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@cygwin.com Red Hat, Inc. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
