[c#] How do I get the handle of a console application's window



Answers

Here's a robust way to do this:

The related functions from the Console Win32 API are:

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool AttachConsole(uint dwProcessId);
[DllImport("kernel32.dll")]
static extern IntPtr GetConsoleWindow();
[DllImport("kernel32.dll", SetLastError=true, ExactSpelling=true)]
static extern bool FreeConsole();
  • For the console the current process is attached to, just GetConsoleWindow() is enough
  • For the console another process is attached to, attach to it as well with AttachConsole, call GetConsoleWindow, them immediately detach with FreeConsole.

For the extra cautious, register a console event handler before attaching (and unregister it after detaching) as well so you don't accidentally get terminated if a console event happens in the tiny time frame you're attached to the console:

[DllImport("kernel32.dll")]
static extern bool SetConsoleCtrlHandler(ConsoleCtrlDelegate HandlerRoutine,
   bool Add);
delegate Boolean ConsoleCtrlDelegate(CtrlTypes CtrlType);
enum CtrlTypes : uint {
    CTRL_C_EVENT = 0,
    CTRL_BREAK_EVENT,
    CTRL_CLOSE_EVENT,  
    CTRL_LOGOFF_EVENT = 5,
    CTRL_SHUTDOWN_EVENT
}

bool is_attached=false;    
ConsoleCtrlDelegate ConsoleCtrlDelegateDetach = delegate(CtrlType) {
     if (is_attached = !FreeConsole())
         Trace.Error('FreeConsole on ' + CtrlType + ': ' + new Win32Exception());
     return true;
};

Making changes to the current process just to read something is rather ugly (when this is a console process, this gets really ugly since it requires a helper process to avoid terminating the current console). Nevertheless, further investigation shows that there's no other way short of injecting into the csrss process or the target process.

Console correspondence information is located in and managed by csrss.exe (or a multitude of those, one for each session, since Vista), so it can't be retrieved with the likes of ReadProcessMemory. All that csrss exposes is the CSRSS LPC API. There's only one relevant function in the full API list, SrvGetConsoleWindow. And it doesn't accept a PID but determines that of the calling party as seen in an alternative implementation or the function's disassembly in winsrv.dll.

Question

Can someone tell me how to get the handle of a Windows console application in C#? In a Windows Forms application, I would normally try this.Handle.




I've just solved this problem for myself (unfortunately before seeing Thomas's answer which is much quicker). Well, here's another way for those who are not satisfied with his answer. I'm writing this answer because I want to provide another answer + a better way to design the Program class if you're treating your console as a Window. Let's begin with that design:

I've kind of changed the default style of the Program class. I've actually made it into a class that has a program in it, and not just one method which represent it and uses other classes for content. (If you don't know what I mean, not important).

The reason I had to do it is because I wanted to write the following event handler:

private void CatchUnhandled(Object sender, UnhandledExceptionEventArgs e)
{
    var exception = e.ExceptionObject as Exception;
    MessageBox.Show(this, exception.Message, "Error"); // Check out 1st arg.
}

It overloads this method MessageBox.Show(IWin32Window, String, String).

Because Console doesn't implement IWin32Window, I had to implement it myself, of course, in order to just call this in the 1st argument.

Here is the implementation of it and everything else:

Note: this code is copy-pasted from my application, you can feel free to change the access modifiers

Program Class Declaration:

internal class Program : IWin32Window
{
    ...
}

IWin32Window Implementation:

public IntPtr Handle
{
    get { return NativeMethods.GetConsoleWindow(); }
}

It uses the following class:

internal static class NativeMethods
{
    [DllImport("kernel32.dll")]
    internal static extern IntPtr GetConsoleWindow();
}

Now, the problem is that you can't actually call this in Main, being a static method, so whatever was in Main I've moved to a new method named Start and all Main is doing is creating a new Program and calling Start.

private static void Main()
{
    new Program().Start();
}

private void Start()
{
    AppDomain.CurrentDomain.UnhandledException += CatchUnhandled;

    throw new Exception();
}

The result was, of course, a message-box with my console's window as an owner.
Using this method for a message-box, is of course only one application of this method.




In a console application which streamed diagostics to the console, and for which I wanted to disable mouse input, I tried GetConsoleWindow(), Process.GetCurrentProcess().MainWindowHandle, and FindWindowByCaption(IntPtr.Zero, Console.Title). Each of these returned the same non-zero handle, but when I tried to use that handle in SetConsoleMode it threw a "Invalid Handle" exception. Finally I tried SetConsoleMode(GetStdHandle(STD_INPUT_HANDLE), mode | ENABLE_EXTENDED_FLAGS)) with STD_INPUT_HANDLE defined as -10, and it worked. MS's documentation suggests that handles to consoles may be reassigned, and I am not comfortable or happy with this solution, but so far it is the only thing I've found that allows me to disable quick edit mode programmatically. GetStdHandle(STD_INPUT_HANDLE) returns '3', the other calls return a 7 digit value that varies each time the program is run.






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