From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sun, 18 Nov 2018 12:04:59 +0000 (+0000)
Subject: Make the fallback timer work.
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~bjharris/git?a=commitdiff_plain;h=b1a7cffc39aedb4a0298e294b8d022424c287d8f;p=clunk.git

Make the fallback timer work.

It has a null signal handler, which has the side-effect of causing
clock_nanosleep to return EINTR.
---

diff --git a/clunk.c b/clunk.c
index 32d7db7..4d62324 100644
--- a/clunk.c
+++ b/clunk.c
@@ -124,11 +124,19 @@ init_statefile(char const *statefilename)
 	}
 }
 
+static void
+alrm_handler(int signo)
+{
+
+	/* Do nothing.  The mere presence of this handler is enough. */
+}
+
 static void
 init(int argc, char **argv)
 {
 	struct timespec ts;
 	struct sigevent sev;
+	struct sigaction sa;
 	int opt;
 
 	tzset();
@@ -139,6 +147,11 @@ init(int argc, char **argv)
 	sev.sigev_signo = SIGALRM;
 	if (timer_create(CLOCK_MONOTONIC, &sev, &fallback_timer) != 0)
 		err(1, "timer_create");
+	sa.sa_handler = alrm_handler;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = 0;
+	if (sigaction(SIGALRM, &sa, NULL) != 0)
+		err(1, "sigaction");
 	if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
 		err(1, "clock_gettime");
 	if (localtime_r(&ts.tv_sec, &displayed) == NULL)
@@ -186,6 +199,7 @@ static void
 run()
 {
 	struct timespec ts;
+	struct itimerspec its;
 	struct tm tm;
 	int tick;
 
@@ -212,10 +226,19 @@ run()
 		/* Choose when next tick will be. */
 		ts.tv_nsec = 1000000000 - pulsewidth;
 		ts.tv_sec += tick - 1;
+		its.it_value.tv_sec = 35;
+		its.it_value.tv_nsec = 0;
+		its.it_interval.tv_sec = 1;
+		its.it_interval.tv_nsec = 0;
+		if (timer_settime(fallback_timer, 0, &its, NULL) != 0)
+			err(1, "timer_settime (arm)");
 		errno =	clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME,
 					&ts, NULL);
-		if (errno != 0)
+		its.it_value.tv_sec = 0;
+		if (errno != 0 && errno != EINTR)
 			err(1, "clock_nanosleep");
+		if (timer_settime(fallback_timer, 0, &its, NULL) != 0)
+			err(1, "timer_settime (disarm)");
 	}
 }