第一话,先谈谈数组赋值吧。恩,在C语言中数组赋值和结构体赋值很简单,就是使用=,memcpy操作嘛.
但最近在看关于队列调度的内核实现代码时,发现如下奇怪的赋值语句。(具体程序见linux-2.6.8:net/core/Rtnetlink.c的539行)
- #defineRTM_MAX(RTM_BASE+47)
- #defineRTM_GETLINK(RTM_BASE+2)
- struct rtnetlink_link
- {
- int (*doit)(struct sk_buff *, struct nlmsghdr*, void *attr);
- int (*dumpit)(struct sk_buff *, struct netlink_callback *cb);
- };
- static struct rtnetlink_link link_rtnetlink_table[RTM_MAX-RTM_BASE+1] =
- //RTM_MAX-RTM_BASE+1=48
- {
- [RTM_GETLINK - RTM_BASE] = { .dumpit = rtnetlink_dump_ifinfo },
- [RTM_SETLINK - RTM_BASE] = { .doit = do_setlink },
- [RTM_G - RTM_BASE] = { .dumpit = rtnetlink_dump_all },
- [RTM_GETROU - RTM_BASE] = { .dumpit = rtnetlink_dump_all },
- [RTM_NEWNEIGH - RTM_BASE] = { .doit = neigh_add },
- [RTM_DELNEIGH - RTM_BASE] = { .doit = neigh_delete },
- [RTM_GETNEIGH - RTM_BASE] = { .dumpit = neigh_dump_info }
- };