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buffer: fix check of buffer and rearrange conditional #8739

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buffer: fix check of buffer and rearrange conditional #8739

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buffer: fix check of buffer and rearrange conditional
ojss Sep 23, 2016
7f735d4
test: add check for a particular codepath
ojss Sep 23, 2016
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4 changes: 2 additions & 2 deletions lib/buffer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -264,8 +264,8 @@ function fromObject(obj) {
}

if (obj) {
if (isArrayBuffer(obj.buffer) || 'length' in obj ||
isSharedArrayBuffer(obj)) {
if ('length' in obj || isArrayBuffer(obj.buffer) ||
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@trevnorris trevnorris Sep 23, 2016

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here we go. can we not use the in check? very expensive. why not just do another typeof obj.length check?

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@addaleax addaleax Sep 23, 2016

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That would break hypothetical code which actually explicitly sets obj.length = undefined, right? I would be okay with that, just making sure.

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@trevnorris trevnorris Sep 24, 2016

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yes. it would cause this one edge case to throw:

Buffer.from({ 0: 'a', 1: 'b', length: undefined })

since this isn't documented or tested i feel like it's a valid minor version change.

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@ojss ojss Sep 25, 2016

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I shall change that sometime today @trevnorris.

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@trevnorris trevnorris Sep 27, 2016

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@ojss If it doesn't happen here, don't sweat it. Removing in isn't directly tied to this PR.

isSharedArrayBuffer(obj.buffer)) {
if (typeof obj.length !== 'number' || obj.length !== obj.length) {
return new FastBuffer();
}
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2 changes: 2 additions & 0 deletions test/parallel/test-buffer-sharedarraybuffer.js
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Expand Up @@ -27,3 +27,5 @@ assert.deepStrictEqual(arr_buf, ar_buf, 0);
// Checks for calling Buffer.byteLength on a SharedArrayBuffer

assert.strictEqual(Buffer.byteLength(sab), sab.byteLength, 0);

assert.doesNotThrow(() => Buffer.from({buffer: sab}));