From 3149cdbc810be0a35ab14d0307f0d464a7e18f7f Mon Sep 17 00:00:00 2001
From: Asher Gomez <ashersaupingomez@gmail.com>
Date: Tue, 23 Apr 2024 17:50:21 +1000
Subject: [PATCH] fix(bytes): `equals()` works with subarray (#4630)

fix(bytes): `equals()` works with `.subarray()`
---
 bytes/equals.ts      |  4 ++--
 bytes/equals_test.ts | 18 +++++++++++++++++-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/bytes/equals.ts b/bytes/equals.ts
index e9323fedcf54..c0969612af55 100644
--- a/bytes/equals.ts
+++ b/bytes/equals.ts
@@ -28,8 +28,8 @@ function equalsNaive(a: Uint8Array, b: Uint8Array): boolean {
 function equals32Bit(a: Uint8Array, b: Uint8Array): boolean {
   const len = a.length;
   const compressible = Math.floor(len / 4);
-  const compressedA = new Uint32Array(a.buffer, 0, compressible);
-  const compressedB = new Uint32Array(b.buffer, 0, compressible);
+  const compressedA = new Uint32Array(a, 0, compressible);
+  const compressedB = new Uint32Array(b, 0, compressible);
   for (let i = compressible * 4; i < len; i++) {
     if (a[i] !== b[i]) return false;
   }
diff --git a/bytes/equals_test.ts b/bytes/equals_test.ts
index 84e26fae93a7..ad9d0fa207a8 100644
--- a/bytes/equals_test.ts
+++ b/bytes/equals_test.ts
@@ -1,6 +1,6 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 import { equals } from "./equals.ts";
-import { assert } from "../assert/mod.ts";
+import { assert, assertEquals, assertNotEquals } from "../assert/mod.ts";
 
 Deno.test("equals()", () => {
   const v = equals(new Uint8Array([0, 1, 2, 3]), new Uint8Array([0, 1, 2, 3]));
@@ -32,3 +32,19 @@ Deno.test("equals() handles randomized testing", () => {
     assert(!equals(arr1, arr3));
   }
 });
+
+// https://github.com/denoland/deno_std/issues/3603
+Deno.test("equals() works with .subarray()", () => {
+  const a = new Uint8Array(1001).subarray(1);
+  const b = new Uint8Array(1000);
+  a[0] = 123;
+  b[0] = 123;
+  assertEquals(a, b);
+  assert(equals(a, b));
+
+  const c = new Uint8Array(1001).subarray(1);
+  const d = new Uint8Array(1000);
+  c[999] = 123;
+  assertNotEquals(c, d); // ok
+  assert(!equals(c, d));
+});