Copilot commented on code in PR #51169:
URL: https://github.com/apache/arrow/pull/51169#discussion_r4090753494
##########
cpp/src/gandiva/gdv_function_stubs.cc:
##########
@@ -204,11 +206,51 @@ CRC_FUNCTION(utf8)
CRC_FUNCTION(binary)
int32_t gdv_fn_dec_from_string(int64_t context, const char* in, int32_t
in_length,
- int32_t* precision_from_str, int32_t*
scale_from_str,
- int64_t* dec_high_from_str, uint64_t*
dec_low_from_str) {
+ int32_t out_scale, int32_t* precision_from_str,
+ int32_t* scale_from_str, int64_t*
dec_high_from_str,
+ uint64_t* dec_low_from_str) {
arrow::Decimal128 dec;
- auto status = arrow::Decimal128::FromString(std::string(in, in_length), &dec,
- precision_from_str,
scale_from_str);
+ const std::string_view input(in, in_length);
+ auto status =
+ arrow::Decimal128::FromString(input, &dec, precision_from_str,
scale_from_str);
+ if (!status.ok() ||
+ static_cast<int64_t>(*scale_from_str) - out_scale >
arrow::Decimal128::kMaxScale) {
+ arrow::internal::DecimalComponents components;
+ if (arrow::internal::ParseDecimalComponents(input.data(), input.size(),
+ &components)) {
+ std::string digits(components.whole_digits);
+ digits.append(components.fractional_digits);
+ digits.erase(0, digits.find_first_not_of('0'));
+ const int64_t num_digits =
+ static_cast<int64_t>(digits.size()) + out_scale -
+ static_cast<int64_t>(components.fractional_digits.size()) +
components.exponent;
+ bool round_up = false;
+ if (num_digits < 0 || num_digits > arrow::Decimal128::kMaxPrecision) {
+ digits = "0";
Review Comment:
This fallback runs for every non-OK result from `Decimal128::FromString`,
not only raw-limb overflow. A validly parsed but out-of-range exponent is
therefore converted to zero: for example, `1e2147483647` is rejected by the
parser because its required positive scale exceeds `kMaxScale`, but `num_digits
> kMaxPrecision` sets `digits` to `"0"`, the retry succeeds, and the cast
returns zero. The same issue occurs for exponent/scale arithmetic overflow such
as `1e-2147483648`; distinguish recoverable rescaling cases from parser range
errors before retrying.
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