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/*
* Copyright (C) 2008 Karel Zak <kzak@redhat.com>
* Copyright (C) 1999-2008 by Theodore Ts'o
*
* (based on list.h from e2fsprogs)
*/
#ifndef UTIL_LINUX_LIST_H
#define UTIL_LINUX_LIST_H
/* TODO: use AC_C_INLINE */
#ifdef __GNUC__
#define _INLINE_ static __inline__
#else /* For Watcom C */
#define _INLINE_ static inline
#endif
/*
* Simple doubly linked list implementation.
*
* Some of the internal functions ("__xxx") are useful when
* manipulating whole lists rather than single entries, as
* sometimes we already know the next/prev entries and we can
* generate better code by using them directly rather than
* using the generic single-entry routines.
*/
struct list_head {
struct list_head *next, *prev;
};
#define LIST_HEAD_INIT(name) { &(name), &(name) }
#define LIST_HEAD(name) \
struct list_head name = LIST_HEAD_INIT(name)
#define INIT_LIST_HEAD(ptr) do { \
(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)
/*
* Insert a new entry between two known consecutive entries.
*
* This is only for internal list manipulation where we know
* the prev/next entries already!
*/
_INLINE_ void __list_add(struct list_head * add,
struct list_head * prev,
struct list_head * next)
{
next->prev = add;
add->next = next;
add->prev = prev;
prev->next = add;
}
/**
* list_add - add a new entry
* @add: new entry to be added
* @head: list head to add it after
*
* Insert a new entry after the specified head.
* This is good for implementing stacks.
*/
_INLINE_ void list_add(struct list_head *add, struct list_head *head)
{
__list_add(add, head, head->next);
}
/**
* list_add_tail - add a new entry
* @add: new entry to be added
* @head: list head to add it before
*
* Insert a new entry before the specified head.
* This is useful for implementing queues.
*/
_INLINE_ void list_add_tail(struct list_head *add, struct list_head *head)
{
__list_add(add, head->prev, head);
}
/*
* Delete a list entry by making the prev/next entries
* point to each other.
*
* This is only for internal list manipulation where we know
* the prev/next entries already!
*/
_INLINE_ void __list_del(struct list_head * prev,
struct list_head * next)
{
next->prev = prev;
prev->next = next;
}
/**
* list_del - deletes entry from list.
* @entry: the element to delete from the list.
*
* list_empty() on @entry does not return true after this, @entry is
* in an undefined state.
*/
_INLINE_ void list_del(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
}
/**
* list_del_init - deletes entry from list and reinitialize it.
* @entry: the element to delete from the list.
*/
_INLINE_ void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
INIT_LIST_HEAD(entry);
}
/**
* list_empty - tests whether a list is empty
* @head: the list to test.
*/
_INLINE_ int list_empty(struct list_head *head)
{
return head->next == head;
}
/**
* list_last_entry - tests whether is entry last in the list
* @entry: the entry to test.
* @head: the list to test.
*/
_INLINE_ int list_last_entry(struct list_head *entry, struct list_head *head)
{
return head->prev == entry;
}
/**
* list_splice - join two lists
* @list: the new list to add.
* @head: the place to add it in the first list.
*/
_INLINE_ void list_splice(struct list_head *list, struct list_head *head)
{
struct list_head *first = list->next;
if (first != list) {
struct list_head *last = list->prev;
struct list_head *at = head->next;
first->prev = head;
head->next = first;
last->next = at;
at->prev = last;
}
}
/**
* list_entry - get the struct for this entry
* @ptr: the &struct list_head pointer.
* @type: the type of the struct this is embedded in.
* @member: the name of the list_struct within the struct.
*/
#define list_entry(ptr, type, member) \
((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
/**
* list_for_each - iterate over elements in a list
* @pos: the &struct list_head to use as a loop counter.
* @head: the head for your list.
*/
#define list_for_each(pos, head) \
for (pos = (head)->next; pos != (head); pos = pos->next)
/**
* list_for_each_backwardly - iterate over elements in a list in reverse
* @pos: the &struct list_head to use as a loop counter.
* @head: the head for your list.
*/
#define list_for_each_backwardly(pos, head) \
for (pos = (head)->prev; pos != (head); pos = pos->prev)
/**
* list_for_each_safe - iterate over elements in a list, but don't dereference
* pos after the body is done (in case it is freed)
* @pos: the &struct list_head to use as a loop counter.
* @pnext: the &struct list_head to use as a pointer to the next item.
* @head: the head for your list (not included in iteration).
*/
#define list_for_each_safe(pos, pnext, head) \
for (pos = (head)->next, pnext = pos->next; pos != (head); \
pos = pnext, pnext = pos->next)
#undef _INLINE_
#endif /* UTIL_LINUX_LIST_H */
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