hang on exit

Markus Friedl markus at openbsd.org
Thu Feb 14 08:30:07 EST 2002

On Wed, Feb 13, 2002 at 01:15:42PM -0800, Frank Cusack wrote:
> On Mon, Feb 04, 2002 at 08:32:26PM +0100, Markus Friedl wrote:
> > untested, as i don't have access to a system that
> > shows the hang-on-exit problem.
> > +	options->allow_data_loss_on_pty = -1;
> Can someone explain why this has been discouraged for a long time based
> on it "allowing data loss", when on obsd it does this by default?

are you talking about the kernel?

> It
> is my understanding that a patch like this has not made it into the distro
> because of concerns that an active background process might have data to
> send us.

all other patches did discard data for the non-pty case, too, and this
is not acceptible.

nobody can tell us why sshd receives an EOF when reading from a pty if
there are backgrounded processes on BSD systems and not on other

i sent this patch to so people can test whether discarding data
would indeed help for the hang-on-exit problem, so that we can
decide whether we do this by default. this would match the telnetd
behaviour, but sshd != telnetd, and i really don't like the idea
of loosing data.


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