Mail Archives: cygwin/2005/02/17/07:15:28
On Feb 14 21:19, Eric Blake wrote:
> Corinna Vinschen <corinna-cygwin <at> cygwin.com> writes:
> > > With coreutils 5.3.0-2 and various snapshots, I am seeing regressions in
> shred(1)caused by cygwin changes:
> >
> > As far as fsync is affected, I don't see how that could ever fail, except
> > the Windows call fails for some reason. The fsync code hasn't changed
> > for quite some time.
>
> I found what is causing this. Coreutils shred uses the following code:
> int dir_fd = open (dir, O_WRONLY | O_NOCTTY);
So it tries to open directories for writing despite of POSIX not allowing
this? How weird.
> POSIX requires that open fail with EISDIR on open with O_WRONLY or O_RDWR on a
> directory, and you implemented that in a patch on Jan 6. So with 1.5.12, shred
> got a writeable fd from the first open, but with snapshots after Jan 6 it has
> only a readable fd from the second open. But fsync() is implemented with
> FlushFileBuffers, which requires write access to the handle it is about to
> flush, so it now fails with EACCES.
>
> I don't know if it is better to patch open_fs() to additionally grant
> GENERIC_WRITE access when opening directories as O_RDONLY (since that is the
> only way to open a directory), or to patch fsync() to temporarily grant write
> access to a directory for the duration of the flush. But it is a definite
> regression from 1.5.12 that should be fixed.
>
> I also think that fsync() could be patched to return EINVAL on non-directory
> file descriptors that were opened as O_RDONLY, rather than performing a failed
> FlushFileBuffers and getting EACCES, as a closer match to the errors allowed by
> POSIX. http://www.opengroup.org/onlinepubs/009695399/functions/fsync.html
I'm pretty busy with non-Cygwin stuff at the moment. But you know,
http://cygwin.com/acronyms/#PTC .
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader mailto:cygwin AT cygwin DOT com
Red Hat, Inc.
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