path: handle extended-length windows entry paths

Normalize `\\?\` drive and UNC prefixes before resolution so
namespaced entry points follow standard Windows path semantics.

Fixes: #62446
Signed-off-by: jazelly <xzha4350@gmail.com>

Author: jazelly

src/path.cc

@@ -98,6 +98,28 @@ constexpr bool IsWindowsDeviceRoot(const char c) noexcept {
   return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
 }
 
+// Strip Windows extended-length path prefix (\\?\) only when it wraps a
+// drive letter path (\\?\C:\...) or a UNC path (\\?\UNC\...).
+// Device paths like \\?\PHYSICALDRIVE0 are left unchanged.
+// See: https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file
+static void StripExtendedPathPrefix(std::string& path) {
+  if (path.size() >= 4 && path[0] == '\\' && path[1] == '\\' &&
+      path[2] == '?' && path[3] == '\\') {
+    // \\?\C:\ -> C:\ (extended drive path)
+    if (path.size() >= 6 && IsWindowsDeviceRoot(path[4]) && path[5] == ':') {
+      path = path.substr(4);
+      return;
+    }
+    // \\?\UNC\server\share -> \\server\share (extended UNC path)
+    if (path.size() >= 8 && ToLower(path[4]) == 'u' &&
+        ToLower(path[5]) == 'n' && ToLower(path[6]) == 'c' &&
+        path[7] == '\\') {
+      path = "\\\\" + path.substr(8);
+      return;
+    }
+  }
+}
+
 std::string PathResolve(Environment* env,
                         const std::vector<std::string_view>& paths) {
   std::string resolvedDevice = "";
@@ -132,6 +154,10 @@ std::string PathResolve(Environment* env,
       }
     }
 
+    // Strip extended-length path prefix (\\?\C:\... -> C:\...,
+    // \\?\UNC\... -> \\...) before processing.
+    StripExtendedPathPrefix(path);
+
     const size_t len = path.length();
     int rootEnd = 0;
     std::string device = "";

test/cctest/test_path.cc

@@ -43,6 +43,14 @@ TEST_F(PathTest, PathResolve) {
             "\\\\.\\PHYSICALDRIVE0");
   EXPECT_EQ(PathResolve(*env, {"\\\\?\\PHYSICALDRIVE0"}),
             "\\\\?\\PHYSICALDRIVE0");
+  // Extended-length path prefix (\\?\) should be stripped for drive paths
+  EXPECT_EQ(PathResolve(*env, {"\\\\?\\C:\\foo"}), "C:\\foo");
+  EXPECT_EQ(PathResolve(*env, {"\\\\?\\C:\\"}), "C:\\");
+  // Extended-length UNC path prefix (\\?\UNC\) should be stripped
+  EXPECT_EQ(PathResolve(*env, {"\\\\?\\UNC\\server\\share"}),
+            "\\\\server\\share\\");
+  EXPECT_EQ(PathResolve(*env, {"\\\\?\\UNC\\server\\share\\dir"}),
+            "\\\\server\\share\\dir");
 #else
   EXPECT_EQ(PathResolve(*env, {"/var/lib", "../", "file/"}), "/var/file");
   EXPECT_EQ(PathResolve(*env, {"/var/lib", "/../", "file/"}), "/file");
@@ -85,6 +93,11 @@ TEST_F(PathTest, ToNamespacedPath) {
           .ToLocalChecked());
   ToNamespacedPath(*env, &data_4);
   EXPECT_EQ(data_4.ToStringView(), "\\\\?\\c:\\Windows\\System");
+  BufferValue data_5(
+      isolate_,
+      v8::String::NewFromUtf8(isolate_, "\\\\?\\C:\\").ToLocalChecked());
+  ToNamespacedPath(*env, &data_5);
+  EXPECT_EQ(data_5.ToStringView(), "\\\\?\\C:\\");
 #else
   BufferValue data(
       isolate_,

test/es-module/test-esm-long-path-win.js

@@ -47,6 +47,28 @@ describe('long path on Windows', () => {
     tmpdir.refresh();
   });
 
+  it('check extended-length path in executeUserEntryPoint', async () => {
+    const packageDirPath = tmpdir.resolve('issue-62446');
+    const mainJsFilePath = path.resolve(packageDirPath, 'main.js');
+    const namespacedMainJsPath = path.toNamespacedPath(mainJsFilePath);
+
+    tmpdir.refresh();
+
+    fs.mkdirSync(packageDirPath);
+    fs.writeFileSync(mainJsFilePath, 'console.log("hello world");');
+
+    const { code, signal, stderr, stdout } = await spawnPromisified(
+      execPath,
+      [namespacedMainJsPath],
+    );
+    assert.strictEqual(stderr.trim(), '');
+    assert.strictEqual(stdout.trim(), 'hello world');
+    assert.strictEqual(code, 0);
+    assert.strictEqual(signal, null);
+
+    tmpdir.refresh();
+  });
+
   it('check long path in LegacyMainResolve - 1', () => {
     // Module layout will be the following:
     //  package.json

test/parallel/test-fs-realpath.js

@@ -558,6 +558,22 @@ function test_root_with_null_options(realpath, realpathSync, cb) {
   }));
 }
 
+function test_windows_namespaced_path(realpath, realpathSync, cb) {
+  if (!common.isWindows) {
+    cb();
+    return;
+  }
+
+  const entry = tmp('issue-62446-entry.js');
+  fs.writeFileSync(entry, 'console.log("ok");');
+  const namespacedEntry = path.toNamespacedPath(entry);
+
+  assertEqualPath(realpathSync(namespacedEntry), path.resolve(entry));
+  asynctest(realpath, [namespacedEntry], cb, function(err, result) {
+    assertEqualPath(result, path.resolve(entry));
+  });
+}
+
 // ----------------------------------------------------------------------------
 
 const tests = [
@@ -579,6 +595,7 @@ const tests = [
   test_up_multiple_with_null_options,
   test_root,
   test_root_with_null_options,
+  test_windows_namespaced_path,
 ];
 const numtests = tests.length;
 let testsRun = 0;