Bug#43023: libc 2.1.1-10 makes it impossible to use stdout reliably

[Ian Jackson <ian@davenant.greenend.org.uk>]

H.J. Lu writes ("Re: Fwd: Bug#43023: libc 2.1.1-10 makes it impossible to use stdout"):
> I cannot duplicate your testcase. A gdb backtrace may help.

*cough*

Interestingly, neither could I - the libc6 2.1 machine I have here
didn't work properly.  It turns out that if you have the Debian
libc6-dev 2.0.x but our libc6 2.1.x runtime then it doesn't work.
That it is possible to install that combination is due to a completely
unrelated bug in dpkg (which is my fault).  If I install libc6-dev
version 2.1.x then things work correctly - ie, my program can fclose
stdout without segfaulting.

My apologies for wasting your time.

Clearly, after having just got egg on my face, I'm reluctant to push
my view that the default behaviour of the libc should be changed so
that programs which fail to fclose stdout are made reliable
retrospectively.  But, I still believe this: there is a great deal of
code that fails to fclose stdout before exiting, and more is being
written all the time.  The alternative to changing the libc is a
massive code review and education campaign.

Joel: as a matter of general procedure, I think you should try to
reproduce bugs before you pass them upstream - especially things like
libc bugs.  If you can't reproduce them then the user (me in this
case) has probably done something wrong and there is no need to bother
the upstream maintainer if you can figure out what it is.

That's not to say that users shouldn't check for having screwed up ...

Thank you all, and my apologies again.

Ian.