Re: line BRK detection on ttyS0

Mark Hounschell
2010-09-23T20:48:16Z

On 09/22/2010 08:03 PM, Alan Cox wrote:
> On Wed, 22 Sep 2010 15:36:48 -0400
> Mark Hounschell <markh@compro.net> wrote:
>
>> Does the kernel support sending a SIGINT from a line BRK on ttyS0 to a thread of a process
>> where the process has a controlling terminal that is NOT ttyS0 and the thread is using ttyS0
>> in a cfmakeraw mode? I see doc that implies that ttyS0 must be the controlling terminal but
>> can my thread have a controlling terminal while my main process has it's own ?
>
> If they have two different ttys open then yes at least as far as Linux is
> concerned. I don't know how glibc handles it as it can do signal groups
> and the like and delivery of signals to process not threads etc.
>
> You can see parity anyway. In PARMRK mode you get \377 \0 [whatever] for
> parity/break etc but \377 is also doubled for a real one - ie \377 \377
>

\377 \0 or [whatever] just looks like valid data to my thread though.
So you're saying it's gonna be a glibc thing and not a kernel thing that
prevents my thread from getting a signal?

Thanks
Mark