timebase: Rollback 2037+ dates to GPS eopch 1.

Dates past 18-Jan-2038 break 32-bit time_t, and are a while
off from now.  So roll the GPS epoch back to 1 when week
is past week 968 in epoch 2 (late in 2037).

This fixes one GREIS regression, and allows the rollback of two
more to their correct date.

All regressions now pass again.  Until 2037...

1 files changed, 6 insertions, 0 deletions

diff --git a/timebase.c b/timebase.c
index cf28769d..bdade00a 100644
--- a/timebase.c
+++ b/timebase.c
@@ -347,6 +347,12 @@ timestamp_t gpsd_gpstime_resolve(struct gps_device_t *session,
 	++session->context->rollovers;
     }
 
+    if ((967 < week) && (2 == session->context->rollovers)) {
+        /* week 968 in GPS epoch 2, is 2038-01-18.
+         * This hits time_t rollover bug.
+         * Must be a regression from epoch 1 */
+	session->context->rollovers = 1;
+    }
     /*
      * This guard copes with both conventional GPS weeks and the "extended"
      * 15-or-16-bit version with no wraparound that appears in Zodiac