wrap rather than overflow timestamps

src/timestamp.rs

@@ -72,6 +72,11 @@ impl Timestamp {
 
     /// Construct a `Timestamp` from an RFC4122 timestamp and counter, as used
     /// in versions 1 and 6 UUIDs.
+    ///
+    /// # Overflow
+    ///
+    /// If conversion from RFC4122 ticks to the internal timestamp format would overflow
+    /// it will wrap.
     pub const fn from_rfc4122(ticks: u64, counter: u16) -> Self {
         #[cfg(not(any(feature = "v1", feature = "v6")))]
         {
@@ -89,6 +94,11 @@ impl Timestamp {
     }
 
     /// Construct a `Timestamp` from a Unix timestamp, as used in version 7 UUIDs.
+    ///
+    /// # Overflow
+    ///
+    /// If conversion from RFC4122 ticks to the internal timestamp format would overflow
+    /// it will wrap.
     pub fn from_unix(context: impl ClockSequence<Output = u16>, seconds: u64, nanos: u32) -> Self {
         #[cfg(not(any(feature = "v1", feature = "v6")))]
         {
@@ -110,6 +120,11 @@ impl Timestamp {
 
     /// Get the value of the timestamp as an RFC4122 timestamp and counter,
     /// as used in versions 1 and 6 UUIDs.
+    ///
+    /// # Overflow
+    ///
+    /// If conversion from RFC4122 ticks to the internal timestamp format would overflow
+    /// it will wrap.
     #[cfg(any(feature = "v1", feature = "v6"))]
     pub const fn to_rfc4122(&self) -> (u64, u16) {
         (
@@ -119,21 +134,26 @@ impl Timestamp {
     }
 
     /// Get the value of the timestamp as a Unix timestamp, as used in version 7 UUIDs.
+    ///
+    /// # Overflow
+    ///
+    /// If conversion from RFC4122 ticks to the internal timestamp format would overflow
+    /// it will wrap.
     pub const fn to_unix(&self) -> (u64, u32) {
         (self.seconds, self.nanos)
     }
 
     #[cfg(any(feature = "v1", feature = "v6"))]
     const fn unix_to_rfc4122_ticks(seconds: u64, nanos: u32) -> u64 {
-        let ticks = UUID_TICKS_BETWEEN_EPOCHS + seconds * 10_000_000 + nanos as u64 / 100;
+        let ticks = UUID_TICKS_BETWEEN_EPOCHS.wrapping_add(seconds.wrapping_mul(10_000_000)).wrapping_add(nanos as u64 / 100);
 
         ticks
     }
 
     const fn rfc4122_to_unix(ticks: u64) -> (u64, u32) {
         (
-            (ticks - UUID_TICKS_BETWEEN_EPOCHS) / 10_000_000,
-            ((ticks - UUID_TICKS_BETWEEN_EPOCHS) % 10_000_000) as u32 * 100,
+            ticks.wrapping_sub(UUID_TICKS_BETWEEN_EPOCHS) / 10_000_000,
+            (ticks.wrapping_sub(UUID_TICKS_BETWEEN_EPOCHS) % 10_000_000) as u32 * 100,
         )
     }
 
@@ -268,6 +288,7 @@ fn now() -> (u64, u32) {
 
     #[wasm_bindgen]
     extern "C" {
+        // NOTE: This signature works around https://bugzilla.mozilla.org/show_bug.cgi?id=1787770
         #[wasm_bindgen(js_namespace = Date, catch)]
         fn now() -> Result<f64, JsValue>;
     }
@@ -401,3 +422,17 @@ pub mod context {
         }
     }
 }
+
+#[cfg(all(test, any(feature = "v1", feature = "v6")))]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn rfc4122_unix_wraps() {
+        // Ensure timestamp conversions never panic
+        Timestamp::unix_to_rfc4122_ticks(u64::MAX, 0);
+        Timestamp::unix_to_rfc4122_ticks(0, u32::MAX);
+
+        Timestamp::rfc4122_to_unix(u64::MAX);
+    }
+}