * list_for_each - iterate through a list. |
| * @h: the list_head (warning: evaluated multiple times!) |
| * @i: the structure containing the list_node |
| * @member: the list_node member of the structure |
| * |
| * This is a convenient wrapper to iterate @i over the entire list. It's |
| * a for loop, so you can break and continue as normal. |
| * |
| * Example: |
| * list_for_each(&parent->children, child, list) |
| * printf("Name: %s\n", child->name); |
| */ |
| #define list_for_each(h, i, member) \ |
| list_for_each_off(h, i, list_off_var_(i, member)) |
| |
| /** |
| * list_for_each_rev - iterate through a list backwards. |
| * @h: the list_head |
| * @i: the structure containing the list_node |
| * @member: the list_node member of the structure |
| * |
| * This is a convenient wrapper to iterate @i over the entire list. It's |
| * a for loop, so you can break and continue as normal. |
| * |
| * Example: |
| * list_for_each_rev(&parent->children, child, list) |
| * printf("Name: %s\n", child->name); |
| */ |
| #define list_for_each_rev(h, i, member) \ |
| for (i = container_of_var(list_debug(h)->n.prev, i, member); \ |
| &i->member != &(h)->n; \ |
| i = container_of_var(i->member.prev, i, member)) |
| |
| /** |
| * list_for_each_safe - iterate through a list, maybe during deletion |
| * @h: the list_head |
| * @i: the structure containing the list_node |
| * @nxt: the structure containing the list_node |
| * @member: the list_node member of the structure |
| * |
| * This is a convenient wrapper to iterate @i over the entire list. It's |
| * a for loop, so you can break and continue as normal. The extra variable |
| * @nxt is used to hold the next element, so you can delete @i from the list. |
| * |
| * Example: |
| * struct child *next; |
| * list_for_each_safe(&parent->children, child, next, list) { |
| * list_del(&child->list); |
| * parent->num_children--; |
| * } |
| */ |
| #define list_for_each_safe(h, i, nxt, member) \ |
| list_for_each_safe_off(h, i, nxt, list_off_var_(i, member)) |
| |
| /** |
| * list_for_each_off - iterate through a list of memory regions. |
| * @h: the list_head |
| * @i: the pointer to a memory region which contains list node data. |
| * @off: offset(relative to @i) at which list node data resides. |
| * |
| * This is a low-level wrapper to iterate @i over the entire list, used to |
| * implement all oher, more high-level, for-each constructs. It's a for loop, |
| * so you can break and continue as normal. |
| * |
| * WARNING! Being the low-level macro that it is, this wrapper doesn't know |
| * nor care about the type of @i. The only assumtion made is that @i points |
| * to a chunk of memory that at some @offset, relative to @i, contains a |
| * properly filled `struct node_list' which in turn contains pointers to |
| * memory chunks and it's turtles all the way down. With all that in mind |
| * remember that given the wrong pointer/offset couple this macro will |
| * happily churn all you memory until SEGFAULT stops it, in other words |
| * caveat emptor. |
| * |
| * It is worth mentioning that one of legitimate use-cases for that wrapper |
| * is operation on opaque types with known offset for `struct list_node' |
| * member(preferably 0), because it allows you not to disclose the type of |
| * @i. |
| * |
| * Example: |
| * list_for_each_off(&parent->children, child, |
| * offsetof(struct child, list)) |
| * printf("Name: %s\n", child->name); |
| */ |
| #define list_for_each_off(h, i, off) \ |
| for (i = list_node_to_off_(list_debug(h)->n.next, (off)); \ |
| list_node_from_off_((void *)i, (off)) != &(h)->n; \ |
| i = list_node_to_off_(list_node_from_off_((void *)i, (off))->next, \ |
| (off))) |
| |
| /** |
| * list_for_each_safe_off - iterate through a list of memory regions, maybe |
| * during deletion |
| * @h: the list_head |
| * @i: the pointer to a memory region which contains list node data. |
| * @nxt: the structure containing the list_node |
| * @off: offset(relative to @i) at which list node data resides. |
| * |
| * For details see `list_for_each_off' and `list_for_each_safe' |
| * descriptions. |
| * |
| * Example: |
| * list_for_each_safe_off(&parent->children, child, |
| * next, offsetof(struct child, list)) |
| * printf("Name: %s\n", child->name); |
| */ |
| #define list_for_each_safe_off(h, i, nxt, off) \ |
| for (i = list_node_to_off_(list_debug(h)->n.next, (off)), \ |
| nxt = list_node_to_off_(list_node_from_off_(i, (off))->next, \ |
| (off)); \ |
| list_node_from_off_(i, (off)) != &(h)->n; \ |
| i = nxt, \ |
| nxt = list_node_to_off_(list_node_from_off_(i, (off))->next, \ |
| (off))) |
| |
| |
| /* Other -off variants. */ |
| #define list_entry_off(n, type, off) \ |
| ((type *)list_node_from_off_((n), (off))) |
| |
| #define list_head_off(h, type, off) \ |
| ((type *)list_head_off((h), (off))) |
| |
| #define list_tail_off(h, type, off) \ |
| ((type *)list_tail_((h), (off))) |
| |
| #define list_add_off(h, n, off) \ |
| list_add((h), list_node_from_off_((n), (off))) |
| |
| #define list_del_off(n, off) \ |
| list_del(list_node_from_off_((n), (off))) |
| |
| #define list_del_from_off(h, n, off) \ |
| list_del_from(h, list_node_from_off_((n), (off))) |
| |
| /* Offset helper functions so we only single-evaluate. */ |
| static inline void *list_node_to_off_(struct list_node *node, size_t off) |
| { |
| return (void *)((char *)node - off); |
| } |
| static inline struct list_node *list_node_from_off_(void *ptr, size_t off) |
| { |
| return (struct list_node *)((char *)ptr + off); |
| } |
| |
| /* Get the offset of the member, but make sure it's a list_node. */ |
| #define list_off_(type, member) \ |
| (container_off(type, member) + \ |
| check_type(((type *)0)->member, struct list_node)) |
| |
| #define list_off_var_(var, member) \ |
| (container_off_var(var, member) + \ |
| check_type(var->member, struct list_node)) |
| |
| #endif /* CCAN_LIST_H */ |