linux 内核的链表操作方法

/* *************************************************************** * File Name:    list_head_struct.c * Declaration:   *      linux 内核中的链表操作 *      struct lish_head 双向链表结构 *      链表结构中不包含用户数据结构，而是用户数据结构包含链表结构 *      可以在一个链表中有不同的数据类型 *      也可以不同的数据类型链表中用同一套链表操作函数 *      而不需要根据不同类型做多一套链表函数 *      主要由宏实现 *      list_entry() 宏返回节点的宿主结构指针 * *      c学习理解： *      value = ({代码段}); *      value = 代码段中最后一个语句的值??? *      相当于汇编里 ax eax rax 寄存器传值??? * *      这个程序用同一套宏或函数操作两个不同的用户自定义结构 *      Point 坐标X Y *      Pet   宠物名及类型 * *      1: 输入3个坐标加入坐标链表 *      2: 输入3个宠物加入宠物链表 *      3: 输出两个链表内容 *      4: 释放所用内存空间 * * Author:       jiaga * Created Time: 2014年09月21日 星期日 11时09分14秒 *************************************************************** */#include <stdio.h>#include <stdlib.h>#define LEN 20/* linux 中不使用的内存地址？？？ 用于初始化？？？ */#define POISON_POINTER_DELTA 0#define LIST_POISON1  ((void *) 0x00100100 + POISON_POINTER_DELTA)#define LIST_POISON2  ((void *) 0x00200200 + POISON_POINTER_DELTA)/**  * 声明并初始化循环链表头，前后都指向自己 * 亚节点，实际表起始位置 head->next */#define LIST_HEAD_INIT(name) { &(name), &(name) }#define LIST_HEAD(name) \        struct list_head name = LIST_HEAD_INIT(name)/* 用于从链表节点指针取得宿主结构类型的指针 */#define offsetof(type, member) ((size_t)&((type *)0)->member)#define container_of(ptr, type, member) ({                              \                const __typeof( ((type*)0)->member ) *__mptr = (ptr);   \                (type *)( (char *)__mptr - offsetof(type, member) );})  \#define list_entry(ptr, type, member) \        container_of(ptr, type, member)/* 遍历链表 */#define list_for_each(pos, head) \        for (pos = (head)->next; pos != (head); pos = pos->next)#define list_for_each_safe(pos, n, head)        \        for (pos = (head)->next, n = pos->next; \                        pos != (head);          \                        pos = n, n = pos->next)struct list_head {        struct list_head *next, *prev;};/* 用户数据结构 将list_head 嵌入其中 *//* 坐标 */typedef struct point {        struct list_head point_node;        float x;        float y;}Point;/* 宠物名及类型 */typedef struct pet {        struct list_head pet_node;        char name[LEN];        char kind[LEN];}Pet;void INIT_LIST_HEAD(struct list_head *list){        list->next = list;        list->prev = list;}static 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;}void list_add(struct list_head *new,              struct list_head *head){        __list_add(new, head, head->next);}static void __list_del(struct list_head *prev,                       struct list_head *next){        next->prev = prev;        prev->next = next;}void list_del(struct list_head *entry){        __list_del(entry->prev, entry->next);        entry->next = NULL;        entry->prev = NULL;        /*         entry->next = LIST_POISON2;        entry->prev = LIST_POISON2;        */}/* user for debug, print addr msg */void print_node_addr(struct list_head *head){        printf("curr: %p  next: %p  prev: %p\n",                         head,                         head->next,                         head->prev);}Point* new_point(){        Point *point;        point = (Point *)malloc(sizeof(Point));        printf("Please input x and y: ");        scanf(" %f %f", &point->x, &point->y);        INIT_LIST_HEAD(&point->point_node);        return point;}Pet* new_pet(){        Pet *pet;        pet = (Pet *)malloc(sizeof(Pet));        printf("Please input pet name: ");        scanf("%s", pet->name);        printf("Please input pet kind: ");        scanf("%s", pet->kind);        INIT_LIST_HEAD(&pet->pet_node);        return pet;}int main(void){        LIST_HEAD(points);              /* 声明链表头结点            */        LIST_HEAD(pets);                /* 声明链表头结点            */        /* 这两个可以通用,相当于for循环中的i, 为了看得明白多声明一个 */        struct list_head *point;        /* 遍历索引                  */        struct list_head *pet;          /* 遍历索引                  */        struct list_head *tmp; /* 用于释放节点时临时保存下一节点的指针 */        Point *c_point;                 /* 用于操作用户数据类型      */        Pet *c_pet;                     /* 用于操作用户数据类型      */        int i;                /* 创建新结点并获取输入 */        for (i = 0; i < 3; i++) {                c_point = new_point();                   /* 获取输入 */                list_add(&c_point->point_node, &points); /* 加入链表 */        }        for (i = 0; i < 3; i++) {                c_pet = new_pet();                       /* 获取输入 */                list_add(&c_pet->pet_node, &pets);       /* 加入链表 */        }                list_for_each(point, &points) {                c_point = list_entry(point, Point, point_node);                printf("x = %.2f  y = %.2f\n", c_point->x, c_point->y);        }        list_for_each(pet, &pets) {                c_pet = list_entry(pet, Pet, pet_node);                printf("name: %-10s  kind: %-10s\n",                                 c_pet->name, c_pet->kind);        }        /* 从points链表中删除节点并释放内存空间 */        list_for_each_safe(point, tmp, &points) {                c_point = list_entry(point, Point, point_node);                list_del(point);                free(c_point);        }        /*         * 不用list_for_each_safe宏的删除操作        point = points.next;        while (point != &points) {                tmp = point->next;                c_point = list_entry(point, Point, point_node);                list_del(point);                point = tmp;                free(c_point);        }        */        /* 删除 pets 链表节点 */        pet = pets.next;        while (pet!= &pets) {                tmp = pet->next;                c_pet = list_entry(pet, Pet, pet_node);                list_del(pet);                pet = tmp;                free(c_pet);        }        return 0;}

运行结果：

Please input x and y: <strong>1.2 2.3</strong>Please input x and y: <strong>3.4 4.5</strong>Please input x and y: <strong>5.6 6.7</strong>Please input pet name: <strong>Mickey</strong>Please input pet kind: <strong>Mouse</strong>Please input pet name: <strong>Donald</strong>Please input pet kind: <strong>Duck</strong>Please input pet name: <strong>Xiyangyang</strong>Please input pet kind: <strong>Sheep</strong>x = 5.60  y = 6.70x = 3.40  y = 4.50x = 1.20  y = 2.30name: Xiyangyang  kind: Sheep     name: Donald      kind: Duck      name: Mickey      kind: Mouse