[Win32] Remotely execute functions of a D program

[Rainer Schuetze]

On 14.09.2012 20:53, alex wrote:
> On Friday, 14 September 2012 at 18:35:53 UTC, Sean Kelly wrote:
>> On Sep 14, 2012, at 10:34 AM, alex <info at alexanderbothe.com> wrote:
>>
>>> 1) So to anyone who's got richer experiences in programming assembler
>>> and hacking/'debugging' programs than I - how would you do it?
>>> 2) And why can't I inject a D DLL right into the program? I tried it
>>> with a C DLL, it's working with that one, but then I don't have
>>> access to D-specific functions..
>>> Looking at that, would it make a difference to use dmc to build/link
>>> a dll as a D/C++ hybrid or something?
>>
>> You might want to check the madCodeHook library.  It works well, and
>> there's a version that includes source code.  Though now that I check
>> the site, it doesn't look like you can get the source-included one for
>> free any more.
>
> The primary injection routine and how it works is not the problem - I
> can successfully insert a MSVC++ Dll without any problems into a D
> program. (I've used this https://github.com/jeffora/extemory library btw
> - it's for c# :-))
> Anyway, on a DLL built with dmc or dmd 1/2, the main program immediately
> crashes or unloads the dll when returning false in the DllMain()
>
> So how to insert a D DLL into a D program?

I recently implemented an injection DLL aswell, in D, but without any 
runtime library: 
https://github.com/rainers/visuald/blob/master/tools/filemonitor.d

The command line to build it is
dmd -offilemonitor.dll -defaultlib=user32.lib -L/ENTRY:_DllMain at 12 
filemonitor.d

It also crashed when using the standard DLL framework, my suspicion is 
that the druntime-initialization isn't properly run for the injected 
DLL. If you are creating the process suspended, the main thread cannot 
run, so initialization might have to be done differently. But I haven't 
investigated any further, I was fine with just using the Windows API.

For C/C++ the VS debugger can already call functions in the debuggee as 
a side effect to watch expressions, so it should work for D aswell. It 
might be a little complicated to specify the correct symbols, though.

To improve debugging experience in VS I think the better approach would 
be to extend the capabilities of mago, the debug engine explicitely 
built for dmd generated executables. Unfortunately development of it has 
stalled.