Re: Open conformance issues & plans

[Rich Felker <dalias@libc.org>]

On Thu, Aug 23, 2018 at 04:41:24PM -0400, Rich Felker wrote:
> (Found by Adelie Linux's efforts to meet POSIX conformance)

Some updates:

> 5. psiginfo
> 
> Wrongly affecting wide/byte orientation of stderr. Needs to take the
> stdio lock itself so it can save and restore the orientation around
> the call to fprintf.

Fixed.

> 6. fileno & non-fd FILEs
> 
> fileno is reportedly returning 0 for memory streams. This seems
> implausible (they all set f->fd=-1) but it definitely is failing to
> set errno to EBADF when f->fd is negative, which it's required to do
> for FILEs without an underlying fd.

Fixed.

> 7. fmemopen & open_[w]memstream
> 
> fmemopen mode w+ reportedly doesn't truncate buffer.

Fixed.

> open_[w]memstream don't pre-set the stream orientation to byte/wide as
> they're supposed to (this is a stupid requirement; conceptually
> there's no reason you couldn't have a wide memstream being written via
> byte operations, or vice versa, but it's a requirement anyway...).

Fixed.

> I think there are other known conformance problems here and in
> open_[w]memstream that weren't reported.

Possibly still open.

> 12. strtof/d/ld and ERANGE
> 
> Apparently they don't always set ERANGE on underflow like they're
> supposed to. Need to investigate whether we're trying and failing or
> what.

Confirmed, but I'm still unsure of the details. For some subnormals
ERANGE is reported, but not for the maximal one or some other
large-ish values I tested.

> There are also several math issues and small details I didn't mention
> which came up in the Adelie testing, which I've omitted here because
> this is getting too long.

A number of other issues were since reported and also fixed:

- Deadlock in async self-cancellation
- Failure of pthread_barrierattr_setpshared to check for invalid arg
- Wrong return value for system() failure (old bug on list)
- Several sysconf values that were wrong
- The wide printf %c didn't honor field width
- Async cancellation was crashingly broken on powerpc64 and sh-fdpic

And some not reported but fixed anyway:

- stderr was not flushed at exit if buffered
- vfprintf of unbuffered stream didn't set orientation or properly
  initialize write mode
- perror wrongly set stream orientation for stderr

Fixing these kind of things while the reports are quickly coming in
has been a big part of what's kept me from making a release, but I
feel like one is way past overdue now and definitely in order. I'm
going to start preparing notes on what's changed, reviewing whether
there's anything else important pending, and try to get one out asap
now.

Rich