1 files changed, 21 insertions, 2 deletions
diff --git a/date.c b/date.c
index 83b4166344..e1a2cee568 100644
--- a/date.c
+++ b/date.c
@@ -184,8 +184,10 @@ const char *show_date(unsigned long time, int tz, enum date_mode mode)
 		tz = local_tzoffset(time);
 
 	tm = time_to_tm(time, tz);
-	if (!tm)
-		return NULL;
+	if (!tm) {
+		tm = time_to_tm(0, 0);
+		tz = 0;
+	}
 
 	strbuf_reset(&timebuf);
 	if (mode == DATE_SHORT)
@@ -1113,3 +1115,20 @@ unsigned long approxidate_careful(const char *date, int *error_ret)
 	gettimeofday(&tv, NULL);
 	return approxidate_str(date, &tv, error_ret);
 }
+
+int date_overflows(unsigned long t)
+{
+	time_t sys;
+
+	/* If we overflowed our unsigned long, that's bad... */
+	if (t == ULONG_MAX)
+		return 1;
+
+	/*
+	 * ...but we also are going to feed the result to system
+	 * functions that expect time_t, which is often "signed long".
+	 * Make sure that we fit into time_t, as well.
+	 */
+	sys = t;
+	return t != sys || (t < 1) != (sys < 1);
+}