Bug#841935: pbuilder: incorrect permissions on /dev/ptmx breaks openpty()

[Thorsten Glaser]

Simon McVittie dixit:

>If you do a `pbuilder login` (or use your failing-build hook) and run
>tty(1) at the resulting prompt, what do you get?

(pbuild5766)root at tglase:/# tty
not a tty

>I'm surprised by this. I would have expected that interactive use of
>tty things inside pbuilder would have started failing when you upgraded
>to a v4.7+ kernel, because the /dev/pts inside the chroot would no longer
>be able to "see" the terminal that is on pbuilder's stdin.

Interestingly enough, the shell does still work. According to
strace, this is because /dev/tty is still operable.

>I should point out that if your chroots are sufficiently old, and you
>are operating via an "upgrade old chroots" model, then the chroots are
>not as minimal as they should be (for instance init is no longer Essential

I know, which is why I said manual package cleanup above.

>in stretch). However, you're using pbuilder and not sbuild, so you
>have already accepted some risk of having your build environment not match
>official buildds' build environments.

Indeed, but that’s actually not a bad thing (I think) because
such diversity often happens to catch a class of bugs. After
all, sbuild isn’t error-free, and the official buildds aren’t
the official definition of the environment (only the other way
round, they try to get close to that). I resurrected an entire
ports architecture with cowbuilder and hand-written shell scripts
AND set up buildds afterwards so I’m quite aware ☺

But let’s not get too OT here ;-) I’m sure you meant well.

bye,
//mirabilos
-- 
Yay for having to rewrite other people's Bash scripts because bash
suddenly stopped supporting the bash extensions they make use of
	-- Tonnerre Lombard in #nosec