Allow Registry Iterator functions to use a specified WOW64 mode when iterating.

chrome/installer/util/app_commands.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/installer/util/app_commands.h"
 
 #include "base/logging.h"
 #include "base/win/registry.h"
 #include "chrome/installer/util/google_update_constants.h"
 #include "chrome/installer/util/work_item_list.h"
@@ skipping 15 matching lines @@
   }
 
   using base::win::RegistryKeyIterator;
   static const wchar_t kEmptyString[] = L"";
 
   commands_.clear();
 
   RegKey cmd_key;
   LONG result;
   AppCommand command;
-  for (RegistryKeyIterator key_iterator(key.Handle(), kEmptyString);
-       key_iterator.Valid(); ++key_iterator) {
+  for (RegistryKeyIterator key_iterator(
+           key.Handle(), kEmptyString, KEY_WOW64_32KEY);

[grt (UTC plus 2), 2014/10/01 17:14:30]

this is ugly. it so happens that it's correct, but it isn't clear from the
interface.

[Will Harris, 2014/10/01 17:20:21]

yes, and it's not by coincidence, I manually went through every call to check
what access to supply.

I agree it's ugly - I considered:

 - exposing an interface on RegKey to determine what wow64access it had
originally been opened with, then we could pass this into RegistryKeyIterator
 - adding a new constructor on RegistryKeyIterator to take a RegKey instead of a
handle (but I think this would be against chromium coding standard)

If you have any suggestions how this could be made more elegant they would be
appreciated.

[grt (UTC plus 2), 2014/10/01 17:33:49]

I wish I did. The whys and wherefores for these magic bitness values are fairly
hard to understand/remember.

[cpu_(ooo_6.6-7.5), 2014/10/06 19:48:57]

you can have as many constructors as you need, in particular peppering the
codebase with (.., 0) is bad form.

[Will Harris, 2014/10/07 02:03:16]

Done.

+       key_iterator.Valid();
+       ++key_iterator) {
     const wchar_t* name = key_iterator.Name();
     result = cmd_key.Open(key.Handle(), name, KEY_QUERY_VALUE);
     if (result != ERROR_SUCCESS) {
       LOG(ERROR) << "Failed to open key \"" << name
                  << "\" with last-error code " << result;
     } else if (command.Initialize(cmd_key)) {
       commands_[name] = command;
     } else {
       VLOG(1) << "Skipping over key \"" << name
               << "\" as it does not appear to hold a product command.";
@@ skipping 34 matching lines @@
 
 bool AppCommands::Remove(const std::wstring& command_id) {
   return commands_.erase(command_id) != 0;
 }
 
 AppCommands::CommandMapRange AppCommands::GetIterators() const {
   return std::make_pair(commands_.begin(), commands_.end());
 }
 
 }  // namespace installer