From 78c5c4c208ebfad5f24f262abc9f3c03651d0909 Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webmaster@geoffreybooth.com>
Date: Tue, 19 May 2020 21:47:31 -0700
Subject: [PATCH] module: fix check for package.json at volume root

Fix package.json files at the volume root so that
when they contain {"type": "module"}, they behave
as documented, like such a package.json file in
any other folder.

Fixes: https://github.com/nodejs/node/issues/33438

PR-URL: https://github.com/nodejs/node/pull/33476
Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: Jan Krems <jan.krems@gmail.com>
---
 lib/internal/modules/cjs/loader.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index 0c34e3425567ab..35eabb55f2b2ea 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -41,6 +41,7 @@ const {
   SafeMap,
   String,
   StringPrototypeIndexOf,
+  StringPrototypeLastIndexOf,
   StringPrototypeMatch,
   StringPrototypeSlice,
   StringPrototypeStartsWith,
@@ -286,12 +287,13 @@ function readPackageScope(checkPath) {
   const rootSeparatorIndex = checkPath.indexOf(path.sep);
   let separatorIndex;
   while (
-    (separatorIndex = checkPath.lastIndexOf(path.sep)) > rootSeparatorIndex
+    (separatorIndex = StringPrototypeLastIndexOf(checkPath, path.sep)) >=
+     rootSeparatorIndex
   ) {
     checkPath = checkPath.slice(0, separatorIndex);
     if (checkPath.endsWith(path.sep + 'node_modules'))
       return false;
-    const pjson = readPackage(checkPath);
+    const pjson = readPackage(checkPath + path.sep);
     if (pjson) return {
       path: checkPath,
       data: pjson