using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Runtime.InteropServices;

 

namespace MS.SDKMSDNKeywordIndex

{

    class NativeMethods

    {

        [DllImport("Wtsapi32.dll")]

        private static extern bool WTSQuerySessionInformation(System.IntPtr hServer, int sessionId, WTSInfoClass wtsInfoClass, out System.IntPtr ppBuffer, out uint pBytesReturned);

 

        [DllImport("wtsapi32.dll", ExactSpelling = true, SetLastError = false)]

        private static extern void WTSFreeMemory(IntPtr memory);

 

        private enum WTSInfoClass

        {

            WTSInitialProgram,

            WTSApplicationName,

            WTSWorkingDirectory,

            WTSOEMId,

            WTSSessionId,

            WTSUserName,

            WTSWinStationName,

            WTSDomainName,

            WTSConnectState,

            WTSClientBuildNumber,

            WTSClientName,

            WTSClientDirectory,

            WTSClientProductId,

            WTSClientHardwareId,

            WTSClientAddress,

            WTSClientDisplay,

            WTSClientProtocolType

        }

 

        private static IntPtr WTS_CURRENT_SERVER_HANDLE = IntPtr.Zero;

        private static int WTS_CURRENT_SESSION = -1;

 

        public static int GetSessionNumber()

        {

            IntPtr pSessionId = IntPtr.Zero;

            Int32 sessionId = 0;

            uint bytesReturned;

 

            try

            {

                bool retVal = WTSQuerySessionInformation(WTS_CURRENT_SERVER_HANDLE, WTS_CURRENT_SESSION, WTSInfoClass.WTSSessionId, out pSessionId, out bytesReturned);

                if (retVal)

                    sessionId = Marshal.ReadInt32(pSessionId);

            }

            finally

            {

                if (pSessionId != IntPtr.Zero)

                    WTSFreeMemory(pSessionId);

            }

 

            return sessionId;

        }

    }

}