X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Flist%2Flist.h;h=275442d23da05cb8fe9c462e75ffd589fa97e374;hp=d47e13253b56596d83fac64cf7fef1b907b9dc40;hb=c2fbfe5282ba264f3485586e7efa8a5967f2d386;hpb=9ca74a8e616261a3afebcc52472a25f2d551e2b6

diff --git a/ccan/list/list.h b/ccan/list/list.h
index d47e1325..275442d2 100644
--- a/ccan/list/list.h
+++ b/ccan/list/list.h
@@ -1,7 +1,12 @@
+/* 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
@@ -39,7 +44,7 @@ struct list_head
 };
 
 /**
- * list_check - check a list for consistency
+ * list_check - check head of a list for consistency
  * @h: the list_head
  * @abortstr: the location to print on aborting, or NULL.
  *
@@ -51,12 +56,14 @@ struct list_head
  * 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, parent->num_children);
+ *		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);
@@ -64,17 +71,72 @@ struct list_head
  */
 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 debug_list(h) list_check((h), __func__)
+#define list_debug(h, loc) list_check((h), loc)
+#define list_debug_node(n, loc) list_check_node((n), loc)
 #else
-#define debug_list(h) (h)
+#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;
  */
@@ -84,21 +146,46 @@ static inline void list_head_init(struct list_head *h)
 }
 
 /**
- * LIST_HEAD - define and initalized empty list_head
- * @name: the name of the list.
+ * list_node_init - initialize a list_node
+ * @n: the list_node to link to itself.
  *
- * 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.
+ * 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:
- *	// Header:
- *	extern struct list_head my_list;
+ *	struct child c1, c2, c3;
+ *	LIST_HEAD(h);
  *
- *	// C file:
- *	LIST_HEAD(my_list);
+ *	list_add_tail(&h, &c1.list);
+ *	list_add_tail(&h, &c3.list);
+ *	list_add_after(&h, &c1.list, &c2.list);
  */
-#define LIST_HEAD(name) \
-	struct list_head name = { { &name.n, &name.n } }
+#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.
@@ -107,16 +194,46 @@ static inline void list_head_init(struct list_head *h)
  *
  * 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)
+#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)debug_list(h);
+	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);
 }
 
 /**
@@ -129,28 +246,71 @@ static inline void list_add(struct list_head *h, struct list_node *n)
  *	list_add_tail(&parent->children, &child->list);
  *	parent->num_children++;
  */
-static inline void list_add_tail(struct list_head *h, struct list_node *n)
+#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 bool list_empty_(const struct list_head *h, const char* abortstr)
 {
-	n->next = &h->n;
-	n->prev = h->n.prev;
-	h->n.prev->next = n;
-	h->n.prev = n;
-	(void)debug_list(h);
+	(void)list_debug(h, abortstr);
+	return h->n.next == &h->n;
 }
 
 /**
- * list_del - delete an entry from a linked list.
+ * 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(), list_del_init()
+ *
  * Example:
  *	list_del(&child->list);
  *	parent->num_children--;
  */
-static inline void list_del(struct list_node *n)
+#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;
-	(void)debug_list(n->next);
 #ifdef CCAN_LIST_DEBUG
 	/* Catch use-after-del. */
 	n->next = n->prev = NULL;
@@ -158,18 +318,87 @@ static inline void list_del(struct list_node *n)
 }
 
 /**
- * list_empty - is a list empty?
- * @h: the list_head
+ * list_del_init - delete a node, and reset it so it can be deleted again.
+ * @n: the list_node to be deleted.
  *
- * If the list is empty, returns true.
+ * 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:
- *	assert(list_empty(&parent->children) == (parent->num_children == 0));
+ *	list_del_init(&child->list);
+ *	parent->num_children--;
  */
-static inline bool list_empty(const struct list_head *h)
+#define list_del_init(n) list_del_init_(n, LIST_LOC)
+static inline void list_del_init_(struct list_node *n, const char *abortstr)
 {
-	(void)debug_list(h);
-	return h->n.next == &h->n;
+	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
 }
 
 /**
@@ -179,9 +408,11 @@ static inline bool list_empty(const struct list_head *h)
  * @member: the list_node member of the type
  *
  * Example:
- *	struct child *c;
  *	// First list entry is children.next; convert back to child.
- *	c = list_entry(parent->children.next, struct child, list);
+ *	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)
 
@@ -196,9 +427,46 @@ static inline bool list_empty(const struct list_head *h)
  * 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_top(h, type, member) \
-	(list_empty(h) ? NULL : list_entry((h)->n.next, type, member))
+#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
@@ -211,13 +479,22 @@ static inline bool list_empty(const struct list_head *h)
  * Example:
  *	struct child *last;
  *	last = list_tail(&parent->children, struct child, list);
+ *	if (!last)
+ *		printf("Empty list!\n");
  */
 #define list_tail(h, type, member) \
-	(list_empty(h) ? NULL : list_entry((h)->n.prev, 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
+ * @h: the list_head (warning: evaluated multiple times!)
  * @i: the structure containing the list_node
  * @member: the list_node member of the structure
  *
@@ -225,14 +502,49 @@ static inline bool list_empty(const struct list_head *h)
  * a for loop, so you can break and continue as normal.
  *
  * Example:
- *	struct child *c;
- *	list_for_each(&parent->children, c, list)
- *		printf("Name: %s\n", c->name);
+ *	list_for_each(&parent->children, child, list)
+ *		printf("Name: %s\n", child->name);
  */
 #define list_for_each(h, i, member)					\
-	for (i = container_of_var(debug_list(h)->n.next, i, member);	\
-	     &i->member != &(h)->n;					\
-	     i = container_of_var(i->member.next, 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
@@ -246,15 +558,270 @@ static inline bool list_empty(const struct list_head *h)
  * @nxt is used to hold the next element, so you can delete @i from the list.
  *
  * Example:
- *	struct child *c, *n;
- *	list_for_each_safe(&parent->children, c, n, list) {
- *		list_del(&c->list);
+ *	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)				\
-	for (i = container_of_var(debug_list(h)->n.next, i, member),	\
-		nxt = container_of_var(i->member.next, i, member);	\
-	     &i->member != &(h)->n;					\
-	     i = nxt, nxt = container_of_var(i->member.next, i, 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 */