How to attach a process to the current debugger programmatically?

Question

I have 2 projects in the solution that compile to A.exe and B.exe
A will start B and connect to it through a named pipe. I want to test the connection between them so I'd like to attach to both at the same time. Doing that manually every time is very tedious and inconvenient, especially when B will close after a timeout if it doesn't receive any data from A. Therefore I tried this

if (IsDebuggerPresent())
    DebugActiveProcess(processId);

However it seems B is attached to A's debugger instead of Visual Studio's. So how can I attach B to VS debugger automatically?

I have windbg at hand for debugging crash dumps so it may also be a solution, as long as it can be done without multiple user interactions

Answer 1

Attach to a process B programatically

Method 1: Using VS

1. Open B.vcxproj and not your solution (.sln containning projects A and B)
2. Put your breakpoints

3. Run this dos command from your project A via system() (or other variant):

   devenv /nosplash /run "G:\Logiciels\B\B.vcxproj" /nosplash /debugexe

4. devenv is a command in your VS path. In my case it in:

   C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC

5. When you run this command, B project is opened and break point reached.

Method 2: Using Windbg

Just call this command:

windbg -p ProcessID

Attach to a process B graphically

Open your B project in another instance, and attach to it like this :

And select your B.exe: