Memory Violation Dynamically Appending to Methods at runtime

Question

Disclaimer: I\'m doing this for learning purposes. This is not going to be used in code.

I\'m trying to understand how method table are structure fo

Answer 1

I suppose you have already seen: Dynamically replace the contents of a C# method?

I have adapted some of those methods in my own project @ https://github.com/juliusfriedman/net7mma_core/blob/master/Concepts/Classes/MethodHelper.cs

I think the problem is that if your are running with the Debugger Attached then you need to also handle the portion of the logic which is currently defined by IFDEF at compilation time and replace that with an System.Diagnostics.Debugger.IsAttached although the offsets calculations (to jump over the debugger injected code) will probably have to change depending on various things like the version of the framework in use.

See https://github.com/juliusfriedman/net7mma_core/blob/master/Concepts/Classes/MethodHelper.cs#L35

This works for me in .Net Core 3.1 when the debugger IS NOT attached and I am running in Release mode, when running in Debug mode with or without the debugger attached or in Release mode with the debugger attached I receive different exceptions. (In debug I receive Arithmetic Overflow, while in release I receive Execution Engine Exception).

Furthermore this only works until the JIT Tiering kicks in, if I run the method a 2nd time without the debugger attached I am getting a Internal CLR Error.

I believe this has to do with the code injected by the debugger when attached and to be honest I am not up to do date on exactly what the debugger is injecting when attached.

I would make a simplified repo of the problem and ask a question @ https://github.com/dotnet/runtime if you need this to work with the debugger attached and I am sure someone there will guide you in the right direction.