From 740c95819f0468345eebc44792c29c6e82b9820e Mon Sep 17 00:00:00 2001
From: Derek Lewis <DerekNonGeneric@inf.is>
Date: Sun, 2 Aug 2020 17:27:51 -0400
Subject: [PATCH] module: fix check for package.json at volume root

This patch converts the "read package scope" algorithm's while loop
into a do-while loop enabling items at the filesystem root dir to
be considered within the scope of a sibling package.json also at the
filesystem root dir.

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

Co-authored-by: Guy Bedford <guybedford@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/34595
Backport-PR-URL: https://github.com/nodejs/node/pull/35385
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Mary Marchini <oss@mmarchini.me>
---
 doc/api/esm.md                     |  2 +-
 lib/internal/modules/cjs/loader.js | 21 ++++++++++++---------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/doc/api/esm.md b/doc/api/esm.md
index cefa06d66d6f93..341bc4c3cd64f4 100644
--- a/doc/api/esm.md
+++ b/doc/api/esm.md
@@ -1854,11 +1854,11 @@ _conditions_)
 
 > 1. Let _scopeURL_ be _url_.
 > 1. While _scopeURL_ is not the file system root,
+>    1. Set _scopeURL_ to the parent URL of _scopeURL_.
 >    1. If _scopeURL_ ends in a _"node_modules"_ path segment, return **null**.
 >    1. Let _pjson_ be the result of **READ_PACKAGE_JSON**(_scopeURL_).
 >    1. If _pjson_ is not **null**, then
 >       1. Return _pjson_.
->    1. Set _scopeURL_ to the parent URL of _scopeURL_.
 > 1. Return **null**.
 
 **READ_PACKAGE_JSON**(_packageURL_)
diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index e890bee787a1af..280c42b5098d80 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -41,6 +41,9 @@ const {
   RegExpPrototypeTest,
   SafeMap,
   SafeSet,
+  StringPrototypeEndsWith,
+  StringPrototypeIndexOf,
+  StringPrototypeLastIndexOf,
   StringPrototypeMatch,
   StringPrototypeSlice,
   StringPrototypeStartsWith,
@@ -58,6 +61,7 @@ const assert = require('internal/assert');
 const fs = require('fs');
 const internalFS = require('internal/fs/utils');
 const path = require('path');
+const { sep } = path;
 const { internalModuleStat } = internalBinding('fs');
 const packageJsonReader = require('internal/modules/package_json_reader');
 const { safeGetenv } = internalBinding('credentials');
@@ -276,20 +280,19 @@ function readPackage(requestPath) {
 }
 
 function readPackageScope(checkPath) {
-  const rootSeparatorIndex = checkPath.indexOf(path.sep);
+  const rootSeparatorIndex = StringPrototypeIndexOf(checkPath, sep);
   let separatorIndex;
-  while (
-    (separatorIndex = checkPath.lastIndexOf(path.sep)) > rootSeparatorIndex
-  ) {
-    checkPath = checkPath.slice(0, separatorIndex);
-    if (checkPath.endsWith(path.sep + 'node_modules'))
+  do {
+    separatorIndex = StringPrototypeLastIndexOf(checkPath, sep);
+    checkPath = StringPrototypeSlice(checkPath, 0, separatorIndex);
+    if (StringPrototypeEndsWith(checkPath, sep + 'node_modules'))
       return false;
-    const pjson = readPackage(checkPath);
+    const pjson = readPackage(checkPath + sep);
     if (pjson) return {
+      data: pjson,
       path: checkPath,
-      data: pjson
     };
-  }
+  } while (separatorIndex > rootSeparatorIndex);
   return false;
 }