// csc signal.cs

using System;
using System.Diagnostics;
using System.Threading;
using System.Runtime.InteropServices;

[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
delegate void SignalHandler(int sig);

public class SignalTest {

    [DllImport("msvcrt.dll", PreserveSig = true)]
    static extern int raise(int sig);

    [DllImport("msvcrt.dll", PreserveSig = true)]
    static extern SignalHandler signal(int sig, SignalHandler handler);

    // Store in a static to prevent it from being garbage collected
    static SignalHandler _Handler = new SignalHandler(MyHandler);

    const int SIGINT = 2; // Ctrl-C
    const int SIGFPE = 8;
    const int SIGTERM = 15; // process termination
    const int signalToTest = SIGFPE;

    static string GetCurrentThreadInfo() {
        return String.Format("{0}({1})", Thread.CurrentThread.Name, Thread.CurrentThread.ManagedThreadId);
    }

    static void MyHandler(int sig) {
        Console.WriteLine("Signal {0} raised on thread {1}", sig, GetCurrentThreadInfo());
        Console.WriteLine(new StackTrace());

        signal(sig, _Handler); // reinstall handler so that we can keep looping

        Console.Write("In handler. Press any key...");
        Console.ReadKey();
    }

    static void RunTest() {
        Console.WriteLine("Test thread : " + GetCurrentThreadInfo());
        signal(signalToTest, _Handler);

        while(true) {
            Console.Write("Press any key (q to abort)...");
            ConsoleKeyInfo keyPressed = Console.ReadKey();
            if (keyPressed.KeyChar == 'q') {
                break;
            }

            Console.WriteLine("Raising signal...");
            // raise(signalToTest);
            double y = 0.0;
            double x = 1.0 / y;
            Console.WriteLine(x);
        }

        Console.WriteLine("Done");
	}

    public static void Main(string[] args) {
        Console.WriteLine("Main thread : " + GetCurrentThreadInfo());

        // Create a new thread to show that raise runs the handler on the thread raise is called 
        // from, not necessarily on the main thread
        Thread thread = new Thread(new ThreadStart(RunTest));
        thread.Start();
        thread.Join();
    }
}