Cannot get user level registry value even using RegOpenCurrentUser from system service - c++

Question

I wrote a system service, in which I want to get the active user's one registry value under HKEY_CURRENT_USER. I wrote the code as below. However, it seems it can only get the system level registry value, cannot get the active user's registry value. See the code below. Where is the problem? Something missing?
void GetUserRegistryFromSystemService()
{
#ifdef Q_OS_WIN
DWORD sessionId = WTSGetActiveConsoleSessionId();
qInfo() << "Session ID = " << sessionId;
wchar_t * ppUserName[100];
DWORD sizeOfUserName;
WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, sessionId, WTSUserName, ppUserName, &sizeOfUserName);
qInfo() << "Windows User Name = " << QString::fromWCharArray(*ppUserName);
std::wstring strValueOfBinDir = L"Unknown Value";
LONG regOpenResult = ERROR_SUCCESS;
HANDLE hUserToken = NULL;
HANDLE hFakeToken = NULL;
if (WTSQueryUserToken(sessionId, &hUserToken))
{
if (DuplicateTokenEx(hUserToken, TOKEN_ASSIGN_PRIMARY | TOKEN_ALL_ACCESS, 0, SecurityImpersonation, TokenPrimary, &hFakeToken) == TRUE)
{
qInfo() << "Before ImpersonateLoggedOnUser()......";
if (ImpersonateLoggedOnUser(hFakeToken))
{
HKEY hKey;
regOpenResult = RegOpenCurrentUser(KEY_READ, &hKey);
if (regOpenResult != ERROR_SUCCESS)
{
qCritical() << "Failed to call RegOpenCurrentUser(), Error is " << regOpenResult;
}
// Fails to get this hive, will get the default value "Unkown"
RegOpenKeyEx(HKEY_CURRENT_USER,
TEXT("Software\\Baidu\\BaiduYunGuanjia"),
0,
KEY_READ,
&hKey);
GetStringRegKey(hKey, TEXT("installDir"), strValueOfBinDir, TEXT("Unknown"));
// It can get the following hive successfully
// RegOpenKeyEx(HKEY_LOCAL_MACHINE,
// TEXT("Software\\GitForWindows"),
// 0,
// KEY_READ,
// &hKey);
// GetStringRegKey(hKey, TEXT("InstallPath"), strValueOfBinDir, TEXT("Unknown"));
RevertToSelf();
}
else
{
qCritical() << "Failed to ImpersonateLoggedOnUser...";
}
CloseHandle(hFakeToken);
}
else
{
qCritical() << "Failed to call DuplicateTokenEx...";
}
CloseHandle(hUserToken);
}
else
{
qCritical() << "Failed to get the user token of session " << sessionId;
}
qInfo() << "The value of Registry is " << QString::fromWCharArray( strValueOfBinDir.c_str() );
#endif
}

Answer 1

You should use HKEY handle received from RegOpenCurrentUser in the RegOpenKeyEx instead of HKEY_CURRENT_USER:
regOpenResult = RegOpenCurrentUser(KEY_READ, &hKey);
if (regOpenResult != ERROR_SUCCESS)
{
qCritical() << "Failed to call RegOpenCurrentUser(), Error is " << regOpenResult;
}
HKEY hSubKey;
// Fails to get this hive, will get the default value "Unkown"
RegOpenKeyEx(hKey, TEXT("Software\\Baidu\\BaiduYunGuanjia"), 0, KEY_READ, &hSubKey);