OpenEuphoria

Re: BREAKing into Euphoria

• Posted by Andy Drummond <andy at k?strel?ele.com> Sep 12, 2007
• 1952 views

Pete Lomax wrote:
> 
> I got some "interesting" results (random crashes mainly) from this, however
> enough of it works to show that something is possible (comments, Rob?):
> Maybe there is a generic problem with trace in call_back routines??
> 
> }}}
<eucode>
> -- NOTE: this is probably incompatible with allow_break/check_break().
> with trace
> 
> include misc.e
> 
> constant CTRL_C_EVENT	    = 0,
> 	 CTRL_BREAK_EVENT   = 1
> 
> function HandlerRoutine(integer event)
>     if event = CTRL_C_EVENT
>     or event = CTRL_BREAK_EVENT then
> trace(1)
> sleep(2)
>         return 1	    -- handled
>     end if
>     return 0		    -- not handled
> end function
> 
> atom kernel32, xSetConsoleCtrlHandler, cbHR
> include dll.e
> 
>     kernel32 = open_dll("kernel32.dll")
> 
>     xSetConsoleCtrlHandler = define_c_func(kernel32,"SetConsoleCtrlHandler",
> 	{C_POINTER, --	PHANDLER_ROUTINE  pHandlerRoutine,  // address of handler
> function
> 	 C_INT},    --	BOOL  fAdd  // handler to add or remove
> 	C_INT)	    -- BOOL
> 
>     cbHR = call_back(routine_id("HandlerRoutine"))
>     if not c_func(xSetConsoleCtrlHandler,{cbHR,1}) then ?9/0 end if
> 
> with trace
> 
> while 1 do
>     puts(1,"sleeping\n")
>     sleep(2)
>     puts(1,"awake\n")
> end while
> </eucode>
{{{

> 
> I suspect that if you could somehow call the trace(1) in HandlerRoutine but
> not then trace any lines in that code, it might actually work.
> 
> When not interpreting source, or under an allow_break(False), then Ctrl Break
> should not attempt to fire up the trace window, otherwise it should.
> I don't think changing Ctrl C is a good idea, too easy to accidentally hit,
> plus eg Edita happily uses it for Copy w/out problems as is.
> 
> Regards,
> Pete

Pete,
That look pretty much what I was after. I understand that it might well not be 
possible to trace once the break has been executed, but if I can tell where I
am in the program then I can start the safer but more laborious technique of 
putting in trace(1) - or even trace(3) - calls. At present I have no idea
where I am executing when everything dies on me. I just need to go Click!
and find out which line of the program was executing at the time.
We will see...
Andy