Re: odd ATF failure for sh: ulimit_redirection_interaction failed

[Robert Elz <kre%munnari.OZ.AU@localhost>]

OK, I see what is going on now.

The difference for you is your initial ulimit -n
value.  Not that it is big, but that when
reduced the way that test does it, getting
smaller and smaller till < 16, it happens to
land on a value < 10 as the first such limit
it tries.  Using the default max fd value
doesn't do that, it reaches 15 or something
and stops.   sh does not work well with less than
10 available fds.

Two things I need to do ... second make the
test more rational in its ulimit choices, not
going under 10 where things get weird.

But first, make sh give a better inducation what
the problem is when this kind of thing does
happen.

The error message produced is one that should
normally never be seen, while it is related
to the >&18 it was doing, that operation is
not where the error happened (if that failed
you"d get a much more rational error msg).

Rather, the problem is that echo is a builtin
(change it to be /bin/echo and apart from
being slower it will probably work)

When there are redirections in builtins, the
existing fd (if any) must be moved elsewhere
so it can be restored after the builtin exits.
sh always moves to a fd > 10 for this use.

When the limit is < 10 that fails, and that's
the cause of the problem.

I will fix, sometime soon - sh first so you
can confirm a more rational error msg, and
then the test to avoid generating this
situation.

kre

ps: attempting to follow fd usages inside sh
is not something for the faint of heart.