Re: [PR] Floor pre-epoch Timestamp seconds in DateTimeConverter.convertToType [commons-beanutils]

["Copilot (via GitHub)" <gi...@apache.org>]

Copilot commented on code in PR #433:
URL: https://github.com/apache/commons-beanutils/pull/433#discussion_r3740635772


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src/main/java/org/apache/commons/beanutils2/converters/DateTimeConverter.java:
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@@ -200,7 +200,7 @@ protected <T> T convertToType(final Class<T> targetType, final Object value) thr
             // didn't include the milliseconds. The following code
             // ensures it works consistently across JDK versions
             final java.sql.Timestamp timestamp = (java.sql.Timestamp) value;
-            long timeInMillis = timestamp.getTime() / 1000 * 1000;
+            long timeInMillis = Math.floorDiv(timestamp.getTime(), 1000) * 1000;
             timeInMillis += timestamp.getNanos() / 1000000;
             return toDate(targetType, timeInMillis);

Review Comment:
   `Math.floorDiv(timestamp.getTime(), 1000) * 1000` can overflow for extreme pre-epoch values (e.g., `timestamp.getTime()` in `[Long.MIN_VALUE, Long.MIN_VALUE + 999]`), producing a positive millisecond value and breaking conversion. The previous truncating expression avoided this overflow. Consider keeping floor semantics for representable cases while guarding the `-1000` adjustment to avoid underflow near `Long.MIN_VALUE`.



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