Re: close(2) failure cases (was: some fixes to musl)

[Rich Felker <dalias@aerifal.cx>]

On Sun, Jul 24, 2011 at 01:19:18PM +0400, Vasiliy Kulikov wrote:
> I've looked at some Linux code related to close().  It may fail iff
> file_ops->flush() is not NULL, and close() fails iff ->flush() fails.

Thank you for making the effort to investigate!

> Even if close() fails, the fd is freed.  So fd leakage is impossible.

Is this true even in the case of EINTR?

> As musl is Linux specific libc, you're free to rely on Linux specific
> restrictions/features.  However, I don't know whether close()
> implementation is guaranteed to be errorless for these types of files.
> If no, it may be changed in the future by introducing some new feature
> (and it will not break POSIX as POSIX explicitly defines close()
> failure possibility).  It's very unlikely though, as breaking tons of
> programs relying on implicit Linux behaviour is not encouraged by Linus.

Not only does it break lots of programs; it also makes fixing those
programs impossible. There is simply no way to recovery from failed
resource deallocation. (Think of C++ and RAII...)

Rich