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Date: Fri, 8 May 2015 13:43:16 -0400
From: Mathieu Laprise <>
Subject: Re: [core john] [Johnny] Windows event loop

On Fri, May 8, 2015 at 12:39 PM, Aleksey Cherepanov <>

> If you AttachConsole(), can't you just send Ctrl-C?
> Though it is not clear to me: does CTRL_BREAK make john to save state
> on exit? Or is it just a way to kill the process?
If you mean sending Ctrl-C to stdin, I saw there,
that it didn't work the same way if we send it with stdin(at least on unix).

If you mean sending CTRL_C_EVENT,
In John, signal.c, all CTRL_XXX_EVENTS are handled by this code for

#ifdef __CYGWIN32__

	SetConsoleCtrlHandler(sig_handle_abort_ctrl, TRUE);


#ifdef __CYGWIN32__

static CALLBACK BOOL sig_handle_abort_ctrl(DWORD ctrltype)



	return TRUE;



So, sending event CTRL_C_EVENT or CTRL_BREAK_EVENT, both call
sig_handle_abord(SIGINT) which will handle cleaning or other stuff needed
by John like if it was from the tty. So john saves its state.

However, in my tests, I got the same result as Shaktra for CTRL_C (returned
true but wasn't sent). Here is what he said on stackoverflow.

> It is very important that each step is done like this. I've been trying
> all different kinds of combinations but this combination is the only one
> that works. You can't send a CTRL_C event. It will return success but will
> be ignored by the process. CTRL_BREAK is the only one that works. Doesn't
> really matter since they will both call ExitProcess() in the end. (EDIT by
> me: In our specific case, we reimplemented the handler so
> sig_handle_abort_ctrl() will be called before)

Aleksey said:

> I am pretty sure that you've tried `taskkill` without /f to kill john
> from cmd. It did not work, right?

Yeah exactly, I didn't get it to work.

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