Date: Mon, 16 Nov 2009 14:56:44 +0100
From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: Seems like treatment of NTFS ADS (foo:bar) changed between 1.5   	and 1.7 but not mentioned in What's Changed
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On Nov 16 13:32, Andy Koppe wrote:
> 2009/11/16 Thomas Wolff:
> > But with it being supported, "foo:bar" *is* a POSIX filename and can quite
> > transparently be handled like a file
> 
> If you create a file called "foo:bar" in Cygwin 1.5, a directory
> listing will actually show a file called "foo" of size 0. You have to
> already know that "foo:bar" exists to access it, and there's no way in
> Cygwin to find those files.
> 
> Furthermore, if you delete the file "foo", you'll also delete
> "foo:bar" and any other ADSs of "foo". Again, something that POSIX
> programs don't expect.

Or, just for kicks, try to create a file "abc:def:ghi" under 1.5 or,
FWIW, under CMD.

> > Moreover, this transparent mapping would also solve the copy/backup problem
> > discussed in the other thread (was it "rsync"?) and actually all problems at
> > once, like including these things in zip archives etc.
> 
> Zip would never know about the ADSs, because they don't show up in
> directory listings. Same in cmd.exe, btw.
> 
> I guess they could be included in Cygwin directory listings, but
> - It would be a chunky piece of work to implement it.
> - It would slow down directory operations.
> - Non-POSIX behaviours would remain: creating "foo:bar" would create
> an empty "foo" and deleting "foo" would also delete "foo:bar" and any
> other ADSs.
> 
> I think they'd need a special API if they were to be supported. Do
> they fit into the xattr stuff?

No, xattrs and ADS are entirely different beasts.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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