1 files changed, 17 insertions, 0 deletions
diff --git a/date.c b/date.c
index 57331ed406..2dae471dd1 100644
--- a/date.c
+++ b/date.c
@@ -1085,3 +1085,20 @@ 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);
+}