1 #include <stdio.h>
2 #include <unistd.h>
3 #include <signal.h>
4 #include <errno.h>
5 #include <sys/wait.h>
6 #include <string.h>
7 
8 /* Make sure that a blocking syscall restarts if hit by a signal,
9    and SA_RESTART is set */
10 
11 static void handler(int s)
12 {
13 }
14 
15 int main()
16 {
17 	int pid;
18 	int fds[2];
19 
20 	if (pipe(fds) == -1) {
21 		perror("FAIL: pipe\n");
22 		return 1;
23 	}
24 
25 	pid = fork();
26 
27 	if (pid == -1) {
28 		perror("fork failed");
29 		return 1;
30 	}
31 
32 	if (pid == 0) {
33 		char ch = '?';
34 		int ret;
35 		struct sigaction sa;
36 
37 		sa.sa_handler = handler;
38 		sigfillset(&sa.sa_mask);
39 		sa.sa_flags = SA_RESTART;
40 
41 		sigaction(SIGUSR1, &sa, NULL);
42 
43 		close(fds[1]);
44 		ret = read(fds[0], &ch, 1);
45 
46 		if (ret != 1 || ch != 'x')
47 			fprintf(stderr, "FAIL: expected 1 byte, not %d/%s/%c\n",
48 				ret, strerror(errno), ch);
49 	} else {
50 		signal(SIGPIPE, SIG_IGN);
51 
52 		close(fds[0]);
53 		sleep(1);
54 		kill(pid, SIGUSR1);
55 		sleep(1);
56 		write(fds[1], "x", 1);
57 
58 		waitpid(pid, NULL, 0);
59 	}
60 
61 	return 0;
62 }
63