C語言雙向循環鏈表api（源自gluster源碼）

C語言雙向循環鏈表api（源自gluster源碼）
基本的操作如增加、刪除和遍歷等

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*定義表頭*/
struct list_head {
    struct list_head *next;
    struct list_head *prev;
};

/*表頭初始化*/
#define INIT_LIST_HEAD(head) do {           \
        (head)->next = (head)->prev = head; \
    } while (0)

/*增加*/
static inline void
list_add (struct list_head *new, struct list_head *head)
{
    new->prev = head;
    new->next = head->next;

    new->prev->next = new;
    new->next->prev = new;
}

/*刪除*/
static inline void
list_del (struct list_head *old)
{
    old->prev->next = old->next;
    old->next->prev = old->prev;

    old->next = (void *)0xbabebabe;
    old->prev = (void *)0xcafecafe;
}

/*判斷鏈表是否爲空*/
static inline int
list_empty (struct list_head *head)
{
    return (head->next == head);
}

#define list_entry(ptr, type, member)                   \
    ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

#define list_for_each(pos, head)                                        \
    for (pos = (head)->next; pos != (head); pos = pos->next)

/*遍歷，關於list_for_each_entry，百度*/
#define list_for_each_entry(pos, head, member)              \
    for (pos = list_entry((head)->next, typeof(*pos), member);  \
         &pos->member != (head);                    \
         pos = list_entry(pos->member.next, typeof(*pos), member))

/*例：先定義一個結構體*/
typedef struct student
{                   
    int num;        //學號
    int score;      //分數
    char name[20];
    struct list_head student_list;
}STU;

STU *head=NULL;

int main(void)
{
    STU *new=NULL;

    new = (STU *)malloc(sizeof(STU));
    bzero(new, sizeof(STU));
    new->num = 8;
    new->score = 8;
    strcpy(new->name, "8888");
    /*鏈表初始化*/
    if(head == NULL)
    {
        // head = (STU *)malloc(sizeof(STU));
        // bzero(head, sizeof(STU));
        head = new;
        INIT_LIST_HEAD(&head->student_list);
    }
    else
    {
        list_add(&new->student_list, &head->student_list);
    }

    if(list_empty(&head->student_list))
    {
        printf("list only head\n");
        printf("head->num:%d, score:%d, name:%s\n", head->num, head->score, head->name);
    }
    /*將新成員插入鏈表*/
    int i;
    for(i=0;i<5;i++)
    {
        new = (STU *)malloc(sizeof(STU));
        bzero(new, sizeof(STU));
        new->num = i;
        new->score = i+1;
        strcpy(new->name, "2233");
        list_add(&new->student_list, &head->student_list);
    }
    /*刪除指定的成員*/
    STU *pos=NULL;
    list_for_each_entry(pos, &head->student_list, student_list)
    {
        if(pos->num == 2){
            list_del(&pos->student_list);
            free(pos);
            pos = NULL;
            break;
            // printf("num:%d, score:%d, name:%s\n", pos->num, pos->score, pos->name);
        }
    }
    /*遍歷鏈表*/
    list_for_each_entry(pos, &head->student_list, student_list)
    {
        printf("num:%d, score:%d, name:%s\n", pos->num, pos->score, pos->name);
    }
    return 0;
}