pitrou commented on a change in pull request #9395:
URL: https://github.com/apache/arrow/pull/9395#discussion_r577692502
##########
File path: cpp/src/arrow/tensor.cc
##########
@@ -127,14 +162,29 @@ Status CheckTensorStridesValidity(const
std::shared_ptr<Buffer>& data,
return Status::OK();
}
- std::vector<int64_t> last_index(shape);
- const int64_t n = static_cast<int64_t>(shape.size());
- for (int64_t i = 0; i < n; ++i) {
- --last_index[i];
+ // Check the largest offset can be computed without overflow
+ const size_t ndim = shape.size();
+ int64_t largest_offset = 0;
+ for (size_t i = 0; i < ndim; ++i) {
+ if (shape[i] == 0) continue;
+ if (strides[i] < 0) {
+ // TODO(mrkn): Support negative strides for sharing views
+ return Status::Invalid("negative strides not supported");
+ }
+
+ int64_t dim_offset;
+ if (!internal::MultiplyWithOverflow(shape[i] - 1, strides[i],
&dim_offset)) {
+ if (!internal::AddWithOverflow(largest_offset, dim_offset,
&largest_offset)) {
+ continue;
+ }
+ }
+
+ return Status::Invalid(
+ "offsets computed from shape and strides would not fit in 64-bit
integer");
}
- int64_t last_offset = Tensor::CalculateValueOffset(strides, last_index);
+
const int byte_width = internal::GetByteWidth(*type);
- if (last_offset + byte_width > data->size()) {
+ if (largest_offset + byte_width > data->size()) {
Review comment:
To avoid addition overflow, this should be `largest_offset >
data->size() - byte_width`.
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