Gracefully handling Ctrl+C ignores Program Main exit code.

[NTaylorMullen]

Repro:

• dotnet new console
• Paste the repro code below into Program.cs
• dotnet run
• Hit Ctrl + C
• Look at the last exit code.

We expect in the below repo for the exit code to be 1337

Built a repro that's inspired by ASP.NET's hosting bits here: https://github.com/aspnet/Hosting/blob/88d33cd665736e9c73298d24901c9dc99607d414/src/Microsoft.AspNetCore.Hosting/WebHostExtensions.cs#L134-L162

Repro:

using System;
using System.Threading;
using System.Threading.Tasks;

namespace CtrlCExit
{
    class Program
    {
        static int Main(string[] args)
        {
            var done = new ManualResetEventSlim(false);
            var token = new CancellationTokenSource().Token;
            using (var cts = CancellationTokenSource.CreateLinkedTokenSource(token))
            {
                AttachCtrlcSigtermShutdown(cts, done, shutdownMessage: "Cancel key press received, attempting to exit gracefully.");

                try
                {
                    Console.WriteLine("Waiting for Ctrl+C to be pressed...");
                    cts.Token.WaitHandle.WaitOne();
                }
                finally
                {
                    done.Set();
                }
            }

            Console.WriteLine("Exited gracefully.");
            return 1337;
        }

        private static void AttachCtrlcSigtermShutdown(CancellationTokenSource cts, ManualResetEventSlim resetEvent, string shutdownMessage)
        {
            void Shutdown()
            {
                if (!cts.IsCancellationRequested)
                {
                    if (!string.IsNullOrEmpty(shutdownMessage))
                    {
                        Console.WriteLine(shutdownMessage);
                    }
                    try
                    {
                        cts.Cancel();
                    }
                    catch (ObjectDisposedException) { }
                }

                // Wait on the given reset event
                resetEvent.Wait();
            };

            AppDomain.CurrentDomain.ProcessExit += (sender, eventArgs) => Shutdown();
            Console.CancelKeyPress += (sender, eventArgs) =>
            {
                Shutdown();
                // Don't terminate the process immediately, wait for the Main thread to exit gracefully.
                eventArgs.Cancel = true;
            };
        }
    }
}

/cc @halter73 @Tratcher

[danmoseley]

I repro this, and indeed on .NET Framework it produces 1337

[danmoseley]

-1073741510 (0xC000013A) is STATUS_CTRL_C_EXIT

// {Application Exit by CTRL+C}
// The application terminated as a result of a CTRL+C.
//
#define STATUS_CONTROL_C_EXIT ((NTSTATUS)0xC000013AL)

[danmoseley]

@jeffschwMSFT I didn't debug this, but I'm thinking it's either runtime/hosting model or CLI?

[jkotas]

The problem is that dotnet run process itself is being terminated by Ctrl+C and exiting. It does not repro if you run the repro directly without the intermediate process, like dotnet bin\Debug\netcoreapp3.0\repro.dll.

This is CLI problem. Looks like a dup of https://github.com/dotnet/cli/issues/812 - see comment at https://github.com/dotnet/corefx/issues/5339#issuecomment-171049771