神奇的container_of

最新推荐文章于 2025-06-08 15:31:03 发布

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本文深入探讨了Linux内核中的container_of宏，该宏能够通过结构体成员的指针找到整个结构体的指针，提供了代码示例并详细解释了其工作原理。

linux内核里面有个container_of 方法（准确的说是个宏），可以根据结构体的某个字段的指针求得整个结构体的指针，感觉蛮新颖的，摘录下来。

#include <stdio.h>

#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) ({ \
    void *__mptr = (void *)(ptr); \
    (type *)(__mptr - offsetof(type,member) );})

typedef struct person_t {
  char name[100];
  int age;
  int weight;
} person_t;

void get_person_by_weight(int *wptr) {

  struct person_t *pptr = container_of(wptr, struct person_t, weight);
  printf("person: name=%s, age=%d, weight=%d\n", pptr->name, pptr->age, pptr->weight);
}

int main() {

  person_t p = {
    .name = "wzq",
    .age = 23,
    .weight = 126
  };

  get_person_by_weight(&(p.weight));
}