[RFC v1] man/man2/close.2: CAVEATS: Document divergence from POSIX.1-2024

[Vincent Lefevre]

On 2025-05-17 09:32:52 -0400, Rich Felker wrote:
> On Fri, May 16, 2025 at 04:39:57PM +0200, Vincent Lefevre wrote:
> > On 2025-05-16 09:05:47 -0400, Rich Felker wrote:
> > > FWIW musl adopted the EINPROGRESS as soon as we were made aware of the
> > > issue, and later changed it to returning 0 since applications
> > > (particularly, any written prior to this interpretation) are prone to
> > > interpret EINPROGRESS as an error condition rather than success and
> > > possibly misinterpret it as meaning the fd is still open and valid to
> > > pass to close again.
> > 
> > If I understand correctly, this is a poor choice. POSIX.1-2024 says:
> > 
> > ERRORS
> >   The close() and posix_close() functions shall fail if:
> > [...]
> >   [EINPROGRESS]
> >     The function was interrupted by a signal and fildes was closed
> >     but the close operation is continuing asynchronously.
> > 
> > But this does not mean that the asynchronous close operation will
> > succeed.
> 
> There are no asynchronous behaviors specified for there to be a
> conformance distinction here. The only observable behaviors happen
> instantly, mainly the release of the file descriptor and the process's
> handle on the underlying resource. Abstractly, there is no async
> operation that could succeed or fail.

Sorry, this is old. But a consequence may be memory leak if something
unexpected occurred during what was done asynchronously. There is no
guarantee that *every* resource has been released.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)