From 21a58310f0ba4c0150bde470c1e0596af125b790 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Mon, 29 Jul 2024 00:18:18 +0200
Subject: [PATCH] buffers: faster type check

Also add support for any TypedArray as target.

PR-URL: https://github.com/nodejs/node/pull/54088
---
 lib/buffer.js | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/lib/buffer.js b/lib/buffer.js
index 823a9249eccc52..2d5405ec7b5e61 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -23,6 +23,7 @@
 
 const {
   Array,
+  ArrayBufferIsView,
   ArrayIsArray,
   ArrayPrototypeForEach,
   MathFloor,
@@ -200,9 +201,9 @@ function toInteger(n, defaultVal) {
 }
 
 function _copy(source, target, targetStart, sourceStart, sourceEnd) {
-  if (!isUint8Array(source))
+  if (!ArrayBufferIsView(source))
     throw new ERR_INVALID_ARG_TYPE('source', ['Buffer', 'Uint8Array'], source);
-  if (!isUint8Array(target))
+  if (!ArrayBufferIsView(target))
     throw new ERR_INVALID_ARG_TYPE('target', ['Buffer', 'Uint8Array'], target);
 
   if (targetStart === undefined) {
@@ -217,34 +218,34 @@ function _copy(source, target, targetStart, sourceStart, sourceEnd) {
     sourceStart = 0;
   } else {
     sourceStart = toInteger(sourceStart, 0);
-    if (sourceStart < 0 || sourceStart > source.length)
-      throw new ERR_OUT_OF_RANGE('sourceStart', `>= 0 && <= ${source.length}`, sourceStart);
+    if (sourceStart < 0 || sourceStart > source.byteLength)
+      throw new ERR_OUT_OF_RANGE('sourceStart', `>= 0 && <= ${source.byteLength}`, sourceStart);
   }
 
   if (sourceEnd === undefined) {
-    sourceEnd = source.length;
+    sourceEnd = source.byteLength;
   } else {
     sourceEnd = toInteger(sourceEnd, 0);
     if (sourceEnd < 0)
       throw new ERR_OUT_OF_RANGE('sourceEnd', '>= 0', sourceEnd);
   }
 
-  if (targetStart >= target.length || sourceStart >= sourceEnd)
+  if (targetStart >= target.byteLength || sourceStart >= sourceEnd)
     return 0;
 
   return _copyActual(source, target, targetStart, sourceStart, sourceEnd);
 }
 
 function _copyActual(source, target, targetStart, sourceStart, sourceEnd) {
-  if (sourceEnd - sourceStart > target.length - targetStart)
-    sourceEnd = sourceStart + target.length - targetStart;
+  if (sourceEnd - sourceStart > target.byteLength - targetStart)
+    sourceEnd = sourceStart + target.byteLength - targetStart;
 
   let nb = sourceEnd - sourceStart;
-  const sourceLen = source.length - sourceStart;
+  const sourceLen = source.byteLength - sourceStart;
   if (nb > sourceLen)
     nb = sourceLen;
 
-  if (sourceStart !== 0 || sourceEnd < source.length)
+  if (sourceStart !== 0 || sourceEnd < source.byteLength)
     source = new Uint8Array(source.buffer, source.byteOffset + sourceStart, nb);
 
   TypedArrayPrototypeSet(target, source, targetStart);