//==============================

type

  WTS_INFO_CLASS = (

    WTSInitialProgram,

    WTSApplicationName,

    WTSWorkingDirectory,

    WTSOEMId,

    WTSSessionId,

    WTSUserName,

    WTSWinStationName,

    WTSDomainName,

    WTSConnectState,

    WTSClientBuildNumber,

    WTSClientName,

    WTSClientDirectory,

    WTSClientProductId,

    WTSClientHardwareId,

    WTSClientAddress,

    WTSClientDisplay,

    WTSClientProtocolType,

    WTSIdleTime,

    WTSLogonTime,

    WTSIncomingBytes,

    WTSOutgoingBytes,

    WTSIncomingFrames,

    WTSOutgoingFrames,

    WTSClientInfo,

    WTSSessionInfo,

    WTSSessionInfoEx,

    WTSConfigInfo,

    WTSValidationInfo,

    WTSSessionAddressV4,

    WTSIsRemoteSession

  );

  WTS_CONNECTSTATE_CLASS = (

    WTSActive,

    WTSConnected,

    WTSConnectQuery,

    WTSShadow,

    WTSDisconnected,

    WTSIdle,

    WTSListen,

    WTSReset,

    WTSDown,

    WTSInit

  );

  PWTS_SESSION_INFO = ^WTS_SESSION_INFO;

  WTS_SESSION_INFO = record

    SessionId: DWORD;

    pWinStationName: LPTSTR;

    State: WTS_CONNECTSTATE_CLASS;

  end;

const

  WTS_CURRENT_SERVER_HANDLE: THANDLE = 0;

{ Get Logged in USer }

function WTSEnumerateSessions(hServer: THandle; Reserved: DWORD; Version: DWORD; var ppSessionInfo: PWTS_SESSION_INFO; var pCount: DWORD): BOOL; stdcall; external 'Wtsapi32.dll' name {$IFDEF UNICODE}'WTSEnumerateSessionsW'{$ELSE}'WTSEnumerateSessionsA'{$ENDIF};

function WTSQuerySessionInformation(hServer: THandle; SessionId: DWORD; WTSInfoClass: WTS_INFO_CLASS; var ppBuffer: LPTSTR; var pBytesReturned: DWORD): BOOL; stdcall; external 'Wtsapi32.dll' name {$IFDEF UNICODE}'WTSQuerySessionInformationW'{$ELSE}'WTSQuerySessionInformationA'{$ENDIF};

procedure WTSFreeMemory(pMemory: Pointer); stdcall; external 'Wtsapi32.dll';

//==============================

//==============================

function GetLoggedInUser() : string;

var

  Sessions, Session: PWTS_SESSION_INFO;

  NumSessions, I, NumBytes: DWORD;

  UserName: LPTSTR;

begin

  if not WTSEnumerateSessions(WTS_CURRENT_SERVER_HANDLE, 0, 1, Sessions, NumSessions) then

    RaiseLastOSError;

  try

    if NumSessions > 0 then

    begin

      Session := Sessions;

      for I := 0 to NumSessions-1 do

      begin

        if Session.State = WTSActive then

        begin

          if WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, Session.SessionId, WTSUserName, UserName, NumBytes) then

          begin

            try

              Result := UserName;

            finally

              WTSFreeMemory(UserName);

            end;

          end;

        end;

        Inc(Session);

      end;

    end;

  finally

    WTSFreeMemory(Sessions);

  end;

end;

//==============================