10.13 sigpending函数

函数sigpending被阻塞发送并且当前被调用该函数的进程挂起的信号，这个信号集通过参数set返回.

1. #include<signal.h>
2. int sigpending(sigset_t*set);
3. Returns:0if OK,-1 on error.

Example

1. #include"apue.h"
2. staticvoid sig_quit(int);
4. int main(void)
5. {
6. sigset_t newmask,oldmask,pendmask;
8. if(signal(SIGQUIT, sig_quit)== SIG_ERR)
9. err_sys("can‘t catch SIGQUIT");
11. /*
12. * Block SIGQUIT and save current signal mask
13. *
14. */
15. sigemptyset(&newmask);
16. sigaddset(&newmask, SIGQUIT);
17. if(sigprocmask(SIG_BLOCK,&newmask,&oldmask)<0)
18. err_sys("SIG_BLOCK error");
20. sleep(5);/*SIGOUT here will remain pending*/
22. if(sigpending(&pendmask)<0)
23. err_sys("sigpending error");
24. if(sigismember(&pendmask, SIGQUIT))
25. printf("\nSIGQUIT pending\n");
27. /*
28. * Restore signal mask whick unblocks SIGQUIT.
29. */
30. if(sigprocmask(SIG_SETMASK,&oldmask, NULL)<0)
31. err_sys("SIG_SETMASK error");
33. printf("SIGQUIT unblocked\n");
35. sleep(5);/*SIGQUIT here will terminate with core file */
36. exit(0);
37. }
39. staticvoid sig_quit(int signo)
40. {
41. printf("caught SIGQUIT\n");
42. if(signal(SIGQUIT, SIG_DFL)== SIG_ERR)
43. err_sys("can‘t reset SIGQUIT");
44. }

执行效果如下图:

1. [email protected]:~/UnixProgram/Chapter10$./10_15.exe
2. ^\^\^\
3. SIGQUIT pending
4. caught SIGQUIT
5. SIGQUIT unblocked
6. ^\Quit
7. [email protected]:~/UnixProgram/Chapter10$./10_15.exe
8. SIGQUIT unblocked
9. [email protected]:~/UnixProgram/Chapter10$

来自为知笔记(Wiz)