Fix directory-listing, directory-deletion and file deletion, when links are involved.

runtime/bin/directory_win.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include "bin/directory.h"
 
 #include <errno.h>  // NOLINT
@@ skipping 100 matching lines @@
   return ok;
 }
 
 
 static bool HandleEntry(LPWIN32_FIND_DATAW find_file_data,
                         PathBuffer* path,
                         bool recursive,
                         bool follow_links,
                         DirectoryListing* listing) {
   DWORD attributes = find_file_data->dwFileAttributes;
-  if (!follow_links && (attributes & FILE_ATTRIBUTE_REPARSE_POINT) != 0) {
-    return HandleLink(find_file_data->cFileName, path, listing);
-  } else if ((attributes & FILE_ATTRIBUTE_DIRECTORY) != 0) {
+  if ((attributes & FILE_ATTRIBUTE_REPARSE_POINT) != 0) {
+    if (!follow_links) {
+      return HandleLink(find_file_data->cFileName, path, listing);
+    }
+    // Attempt to list the directory, to see if it's a valid link or not.
+    int path_length = path->length;
+    if (!path->Add(find_file_data->cFileName)) return false;
+    if (!path->Add(L"\\*")) return false;
+    WIN32_FIND_DATAW tmp_file_data;
+    HANDLE find_handle = FindFirstFileW(path->data, &tmp_file_data);
+    path->Reset(path_length);
+    if (find_handle == INVALID_HANDLE_VALUE) {
+      // Invalid handle, report as (broken) link.
+      return HandleLink(find_file_data->cFileName, path, listing);
+    } else {
+      FindClose(find_handle);
+    }
+  }
+  if ((attributes & FILE_ATTRIBUTE_DIRECTORY) != 0) {
     return HandleDir(find_file_data->cFileName,
                      path,
                      recursive,
                      follow_links,
                      listing);
   } else {
     return HandleFile(find_file_data->cFileName, path, listing);
   }
 }
 
@@ skipping 285 matching lines @@
   }
   DWORD flags = MOVEFILE_WRITE_THROUGH;
   int move_status =
       MoveFileExW(system_path, system_new_path, flags);
   free(const_cast<wchar_t*>(system_path));
   free(const_cast<wchar_t*>(system_new_path));
   return (move_status != 0);
 }
 
 #endif  // defined(TARGET_OS_WINDOWS)