From 283189fcce72f98f55d335292db0b3b77a252279 Mon Sep 17 00:00:00 2001
From: ExE Boss <3889017+ExE-Boss@users.noreply.github.com>
Date: Tue, 22 Dec 2020 13:45:00 +0100
Subject: [PATCH] =?UTF-8?q?lib:=20add=C2=A0`SafeArray`=20to=C2=A0`primordi?=
 =?UTF-8?q?als`=20and=C2=A0use=C2=A0it=20for=C2=A0`FreeList`?=
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Refs: https://github.com/nodejs/node/pull/36304#issuecomment-748328076
Refs: https://github.com/nodejs/node/pull/36565
---
 lib/internal/freelist.js                |  3 +-
 lib/internal/per_context/primordials.js | 40 +++++++++++++++++++++++--
 2 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/lib/internal/freelist.js b/lib/internal/freelist.js
index ac2b12c4d45a54..01b423648148e2 100644
--- a/lib/internal/freelist.js
+++ b/lib/internal/freelist.js
@@ -2,6 +2,7 @@
 
 const {
   ReflectApply,
+  SafeArray,
 } = primordials;
 
 class FreeList {
@@ -9,7 +10,7 @@ class FreeList {
     this.name = name;
     this.ctor = ctor;
     this.max = max;
-    this.list = [];
+    this.list = new SafeArray();
   }
 
   alloc() {
diff --git a/lib/internal/per_context/primordials.js b/lib/internal/per_context/primordials.js
index ad5707954738ae..392e31395c0926 100644
--- a/lib/internal/per_context/primordials.js
+++ b/lib/internal/per_context/primordials.js
@@ -109,7 +109,11 @@ const createSafeIterator = (factory, next) => {
   return SafeIterator;
 };
 
-function makeSafe(unsafe, safe) {
+function makeSafe(unsafe, safe, {
+  iteratorMethods = null,
+  constructorProperties = null,
+  prototypeProperties = null,
+} = {}) {
   if (Symbol.iterator in unsafe.prototype) {
     const dummy = new unsafe();
     let next; // We can reuse the same `next` method.
@@ -117,11 +121,11 @@ function makeSafe(unsafe, safe) {
     for (const key of Reflect.ownKeys(unsafe.prototype)) {
       if (!Reflect.getOwnPropertyDescriptor(safe.prototype, key)) {
         const desc = Reflect.getOwnPropertyDescriptor(unsafe.prototype, key);
-        if (
+        if (iteratorMethods?.includes(key) ?? (
           typeof desc.value === 'function' &&
           desc.value.length === 0 &&
           Symbol.iterator in (desc.value.call(dummy) ?? {})
-        ) {
+        )) {
           const createIterator = uncurryThis(desc.value);
           next ??= uncurryThis(createIterator(dummy).next);
           const SafeIterator = createSafeIterator(createIterator, next);
@@ -135,7 +139,14 @@ function makeSafe(unsafe, safe) {
   } else {
     copyProps(unsafe.prototype, safe.prototype);
   }
+  if (prototypeProperties !== null) {
+    Object.defineProperties(safe, prototypeProperties);
+  }
+
   copyProps(unsafe, safe);
+  if (constructorProperties !== null) {
+    Object.defineProperties(safe, constructorProperties);
+  }
 
   Object.setPrototypeOf(safe.prototype, null);
   Object.freeze(safe.prototype);
@@ -146,6 +157,29 @@ primordials.makeSafe = makeSafe;
 
 // Subclass the constructors because we need to use their prototype
 // methods later.
+primordials.SafeArray = makeSafe(
+  Array,
+  class SafeArray extends Array {
+    // This ensures that only the length taking overload is supported,
+    // all other uses should use `SafeArray.from` or `SafeArray.of`.
+    // This is necessary to support `ArraySpeciesCreate`, which invokes
+    // the constructor with argument `length`:
+    // https://tc39.es/ecma262/#sec-arrayspeciescreate
+    constructor(length = 0) {
+      super(+length);
+    }
+  },
+  {
+    // Many of the array methods have a length of 0 and return
+    // a primitive or an iterable that isn't an iterator, which breaks
+    // the assumptions about which methods return iterators in `makeSafe`
+    iteratorMethods: ['entries', 'keys', 'values', Symbol.iterator],
+    // `Array` doesn't have a `Symbol.toStringTag` by default
+    prototypeProperties: {
+      [Symbol.toStringTag]: { value: 'SafeArray' }
+    }
+  }
+);
 primordials.SafeMap = makeSafe(
   Map,
   class SafeMap extends Map {}