win api and c# - desktops

Question

Okay, so I found this class online that "creates" a second desktop which does not run anything (ie, explorer.exe is not called and so forth).

However, this newly created desktop refuses to shutdown and go back to the orignal desktop. I have no idea whats going on. So if someone can try it on their machine, it would be very helpful.

note: assume all win api headers have been declared and work.

The class that "locks" the current dekstop:

namespace Locker
{
    class CLocker
    {
        public static int DesktopHandle;                    // Hold desktop handle.
        public static int oldDesktopHandle;
        public static int DesktopInputID;                   // Hold desktop input id.
        public static int DesktopThreadID;                  // Hold desktop thread id.
        static string DesktopName = "DL.Locker.Desktop";    // Hold the name of new created desktop.
        static FileStream TaskMan;                          // Hold the file stream object to control task manager.
        static string FastSwitching = string.Empty;         // Hold the original value of fast switching i.e. welcome screen
        static string ShutdownWithoutLogin = string.Empty;  // Hold the original value of showinh the shutdown button on welcome screen.

        /// <summary>
        /// Enabled used to enable or disable the locker
        /// </summary>
        public static bool Enabled
        {
            set
            {
                SetProcessPriorityHigh();                       // Set the process priority to high.
                if (value)                                      // Enable or disable the locker?
                {
                    CreateNewDesktop();                         // Creating new desktop.
                    StartProcess(Application.ExecutablePath);   // Starting the locker form, to allow the user to enter login info.
                }
                else
                {
                    DestroyDesktop();                           // Destroy the desktop.
                    ExitProcess(0);                             // Exit the current process, if desktop attached with no process, default desktop will be activated.
                }
            }
        }

        public static bool NeedBootStrapping()
        {
            Console.WriteLine((GetDesktopName() != DesktopName).ToString());
            return (GetDesktopName() != DesktopName);
        }

        static string GetDesktopName()
        {
            int DLength = 0, DHandle = GetThreadDesktop(GetCurrentThreadId());
            StringBuilder DName = new StringBuilder();
            GetUserObjectInformation(DHandle, UOI_NAME, DName, 0, ref DLength);
            if (DLength != 0) GetUserObjectInformation(DHandle, UOI_NAME, DName, DLength, ref DLength);
            Console.WriteLine(DName.ToString());
            return (DName.ToString());
        }

        static void CreateNewDesktop()
        {
            DesktopThreadID = GetThreadDesktop(GetCurrentThreadId());
            DesktopInputID = OpenInputDesktop(0, false, DESKTOP_SWITCHDESKTOP);
            DesktopHandle = CreateDesktop(DesktopName, "", 0, 0, GENERIC_ALL, 0);
            if (DesktopHandle != 0)
            {
                SetThreadDesktop(DesktopHandle);
                SwitchDesktop(DesktopHandle);
            }
        }

        public static void DestroyDesktop()
        {
            SwitchDesktop(DesktopInputID);
            DesktopInputID = 0;
            SetThreadDesktop(DesktopInputID);
            DesktopThreadID = 0;
            CloseDesktop(DesktopHandle);
            DesktopHandle = 0;
        }

        static void StartProcess(string Path)
        {
            MessageBox.Show("Hello from startProcess");
            DestroyDesktop();
        }

        static void SetProcessPriorityHigh()
        {
            SetThreadPriority(GetCurrentThread(), THREAD_BASE_PRIORITY_MAX);
            SetPriorityClass(GetCurrentProcess(), REALTIME_PRIORITY_CLASS);
        }
    }
}

And the main() function:

static void Main()
        {
            if (CLocker.NeedBootStrapping())
                CLocker.Enabled = true;        // Check if we need boot strapping or not, if true then a new desktop will created.
            else  // Run application as usual.
            {
                MessageBox.Show("Hello, this is your new desktop");
                CLocker.Enabled = false;
            }
        }

Update: This code does not compile. It comes up with about 40 red squiggly lines underneath the words saying "Does not exists in current context".

It screwed up your machine, so now you want one of us to try it and screw up our machine too? — Ryan Lundy, Feb 04 '09 at 01:55
It didnt screw up my machine. It creates a new desktop, but dosnt go back tot he old one automatically. Youc an ctrl/alt/del it, go to task manager and run explorer.exe your self. — masfenix, Feb 04 '09 at 02:09
You find some code, you don't understand it, but you actually want to _use_ it? Maybe you'd do better to learn about how desktops work first. — John Saunders, Aug 16 '09 at 13:04

score 1 · Answer 1 · answered Aug 22 '09 at 03:23

Dont pop a message box, which requires user input to clear, on a hidden desktop instance. That's usually the down fall of hosting UI code in services as well.

Also, it's a good idea to research any and all unmanaged API calls before just running the code.

win api and c# - desktops

1 Answers1