[wimlib] / include / wimlib / list.h

/*
 * This file is based on include/linux/list.h in the Linux kernel source code.
 */

#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H

#include <stddef.h>

struct list_head {
        struct list_head *next, *prev;
};
struct hlist_head {
        struct hlist_node *first;
};

struct hlist_node {
        struct hlist_node *next, **pprev;
};

/*
 * 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.
 */

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#ifdef LIST_HEAD /* BSD sys/queue.h defines this... */
#  undef LIST_HEAD
#endif

#define LIST_HEAD(name) \
        struct list_head name = LIST_HEAD_INIT(name)

static inline void INIT_LIST_HEAD(struct list_head *list)
{
        list->next = list;
        list->prev = list;
}

/*
 * Insert a new entry between two known consecutive entries.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void __list_add(struct list_head *new,
                              struct list_head *prev,
                              struct list_head *next)
{
        next->prev = new;
        new->next = next;
        new->prev = prev;
        prev->next = new;
}

/**
 * list_add - add a new entry
 * @new: 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.
 */
static inline void list_add(struct list_head *new, struct list_head *head)
{
        __list_add(new, head, head->next);
}

/**
 * list_add_tail - add a new entry
 * @new: 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.
 */
static inline void list_add_tail(struct list_head *new, struct list_head *head)
{
        __list_add(new, head->prev, head);
}

/**
 * list_replace - replace old entry by new one
 * @old : the element to be replaced
 * @new : the new element to insert
 *
 * If @old was empty, it will be overwritten.
 */
static inline void list_replace(struct list_head *old,
                                struct list_head *new)
{
        new->next = old->next;
        new->next->prev = new;
        new->prev = old->prev;
        new->prev->next = new;
}

static inline void list_replace_init(struct list_head *old,
                                        struct list_head *new)
{
        list_replace(old, new);
        INIT_LIST_HEAD(old);
}

/*
 * 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!
 */
static 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.
 * Note: list_empty() on entry does not return true after this, the entry is
 * in an undefined state.
 */
static 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.
 */
static inline void list_del_init(struct list_head *entry)
{
        list_del(entry);
        INIT_LIST_HEAD(entry);
}

/**
 * list_empty - tests whether a list is empty
 * @head: the list to test.
 */
static inline int list_empty(const struct list_head *head)
{
        return head->next == head;
}

/**
 * list_is_singular - tests whether a list has just one entry.
 * @head: the list to test.
 */
static inline int list_is_singular(const struct list_head *head)
{
        return !list_empty(head) && (head->next == head->prev);
}

static inline void __list_splice(const struct list_head *list,
                                 struct list_head *prev,
                                 struct list_head *next)
{
        struct list_head *first = list->next;
        struct list_head *last = list->prev;

        first->prev = prev;
        prev->next = first;

        last->next = next;
        next->prev = last;
}

/**
 * list_splice - join two lists, this is designed for stacks
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 */
static inline void list_splice(const struct list_head *list,
                                struct list_head *head)
{
        if (!list_empty(list))
                __list_splice(list, head, head->next);
}

/* Move the entire list @old to the list @new, overwriting it. */
static inline void list_transfer(struct list_head *old,
                                 struct list_head *new)
{
        struct list_head *prev, *next;

        if (list_empty(old)) {
                INIT_LIST_HEAD(new);
        } else {
                prev = old->prev;
                next = old->next;
                new->next = next;
                new->prev = prev;
                prev->next = new;
                next->prev = new;
        }
}

/**
 * list_move - delete from one list and add as another's head
 * @list: the entry to move
 * @head: the head that will precede our entry
 */
static inline void list_move(struct list_head *list, struct list_head *head)
{
        list_del(list);
        list_add(list, head);
}

/**
 * list_move_tail - delete from one list and add as another's tail
 * @list: the entry to move
 * @head: the head that will follow our entry
 */
static inline void list_move_tail(struct list_head *list,
                                  struct list_head *head)
{
        list_del(list);
        list_add_tail(list, head);
}

/**
 * list_splice_tail - join two lists, each list being a queue
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 */
static inline void list_splice_tail(struct list_head *list,
                                struct list_head *head)
{
        if (!list_empty(list))
                __list_splice(list, head->prev, head);
}

/**
 * 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) \
        container_of(ptr, type, member)

/**
 * list_first_entry - get the first element from a list
 * @ptr:        the list head to take the element from.
 * @type:       the type of the struct this is embedded in.
 * @member:     the name of the list_struct within the struct.
 *
 * Note, that list is expected to be not empty.
 */
#define list_first_entry(ptr, type, member) \
        list_entry((ptr)->next, type, member)

/**
 * list_last_entry - get the last element from a list
 * @ptr:        the list head to take the element from.
 * @type:       the type of the struct this is embedded in.
 * @member:     the name of the list_struct within the struct.
 *
 * Note, that list is expected to be not empty.
 */
#define list_last_entry(ptr, type, member) \
        list_entry((ptr)->prev, type, member)

/**
 * list_first_entry_or_null - get the first element from a list
 * @ptr:        the list head to take the element from.
 * @type:       the type of the struct this is embedded in.
 * @member:     the name of the list_struct within the struct.
 *
 * Note that if the list is empty, it returns NULL.
 */
#define list_first_entry_or_null(ptr, type, member) \
        (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)

/**
 * list_next_entry - get the next element in list
 * @pos:        the type * to cursor
 * @member:     the name of the list_struct within the struct.
 */
#define list_next_entry(pos, member) \
        list_entry((pos)->member.next, typeof(*(pos)), member)

/**
 * list_prev_entry - get the prev element in list
 * @pos:        the type * to cursor
 * @member:     the name of the list_struct within the struct.
 */
#define list_prev_entry(pos, member) \
        list_entry((pos)->member.prev, typeof(*(pos)), member)


/**
 * list_for_each        -       iterate over a list
 * @pos:        the &struct list_head to use as a loop cursor.
 * @head:       the head for your list.
 */
#define list_for_each(pos, head) \
        for (pos = (head)->next; pos != (head); pos = pos->next)

/**
 * list_for_each_safe - iterate over a list safe against removal of list entry
 * @pos:        the &struct list_head to use as a loop cursor.
 * @n:          another &struct list_head to use as temporary storage
 * @head:       the head for your list.
 */
#define list_for_each_safe(pos, n, head) \
        for (pos = (head)->next, n = pos->next; pos != (head); \
                pos = n, n = pos->next)

/**
 * list_for_each_entry  -       iterate over list of given type
 * @pos:        the type * to use as a loop cursor.
 * @head:       the head for your list.
 * @member:     the name of the list_struct within the struct.
 */
#define list_for_each_entry(pos, head, member)                          \
        for (pos = list_first_entry(head, typeof(*pos), member);        \
             &pos->member != (head);                                    \
             pos = list_next_entry(pos, member))

/**
 * list_for_each_entry_reverse - iterate backwards over list of given type.
 * @pos:        the type * to use as a loop cursor.
 * @head:       the head for your list.
 * @member:     the name of the list_struct within the struct.
 */
#define list_for_each_entry_reverse(pos, head, member)                  \
        for (pos = list_last_entry(head, typeof(*pos), member);         \
             &pos->member != (head);                                    \
             pos = list_prev_entry(pos, member))

/**
 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 * @pos:        the type * to use as a loop cursor.
 * @n:          another type * to use as temporary storage
 * @head:       the head for your list.
 * @member:     the name of the list_struct within the struct.
 */
#define list_for_each_entry_safe(pos, n, head, member)                  \
        for (pos = list_entry((head)->next, typeof(*pos), member),      \
                n = list_entry(pos->member.next, typeof(*pos), member); \
             &pos->member != (head);                                    \
             pos = n, n = list_entry(n->member.next, typeof(*n), member))

/*
 * Double linked lists with a single pointer list head.
 * Mostly useful for hash tables where the two pointer list head is
 * too wasteful.
 * You lose the ability to access the tail in O(1).
 */

#define HLIST_HEAD_INIT { .first = NULL }
#define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }
#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
static inline void INIT_HLIST_NODE(struct hlist_node *h)
{
        h->next = NULL;
        h->pprev = NULL;
}

static inline int hlist_unhashed(const struct hlist_node *h)
{
        return !h->pprev;
}

static inline int hlist_empty(const struct hlist_head *h)
{
        return !h->first;
}

static inline void __hlist_del(struct hlist_node *n)
{
        struct hlist_node *next = n->next;
        struct hlist_node **pprev = n->pprev;
        *pprev = next;
        if (next)
                next->pprev = pprev;
}

static inline void hlist_del(struct hlist_node *n)
{
        __hlist_del(n);
#if 0
        n->next = LIST_POISON1;
        n->pprev = LIST_POISON2;
#endif
}

static inline void hlist_del_init(struct hlist_node *n)
{
        if (!hlist_unhashed(n)) {
                __hlist_del(n);
                INIT_HLIST_NODE(n);
        }
}

static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
{
        struct hlist_node *first = h->first;
        n->next = first;
        if (first)
                first->pprev = &n->next;
        h->first = n;
        n->pprev = &h->first;
}

#define hlist_entry(ptr, type, member) container_of(ptr,type,member)

#define hlist_for_each(pos, head) \
        for (pos = (head)->first; pos ; pos = pos->next)

#define hlist_for_each_safe(pos, n, head) \
        for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
             pos = n)

/**
 * hlist_for_each_entry - iterate over list of given type
 * @tpos:       the type * to use as a loop cursor.
 * @pos:        the &struct hlist_node to use as a loop cursor.
 * @head:       the head for your list.
 * @member:     the name of the hlist_node within the struct.
 */
#define hlist_for_each_entry(tpos, pos, head, member)                    \
        for (pos = (head)->first;                                        \
             pos &&                                                      \
                ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
             pos = pos->next)

/**
 * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
 * @tpos:       the type * to use as a loop cursor.
 * @pos:        the &struct hlist_node to use as a loop cursor.
 * @n:          another &struct hlist_node to use as temporary storage
 * @head:       the head for your list.
 * @member:     the name of the hlist_node within the struct.
 */
#define hlist_for_each_entry_safe(tpos, pos, n, head, member)            \
        for (pos = (head)->first;                                        \
             pos && ({ n = pos->next; 1; }) &&                           \
                ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
             pos = n)

#endif