Registry overriding doesn't seem to work across multiple processes prior to Win8, instead simply ha…

chrome/browser/importer/ie_importer_test_registry_overrider_win.cc

 // Copyright (c) 2013 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/browser/importer/ie_importer_test_registry_overrider_win.h"
 
 #include <windows.h>
 
 #include <string>
 
 #include "base/environment.h"
 #include "base/guid.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
 #include "base/win/registry.h"
 
 namespace {
 
 // The key to which a random subkey will be appended. This key itself will never
 // be deleted.
-const wchar_t kTestHKCUOverrideKey[] = L"SOFTWARE\\Chromium Unit Tests";
+const wchar_t kTestHKCUOverrideKeyPrefix[] = L"SOFTWARE\\Chromium Unit Tests\\";
 const char kTestHKCUOverrideEnvironmentVariable[] =
     "IE_IMPORTER_TEST_OVERRIDE_HKCU";
 
-base::string16 GetTestKeyFromSubKey(const base::string16& subkey) {
-  base::string16 key(kTestHKCUOverrideKey);
-  key.push_back(L'\\');
-  key.append(subkey);
-  return key;
+// Reads the environment variable set by a previous call to
+// SetTestRegistryOverride() into |key| if it exists and |key| is not NULL.
+// Returns true if the variable was successfully read.
+bool GetTestKeyFromEnvironment(base::string16* key) {
+  scoped_ptr<base::Environment> env(base::Environment::Create());
+  std::string value;
+  bool result = env->GetVar(kTestHKCUOverrideEnvironmentVariable, &value);
+  if (result)
+    *key = UTF8ToUTF16(value);
+  return result;
 }
 
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
 // IEImporterTestRegistryOverrider, public:
 
 IEImporterTestRegistryOverrider::IEImporterTestRegistryOverrider()
-    : override_performed_(false), override_initiated_(false) {
+    : override_initiated_(false) {
 }
 
 IEImporterTestRegistryOverrider::~IEImporterTestRegistryOverrider() {
-  base::AutoLock auto_lock(lock_.Get());
-  if (override_performed_) {
-    override_active_in_process_ = false;
+  if (override_initiated_) {
+    base::string16 key;
+    if (!GetTestKeyFromEnvironment(&key)) {

[robertshield, 2013/05/22 19:31:35]

The environment is process-global, but override_initiated_ is local to an
instance of this class. So.. if two of these are created, this NOTREACHED will
be reached.

[gab, 2013/05/22 20:07:40]

Changed as discussed.

+      NOTREACHED();
+    } else {
+      base::win::RegKey reg_key(HKEY_CURRENT_USER, key.c_str(), KEY_ALL_ACCESS);
+      DCHECK(reg_key.Valid());
+      reg_key.DeleteKey(L"");
+    }
 
-    DWORD result = RegOverridePredefKey(HKEY_CURRENT_USER, NULL);
-    DLOG_IF(ERROR, result != ERROR_SUCCESS)
-        << "Failed to unset current override";
-
-    if (override_initiated_) {
-      base::string16 subkey;
-      if (!GetSubKeyFromEnvironment(&subkey)) {
-        NOTREACHED();
-      } else {
-        base::string16 key(GetTestKeyFromSubKey(subkey));
-        base::win::RegKey reg_key(HKEY_CURRENT_USER, key.c_str(),
-                                  KEY_ALL_ACCESS);
-        DCHECK(reg_key.Valid());
-        reg_key.DeleteKey(L"");
-      }
-
-      scoped_ptr<base::Environment> env(base::Environment::Create());
-      env->UnSetVar(kTestHKCUOverrideEnvironmentVariable);
-    }
+    scoped_ptr<base::Environment> env(base::Environment::Create());
+    env->UnSetVar(kTestHKCUOverrideEnvironmentVariable);
   }
 }
 
-bool IEImporterTestRegistryOverrider::SetRegistryOverride() {
-  base::AutoLock auto_lock(lock_.Get());
-  DCHECK(!GetSubKeyFromEnvironment(NULL));
+bool IEImporterTestRegistryOverrider::SetTestRegistryOverride() {
+  DCHECK(!GetTestKeyFromEnvironment(NULL));
+
   override_initiated_ = true;
+
   scoped_ptr<base::Environment> env(base::Environment::Create());
-  const base::string16 random_subkey(UTF8ToUTF16(base::GenerateGUID()));
-  return StartRegistryOverride(random_subkey) &&
-      env->SetVar(kTestHKCUOverrideEnvironmentVariable,
-                  UTF16ToUTF8(random_subkey));
+
+  base::string16 random_key(kTestHKCUOverrideKeyPrefix);
+  random_key.append(UTF8ToUTF16(base::GenerateGUID()));
+
+  return env->SetVar(kTestHKCUOverrideEnvironmentVariable,
+                     UTF16ToUTF8(random_key));
 }
 
-bool IEImporterTestRegistryOverrider::StartRegistryOverrideIfNeeded() {
-  base::AutoLock auto_lock(lock_.Get());
-  base::string16 subkey;
-  if (!GetSubKeyFromEnvironment(&subkey))
-    return true;
-  return StartRegistryOverride(subkey);
+base::string16 IEImporterTestRegistryOverrider::GetTestRegistryOverride() {

[robertshield, 2013/05/22 19:31:35]

// static

[gab, 2013/05/22 20:07:40]

Done.

+  base::string16 key;
+  if (!GetTestKeyFromEnvironment(&key))
+    return string16();
+  return key;
 }
-
-////////////////////////////////////////////////////////////////////////////////
-// IEImporterTestRegistryOverrider, private:
-
-bool IEImporterTestRegistryOverrider::StartRegistryOverride(
-    const base::string16& subkey) {
-  lock_.Get().AssertAcquired();
-  // Override the registry whether |override_active_in_process_| or not as some
-  // Windows API calls seem to reset the override (IUrlHistoryStg2::AddUrl is
-  // suspected on Win7-). However, make sure to first undo any existing override
-  // as this method will otherwise generate a fake key within the current fake
-  // key.
-  DWORD result = RegOverridePredefKey(HKEY_CURRENT_USER, NULL);
-  DLOG_IF(ERROR, result != ERROR_SUCCESS) << "Failed to unset current override";
-
-  const base::string16 key(GetTestKeyFromSubKey(subkey));
-  base::win::RegKey temp_hkcu_hive_key;
-  result = temp_hkcu_hive_key.Create(HKEY_CURRENT_USER, key.c_str(),
-                                     KEY_ALL_ACCESS);
-  if (result != ERROR_SUCCESS || !temp_hkcu_hive_key.Valid()) {
-    DPLOG(ERROR) << result;
-    return false;
-  }
-
-  if (!override_active_in_process_) {
-    // Only take ownership of the override if it wasn't already set in this
-    // process.
-    override_performed_ = true;
-    override_active_in_process_ = true;
-  }
-  return RegOverridePredefKey(HKEY_CURRENT_USER,
-                              temp_hkcu_hive_key.Handle()) == ERROR_SUCCESS;
-}
-
-bool IEImporterTestRegistryOverrider::GetSubKeyFromEnvironment(
-    base::string16* subkey) {
-  lock_.Get().AssertAcquired();
-  scoped_ptr<base::Environment> env(base::Environment::Create());
-  std::string value;
-  bool result = env->GetVar(kTestHKCUOverrideEnvironmentVariable, &value);
-  if (result && subkey)
-    *subkey = UTF8ToUTF16(value);
-  return result;
-}
-
-// static
-bool IEImporterTestRegistryOverrider::override_active_in_process_ = false;
-
-// static
-base::LazyInstance<base::Lock>::Leaky IEImporterTestRegistryOverrider::lock_ =
-    LAZY_INSTANCE_INITIALIZER;