linux 链表之： list.h移植

链表是内核中非常非常重要的基础设施，并且在应用层也可将该套设施拿过来用。

这里就是将内核的list.h中部分接口拿到应用层用，其实应用层、内核层都一样，

这里之所以在应用层操作，只是因为测试更为方便。

将内核中的链表list.h移植到应用层的文件如下：

root@ubuntu:/mnt/shared/kernelbox/list# tree
.
├── list.h //内核中的list.h移植过来
├── listuse.c//测试代码
├── Makefile //Makefile
└── poison.h //list.h需要包含的宏

0 directories, 4 files

移植后的list.h源码：

root@ubuntu:/mnt/shared/kernelbox/list# cat list.h 
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/const.h>
#include "poison.h"
/*
 * 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 offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)

/**
 * container_of - cast a member of a structure out to the containing structure
 * @ptr:        the pointer to the member.
 * @type:       the type of the container struct this is embedded in.
 * @member:     the name of the member within the struct.
 *
 */
#define container_of(ptr, type, member) ({                              const typeof( ((type *)0)->member ) *__mptr = (ptr);            (type *)( (char *)__mptr - offsetof(type,member) );})



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

#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);
}

/*
 * 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_entry(struct list_head *entry)
{
        __list_del(entry->prev, entry->next);
}

static inline void list_del(struct list_head *entry)
{
        __list_del(entry->prev, entry->next);
        entry->next = LIST_POISON1;
        entry->prev = LIST_POISON2;
}

/**
 * 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);
}

/**
 * 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(entry);
        INIT_LIST_HEAD(entry);
}

/**
 * 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_entry(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_entry(list);
        list_add_tail(list, head);
}

/**
 * list_is_last - tests whether @list is the last entry in list @head
 * @list: the entry to test
 * @head: the head of the list
 */
static inline int list_is_last(const struct list_head *list,
                                const struct list_head *head)
{
        return list->next == head;
}

/**
 * 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_empty_careful - tests whether a list is empty and not being modified
 * @head: the list to test
 *
 * Description:
 * tests whether a list is empty _and_ checks that no other CPU might be
 * in the process of modifying either member (next or prev)
 *
 * NOTE: using list_empty_careful() without synchronization
 * can only be safe if the only activity that can happen
 * to the list entry is list_del_init(). Eg. it cannot be used
 * if another CPU could re-list_add() it.
 */
static inline int list_empty_careful(const struct list_head *head)
{
        struct list_head *next = head->next;
        return (next == head) && (next == head->prev);
}

/**
 * list_rotate_left - rotate the list to the left
 * @head: the head of the list
 */
static inline void list_rotate_left(struct list_head *head)
{
        struct list_head *first;

        if (!list_empty(head)) {
                first = head->next;
                list_move_tail(first, 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_cut_position(struct list_head *list,
                struct list_head *head, struct list_head *entry)
{
        struct list_head *new_first = entry->next;
        list->next = head->next;
        list->next->prev = list;
        list->prev = entry;
        entry->next = list;
        head->next = new_first;
        new_first->prev = head;
}

/**
 * list_cut_position - cut a list into two
 * @list: a new list to add all removed entries
 * @head: a list with entries
 * @entry: an entry within head, could be the head itself
 *      and if so we won't cut the list
 *
 * This helper moves the initial part of @head, up to and
 * including @entry, from @head to @list. You should
 * pass on @entry an element you know is on @head. @list
 * should be an empty list or a list you do not care about
 * losing its data.
 *
 */
static inline void list_cut_position(struct list_head *list,
                struct list_head *head, struct list_head *entry)
{
        if (list_empty(head))
                return;
        if (list_is_singular(head) &&
                (head->next != entry && head != entry))
                return;
        if (entry == head)
                INIT_LIST_HEAD(list);
        else
                __list_cut_position(list, head, entry);
}

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);
}

/**
 * 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_splice_init - join two lists and reinitialise the emptied list.
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 *
 * The list at @list is reinitialised
 */
static inline void list_splice_init(struct list_head *list,
                                    struct list_head *head)
{
        if (!list_empty(list)) {
                __list_splice(list, head, head->next);
                INIT_LIST_HEAD(list);
        }
}

/**
 * list_splice_tail_init - join two lists and reinitialise the emptied list
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 *
 * Each of the lists is a queue.
 * The list at @list is reinitialised
 */
static inline void list_splice_tail_init(struct list_head *list,
                                         struct list_head *head)
{
        if (!list_empty(list)) {
                __list_splice(list, head->prev, head);
                INIT_LIST_HEAD(list);
        }
}

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

/**
 * 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_prev_safe - iterate over a list backwards 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_prev_safe(pos, n, head)         for (pos = (head)->prev, n = pos->prev;              pos != (head);              pos = n, n = pos->prev)

/**
 * 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_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
 * @pos:        the type * to use as a start point
 * @head:       the head of the list
 * @member:     the name of the list_struct within the struct.
 *
 * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
 */
#define list_prepare_entry(pos, head, member)         ((pos) ? : list_entry(head, typeof(*pos), member))

/**
 * list_for_each_entry_continue - continue iteration 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.
 *
 * Continue to iterate over list of given type, continuing after
 * the current position.
 */
#define list_for_each_entry_continue(pos, head, member)                         for (pos = list_next_entry(pos, member);                                     &pos->member != (head);                                                 pos = list_next_entry(pos, member))

/**
 * list_for_each_entry_continue_reverse - iterate backwards from the given point
 * @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.
 *
 * Start to iterate over list of given type backwards, continuing after
 * the current position.
 */
#define list_for_each_entry_continue_reverse(pos, head, member)                 for (pos = list_prev_entry(pos, member);                                     &pos->member != (head);                                                 pos = list_prev_entry(pos, member))

/**
 * list_for_each_entry_from - iterate over list of given type from the current point
 * @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.
 *
 * Iterate over list of given type, continuing from current position.
 */
#define list_for_each_entry_from(pos, head, member)                             for (; &pos->member != (head);                                               pos = list_next_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_first_entry(head, typeof(*pos), member),                        n = list_next_entry(pos, member);                                    &pos->member != (head);                                                 pos = n, n = list_next_entry(n, member))

/**
 * list_for_each_entry_safe_continue - continue list iteration safe against removal
 * @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.
 *
 * Iterate over list of given type, continuing after current point,
 * safe against removal of list entry.
 */
#define list_for_each_entry_safe_continue(pos, n, head, member)                         for (pos = list_next_entry(pos, member),                                                n = list_next_entry(pos, member);                                            &pos->member != (head);                                                         pos = n, n = list_next_entry(n, member))

/**
 * list_for_each_entry_safe_from - iterate over list from current point safe against removal
 * @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.
 *
 * Iterate over list of given type from current point, safe against
 * removal of list entry.
 */
#define list_for_each_entry_safe_from(pos, n, head, member)                             for (n = list_next_entry(pos, member);                                               &pos->member != (head);                                                         pos = n, n = list_next_entry(n, member))

/**
 * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
 * @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.
 *
 * Iterate backwards over list of given type, safe against removal
 * of list entry.
 */
#define list_for_each_entry_safe_reverse(pos, n, head, member)                  for (pos = list_last_entry(head, typeof(*pos), member),                         n = list_prev_entry(pos, member);                                    &pos->member != (head);                                                 pos = n, n = list_prev_entry(n, member))

/**
 * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
 * @pos:        the loop cursor used in the list_for_each_entry_safe loop
 * @n:          temporary storage used in list_for_each_entry_safe
 * @member:     the name of the list_struct within the struct.
 *
 * list_safe_reset_next is not safe to use in general if the list may be
 * modified concurrently (eg. the lock is dropped in the loop body). An
 * exception to this is if the cursor element (pos) is pinned in the list,
 * and list_safe_reset_next is called after re-taking the lock and before
 * completing the current iteration of the loop body.
 */
#define list_safe_reset_next(pos, n, member)                                    n = list_next_entry(pos, 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).
 */