C++ WILとWindows Update Agent APIでWUA APIのバージョンを取得する

WILとWindows Update Agent API（WUA API）でWindowsUpdateAgentInfoを作成・管理してWUA APIのバージョンを取得するサンプルコードです。

// C++20

#include <iostream>

#pragma comment(lib, "propsys.lib")
#define STRICT
#define NOMINMAX
#include <Windows.h>
#include <propvarutil.h>
#include <wuapi.h>

#include <wil/com.h>
#include <wil/resource.h>

namespace wil_util
{
    using namespace wil;

    template <typename T>
    concept com_raw_ptr_callable = requires(T t) { com_raw_ptr(t); };

    template <com_raw_ptr_callable STRING_TYPE>
    unique_variant make_unique_variant_from_string_failfast(STRING_TYPE& psz)
    {
        unique_variant var;
        FAIL_FAST_IF_FAILED(InitVariantFromString(str_raw_ptr(psz), &var));
        return std::move(var);
    }

    inline auto make_cotaskmem_string_from_variant_get_failfast(const VARIANT& var)
    {
        LPWSTR psz;
        FAIL_FAST_IF_FAILED(VariantGetStringElem(var, 0, &psz));
        return make_cotaskmem_string_failfast(psz);
    }
}

int main()
{
    auto couninit = wil::CoInitializeEx_failfast();

    auto infoIdApiMajorVersion = wil_util::make_unique_variant_from_string_failfast(L"ApiMajorVersion");
    auto infoIdApiMinorVersion = wil_util::make_unique_variant_from_string_failfast(L"ApiMinorVersion");
    auto infoIdProductVersionString = wil_util::make_unique_variant_from_string_failfast(L"ProductVersionString");

    auto windowsUpdateAgentInfo = wil::CoCreateInstanceFailFast<WindowsUpdateAgentInfo, IWindowsUpdateAgentInfo>();

    wil::unique_variant apiMajorVersion;
    wil::unique_variant apiMinorVersion;
    wil::unique_variant productVersionString;
    FAIL_FAST_IF_FAILED(windowsUpdateAgentInfo->GetInfo(infoIdApiMajorVersion, &apiMajorVersion));
    FAIL_FAST_IF_FAILED(windowsUpdateAgentInfo->GetInfo(infoIdApiMinorVersion, &apiMinorVersion));
    FAIL_FAST_IF_FAILED(windowsUpdateAgentInfo->GetInfo(infoIdProductVersionString, &productVersionString));

    std::wcout << L"API Version: " << apiMajorVersion.intVal << L"." << apiMinorVersion.intVal << std::endl;
    std::wcout << L"Product Version String: "
        << wil_util::make_cotaskmem_string_from_variant_get_failfast(productVersionString).get() << std::endl;

    return 0;
}

参考

• Wuapi.h header - Win32 apps | Microsoft Docs