container_of()

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#include <stdio.h> /* #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) */ struct test { int a; char *b; }; int main(int argc, char *argv[]) { //通过struct test成员b返回struct的入口地址 //container_of(&tmp.b, (struct test), b);    struct test tmp; struct test *ptmp; int offset; tmp.a = 10; printf("&tmp.a = %02x, &tmp.b = %02x\n", &tmp.a, &tmp.b); //定义一个 _mptr指针， 类型为struct test结构体中b成员的类型 //typeof 为获取（（（struct test＊）0）->b)的类型，此处此类型为char* const typeof(((struct test *)0)->b) *_mptr = &tmp.b; printf("_mptr = %02x\n", _mptr); //#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) //TYPE是某struct的类型 0是一个假想TYPE类型struct,MEMBER是该struct中的一个成员.  //由于该struct的基地址为0, MEMBER的地址就是该成员相对与struct头地址的偏移量. offset = (int)(&((struct test *)0)->b); printf("offset = %d\n", offset); //_mptr的地址减去MEMBER在该struct中的偏移量得到的地址, 再转换成type型指针. 该指针就是struct的入口地址了. ptmp = (struct test *)((char *)_mptr - offset); printf("tmp = %02x, ptmp = %02x\n", &tmp, ptmp); printf("ptmp->a = %d\n", ptmp->a); return 0; } 输出结果： $ ./a.out &tmp.a = bfffe6a0, &tmp.b = bfffe6a4 _mptr = bfffe6a4 offset = 4 tmp = bfffe6a0, ptmp = bfffe6a0 ptmp->a = 10