Cirrus Logic CS485 Manual de usuario descargar pdf (Pagina 45)

CS485G Spring 2015 45

(a) Terminate

(b) Ignore

(d) Temporarily stop the process.

(e) Continue the process from a temporary stop.

(f) Catch the signal by installing a procedure in the process called

a signal handler.

(g) Temporarily block the signal (the signal becomes pending; fur-

ther identical signals are ignored while it is pending).

(h) Unblock a pending signal

9. When a signal handler runs, the process is temporarily interrupted;

it resumes when the signal handler ﬁnishes.

1 #include <stdlib.h>

2 #include <stdio.h>

3 #include <signal.h>

4 void handler(int sig) {

5 safe_printf("You hit ctrl-c\n");

6 sleep(2);

7 safe_printf("Well...");

8 sleep(1);

9 printf("OK\n");

10 exit(0);

11 }

12 main() {

13 signal(SIGINT, handler); /

install handler

14 while(1) { // busy loop

15 }

16 }

10. If an arriving signal interrupts a long system call (such as read()),

different versions of Unix have different behaviors when the signal

handler ﬁnishes: Continue the long system call (Linux), abort the

long system call with an EINTER error.

11. A function is async-signal-safe if all its variables are local (so it is

reentrant) or non-interruptible.

(a) Such functions may be called even from inside a handler.

1 2 ... 40 41 42 43 44 45 46 47 48 49 50 ... 66 67

Sin comentarios

Cirrus Logic CS485 Manual de usuario Pagina 45