Handle monotonic clock going backwards during runtime

[rust-lightning] / lightning / src / util / time.rs

diff --git a/lightning/src/util/time.rs b/lightning/src/util/time.rs
index d3768aa7ca6441d2943c5ac080e57113ab9d957d..f450dc2c3015ae4da00faa2d609d01542753b85d 100644 (file)
--- a/lightning/src/util/time.rs
+++ b/lightning/src/util/time.rs
@@ -65,7 +65,12 @@ impl Time for std::time::Instant {
        }
 
        fn duration_since(&self, earlier: Self) -> Duration {
-               self.duration_since(earlier)
+               // On rust prior to 1.60 `Instant::duration_since` will panic if time goes backwards.
+               // However, we support rust versions prior to 1.60 and some users appear to have "monotonic
+               // clocks" that go backwards in practice (likely relatively ancient kernels/etc). Thus, we
+               // manually check for time going backwards here and return a duration of zero in that case.
+               let now = Self::now();
+               if now > earlier { now - earlier } else { Duration::from_secs(0) }
        }
 
        fn duration_since_epoch() -> Duration {