From 1849c2cc999da5c30d2a4497abbcf06a4ba88394 Mon Sep 17 00:00:00 2001
From: Brian White <mscdex@mscdex.net>
Date: Fri, 24 Jan 2020 02:44:15 -0500
Subject: [PATCH] buffer: improve fill(number) performance

PR-URL: https://github.com/nodejs/node/pull/31489
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
---
 lib/buffer.js | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/lib/buffer.js b/lib/buffer.js
index 01b9ea97f95a68..5a6b75c33e5be6 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -34,9 +34,12 @@ const {
   ObjectCreate,
   ObjectDefineProperties,
   ObjectDefineProperty,
+  ObjectGetOwnPropertyDescriptor,
+  ObjectGetPrototypeOf,
   ObjectSetPrototypeOf,
   SymbolSpecies,
   SymbolToPrimitive,
+  Uint8ArrayPrototype,
 } = primordials;
 
 const {
@@ -101,6 +104,13 @@ const {
   addBufferPrototypeMethods
 } = require('internal/buffer');
 
+const TypedArrayPrototype = ObjectGetPrototypeOf(Uint8ArrayPrototype);
+
+const TypedArrayProto_byteLength =
+      ObjectGetOwnPropertyDescriptor(TypedArrayPrototype,
+                                     'byteLength').get;
+const TypedArrayFill = TypedArrayPrototype.fill;
+
 FastBuffer.prototype.constructor = Buffer;
 Buffer.prototype = FastBuffer.prototype;
 addBufferPrototypeMethods(Buffer.prototype);
@@ -1001,11 +1011,22 @@ function _fill(buf, value, offset, end, encoding) {
       return buf;
   }
 
-  const res = bindingFill(buf, value, offset, end, encoding);
-  if (res < 0) {
-    if (res === -1)
-      throw new ERR_INVALID_ARG_VALUE('value', value);
-    throw new ERR_BUFFER_OUT_OF_BOUNDS();
+
+  if (typeof value === 'number') {
+    // OOB check
+    const byteLen = TypedArrayProto_byteLength.call(buf);
+    const fillLength = end - offset;
+    if (offset > end || fillLength + offset > byteLen)
+      throw new ERR_BUFFER_OUT_OF_BOUNDS();
+
+    TypedArrayFill.call(buf, value, offset, end);
+  } else {
+    const res = bindingFill(buf, value, offset, end, encoding);
+    if (res < 0) {
+      if (res === -1)
+        throw new ERR_INVALID_ARG_VALUE('value', value);
+      throw new ERR_BUFFER_OUT_OF_BOUNDS();
+    }
   }
 
   return buf;