Require PLATFORM_FILE_BACKUP_SEMANTICS to open a directory

base/platform_file_win.cc

Index: base/platform_file_win.cc
diff --git a/base/platform_file_win.cc b/base/platform_file_win.cc
index 07b5c48c22bf1add6aaf77e93cb63a0ee36d6da7..449910d3ec11104488c7517d0650b26eada985ae 100644
--- a/base/platform_file_win.cc
+++ b/base/platform_file_win.cc
@@ -86,6 +86,19 @@ PlatformFile CreatePlatformFileUnsafe(const FilePath& name,
   HANDLE file = CreateFile(name.value().c_str(), access, sharing, NULL,
                            disposition, create_flags, NULL);
 
+  if (INVALID_HANDLE_VALUE != file){

[Peter Kasting, 2014/03/14 02:23:10]

Drive-by: Please write (file != INVALID_HANDLE_VALUE).  See the "Code
formatting" section of http://dev.chromium.org/developers/coding-style .

+    // Don't allow directories to be opened without the proper flag (block ADS).
+    if (!(flags & PLATFORM_FILE_BACKUP_SEMANTICS)) {
+      BY_HANDLE_FILE_INFORMATION info = { 0 };
+      DCHECK(GetFileInformationByHandle(file, &info));

[Peter Kasting, 2014/03/14 02:23:10]

Never do real work in a DCHECK.  In non-DCHECK builds this will get compiled to
nothing, and |info| will never be initialized.

Do something like this instead:

  bool success = ...;
  DCHECK(success);

+      if (info.dwFileAttributes & (FILE_ATTRIBUTE_DIRECTORY |
+                                   FILE_ATTRIBUTE_REPARSE_POINT)) {
+        CloseHandle(file);
+        file = INVALID_HANDLE_VALUE;
+      }
+    }
+  }
+
   if (created && (INVALID_HANDLE_VALUE != file)) {
     if (flags & (PLATFORM_FILE_OPEN_ALWAYS))
       *created = (ERROR_ALREADY_EXISTS != GetLastError());