From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: fstat st_size on open files on Parallels filesystem is wrong
Date: Wed, 21 Oct 2015 11:07:00 -0000 [thread overview]
Message-ID: <20151021110734.GO5319@calimero.vinschen.de> (raw)
In-Reply-To: <22038.38637.802707.846218@compute03.cs.columbia.edu>
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On Oct 8 12:16, Jonathan Lennox wrote:
> Hi, following up on this issue from last year. The message I'm replying to
> is at <https://cygwin.com/ml/cygwin/2014-04/msg00524.html>.
>
> The problem is weird behavior in Parallels Desktop-hosted Windows VMs, when
> accessing the host's native Mac OS X filesystem. See the thread for the
> details.
>
> On Wednesday, April 23 2014, "Corinna Vinschen" wrote to "cygwin@cygwin.com" saying:
>
> > > At this point this is looking pretty clearly like a Parallels Tools bug.
> > > I'll report it to them.
> >
> > Yes, that sounds good. Given that, I'm wondering if we should try to
> > workaround this problem at all or rather wait to see if the vendor will
> > fix the issue.
>
> No such luck, despite two major version revisions of Parallels Desktop (I'm
> now on version 11.0.2) and moving to Windows 10 as the guest OS -- the bug
> perists, unchanged. So it looks like Cygwin will need to add a workaround
> for this filesystem to fix the problem.
Ok, we could do that. Can you compile and run the testcase from
https://cygwin.com/ml/cygwin/2014-04/msg00523.html again? Does it
still show 0 vs. 12 bytes? Dumb extra test: Does the output change
if you reorder the calls, requesting FileStandardInformation first,
FileNetworkOpenInformation second?
> The output of /usr/lib/csih/getVolInfo seems to be unchanged from the output
> I reported last year.
>
> > Thanks. This looks pretty much like a filesystem pretending to be
> > FAT-like. There may be another problem lurking, which is, are the inode
> > numbers (called "FileId" or "IndexNumber" in Windows) persistant? With
> > FAT this is not the case, and given the above, it might be a problem...
> >
> > ...or not. I just realize that Cygwin doesn't even try to use the
> > FileId as inode number on filesystems with FILE_PERSISTENT_ACLS==FALSE
> > so, never mind.
> >
> > OTOH, does it support hardlinks? If so, two hardlinks to the
> > same file would have different inode numbers on Cygwin.
>
> How would I figure these points out?
Just create a hardlink on that drive using native means:
$ touch foo
$ cmd /c mklink /h bar foo
Error at this point? No hardlinks. Otherwise:
$ ls -li foo bar
Are the inode numbers identical? Congrats, hardlinks work. But given
the general FAT-iness of the getVolInfo output, I guess it doesn't
maintain hardlinks.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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next prev parent reply other threads:[~2015-10-21 11:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-21 18:27 lennox
2014-04-21 18:35 ` Andrey Repin
2014-04-21 18:46 ` lennox
2014-04-22 8:16 ` Corinna Vinschen
2014-04-22 16:09 ` lennox
2014-04-22 20:57 ` lennox
2014-04-23 8:41 ` Corinna Vinschen
2014-04-23 16:47 ` lennox
2014-04-23 17:24 ` Corinna Vinschen
2015-10-08 16:16 ` Jonathan Lennox
2015-10-21 11:07 ` Corinna Vinschen [this message]
2015-11-02 9:38 ` Jonathan Lennox
2015-11-02 11:23 ` Corinna Vinschen
2015-11-02 13:08 ` Jonathan Lennox
2015-11-02 14:06 ` Corinna Vinschen
2015-11-02 22:05 ` Jonathan Lennox
2015-11-03 12:19 ` Corinna Vinschen
2015-11-04 6:35 ` Jonathan Lennox
2015-11-04 9:45 ` Corinna Vinschen
2015-11-02 12:52 ` cyg Simple
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