linux第一宏

在ubuntu内下载源代码

进入到下载目录下

user-name@ubuntu:/usr/src$ cd ./linux-source-4.15.0/

搜索宏源码：

vim -t offsetof

987 #ifndef offsetof
 988 # define offsetof(typ, memb)     ((unsigned long)((char *)&(((typ *)0)->memb)))
 989 #endif

vim -t container_of

240 /**
241  * Returns a pointer to the container of this list element.
242  *
243  * Example:
244  * struct foo* f;
245  * f = container_of(&foo->entry, struct foo, entry);
246  * assert(f == foo);
247  *
248  * @param ptr Pointer to the struct list_head.
249  * @param type Data type of the list element.
250  * @param member Member name of the struct list_head field in the list element.
251  * @return A pointer to the data struct containing the list head.
252  */
253 #ifndef container_of
254 #define container_of(ptr, type, member) \
255     (type *)((char *)(ptr) - (char *) &((type *)0)->member)
256 #endif

确实巧妙