1 files changed, 112 insertions, 0 deletions
diff --git a/toolkit/xre/DllPrefetchExperimentRegistryInfo.cpp b/toolkit/xre/DllPrefetchExperimentRegistryInfo.cpp
new file mode 100644
index 0000000000..829999ac45
--- /dev/null
+++ b/toolkit/xre/DllPrefetchExperimentRegistryInfo.cpp
@@ -0,0 +1,112 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#include "DllPrefetchExperimentRegistryInfo.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/NativeNt.h"
+#include "mozilla/ResultExtensions.h"
+
+namespace mozilla {
+
+const wchar_t DllPrefetchExperimentRegistryInfo::kExperimentSubKeyPath[] =
+    L"SOFTWARE"
+    L"\\" MOZ_APP_VENDOR L"\\" MOZ_APP_BASENAME L"\\DllPrefetchExperiment";
+
+Result<Ok, nsresult> DllPrefetchExperimentRegistryInfo::Open() {
+  if (!!mRegKey) {
+    return Ok();
+  }
+
+  DWORD disposition;
+  HKEY rawKey;
+  LSTATUS result = ::RegCreateKeyExW(
+      HKEY_CURRENT_USER, kExperimentSubKeyPath, 0, nullptr,
+      REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, nullptr, &rawKey, &disposition);
+
+  if (result != ERROR_SUCCESS) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  mRegKey.own(rawKey);
+
+  if (disposition == REG_CREATED_NEW_KEY ||
+      disposition == REG_OPENED_EXISTING_KEY) {
+    return Ok();
+  }
+
+  MOZ_ASSERT_UNREACHABLE("Invalid disposition from RegCreateKeyExW");
+  return Err(NS_ERROR_UNEXPECTED);
+}
+
+Result<Ok, nsresult> DllPrefetchExperimentRegistryInfo::ReflectPrefToRegistry(
+    int32_t aVal) {
+  MOZ_TRY(Open());
+
+  mPrefetchMode = aVal;
+
+  LSTATUS status =
+      ::RegSetValueExW(mRegKey.get(), mBinPath.get(), 0, REG_DWORD,
+                       reinterpret_cast<PBYTE>(&aVal), sizeof(aVal));
+
+  if (status != ERROR_SUCCESS) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  return Ok();
+}
+
+Result<Ok, nsresult> DllPrefetchExperimentRegistryInfo::ReadRegistryValueData(
+    DWORD expectedType) {
+  MOZ_TRY(Open());
+
+  int32_t data;
+  DWORD dataLen = sizeof((ULONG)data);
+  DWORD type;
+  LSTATUS status =
+      ::RegQueryValueExW(mRegKey.get(), mBinPath.get(), nullptr, &type,
+                         reinterpret_cast<PBYTE>(&data), &dataLen);
+
+  if (status == ERROR_FILE_NOT_FOUND) {
+    // The registry key has not been created, set to default 0
+    mPrefetchMode = 0;
+    return Ok();
+  }
+
+  if (status != ERROR_SUCCESS) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  if (type != expectedType) {
+    return Err(NS_ERROR_UNEXPECTED);
+  }
+
+  mPrefetchMode = data;
+  return Ok();
+}
+
+AlteredDllPrefetchMode
+DllPrefetchExperimentRegistryInfo::GetAlteredDllPrefetchMode() {
+  Result<Ok, nsresult> result = ReadRegistryValueData(REG_DWORD);
+  if (!result.isOk()) {
+    MOZ_ASSERT(false);
+    return AlteredDllPrefetchMode::CurrentPrefetch;
+  }
+
+  switch (mPrefetchMode) {
+    case 0:
+      return AlteredDllPrefetchMode::CurrentPrefetch;
+    case 1:
+      return AlteredDllPrefetchMode::NoPrefetch;
+    case 2:
+      return AlteredDllPrefetchMode::OptimizedPrefetch;
+    default:
+      MOZ_ASSERT(false);
+      return AlteredDllPrefetchMode::CurrentPrefetch;
+  }
+}
+
+}  // namespace mozilla