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Diffstat (limited to 'ccan/list/list.h')
| -rw-r--r-- | ccan/list/list.h | 656 |
1 files changed, 656 insertions, 0 deletions
diff --git a/ccan/list/list.h b/ccan/list/list.h new file mode 100644 index 0000000..4d1d34e --- /dev/null +++ b/ccan/list/list.h @@ -0,0 +1,656 @@ +/* Licensed under BSD-MIT - see LICENSE file for details */ +#ifndef CCAN_LIST_H +#define CCAN_LIST_H +//#define CCAN_LIST_DEBUG 1 +#include <stdbool.h> +#include <assert.h> +#include <ccan/str/str.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); + +#define LIST_LOC __FILE__ ":" stringify(__LINE__) +#ifdef CCAN_LIST_DEBUG +#define list_debug(h, loc) list_check((h), loc) +#define list_debug_node(n, loc) list_check_node((n), loc) +#else +#define list_debug(h, loc) (h) +#define list_debug_node(n, loc) (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++; + */ +#define list_add(h, n) list_add_(h, n, LIST_LOC) +static inline void list_add_(struct list_head *h, + struct list_node *n, + const char *abortstr) +{ + n->next = h->n.next; + n->prev = &h->n; + h->n.next->prev = n; + h->n.next = n; + (void)list_debug(h, abortstr); +} + +/** + * 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++; + */ +#define list_add_tail(h, n) list_add_tail_(h, n, LIST_LOC) +static inline void list_add_tail_(struct list_head *h, + struct list_node *n, + const char *abortstr) +{ + n->next = &h->n; + n->prev = h->n.prev; + h->n.prev->next = n; + h->n.prev = n; + (void)list_debug(h, abortstr); +} + +/** + * 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)); + */ +#define list_empty(h) list_empty_(h, LIST_LOC) +static inline bool list_empty_(const struct list_head *h, const char* abortstr) +{ + (void)list_debug(h, abortstr); + return h->n.next == &h->n; +} + +/** + * list_empty_nodebug - is a list empty (and don't perform debug checks)? + * @h: the list_head + * + * If the list is empty, returns true. + * This differs from list_empty() in that if CCAN_LIST_DEBUG is set it + * will NOT perform debug checks. Only use this function if you REALLY + * know what you're doing. + * + * Example: + * assert(list_empty_nodebug(&parent->children) == (parent->num_children == 0)); + */ +#ifndef CCAN_LIST_DEBUG +#define list_empty_nodebug(h) list_empty(h) +#else +static inline bool list_empty_nodebug(const struct list_head *h) +{ + return h->n.next == &h->n; +} +#endif + +/** + * 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--; + */ +#define list_del(n) list_del_(n, LIST_LOC) +static inline void list_del_(struct list_node *n, const char* abortstr) +{ + (void)list_debug_node(n, abortstr); + 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 - remove 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 *one; + * one = list_pop(&parent->children, struct child, list); + * if (!one) + * printf("Empty list!\n"); + */ +#define list_pop(h, type, member) \ + ((type *)list_pop_((h), list_off_(type, member))) + +static inline const void *list_pop_(const 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, LIST_LOC)->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_next - get the next entry in a list + * @h: the list_head + * @i: a pointer to an entry in the list. + * @member: the list_node member of the structure + * + * If @i was the last entry in the list, returns NULL. + * + * Example: + * struct child *second; + * second = list_next(&parent->children, first, list); + * if (!second) + * printf("No second child!\n"); + */ +#define list_next(h, i, member) \ + ((list_typeof(i))list_entry_or_null(list_debug(h, \ + __FILE__ ":" stringify(__LINE__)), \ + (i)->member.next, \ + list_off_var_((i), member))) + +/** + * list_prev - get the previous entry in a list + * @h: the list_head + * @i: a pointer to an entry in the list. + * @member: the list_node member of the structure + * + * If @i was the first entry in the list, returns NULL. + * + * Example: + * first = list_prev(&parent->children, second, list); + * if (!first) + * printf("Can't go back to first child?!\n"); + */ +#define list_prev(h, i, member) \ + ((list_typeof(i))list_entry_or_null(list_debug(h, \ + __FILE__ ":" stringify(__LINE__)), \ + (i)->member.prev, \ + list_off_var_((i), member))) + +/** + * list_append_list - empty one list onto the end of another. + * @to: the list to append into + * @from: the list to empty. + * + * This takes the entire contents of @from and moves it to the end of + * @to. After this @from will be empty. + * + * Example: + * struct list_head adopter; + * + * list_append_list(&adopter, &parent->children); + * assert(list_empty(&parent->children)); + * parent->num_children = 0; + */ +#define list_append_list(t, f) list_append_list_(t, f, \ + __FILE__ ":" stringify(__LINE__)) +static inline void list_append_list_(struct list_head *to, + struct list_head *from, + const char *abortstr) +{ + struct list_node *from_tail = list_debug(from, abortstr)->n.prev; + struct list_node *to_tail = list_debug(to, abortstr)->n.prev; + + /* Sew in head and entire list. */ + to->n.prev = from_tail; + from_tail->next = &to->n; + to_tail->next = &from->n; + from->n.prev = to_tail; + + /* Now remove head. */ + list_del(&from->n); + list_head_init(from); +} + +/** + * list_prepend_list - empty one list into the start of another. + * @to: the list to prepend into + * @from: the list to empty. + * + * This takes the entire contents of @from and moves it to the start + * of @to. After this @from will be empty. + * + * Example: + * list_prepend_list(&adopter, &parent->children); + * assert(list_empty(&parent->children)); + * parent->num_children = 0; + */ +#define list_prepend_list(t, f) list_prepend_list_(t, f, LIST_LOC) +static inline void list_prepend_list_(struct list_head *to, + struct list_head *from, + const char *abortstr) +{ + struct list_node *from_tail = list_debug(from, abortstr)->n.prev; + struct list_node *to_head = list_debug(to, abortstr)->n.next; + + /* Sew in head and entire list. */ + to->n.next = &from->n; + from->n.prev = &to->n; + to_head->prev = from_tail; + from_tail->next = to_head; + + /* Now remove head. */ + list_del(&from->n); + list_head_init(from); +} + +/** + * list_for_each_off - iterate through a list of memory regions. + * @h: the list_head + * @i: the pointer to a memory region wich 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. Whith all that in mind + * remember that given the wrong pointer/offset couple this macro will + * happilly churn all you memory untill 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, LIST_LOC)->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 wich 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, LIST_LOC)->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)) + +#if HAVE_TYPEOF +#define list_typeof(var) typeof(var) +#else +#define list_typeof(var) void * +#endif + +/* Returns member, or NULL if at end of list. */ +static inline void *list_entry_or_null(const struct list_head *h, + const struct list_node *n, + size_t off) +{ + if (n == &h->n) + return NULL; + return (char *)n - off; +} +#endif /* CCAN_LIST_H */ |