RegistryHelper::readValue

wstring RegistryHelper::readValue(wstring key, wstring valuename)
{
    wstring result;

    HKEY keyHandle = openKey(key, KEY_QUERY_VALUE | KEY_WOW64_64KEY);

    LSTATUS status;
    DWORD type;
    DWORD bufSize;
    status = RegQueryValueExW(keyHandle, valuename.c_str(), NULL, &type, NULL, &bufSize);
    if (status != ERROR_SUCCESS)
    {
        RegCloseKey(keyHandle);
        throw RegistryException(L"Error while reading registry value " + key + L"\\" + valuename + L": " + StringHelper::getSystemErrorString(status));
    }

    if (type != REG_SZ)
    {
        RegCloseKey(keyHandle);
        throw RegistryException(L"Registry value " + key + L"\\" + valuename + L" has wrong type");
    }

    wchar_t* buf = new wchar_t[bufSize / sizeof(wchar_t) + 1];
    status = RegQueryValueExW(keyHandle, valuename.c_str(), NULL, NULL, (LPBYTE)buf, &bufSize);

    RegCloseKey(keyHandle);

    if (status != ERROR_SUCCESS)
    {
        delete buf;
        throw RegistryException(L"Error while reading registry value " + key + L"\\" + valuename + L": " + StringHelper::getSystemErrorString(status));
    }

    // Remove zero-termination
    if (buf[bufSize / sizeof(wchar_t) - 1] == L'\0')
        bufSize -= sizeof(wchar_t);
    result = wstring((wchar_t*)buf, (wstring::size_type)bufSize / sizeof(wchar_t));
    delete buf;

    return result;
}