From 26d528a642433031e14580cad0db841b6f60897d Mon Sep 17 00:00:00 2001
From: Brent Cook <busterb@gmail.com>
Date: Sat, 19 Jan 2019 04:25:44 -0600
Subject: [PATCH 14/15] use adjtimex over adjtime, check return value and
 adjust offset as needed

---
 src/usr.sbin/ntpd/ntpd.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/src/usr.sbin/ntpd/ntpd.c b/src/usr.sbin/ntpd/ntpd.c
index c3b7ab07e1..8d4bffa3e3 100644
--- a/src/usr.sbin/ntpd/ntpd.c
+++ b/src/usr.sbin/ntpd/ntpd.c
@@ -17,6 +17,9 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#ifdef HAVE_ADJTIMEX
+#include <sys/timex.h>
+#endif
 #include <sys/types.h>
 #include <sys/resource.h>
 #include <sys/socket.h>
@@ -478,21 +481,44 @@ reset_adjtime(void)
 int
 ntpd_adjtime(double d)
 {
-	struct timeval	tv, olddelta;
 	int		synced = 0;
 	static int	firstadj = 1;
+	double threshold = (double)LOG_NEGLIGIBLE_ADJTIME / 1000;
 
 	d += getoffset();
-	if (d >= (double)LOG_NEGLIGIBLE_ADJTIME / 1000 ||
-	    d <= -1 * (double)LOG_NEGLIGIBLE_ADJTIME / 1000)
+	if (d >= threshold || d <= -1 * threshold)
 		log_info("adjusting local clock by %fs", d);
 	else
 		log_debug("adjusting local clock by %fs", d);
+
+#ifdef HAVE_ADJTIMEX
+	int rc;
+
+	long offset = d * 1000000;
+	struct timex tx = { 0 };
+	tx.offset = offset;
+	tx.modes = ADJ_OFFSET_SINGLESHOT | ADJ_STATUS;
+
+	do {
+		rc = adjtimex(&tx);
+	} while (rc == TIME_ERROR && (tx.offset /= 2) > threshold);
+
+	if (rc == TIME_ERROR) {
+		if ((tx.status & ~STA_UNSYNC))
+			log_warn("adjtimex returned TIME_ERROR");
+	} else if (rc < 0) {
+		log_warn("adjtimex failed");
+	} else if (!firstadj && tx.offset == offset) {
+		synced = 1;
+	}
+#else
+	struct timeval	tv, olddelta;
 	d_to_tv(d, &tv);
 	if (adjtime(&tv, &olddelta) == -1)
 		log_warn("adjtime failed");
 	else if (!firstadj && olddelta.tv_sec == 0 && olddelta.tv_usec == 0)
 		synced = 1;
+#endif
 	firstadj = 0;
 	update_time_sync_status(synced);
 	return (synced);
-- 
2.21.0