Socket recv()以前進行select代碼

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收藏備用。

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參數解釋:
sck - socket
buf - 接收緩衝區
size-緩衝區大小
time_out-等待時間(按秒計)若是超時則返回
返回值:收到字節數，0表示超時等錯誤

1. int rcv(int sck, void * buf, int size, int time_out)

2. {

3. if (sck < 1 || !buf || size < 1) return 0;

4. timeval tv = { 0, 0}; timeval * ptv = 0;

5. if (time_out > 0) { tv.tv_sec = time_out; ptv = &tv; }

6. memset(buf, 0, size);

7. int r = 0; char * b = (char*) buf; int sz = size;

8. fd_set rd, er; int total = 0; time_t t0 = time(0); time_t t1 = 0;

9. do {

10. FD_ZERO(&rd); FD_SET(sck, &rd);

11. FD_ZERO(&er); FD_SET(sck, &er);

12. r = select(sck + 1, &rd, 0, &er, ptv);

13. if (r == -1) { nperror("select()"); return -1; }

14. if (FD_ISSET(sck, &er)) {

15. nperror("socket(shutdown)"); return -1;

16. }//end if

17. if (FD_ISSET(sck, &rd)) {

18. r = recv(sck, b, sz, 0);

19. if (r == -1) { nperror("recv()"); return -1; }

20. total += r; sz -= r; b+= r;

21. }//end if

22. if (time_out > 0)

23. t1 = time(0) - t0;

24. else

25. t1 = time_out - 1;

26. //end if

27. }while(sz && t1 < time_out);

28. return total;

29. }//end if