windows/serialInterface: Began building a RAII helper type for intera…

…cting with the Windows registry

src/windows/serialInterface.cxx

@@ -1,9 +1,12 @@
 // SPDX-License-Identifier: BSD-3-Clause
 // SPDX-FileCopyrightText: 2023 1BitSquared <info@1bitsquared.com>
 // SPDX-FileContributor: Written by Rachel Mant <git@dragonmux.network>
+#include <substrate/console>
 #include "windows/serialInterface.hxx"
 #include "bmp.hxx"
 
+using substrate::console;
+
 [[nodiscard]] std::string serialForDevice(const usbDevice_t &device)
 {
 	const auto serialIndex{device.serialNumberIndex()};
@@ -13,6 +16,51 @@
 	return handle.readStringDescriptor(serialIndex);
 }
 
+void displayError(const LSTATUS error, const std::string_view operation, const std::string_view path)
+{
+	char *message{nullptr};
+	FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, nullptr,
+		error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), reinterpret_cast<char *>(&message), 0, nullptr);
+	console.error("Failed to "sv, operation, ' ', path, ", got error "sv, asHex_t<8, '0'>{uint32_t(error)},
+		": "sv, message);
+	LocalFree(message);
+}
+
+struct hklmRegistryKey_t
+{
+private:
+	HKEY handle{static_cast<HKEY>(INVALID_HANDLE_VALUE)};
+
+public:
+	hklmRegistryKey_t() noexcept = default;
+	hklmRegistryKey_t(const hklmRegistryKey_t &) = delete;
+	hklmRegistryKey_t operator =(const hklmRegistryKey_t &) = delete;
+
+	hklmRegistryKey_t(const std::string &path, const REGSAM permissions) :
+		handle
+		{
+			[&]()
+			{
+				auto keyHandle{static_cast<HKEY>(INVALID_HANDLE_VALUE)};
+				if (const auto result{RegOpenKeyEx(HKEY_LOCAL_MACHINE, path.c_str(), 0, permissions, &keyHandle)};
+					result != ERROR_SUCCESS)
+				{
+					displayError(result, "open registry key"sv, path);
+					return static_cast<HKEY>(INVALID_HANDLE_VALUE);
+				}
+				return keyHandle;
+			}()
+		} { }
+
+	~hklmRegistryKey_t() noexcept
+	{
+		if (handle != INVALID_HANDLE_VALUE)
+			RegCloseKey(handle);
+	}
+
+	[[nodiscard]] bool valid() const noexcept { return handle != INVALID_HANDLE_VALUE; }
+};
+
 serialInterface_t::serialInterface_t(const usbDevice_t &usbDevice)
 {
 }