list.h库文件的分析与运用

 lish.h定义双向循环链表的的相关操作。具体的源码分析网上有很多，而且你自己通过阅读注释也可以看懂每个函数的具体功能。接下来就是list.h文件的运用：

由于list.h属于内核模块中的库文件(usr\src\linux-headers-version\include\linux\

而默认加载的是usr\include\下的库文件，不包含list.h

因此需要自己写一个库文件其中包含list.h中的函数

mylist.h

 

 

#ifndef _LINUX_LIST_H
#define _LINUX_LIST_H

#include <linux/stddef.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 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!
 */
#ifndef CONFIG_DEBUG_LIST
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;
}
#else
extern void __list_add(struct list_head *new,
         struct list_head *prev,
         struct list_head *next);
#endif

/**
 * 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.
 */
#ifndef CONFIG_DEBUG_LIST
static inline void list_del(struct list_head *entry)
{
 __list_del(entry->prev, entry->next);
 INIT_LIST_HEAD(entry);
}
#else
extern void list_del(struct list_head *entry);
#endif

/**
 * 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->prev, entry->next);
 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(list->prev, list->next);
 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->prev, list->next);
 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_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)

#define container_of(ptr,type,member) ({                     \
  const typeof( ((type *)0)->member ) *__mptr = (ptr) ;  \
  (type *)( (char *) __mptr - offsetof(type,member) ) ;})

#define offsetof(type,member) \
 ((size_t) &((type *)0)->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_for_each - iterate over a list
 * @pos: the &struct list_head to use as a loop cursor.
 * @head: the head for your list.
 */


/**
 * __list_for_each - iterate over a list
 * @pos: the &struct list_head to use as a loop cursor.
 * @head: the head for your list.
 *
 * This variant differs from list_for_each() in that it's the
 * simplest possible list iteration code, no prefetching is done.
 * Use this for code that knows the list to be very short (empty
 * or 1 entry) most of the time.
 */
#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.
 */


/**
 * 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.
 */


/**
 * 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.
 */


/**
 * 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.
 */

/**
 * 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.
 */


/**
 * 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.
 */

 

/**
 * 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))

/**
 * list_for_each_entry_safe_continue
 * @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_entry(pos->member.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))

/**
 * list_for_each_entry_safe_from
 * @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_entry(pos->member.next, typeof(*pos), member);  \
      &pos->member != (head);      \
      pos = n, n = list_entry(n->member.next, typeof(*n), member))

/**
 * list_for_each_entry_safe_reverse
 * @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_entry((head)->prev, typeof(*pos), member), \
  n = list_entry(pos->member.prev, typeof(*pos), member); \
      &pos->member != (head);      \
      pos = n, n = list_entry(n->member.prev, 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).
 */


#endif

  

list.c

 

#include <stdio.h>
#include <stdlib.h>
#include "mylist.h"
struct Data
{
    char data;
    struct list_head list;
};

typedef struct Data mydata;

void decimal_to_binary();
void binary_to_decimal();
void free_memory(struct list_head *pos,struct list_head *p,struct Data mylist,struct Data *tmp);


int main(int argc ,char *argv[])
{    
    int select = 0;
    printf("**************************************************************\n");
    printf("** 1.Decimal to binary **\n");
    printf("** 2.Binary to decimal **\n");
    printf("** 0.Exit **\n");
    printf("**************************************************************\n");
    printf("Please select which you want to convert:");
    scanf("%d",&select);
    getchar();
    switch (select){
        case 0:printf("Welcome to use next time!\n");break;
        case 1:decimal_to_binary();          break ;
        case 2:binary_to_decimal();              break;
        default:printf("Your select is not right!"); break;
    }

    return 0;
}
/***********************************************************************
 *Function name:dec_to_binary
 *Function Description: The function is used to covert a number from
 *                decimal to binary
 *Parameter:@num ,the decimal which will be coverted
 *Result:Display the num 's binary result
 ***********************************************************************/
void decimal_to_binary()
{
    long number,temp;
    mydata mylist,*tmp;
    struct list_head *pos,*p;
    INIT_LIST_HEAD(&mylist.list);
    
    printf("please input a number you want to convert:");
    scanf("%ld",&number);
    printf("Decemal number %ld's binary is:",number);
    
    if (number == 0) { 

        printf("%ld",number);
        printf("\n");
        return;
    }
    while (number != 0) {
        tmp = (mydata *)malloc(sizeof(mydata));
        temp = number % 2;
        tmp -> data = temp;
        list_add(&(tmp->list),&(mylist.list));
        number = number / 2;
    }
    __list_for_each(pos,&mylist.list) {
        tmp = list_entry(pos,struct Data,list);
        printf("%ld",(long)tmp->data);
    }
    printf("\n");
    



    list_for_each_safe(pos,p,&mylist.list){
        tmp = list_entry(pos,struct Data,list);
        list_del(pos);
        free(tmp);
    }
    if (list_empty(&mylist.list)){
        printf("The list now is empty!\n");
    }
}

/***********************************************************************
 *Function name:dec_to_binary
 *Function Description: The function is used to covert a number from
 *                binary to decimal
 *Parameter:void
 *Result:Display the num 's decimal result
 ***********************************************************************/
void binary_to_decimal()
{
    mydata mylist,*tmp;
    struct list_head *pos,*p;
    char ch = '0';
    long dec = 1; 

    long dec_number = 0;

    INIT_LIST_HEAD(&mylist.list);
    printf("Please input the binary number you want to convert:");
    ch = getchar();
    while ((ch == '0')||(ch == '1')){
        tmp = (struct Data *)malloc(sizeof(struct Data));
        tmp -> data = ch;
        list_add(&(tmp->list),&(mylist.list));
        ch = getchar();
    } 
     __list_for_each(pos,&mylist.list){
        tmp = list_entry(pos,struct Data,list);
        dec_number += (int)(tmp ->data - '0') * dec;
        dec *= 2;
    }
    printf("\n");
    printf("Decimal number is %ld\n",dec_number);


    list_for_each_safe(pos,p,&mylist.list){
        tmp = list_entry(pos,struct Data,list);
        list_del(pos);
        free(tmp);
    }
    if (list_empty(&mylist.list)){
        printf("The list now is empty!\n");
    }
}

 

 

listTest.c

 

#include<stdio.h>
#include<stdlib.h>
#include"mylist.h"
#include<string.h>
struct userinfo{
	char username[20];
	char password[20];
	struct list_head list;
};
typedef struct userinfo UserStruct;

int main(int argc,char *argv[]){
	char username[20],password[20];
	char flag[2]="#";
	UserStruct userlist,*user,*temp,*replacetest,*templist;
	struct list_head *pos,*p;
	//初始化双向循环链表
	INIT_LIST_HEAD(&(userlist.list));
	INIT_LIST_HEAD(&(templist->list));
	printf("please input your username and password:\n");
	scanf("%s",username);
	scanf("%s",password);
	getchar();
	
	//循环添加元素
	while(strcmp(username,flag) && strcmp(password,flag)){
		user=(struct userinfo*)malloc(sizeof(struct userinfo));
		strcpy(user->username,username);
		strcpy(user->password,password);
		list_add_tail(&(user->list),&(userlist.list));
		printf("please input your username and password:\n");
		scanf("%s",username);
		scanf("%s",password);
		getchar();
	}
	
	//利用一个新的节点替换第一个节点
	replacetest=(struct userinfo*)malloc(sizeof(struct userinfo));
	strcpy(replacetest->username,"username");
	strcpy(replacetest->password,"password");
	list_replace_init(userlist.list.next,&(replacetest->list));
	//将一个节点移动到双向循环链表末尾
	list_move_tail(userlist.list.next,&(userlist.list));
	//将一个节点移动到双向循环链表头
	list_move_tail(userlist.list.prev,&(userlist.list));

	if(list_is_last(&(replacetest->list),&(userlist.list))){
		printf("该节点是双向循环链表的最后一个节点\n");
	}

	if(!list_is_singular(&(userlist.list))){
		printf("该双向循环链表有多个节点\n");
	}
	//遍历双向循环链表
	printf("遍历双向循环链表\n");
	__list_for_each(pos,&(userlist.list)){
		temp=list_entry(pos,struct userinfo,list);
		printf("用户名：%s 密码：%s\n",temp->username,temp->password);
	}
	/*
	//双向循环链表的切割
	list_cut_position(&(templist->list),&(userlist.list),userlist.list.next);
	
	//遍历切割的双向循环链表
	printf("遍历切割的双向循环链表\n");
	__list_for_each(pos,&(templist->list)){
		temp=list_entry(pos,struct userinfo,list);
		printf("用户名：%s 密码：%s\n",temp->username,temp->password);
	}
	//合并链表
	__list_splice(&(templist->list),userlist.list.next,userlist.list.next->next);
	list_splice_init(&(templist->list),&(userlist.list));
	
	//遍历合并后双向循环链表
	printf("遍历合并后双向循环链表\n");
	
	__list_for_each(pos,&(userlist.list)){
		temp=list_entry(pos,struct userinfo,list);
		printf("用户名：%s 密码：%s\n",temp->username,temp->password);
	}
	*/
	//释放内存资源
	list_for_each_safe(pos,p,&(userlist.list)){
		temp=list_entry(pos,struct userinfo,list);
		list_del(pos);
		free(temp);
	}
	
	if(list_empty(&(userlist.list))){
		printf("双向循环链表为空\n");
	}



	return 0;
}