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buffer: expose underlying buffer object always
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If the Buffer object's length is zero, or equal to the underlying
buffer object's length, `parent` property returns `undefined`.

    > new Buffer(0).parent
    undefined
    > new Buffer(Buffer.poolSize).parent
    undefined

This patch makes the buffer objects to consistently expose the buffer
object via the `parent` property, always.

Fixes: #8266
PR-URL: #8311
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
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thefourtheye authored and addaleax committed Sep 8, 2016
1 parent e9b6fbb commit c21458a
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Showing 4 changed files with 25 additions and 8 deletions.
4 changes: 0 additions & 4 deletions lib/buffer.js
Original file line number Diff line number Diff line change
Expand Up @@ -410,10 +410,6 @@ Object.defineProperty(Buffer.prototype, 'parent', {
get: function() {
if (!(this instanceof Buffer))
return undefined;
if (this.byteLength === 0 ||
this.byteLength === this.buffer.byteLength) {
return undefined;
}
return this.buffer;
}
});
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2 changes: 1 addition & 1 deletion test/parallel/test-buffer-alloc.js
Original file line number Diff line number Diff line change
Expand Up @@ -994,7 +994,7 @@ if (common.hasCrypto) {

const ps = Buffer.poolSize;
Buffer.poolSize = 0;
assert.strictEqual(Buffer.allocUnsafe(1).parent, undefined);
assert(Buffer.allocUnsafe(1).parent instanceof ArrayBuffer);
Buffer.poolSize = ps;

// Test Buffer.copy() segfault
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4 changes: 1 addition & 3 deletions test/parallel/test-buffer-arraybuffer.js
Original file line number Diff line number Diff line change
Expand Up @@ -13,9 +13,7 @@ const buf = Buffer.from(ab);


assert.ok(buf instanceof Buffer);
// For backwards compatibility of old .parent property test that if buf is not
// a slice then .parent should be undefined.
assert.equal(buf.parent, undefined);
assert.equal(buf.parent, buf.buffer);
assert.equal(buf.buffer, ab);
assert.equal(buf.length, ab.byteLength);

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23 changes: 23 additions & 0 deletions test/parallel/test-buffer-parent-property.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
'use strict';

/*
* Fix for https://github.com/nodejs/node/issues/8266
*
* Zero length Buffer objects should expose the `buffer` property of the
* TypedArrays, via the `parent` property.
*/
require('../common');
const assert = require('assert');

// If the length of the buffer object is zero
assert((new Buffer(0)).parent instanceof ArrayBuffer);

// If the length of the buffer object is equal to the underlying ArrayBuffer
assert((new Buffer(Buffer.poolSize)).parent instanceof ArrayBuffer);

// Same as the previous test, but with user created buffer
const arrayBuffer = new ArrayBuffer(0);
assert.strictEqual(new Buffer(arrayBuffer).parent, arrayBuffer);
assert.strictEqual(new Buffer(arrayBuffer).buffer, arrayBuffer);
assert.strictEqual(Buffer.from(arrayBuffer).parent, arrayBuffer);
assert.strictEqual(Buffer.from(arrayBuffer).buffer, arrayBuffer);

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