Re: undefined behavior in closeout, aggravated by libsigsegv

[Eric Blake]

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According to Bruno Haible on 11/22/2009 5:32 AM:
> Eric Blake wrote on 2009-07-18:
>> fileno(stdout) == 1 by definition of STDOUT_FILENO, so you don't
>> have to go via fileno (you can directly use fcntl(1,...) to learn whether
>> the fd has been closed).
> 
> But the user might have called freopen (..., stdout). In this case,
> fileno (stdout) will no longer be 1.

That is ONLY possible if both:
stdin was closed
the user is not using freopen_safer

in which case the fd will be 0 instead of 1.  There is no way for
freopen() to ever make fileno(stdout) ever be greater than 1.

> So you actually do have to use
> fileno (stdout) in the patch that you committed on 2009-07-18
> <http://lists.gnu.org/archive/html/bug-gnulib/2009-07/msg00040.html>
> 
> Here is a proposed patch:

I'd rather make the patch conditional on whether freopen_safer is also in use.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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