Mail Archives: cygwin/2002/01/08/17:17:23
----- Original Message -----
From: "Christopher Faylor" <cgf AT redhat DOT com>
> On Tue, Jan 08, 2002 at 06:00:16PM +1100, Robert Collins wrote:
> >FWIW this patch (Chris where should I put the in_stub declaration)
>
> There is already an indicator that an execed process is running --
> hExeced, so I don't think you need the 'in_stub' thing.
No, hExeced is set far too early... There is a very narrow window where
we want to ignore CTRL-C.
> However, it seems to me that this solution is racy. If a person types
> CTRL-C during process startup, it's possible that a cygwin process
will
> never see a true cygwin signal. Hmm. I guess this race is already
> in signal_exit, in fact. I have to fix that.
Yes there is. I asked for thoughts, but got none :}. However, note the
requirements to drop the signal:
* The process startup must be in _P_OVERLAY mode.
* The new process must have successfully been created.
* Their must be no cygwin parent to the spawning process, or the
spawning process must be the top of the process group.
* The new process must not have signalled it's creation back to us.
> Regardless, it is not always the correct behavior for CTRL-C just do
> the "default thing". If the execed process is supposed to be ignoring
> SIGINT then it isn't right for the process to exit.
Hangon, look closer.
If the execed process is a *cygwin* process, then my patch makes no
difference - the stub is about to quit no matter what, and from a POSIX
point of view, already has!
If the execed process is not a cygwin process, then it will handle (or
not) CTRL-C itself. We should *not* force quit it when the stub recieves
CTRL-C.
I don't reinstate default behaviour, we simply ignore the keyboard
generated CTRL-C which we know that the non-cygwin child has already
recieved.
> Also, your change seems to make no distinction between a spawned and
> execed process. It looks like if the user had called spawn, a CTRL-C
> would just cause the parent process to die.
No, if the user had called spawn, with mode != _P_OVERLAY, then this
patch makes no difference.
If the user had called spawn with mode == _P_OVERLAY and it's spawning a
cygwin program then the user will notice no difference, or worst case a
_perfectly timed_ CTRL-C is ignored. (Note: Ctrl-Break is not altered).
If the user had called spawn with mode == _P_OVERLAY and it's spawning a
non cygwin program then the user will notice no difference - the non
cygwin program will handle it's own CTRL-C.
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