From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alexander Larsson <alexl@redhat.com>
Subject: Re: interface to ask is a file is hidden
Date: Mon, 13 Oct 2008 12:59:57 +0200
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Cc: Theodore Tso <tytso@mit.edu>,
	=?ISO-8859-1?Q?Nicol=F2?= Chieffo <84yelo3@gmail.com>,
	Jeremy Allison <jra@samba.org>,
	Szabolcs Szakacsits <szaka@ntfs-3g.org>,
	Josef Bacik <jbacik@redhat.com>, linux-fsdevel@vger.kernel.org
To: Anton Altaparmakov <aia21@cam.ac.uk>
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On Mon, 2008-10-13 at 08:29 +0100, Anton Altaparmakov wrote:
> Hi,
> 
> On 10 Oct 2008, at 22:57, Theodore Tso wrote:
> > Ext3 has no concept of "hidden file".  Niether does ext2, ext4, jfs,
> > xfs, reseirfs, ufs, etc.
> >
> > The only ones that would have that concept is vfat (which supports
> > fat16/fat32), ntfs, nfsv4 and cifs/smbfs.  Even a filesystem which
> > normally has very bad taste, MacOS's HFS, doesn't support the hidden
> > attribute.
> 
> Sorry but you are somewhat wrong: UFS, HFS/HFS+, ZFS, and AFP all  
> support the UF_HIDDEN file flag (in addition to the ones you state  
> above).

FreeBSD seems to have added UF_HIDDEN to struct stat.st_flags back in
2006:
http://updraft3.jp.freebsd.org/cgi/query-pr.cgi?pr=kern/94519

They also have other useful flags like immutable, append only, no dump,
etc that certainly apply to ext3 too (i.e. these are settable with
chattr).

Sounds like a very good idea to me. There is even availible unused space
in the userspace/glibc struct stat to add them, and there seems to be
some in the kernel struct too.

They also have chflags/lchflags/fchflags to change these attributes.