實驗：sigsuspend(),sigprocmask()

實驗：sigsuspend(),sigprocmask()

源代碼：

1. /*
2. * Program: pause_suspend.c
3. * To test the difference between sigsuspend() and paus().
4. * Author: zsl
5. * Date: 2014-10-17
6. * First release.
7. * 參見網頁：http://blog.csdn.net/liwentao1091/article/details/6619089
8. *
9. * */
10. #include <stdio.h>
11. #include <stdlib.h>
12. #include <signal.h>
13. #include <unistd.h>
14. #include <string.h>
16. /*
17. * Handler for SIGINT (Ctrl-C), SIGQUIT (Ctrl-\)
18. * */
19. void sig_func(int signo)
20. {
21. if ( SIGINT == signo ) // just print a line.
22. {
23. printf(" SIGINT is processing...\n ");
24. }
25. if ( SIGQUIT == signo ) // print a line and exit.
26. {
27. printf(" SIGQUIT is processing ...\n ");
28. printf(" Now exiting ...\n ");
29. exit(EXIT_SUCCESS);
30. }
31. }
33. int main(void)
34. {
35. int i;
36. sigset_t maskset, set_quit;
38. sigemptyset(&maskset);
39. sigemptyset(&set_quit); // initialize two sets.
40. sigaddset(&maskset, SIGINT); // mask SIGINT
41. sigaddset(&set_quit, SIGQUIT); // suspend SIGQUIT
42. // signal the two signals: SIGINT, SIGQUIT
43. signal(SIGINT, sig_func);
44. signal(SIGQUIT, sig_func);
46. while(1)
47. {
48. /* First to mask the signal of the process: SIGINT */
49. sigprocmask(SIG_BLOCK, &maskset, NULL);
50. for(i = 0; i < 10; i ++)
51. {
52. write(1, "* ", strlen("* "));
53. sleep(1);
54. }
56. printf("\n");
57. #if 1
58. /*
59. * while sigsuspend(), SIGQUIT is blocked.
60. * but SIGINT is unblocked.
61. * If you want to execute the two signals, you
62. * should Ctrl-\, then Ctrl-C.
63. * */
64. printf("Before sigsuspend() ... \n");
65. sigsuspend(&set_quit);
66. #else
67. sigprocmask(SIG_UNBLOCK, &maskset, NULL);
68. pause();
69. #endif
70. }
72. return 0;
73. }

程序的運行：

在打印“* ?”的時候，SIGINT （Ctrl-C）被 阻塞了。而SIGQUIT沒有被阻塞，只要Ctrl-\就會終止程序。

在sigsuspend() 的時候，SIGQUIT （Ctrl-\）被阻塞了，而SIGINT 沒有被阻塞，只要 Ctrl-C 就會進入 signal handler 中執行。。

如果想在 sigsuspend() 中對兩個信號都進行處理，那么在 sigsuspend() 的時候先 SIGQUIT, 然后 SIGINT。

如下是執行效果圖：

來自為知筆記(Wiz)