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test: make buffer sizes 32bit-aware in test-internal-util-construct-sab #61026

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test: make buffer sizes 32bit-aware in test-internal-util-construct-sab #61026

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8 changes: 6 additions & 2 deletions test/parallel/test-internal-util-construct-sab.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,16 +3,20 @@

require('../common');
const assert = require('assert');
const { kMaxLength } = require('buffer');
const { isSharedArrayBuffer } = require('util/types');
const { constructSharedArrayBuffer } = require('internal/util');

// We're testing that we can construct a SAB even when the global is not exposed.
assert.strictEqual(typeof SharedArrayBuffer, 'undefined');

for (const length of [undefined, 0, 1, 2 ** 32]) {
for (const length of [undefined, 0, 1, 2 ** 16]) {
assert(isSharedArrayBuffer(constructSharedArrayBuffer(length)));
}

for (const length of [-1, Number.MAX_SAFE_INTEGER + 1, 2 ** 64]) {
// Specifically test the following cases:
// - out-of-range allocation requests should not crash the process
// - no int64 overflow
for (const length of [-1, kMaxLength + 1, 2 ** 64]) {
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@aduh95 aduh95 Dec 16, 2025

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Don't we want to keep Number.MAX_SAFE_INTEGER + 1 test case?

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@Renegade334 Renegade334 Dec 16, 2025

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The intention behind Number.MAX_SAFE_INTEGER was that this is the maximum array buffer size on 64-bit builds, so that particular test value lives on as kMaxLength + 1.

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@aduh95 aduh95 Dec 16, 2025

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IMO it's still interesting to test with an "unsafe" integer

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@Renegade334 Renegade334 Dec 16, 2025

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That's kinda covered by 2^64, but can add this if preferred

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@aduh95 aduh95 Dec 16, 2025 •
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If it had to be one or the other, I would pick Number.MAX_SAFE_INTEGER + 1 over 2 ** 64, that seems more interesting / intent revelling to me. I don't feel strongly either way, so non-blocking comment

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@Renegade334 Renegade334 Dec 16, 2025

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The significance of 2^64 is that the size is passed via an int64_t intermediate, so has potential to overflow if not correctly clamped. It's a little academic, I can't imagine any of our internals will be allocating terabytes of shared memory 😀

assert.throws(() => constructSharedArrayBuffer(length), RangeError);
}
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