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buffer: isUtf8 and isAscii accept detached TypedArray views #64503
Description
Version
latest main branch
Platform
7.1.2-arch3-1
Subsystem
buffer
What steps will reproduce the bug?
const { isUtf8, isAscii } = require('node:buffer');
const view = new Uint8Array([0xff]);
structuredClone(view.buffer, { transfer: [view.buffer] });
console.log(isUtf8(view));
console.log(isAscii(view));How often does it reproduce? Is there a required condition?
ArrayBufferViewContents reads the view's zero byte length but does not record the detached state of its backing ArrayBuffer.
What is the expected behavior? Why is that the expected behavior?
Both functions should throw ERR_INVALID_STATE, consistent with passing a detached ArrayBuffer directly.
What do you see instead?
Both functions return true.
Activity
jasnell commentedon Jul 14, 2026
It's not obvious this is a bug. In both cases, the detached
ArrayBufferjust comes back as zero-length. These APIs handle zero-length just fine (e.g.isUtf8(new Uint8Array(0))).I do see that the docs say "Throws if the
inputis a detached array buffer" but I kind of view that as a doc error rather than an implementation error.Archkon commentedon Jul 14, 2026
Renegade334 commentedon Jul 14, 2026
We also only check the
detached_property in these two methods AFAICT, all other uses of ABVC in the Buffer API just treat detached buffers as zero-length, including other string-encoding operations likeBuffer.prototype.toString(). I'm ±0 on whether we should be erroring with detached backing ArrayBuffers, but it should be consistent imoArchkon commentedon Jul 14, 2026
Archkon commentedon Jul 14, 2026
jasnell commentedon Jul 15, 2026
Ok, the implementation behavior is a bit inconsistent. I would suggest that the final
isUtf8(transferedArrayBuffer)should just returntrue, being treated as a zero-length.Archkon commentedon Jul 15, 2026
buffer: treat detached ArrayBuffers as empty
buffer: treat detached ArrayBuffers as empty
buffer: treat detached ArrayBuffers as empty
buffer: treat detached ArrayBuffers as empty