C# WPF Console Manager Debug Assert Crash

Question

I am in an interesting predicament with a current project I am working on in dotNet. Currently, my project is a WPF application that configures settings for a console application, then launches the main function of the app (an infinitely looping API Hook that updates objects on a map). Previously, I have been using a solution I found at No output to console from a WPF application?, and the ConsoleManager class that was offered as a solution worked well. I've recently run into the issue where the solution has since stopped working, always failing in both Debug or Release builds at Debug.Assert(_out!=NULL), spitting out the following error message to me.

Process terminated. Assertion failed.
   at CT_API_GUI.ConsoleManager.InvalidateOutAndError() in C:\Users\pixel\RiderProjects\AFMChronotrackAPI\ConsoleManager.cs:line 82
   at CT_API_GUI.ConsoleManager.Show() in C:\Users\pixel\RiderProjects\AFMChronotrackAPI\ConsoleManager.cs:line 38
   at CT_API_GUI.WinApi.Main() in C:\Users\pixel\RiderProjects\AFMChronotrackAPI\WinApi.cs:line 53
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start[TStateMachine](TStateMachine& stateMachine)
   at CT_API_GUI.WinApi.Main()
   at CT_API_GUI.MainWindow.Run_OnClick(Object sender, RoutedEventArgs e) in C:\Users\pixel\RiderProjects\AFMChronotrackAPI\MainWindow.xaml.cs:line 41
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.Controls.Primitives.ButtonBase.OnClick()
   at System.Windows.Controls.Button.OnClick()
   at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
   at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
   at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
   at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.Run()
   at System.Windows.Application.RunDispatcher(Object ignore)
   at System.Windows.Application.RunInternal(Window window)
   at System.Windows.Application.Run()
   at CT_API_GUI.App.Main()

Where line 82 of ConsoleManager is Debug.Assert(_out != NULL)

Currently running dotNet 5.0.302 from the JetBrains Rider IDE 2021.1.5.

I've found that it's a bit more rare to have the WPF application launch the console, but in order to configure the settings properly it makes it the most convenient.

Any help is much appreciated!

Edit: Here is the specific code I am using for the ConsoleManager

using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;

namespace CT_API_GUI
{
    public static class ConsoleManager
    {
        private const string Kernel32_DllName = "kernel32.dll";

        [DllImport(Kernel32_DllName)]
        private static extern bool AllocConsole();

        [DllImport(Kernel32_DllName)]
        private static extern bool FreeConsole();

        [DllImport(Kernel32_DllName)]
        private static extern IntPtr GetConsoleWindow();

        [DllImport(Kernel32_DllName)]
        private static extern int GetConsoleOutputCP();

        public static bool HasConsole
        {
            get { return GetConsoleWindow() != IntPtr.Zero; }
        }

        /// <summary>
        /// Creates a new console instance if the process is not attached to a console already.
        /// </summary>
        public static void Show()
        {
            //#if DEBUG
            if (!HasConsole)
            {
                AllocConsole();
                InvalidateOutAndError();
            }
            //#endif
        }

        /// <summary>
        /// If the process has a console attached to it, it will be detached and no longer visible. Writing to the System.Console is still possible, but no output will be shown.
        /// </summary>
        public static void Hide()
        {
            //#if DEBUG
            if (HasConsole)
            {
                SetOutAndErrorNull();
                FreeConsole();
            }
            //#endif
        }

        public static void Toggle()
        {
            if (HasConsole)
            {
                Hide();
            }
            else
            {
                Show();
            }
        }

        static void InvalidateOutAndError()
        {
            Type type = typeof(System.Console);

            System.Reflection.FieldInfo _out = type.GetField("_out",
                System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic);

            System.Reflection.FieldInfo _error = type.GetField("_error",
                System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic);

            System.Reflection.MethodInfo _InitializeStdOutError = type.GetMethod("InitializeStdOutError",
                System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic);

            Debug.Assert(_out != null);
            Debug.Assert(_error != null);

            Debug.Assert(_InitializeStdOutError != null);

            _out.SetValue(null, null);
            _error.SetValue(null, null);

            _InitializeStdOutError.Invoke(null, new object[] {true});
        }

        static void SetOutAndErrorNull()
        {
            Console.SetOut(TextWriter.Null);
            Console.SetError(TextWriter.Null);
        }
    }
}

lidqy · Accepted Answer · 2021-07-29T22:25:03.290

Moving from .NET Framework 4x to .NET Core the name of the field in System.Console that holds a reference to the StdOut Textwriter has changed from _out in .NET Framework to s_out in .NET Core.

So you need to adjust your reflection code...

#if NET_CORE 
    System.Reflection.FieldInfo _out = type.GetField("s_out", ...);
#else
    System.Reflection.FieldInfo _out = type.GetField("_out", ...);
#endif

Sourcecode System.Console.NET Core https://source.dot.net/#System.Console/System/Console.cs,f907d79481da6ba4

Sourcecode System.Console.NET Framework 4.6 https://github.com/microsoft/referencesource/blob/master/mscorlib/system/console.cs

That was exactly what I needed. Worked like a charm. Thank you so much! — sherlockson, Jul 30 '21 at 13:32

C# WPF Console Manager Debug Assert Crash

1 Answers1