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DEFINITIONS
This source file includes following definitions.
- list_head_init
- list_node_init
- list_add_after_
- list_add_
- list_add_before_
- list_add_tail_
- list_empty_
- list_empty_nodebug
- list_del_
- list_del_init_
- list_del_from
- list_swap_
- list_top_
- list_pop_
- list_tail_
- list_append_list_
- list_prepend_list_
- list_node_to_off_
- list_node_from_off_
- list_entry_or_null
/* Licensed under BSD-MIT - see ccan/licenses/BSD-MIT file for details */
#ifndef CCAN_LIST_H
#define CCAN_LIST_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;
};
#define LIST_LOC __FILE__ ":" stringify(__LINE__)
#define list_debug(h, loc) ((void)loc, h)
#define list_debug_node(n, loc) ((void)loc, n)
/**
* 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_node_init - initialize a list_node
* @n: the list_node to link to itself.
*
* You don't need to use this normally! But it lets you list_del(@n)
* safely.
*/
static inline void list_node_init(struct list_node *n)
{
n->next = n->prev = n;
}
/**
* list_add_after - add an entry after an existing node in a linked list
* @h: the list_head to add the node to (for debugging)
* @p: the existing list_node to add the node after
* @n: the new list_node to add to the list.
*
* The existing list_node must already be a member of the list.
* The new list_node does not need to be initialized; it will be overwritten.
*
* Example:
* struct child c1, c2, c3;
* LIST_HEAD(h);
*
* list_add_tail(&h, &c1.list);
* list_add_tail(&h, &c3.list);
* list_add_after(&h, &c1.list, &c2.list);
*/
#define list_add_after(h, p, n) list_add_after_(h, p, n, LIST_LOC)
static inline void list_add_after_(struct list_head *h,
struct list_node *p,
struct list_node *n,
const char *abortstr)
{
n->next = p->next;
n->prev = p;
p->next->prev = n;
p->next = n;
(void)list_debug(h, abortstr);
}
/**
* 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)
{
list_add_after_(h, &h->n, n, abortstr);
}
/**
* list_add_before - add an entry before an existing node in a linked list
* @h: the list_head to add the node to (for debugging)
* @p: the existing list_node to add the node before
* @n: the new list_node to add to the list.
*
* The existing list_node must already be a member of the list.
* The new list_node does not need to be initialized; it will be overwritten.
*
* Example:
* list_head_init(&h);
* list_add_tail(&h, &c1.list);
* list_add_tail(&h, &c3.list);
* list_add_before(&h, &c3.list, &c2.list);
*/
#define list_add_before(h, p, n) list_add_before_(h, p, n, LIST_LOC)
static inline void list_add_before_(struct list_head *h,
struct list_node *p,
struct list_node *n,
const char *abortstr)
{
n->next = p;
n->prev = p->prev;
p->prev->next = n;
p->prev = 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)
{
list_add_before_(h, &h->n, n, 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 int 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 int 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(), list_del_init()
*
* 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_init - delete a node, and reset it so it can be deleted again.
* @n: the list_node to be deleted.
*
* list_del(@n) or list_del_init() again after this will be safe,
* which can be useful in some cases.
*
* See also:
* list_del_from(), list_del()
*
* Example:
* list_del_init(&child->list);
* parent->num_children--;
*/
#define list_del_init(n) list_del_init_(n, LIST_LOC)
static inline void list_del_init_(struct list_node *n, const char *abortstr)
{
list_del_(n, abortstr);
list_node_init(n);
}
/**
* 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_swap - swap out an entry from an (unknown) linked list for a new one.
* @o: the list_node to replace from the list.
* @n: the list_node to insert in place of the old one.
*
* Note that this leaves @o in an undefined state; it can be added to
* another list, but not deleted/swapped again.
*
* See also:
* list_del()
*
* Example:
* struct child x1, x2;
* LIST_HEAD(xh);
*
* list_add(&xh, &x1.list);
* list_swap(&x1.list, &x2.list);
*/
#define list_swap(o, n) list_swap_(o, n, LIST_LOC)
static inline void list_swap_(struct list_node *o,
struct list_node *n,
const char* abortstr)
{
(void)list_debug_node(o, abortstr);
*n = *o;
n->next->prev = n;
n->prev->next = n;
#ifdef CCAN_LIST_DEBUG
/* Catch use-after-del. */
o->next = o->prev = NULL;
#endif
}
/**
* 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) \
list_for_each_rev_off(h, i, list_off_var_(i, member))
/**
* list_for_each_rev_safe - iterate through a list backwards,
* 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 backwards.
* 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_rev_safe(&parent->children, child, next, list) {
* printf("Name: %s\n", child->name);
* }
*/
#define list_for_each_rev_safe(h, i, nxt, member) \
list_for_each_rev_safe_off(h, i, nxt, list_off_var_(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:
* 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);
}
/* internal macros, do not use directly */
#define list_for_each_off_dir_(h, i, off, dir) \
for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.dir, \
(off)); \
list_node_from_off_((void *)i, (off)) != &(h)->n; \
i = list_node_to_off_(list_node_from_off_((void *)i, (off))->dir, \
(off)))
#define list_for_each_safe_off_dir_(h, i, nxt, off, dir) \
for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.dir, \
(off)), \
nxt = list_node_to_off_(list_node_from_off_(i, (off))->dir, \
(off)); \
list_node_from_off_(i, (off)) != &(h)->n; \
i = nxt, \
nxt = list_node_to_off_(list_node_from_off_(i, (off))->dir, \
(off)))
/**
* 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) \
list_for_each_off_dir_((h),(i),(off),next)
/**
* list_for_each_rev_off - iterate through a list of memory regions backwards
* @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.
*
* See list_for_each_off for details
*/
#define list_for_each_rev_off(h, i, off) \
list_for_each_off_dir_((h),(i),(off),prev)
/**
* 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) \
list_for_each_safe_off_dir_((h),(i),(nxt),(off),next)
/**
* list_for_each_rev_safe_off - iterate backwards 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_rev_off' and `list_for_each_rev_safe'
* descriptions.
*
* Example:
* list_for_each_rev_safe_off(&parent->children, child,
* next, offsetof(struct child, list))
* printf("Name: %s\n", child->name);
*/
#define list_for_each_rev_safe_off(h, i, nxt, off) \
list_for_each_safe_off_dir_((h),(i),(nxt),(off),prev)
/* 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 */
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