[GitHub] [arrow] pitrou commented on a change in pull request #7987: ARROW-9768: [Python] Check overflow in conversion of datetime objects to nanosecond timestamps

[GitBox <gi...@apache.org>]

pitrou commented on a change in pull request #7987:
URL: https://github.com/apache/arrow/pull/7987#discussion_r473907662



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File path: cpp/src/arrow/python/python_to_arrow.cc
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@@ -263,7 +264,12 @@ struct ValueConverter<TimestampType> {
           value = internal::PyDateTime_to_us(dt) - offset * 1000 * 1000;
           break;
         case TimeUnit::NANO:
-          value = internal::PyDateTime_to_ns(dt) - offset * 1000 * 1000 * 1000;
+          // Conversion to nanoseconds can overflow -> check multiply of microseconds
+          value = internal::PyDateTime_to_us(dt);
+          if (arrow::internal::MultiplyWithOverflow(value, 1000, &value)) {
+            return internal::InvalidValue(obj, "out of bounds for nanosecond resolution");
+          }
+          value -= offset * 1000 * 1000 * 1000;

Review comment:
       This subtraction could overflow as well, no?




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