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v8: fix offsets for TypedArray deserialization #12143

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v8: fix offsets for TypedArray deserialization #12143

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2f1009a
v8: fix offsets for TypedArray deserialization
addaleax Mar 31, 2017
625b324
address review suggestion
addaleax Mar 31, 2017
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3 changes: 2 additions & 1 deletion lib/v8.js
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Original file line number Diff line number Diff line change
Expand Up @@ -177,7 +177,8 @@ class DefaultDeserializer extends Deserializer {
} else {
// Copy to an aligned buffer first.
const copy = Buffer.allocUnsafe(byteLength);
bufferBinding.copy(this.buffer, copy, 0, offset, offset + byteLength);
bufferBinding.copy(this.buffer, copy, 0,
byteOffset, byteOffset + byteLength);
return new ctor(copy.buffer,
copy.byteOffset,
byteLength / BYTES_PER_ELEMENT);
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8 changes: 8 additions & 0 deletions test/parallel/test-v8-serdes.js
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Expand Up @@ -118,3 +118,11 @@ const objects = [
assert.deepStrictEqual(buf, ser.releaseBuffer());
assert.strictEqual(des.getWireFormatVersion(), 0x0d);
}

{
// Unaligned Uint16Array read, with padding in the underlying array buffer.
const buf = Buffer.from('0'.repeat(64) + 'ff0d5c0404addeefbe', 'hex')
.slice(32);
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Is the idea here to create a buffer with a byteOffset > 0? An IMO more reliable and future-proof way is this:

let buf = Buffer.alloc(32 + 9);  // Hope I counted the bytes right!
buf.write('0'.repeat(64) + 'ff0d5c0404addeefbe', 'hex');
buf = buf.slice(32);
assert.strictEqual(buf.byteOffset, 32);  // Deterministic byte offset, unlike Buffer.from().slice()
// ...

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@bnoordhuis Yes, that’s the idea. I’ve updated the test with a variant of your suggestion

assert.deepStrictEqual(v8.deserialize(buf),
new Uint16Array([0xdead, 0xbeef]));
}