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`into_arrow_offset_buffer` is a safe function, but it called
`OffsetBuffer::new_unchecked` and pushed the memory-safety requirement onto the caller in
a doc comment:
/// SAFETY: The caller should ensure that the buffer contains monotonically increasing
/// values greater than or equal to zero.
A safe function may not carry unchecked memory-safety preconditions. `OffsetBuffer`
requires its contents to be non-empty, to start at a non-negative value and to be
monotonically non-decreasing; safe code that violates those invariants causes
out-of-bounds reads in downstream Arrow operations such as slicing and child-array
indexing.
Use the checked `OffsetBuffer::new` instead. It validates the offsets and panics on bad
input, which is memory-safe. The signature is unchanged, so callers are unaffected.
Signed-off-by: Jian He <hejia@google.com>
robert3005
reviewed
Oct 5, 2026
| /// | ||
| /// Panics if the buffer is empty, its first offset is negative, or it is not monotonically | ||
| /// increasing -- the invariants `OffsetBuffer` requires of its contents. | ||
| pub fn into_arrow_offset_buffer(self) -> OffsetBuffer<T> { |
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I think we have to adjust the callers to not have to perform revalidation. In general this should perform validation but most of the callers already validated it
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into_arrow_offset_bufferis a safe function, but it calledOffsetBuffer::new_uncheckedand left the invariants to a doc comment ("SAFETY: The caller should ensure..."). A safe function can't carry unchecked memory-safety preconditions.OffsetBufferrequires non-empty, non-negative-first, monotonically non-decreasing offsets, and breaking that from safe code leads to out-of-bounds reads in downstream Arrow slicing and child indexing.This switches to the checked
OffsetBuffer::new, which panics on invalid input. The signature is unchanged.Cost:
OffsetBuffer::newdoes an O(n) validation pass. The callers are invortex-arrow(executor/byte.rs,executor/list.rs). If that cost matters on those paths, the alternative is to makeinto_arrow_offset_bufferanunsafe fnwith a# Safetysection and keepnew_unchecked. Happy to switch to that.Testing
cargo test -p vortex-buffer --all-features,cargo test -p vortex-arrow --all-features, clippy, nightly fmt.AI assistance
This change was prepared with help from an AI coding assistant (Google-internal agentic tooling). I reviewed and verified the change and the tests myself.