1 files changed, 235 insertions, 0 deletions
diff --git a/widget/windows/WinRegistry.h b/widget/windows/WinRegistry.h
new file mode 100644
index 0000000000..8ab221928e
--- /dev/null
+++ b/widget/windows/WinRegistry.h
@@ -0,0 +1,235 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_widget_WinRegistry_h__
+#define mozilla_widget_WinRegistry_h__
+
+#include <windows.h>
+#include <functional>
+#include "nsCOMPtr.h"
+#include "nsString.h"
+#include "nsTArray.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Span.h"
+
+class nsISerialEventTarget;
+
+namespace mozilla::widget::WinRegistry {
+
+// According to MSDN, the following limits apply (in characters excluding room
+// for terminating null character):
+static constexpr size_t kMaxKeyNameLen = 255;
+static constexpr size_t kMaxValueNameLen = 16383;
+
+/// https://learn.microsoft.com/en-us/windows/win32/shell/regsam
+enum class KeyMode : uint32_t {
+  AllAccess = KEY_ALL_ACCESS,
+  QueryValue = KEY_QUERY_VALUE,
+  CreateLink = KEY_CREATE_LINK,
+  CreateSubKey = KEY_CREATE_SUB_KEY,
+  EnumerateSubkeys = KEY_ENUMERATE_SUB_KEYS,
+  Execute = KEY_EXECUTE,
+  Notify = KEY_NOTIFY,
+  Read = KEY_READ,
+  SetValue = KEY_SET_VALUE,
+  Write = KEY_WRITE,
+};
+
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(KeyMode);
+
+enum class StringFlags : uint32_t {
+  // Whether to allow REG_SZ strings.
+  Sz = 1 << 0,
+  // Whether to read EXPAND_SZ strings.
+  ExpandSz = 1 << 1,
+  // Whether to treat MULTI_SZ values as strings. This is a historical
+  // idiosyncrasy of the nsIWindowsRegKey, but most likely not what you want.
+  LegacyMultiSz = 1 << 2,
+  // Whether to expand environment variables in EXPAND_SZ values.
+  // Only makes sense along with the ExpandSz variable.
+  ExpandEnvironment = 1 << 3,
+  // By default, only allow regular Sz, and don't perform environment expansion.
+  Default = Sz,
+};
+
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(StringFlags);
+
+// Convenience alias for legacy WinUtils callers, to preserve behavior.
+// Chances are users of these flags could just look at Sz strings, tho.
+static constexpr auto kLegacyWinUtilsStringFlags =
+    StringFlags::Sz | StringFlags::ExpandSz;
+
+// https://learn.microsoft.com/en-us/windows/win32/sysinfo/registry-value-types
+enum class ValueType : uint32_t {
+  Binary = REG_BINARY,
+  Dword = REG_DWORD,
+  ExpandSz = REG_EXPAND_SZ,
+  Link = REG_LINK,
+  MultiSz = REG_MULTI_SZ,
+  None = REG_NONE,
+  Qword = REG_QWORD,
+  Sz = REG_SZ,
+};
+
+class Key {
+ public:
+  enum CreateFlag {
+    Create,
+  };
+
+  Key() = default;
+  Key(const Key&) = delete;
+  Key(Key&& aOther) { std::swap(mKey, aOther.mKey); }
+
+  Key& operator=(const Key&) = delete;
+  Key& operator=(Key&& aOther) {
+    std::swap(mKey, aOther.mKey);
+    return *this;
+  }
+
+  Key(HKEY aParent, const nsString& aPath, KeyMode aMode, CreateFlag);
+  Key(HKEY aParent, const nsString& aPath, KeyMode aMode);
+
+  Key(const Key& aParent, const nsString& aPath, KeyMode aMode, CreateFlag)
+      : Key(aParent.mKey, aPath, aMode, Create) {}
+  Key(const Key& aParent, const nsString& aPath, KeyMode aMode)
+      : Key(aParent.mKey, aPath, aMode) {}
+
+  ~Key() {
+    if (mKey) {
+      ::RegCloseKey(mKey);
+    }
+  }
+
+  explicit operator bool() const { return !!mKey; }
+
+  uint32_t GetChildCount() const;
+  [[nodiscard]] bool GetChildName(uint32_t aIndex, nsAString& aResult) const;
+  [[nodiscard]] bool RemoveChildKey(const nsString& aName) const;
+
+  uint32_t GetValueCount() const;
+  [[nodiscard]] bool GetValueName(uint32_t aIndex, nsAString& aResult) const;
+  ValueType GetValueType(const nsString& aName) const;
+  bool RemoveValue(const nsString& aName) const;
+
+  Maybe<uint32_t> GetValueAsDword(const nsString& aName) const;
+  bool WriteValueAsDword(const nsString& aName, uint32_t aValue);
+
+  Maybe<uint64_t> GetValueAsQword(const nsString& aName) const;
+  [[nodiscard]] bool WriteValueAsQword(const nsString& aName, uint64_t aValue);
+
+  [[nodiscard]] bool GetValueAsBinary(const nsString& aName,
+                                      nsTArray<uint8_t>&) const;
+  Maybe<nsTArray<uint8_t>> GetValueAsBinary(const nsString& aName) const;
+  [[nodiscard]] bool WriteValueAsBinary(const nsString& aName,
+                                        Span<const uint8_t> aValue);
+
+  [[nodiscard]] bool GetValueAsString(const nsString& aName, nsString& aResult,
+                                      StringFlags = StringFlags::Default) const;
+  Maybe<nsString> GetValueAsString(const nsString& aName,
+                                   StringFlags = StringFlags::Default) const;
+  // Reads a string value into a buffer. Returns Some(length) if the string is
+  // read fully, in which case the passed memory region contains a
+  // null-terminated string.
+  // Doesn't perform environment expansion (and asserts if you pass the
+  // ExpandEnvironment flag).
+  [[nodiscard]] Maybe<uint32_t> GetValueAsString(
+      const nsString& aName, Span<char16_t>,
+      StringFlags = StringFlags::Default) const;
+  [[nodiscard]] Maybe<uint32_t> GetValueAsString(
+      const nsString& aName, Span<wchar_t> aBuffer,
+      StringFlags aFlags = StringFlags::Default) const {
+    return GetValueAsString(
+        aName, Span<char16_t>((char16_t*)aBuffer.data(), aBuffer.Length()),
+        aFlags);
+  }
+
+  [[nodiscard]] bool WriteValueAsString(const nsString& aName,
+                                        const nsString& aValue) {
+    MOZ_ASSERT(mKey);
+    return SUCCEEDED(RegSetValueExW(mKey, aName.get(), 0, REG_SZ,
+                                    (const BYTE*)aValue.get(),
+                                    (aValue.Length() + 1) * sizeof(char16_t)));
+  }
+
+  HKEY RawKey() const { return mKey; }
+
+ private:
+  HKEY mKey = nullptr;
+};
+
+inline bool HasKey(HKEY aRootKey, const nsString& aKeyName) {
+  return !!Key(aRootKey, aKeyName, KeyMode::Read);
+}
+
+// Returns a single string value from the registry into a buffer.
+[[nodiscard]] inline bool GetString(HKEY aRootKey, const nsString& aKeyName,
+                                    const nsString& aValueName,
+                                    Span<char16_t> aBuffer,
+                                    StringFlags aFlags = StringFlags::Default) {
+  Key k(aRootKey, aKeyName, KeyMode::QueryValue);
+  return k && k.GetValueAsString(aValueName, aBuffer, aFlags);
+}
+[[nodiscard]] inline bool GetString(HKEY aRootKey, const nsString& aKeyName,
+                                    const nsString& aValueName,
+                                    Span<wchar_t> aBuffer,
+                                    StringFlags aFlags = StringFlags::Default) {
+  return GetString(aRootKey, aKeyName, aValueName,
+                   Span<char16_t>((char16_t*)aBuffer.data(), aBuffer.Length()),
+                   aFlags);
+}
+[[nodiscard]] inline bool GetString(HKEY aRootKey, const nsString& aKeyName,
+                                    const nsString& aValueName,
+                                    nsString& aBuffer,
+                                    StringFlags aFlags = StringFlags::Default) {
+  Key k(aRootKey, aKeyName, KeyMode::QueryValue);
+  return k && k.GetValueAsString(aValueName, aBuffer, aFlags);
+}
+inline Maybe<nsString> GetString(HKEY aRootKey, const nsString& aKeyName,
+                                 const nsString& aValueName,
+                                 StringFlags aFlags = StringFlags::Default) {
+  Key k(aRootKey, aKeyName, KeyMode::QueryValue);
+  if (!k) {
+    return Nothing();
+  }
+  return k.GetValueAsString(aValueName, aFlags);
+}
+
+class KeyWatcher final {
+ public:
+  using Callback = std::function<void()>;
+
+  KeyWatcher(const KeyWatcher&) = delete;
+
+  const Key& GetKey() const { return mKey; }
+
+  // Start watching a key. The watching is recursive (the whole key subtree is
+  // watched), and the callback is executed every time the key or any of its
+  // descendants change until the watcher is destroyed.
+  //
+  // @param aKey the key to watch. Must have been opened with the
+  //             KeyMode::Notify flag.
+  // @param aTargetSerialEventTarget the target event target to dispatch the
+  //        callback to.
+  // @param aCallback the closure to run every time that registry key changes.
+  KeyWatcher(Key&& aKey, nsISerialEventTarget* aTargetSerialEventTarget,
+             Callback&& aCallback);
+
+  ~KeyWatcher();
+
+ private:
+  static void CALLBACK WatchCallback(void* aContext, BOOLEAN);
+  bool Register();
+
+  Key mKey;
+  nsCOMPtr<nsISerialEventTarget> mEventTarget;
+  Callback mCallback;
+  HANDLE mEvent = nullptr;
+  HANDLE mWaitObject = nullptr;
+};
+
+}  // namespace mozilla::widget::WinRegistry
+
+#endif