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buffer: don't set zero fill for zero-length buffer

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Instantiating a Buffer of length zero would set the kNoZeroFill flag to
true but never actually call ArrayBuffer::Allocator(). Which means the
flag was never set back to false. The result was that the next
allocation would unconditionally not be zero filled.

Add test to ensure Uint8Array's are zero-filled after creating a Buffer
of length zero. This test may falsely succeed, but will not falsely fail.

Fix: https://github.com/nodejs/node/issues/2930
PR-URL: https://github.com/nodejs/node/pull/2931
Reviewed-By: Rod Vagg <rod@vagg.org>
This commit is contained in:
Trevor Norris 2015-09-17 10:48:16 -06:00
parent e0c3d2ad57
commit 0a329d2d1f
2 changed files with 33 additions and 5 deletions
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19
lib/buffer.js
View File

@ -22,7 +22,8 @@ const kNoZeroFill = 0;
function createPool() {
poolSize = Buffer.poolSize;
flags[kNoZeroFill] = 1;
if (poolSize > 0)
flags[kNoZeroFill] = 1;
allocPool = new Uint8Array(poolSize);
Object.setPrototypeOf(allocPool, Buffer.prototype);
poolOffset = 0;
@ -64,7 +65,8 @@ Buffer.__proto__ = Uint8Array;
function SlowBuffer(length) {
if (+length != length)
length = 0;
flags[kNoZeroFill] = 1;
if (length > 0)
flags[kNoZeroFill] = 1;
const ui8 = new Uint8Array(+length);
Object.setPrototypeOf(ui8, Buffer.prototype);
return ui8;
@ -75,8 +77,11 @@ SlowBuffer.__proto__ = Buffer;
function allocate(size) {
if (size === 0)
return SlowBuffer(0);
if (size === 0) {
const ui8 = new Uint8Array(size);
Object.setPrototypeOf(ui8, Buffer.prototype);
return ui8;
}
if (size < (Buffer.poolSize >>> 1)) {
if (size > (poolSize - poolOffset))
createPool();
@ -85,7 +90,11 @@ function allocate(size) {
alignPool();
return b;
} else {
flags[kNoZeroFill] = 1;
// Even though this is checked above, the conditional is a safety net and
// sanity check to prevent any subsequent typed array allocation from not
// being zero filled.
if (size > 0)
flags[kNoZeroFill] = 1;
const ui8 = new Uint8Array(size);
Object.setPrototypeOf(ui8, Buffer.prototype);
return ui8;

19
test/parallel/test-buffer-zero-fill-reset.js Normal file
View File

@ -0,0 +1,19 @@
'use strict';
require('../common');
const assert = require('assert');
function testUint8Array(ui) {
const length = ui.length;
for (let i = 0; i < length; i++)
if (ui[i] !== 0) return false;
return true;
}
for (let i = 0; i < 100; i++) {
new Buffer(0);
let ui = new Uint8Array(65);
assert.ok(testUint8Array(ui), 'Uint8Array is not zero-filled');
}