Thread: Re: [HACKERS] [PATCHES] fork/exec patch

Re: [HACKERS] [PATCHES] fork/exec patch

From
"Magnus Hagander"
Date:
Arrgh - hit send too fast!

>BTW, for the record, here is a quick view of how to make
>actual interrupting calls into another thread. I think you can
>see why I do't think that's a really good option..
>
>When calling the signal, run:
>SuspendThread(mainThread);
>GetThreadContext(mainThread);
save away IP
change IP of context to a *known invalid address*
SetThreadContext(mainThread);
ResumeThread(mainThread);


this means that as soon as the main thread gets back into userspace, it
will throw an EXCEPTION_ACCESS_VIOLATION.


Then you have to wrap the entire backend in a
__try
  backend goes here
__except

Then in the exception handler, you have to check that it was the correct
ACCESS_VIOLATION, do the signal handler, and then tell the exception
handler to continue working where it last was
(EXCEPTION_CONTINUE_EXECUTION).


Downside? This one does *not* fire if the thread is "stuck" in a kernel
call such as.. Yes. WaitForSingleObject(), etc - just the sam eones that
the other solution requires.


This is messy... :-)

//mha