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buffer: coerce offset using Math.trunc()

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This is a partial revert of
14d1a8a631a58408f1e85365a5f2aaa047cc0a5f, which coerced the offset
of Buffer#slice() using the | operator. This causes some edge
cases to be handled incorrectly. This commit restores the old
behavior, but converts offsets to integers using Math.trunc().
This commit does not revert any tests, and adds an additional
regression test.

Refs: https://github.com/nodejs/node/issues/9096
Refs: https://github.com/nodejs/node/pull/9101
PR-URL: https://github.com/nodejs/node/pull/9341
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
This commit is contained in:
cjihrig 2016-10-28 10:35:58 -04:00
parent 379097850d
commit a02b13fe9b
2 changed files with 31 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lib/buffer.js
View File

@ -807,8 +807,10 @@ Buffer.prototype.toJSON = function() {
function adjustOffset(offset, length) {
offset |= 0;
if (offset === 0) {
// Use Math.trunc() to convert offset to an integer value that can be larger
// than an Int32. Hence, don't use offset | 0 or similar techniques.
offset = Math.trunc(offset);
if (offset === 0 || Number.isNaN(offset)) {
return 0;
} else if (offset < 0) {
offset += length;

27
test/parallel/test-buffer-slice.js
View File

@ -72,3 +72,30 @@ assert.strictEqual(0, Buffer.from('hello').slice(0, 0).length);
'bcd'
);
}
{
const buf = Buffer.from('abcdefg');
assert.strictEqual(buf.slice(-(-1 >>> 0) - 1).toString(), buf.toString());
}
{
const buf = Buffer.from('abc');
assert.strictEqual(buf.slice(-0.5).toString(), buf.toString());
}
{
const buf = Buffer.from([
1, 29, 0, 0, 1, 143, 216, 162, 92, 254, 248, 63, 0,
0, 0, 18, 184, 6, 0, 175, 29, 0, 8, 11, 1, 0, 0
]);
const chunk1 = Buffer.from([
1, 29, 0, 0, 1, 143, 216, 162, 92, 254, 248, 63, 0
]);
const chunk2 = Buffer.from([
0, 0, 18, 184, 6, 0, 175, 29, 0, 8, 11, 1, 0, 0
]);
const middle = buf.length / 2;
assert.deepStrictEqual(buf.slice(0, middle), chunk1);
assert.deepStrictEqual(buf.slice(middle), chunk2);
}