In my previous post, I showed how MDbgEngine (available on NuGet) can be used to stop a process when an exception is thrown, and how a minidump can then be created to enable post-mortem debugging.

Using MDbgEngine, you can do much, much more – and all with a very high-level API.Have a look at how you can print a call stack (with argument values!):

process.PostDebugEvent +=
    (sender, e) =>
    {
        log.Log(e.CallbackType.ToString());

        if (e.CallbackType == ManagedCallbackType.OnException2)
        {
            var ce = (CorException2EventArgs)e.CallbackArgs;

            if (ce.EventType == CorDebugExceptionCallbackType.DEBUG_EXCEPTION_FIRST_CHANCE)
            {
                var thread = process.Threads.Lookup(ce.Thread);

                foreach (var frame in thread.Frames)
                {
                    if (!frame.IsManaged || frame.Function.FullName.StartsWith("System."))
                        break;

                    log.Log("{0}({1})", frame.Function.FullName, string.Join(", ", frame.Function.GetArguments(frame).Select(
                        arg => string.Format("{0} = {1}", arg.Name, arg.GetStringValue(false)))));
                }
            }
        }
    };

This code, when attached to an example process, printed logged the following information:

OnException2
AspNet.Default.B(i = 3, t = "test 2")
AspNet.Default.A(i = 1, t = "test")

PADRE – Pluggable Automatic Debugging and Reporting Engine

In the previous blog post, and on Twitter, I’ve already mentioned the idea of turning this into a project. The above sample code is now available on GitHub, along with some boilerplate code in MEF, to make it truly pluggable and a sample ASP.NET application throwing exceptions.

Just open the solution, run it and go to the ASP.NET application to click Button 2. You should get a stack trace in the console window like above.

I’d love to hear some feedback!