GPS driver: Require valid minimum time to allow setting the wall clock. Protection against nulled time fields

1 files changed, 33 insertions, 23 deletions

diff --git a/src/drivers/gps/ubx.cpp b/src/drivers/gps/ubx.cpp
index 05809b361..e197059db 100644
--- a/src/drivers/gps/ubx.cpp
+++ b/src/drivers/gps/ubx.cpp
@@ -748,19 +748,23 @@ UBX::payload_rx_done(void)
 			timeinfo.tm_sec		= _buf.payload_rx_nav_pvt.sec;
 			time_t epoch = mktime(&timeinfo);
 
-			// FMUv2+ boards have a hardware RTC, but GPS helps us to configure it
-			// and control its drift. Since we rely on the HRT for our monotonic
-			// clock, updating it from time to time is safe.
-
-			timespec ts;
-			ts.tv_sec = epoch;
-			ts.tv_nsec = _buf.payload_rx_nav_pvt.nano;
-			if (clock_settime(CLOCK_REALTIME, &ts)) {
-				warn("failed setting clock");
-			}
+			if (epoch > GPS_EPOCH_SECS) {
+				// FMUv2+ boards have a hardware RTC, but GPS helps us to configure it
+				// and control its drift. Since we rely on the HRT for our monotonic
+				// clock, updating it from time to time is safe.
+
+				timespec ts;
+				ts.tv_sec = epoch;
+				ts.tv_nsec = _buf.payload_rx_nav_pvt.nano;
+				if (clock_settime(CLOCK_REALTIME, &ts)) {
+					warn("failed setting clock");
+				}
 
-			_gps_position->time_utc_usec = static_cast<uint64_t>(epoch) * 1000000ULL;
-			_gps_position->time_utc_usec += _buf.payload_rx_nav_timeutc.nano / 1000;
+				_gps_position->time_utc_usec = static_cast<uint64_t>(epoch) * 1000000ULL;
+				_gps_position->time_utc_usec += _buf.payload_rx_nav_timeutc.nano / 1000;
+			} else {
+				_gps_position->time_utc_usec = 0;
+			}
 		}
 
 		_gps_position->timestamp_time		= hrt_absolute_time();
@@ -820,19 +824,25 @@ UBX::payload_rx_done(void)
 			timeinfo.tm_sec		= _buf.payload_rx_nav_timeutc.sec;
 			time_t epoch = mktime(&timeinfo);
 
-			// FMUv2+ boards have a hardware RTC, but GPS helps us to configure it
-			// and control its drift. Since we rely on the HRT for our monotonic
-			// clock, updating it from time to time is safe.
+			// only set the time if it makes sense
 
-			timespec ts;
-			ts.tv_sec = epoch;
-			ts.tv_nsec = _buf.payload_rx_nav_timeutc.nano;
-			if (clock_settime(CLOCK_REALTIME, &ts)) {
-				warn("failed setting clock");
-			}
+			if (epoch > GPS_EPOCH_SECS) {
+				// FMUv2+ boards have a hardware RTC, but GPS helps us to configure it
+				// and control its drift. Since we rely on the HRT for our monotonic
+				// clock, updating it from time to time is safe.
 
-			_gps_position->time_utc_usec = static_cast<uint64_t>(epoch) * 1000000ULL;
-			_gps_position->time_utc_usec += _buf.payload_rx_nav_timeutc.nano / 1000;
+				timespec ts;
+				ts.tv_sec = epoch;
+				ts.tv_nsec = _buf.payload_rx_nav_timeutc.nano;
+				if (clock_settime(CLOCK_REALTIME, &ts)) {
+					warn("failed setting clock");
+				}
+
+				_gps_position->time_utc_usec = static_cast<uint64_t>(epoch) * 1000000ULL;
+				_gps_position->time_utc_usec += _buf.payload_rx_nav_timeutc.nano / 1000;
+			} else {
+				_gps_position->time_utc_usec = 0;
+			}
 		}
 
 		_gps_position->timestamp_time = hrt_absolute_time();