Copilot commented on code in PR #51480:
URL: https://github.com/apache/arrow/pull/51480#discussion_r4090380551
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python/pyarrow/src/arrow/python/numpy_to_arrow.cc:
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@@ -466,6 +467,31 @@ inline Status
NumPyConverter::PrepareInputData(std::shared_ptr<Buffer>* data) {
*data = std::make_shared<NumPyBuffer>(reinterpret_cast<PyObject*>(arr_));
}
+ if (dtype_->type_num == NPY_DATETIME || dtype_->type_num == NPY_TIMEDELTA) {
+ auto metadata =
+
reinterpret_cast<PyArray_DatetimeDTypeMetaData*>(PyDataType_C_METADATA(dtype_));
+ const int64_t multiplier = metadata->meta.num;
+ if (multiplier != 1) {
+ ARROW_ASSIGN_OR_RAISE(auto scaled,
+ AllocateBuffer(sizeof(int64_t) * length_, pool_));
+ auto in_values = reinterpret_cast<const int64_t*>((*data)->data());
+ auto out_values = reinterpret_cast<int64_t*>(scaled->mutable_data());
+ for (int64_t i = 0; i < length_; ++i) {
+ if (null_bitmap_ && !bit_util::GetBit(null_bitmap_->data(), i)) {
+ out_values[i] = 0;
+ } else if (cast_options_.allow_time_overflow) {
+ out_values[i] =
+ static_cast<uint64_t>(in_values[i]) *
static_cast<uint64_t>(multiplier);
+ } else if (::arrow::internal::MultiplyWithOverflow(in_values[i],
multiplier,
Review Comment:
This check only validates the multiplication into the base unit. For inputs
such as `datetime64[10D]` converted to `date32` or `date64`, the subsequent
date conversion can still overflow: `StaticCastBuffer<int64_t, int32_t>` does
not check its narrowing conversion, and the `date64` path multiplies by
`kMillisecondsInDay` with signed arithmetic. Thus `safe=True` can still return
wrapped data or invoke signed-overflow UB, contrary to the stated overflow
behavior; please extend checked/defined overflow handling through those date
conversions as well.
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