socket_listen: interrupt a parent if a child exited

When a child exited, SIGCHLD is sent to parent,
if SIGCHLD has handler without SA_RESTART, the current
syscall will be interrupted.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm/live/static/socket_listen.c

@@ -28,6 +28,8 @@ int init_server();
 
 #define BUF_SIZE 1024
 
+static void sig_hand(int signo) {}
+
 int main(int argc, char **argv)
 {
 	unsigned char buf[BUF_SIZE];
@@ -36,6 +38,10 @@ int main(int argc, char **argv)
 	pid_t pid;
 	int res;
 	uint32_t crc;
+	struct sigaction sa = {
+		.sa_handler	= sig_hand,
+		/* don't set SA_RESTART */
+	};
 
 	test_init(argc, argv);
 
@@ -47,6 +53,10 @@ int main(int argc, char **argv)
 	test_daemon();
 	test_waitsig();
 
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(SIGCHLD, &sa, NULL))
+		fprintf(stderr, "Can't set SIGTERM handler: %m\n");
+
 	pid = test_fork();
 	if (pid < 0) {
 		err("fork failed. Return %d %m", pid);