Is it considered to be ok to not check the return code of close(2) in base?

[Rodney W. Grimes]

> On 01/08/2018 10:55, Rodney W. Grimes wrote:
> >> 08.01.2018 23:13, Eric van Gyzen wrote:
> >>
> >>> Right, which is the reason such bugs are hard to diagnose.  Optionally
> >>> killing the process on close->EBADF would help find buggy code when
> >>> another thread did NOT re-open the file descriptor between the two close
> >>> calls.
> >>
> >> Wouldn't "close(f); assert(errno != EBADF);" be better?
> 
> Putting the code in one place is far better than putting it in N
> places...after /finding/ those N places.  Indeed, the purpose of this
> code is to help people find those places, even in their own code,
> outside of base.

I agree with that.

> > Or even
> > #ifdef DEBUG_CLOSE
> > #define close(f)	close(f); assert(errno != EBADF);
> > #endif
> 
> errno could have been EBADF before the close().  A successful close()
> does not modify errno.  So, this would have be larger, making it even
> more unpalatable.

Ok, so lets get a bit more clever,
#ifdef DEBUG_CLOSE
#define	close(f)	assert(close(f) && errno != EBADF)
#endif

There, now only if close failed do we check errno,
how does that work for you?

And if it doesnt I am sure you can code up a #define that does
work well.

> 
> > Then the people that want to go chasing these errors can,
> > and the rest of us are untouched.
> 
> Every mention in this thread of killing the process has called it
> optional.  Tools, not policy.

I am not certain on that, I think some of the proposals seemed
to make the change non optional, but maybe I was reading too
much between the lines.


-- 
Rod Grimes                                                 rgrimes at freebsd.org