[d8] Fix NormalizePath with relative paths

Bug: v8:12060
Change-Id: Ie78329cd6e9f8b19e3be0ccc0c14ae4a1995fb9d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3098189Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76337}

src/d8/d8.cc

@@ -854,16 +854,21 @@ std::string NormalizePath(const std::string& path,
   std::string segment;
   while (std::getline(segment_stream, segment, '/')) {
     if (segment == "..") {
-      segments.pop_back();
+      if (!segments.empty()) segments.pop_back();
     } else if (segment != ".") {
       segments.push_back(segment);
     }
   }
   // Join path segments.
   std::ostringstream os;
+  if (segments.size() > 1) {
     std::copy(segments.begin(), segments.end() - 1,
               std::ostream_iterator<std::string>(os, "/"));
     os << *segments.rbegin();
+  } else {
+    os << "/";
+    if (!segments.empty()) os << segments[0];
+  }
   return os.str();
 }
 

test/mjsunit/regress/regress-v8-12060.mjs

+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+const paths = [
+  ".",
+  "..",
+  "...",
+  "/",
+  "/..",
+  "/../..",
+  "../..",
+  "./..",
+  "./../",
+  "./../..",
+];
+
+const results = await Promise.allSettled(paths.map(path => import(path)));
+for (let result of results) {
+  assertEquals(result.status, 'rejected');
+}