From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12239 invoked by alias); 16 Jan 2014 09:16:04 -0000 Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Received: (qmail 12229 invoked by uid 89); 16 Jan 2014 09:16:03 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-6.0 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.3.2 X-HELO: calimero.vinschen.de Received: from aquarius.hirmke.de (HELO calimero.vinschen.de) (217.91.18.234) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 16 Jan 2014 09:16:02 +0000 Received: by calimero.vinschen.de (Postfix, from userid 500) id 436A11A0B1A; Thu, 16 Jan 2014 10:16:00 +0100 (CET) Date: Thu, 16 Jan 2014 09:16:00 -0000 From: Corinna Vinschen To: cygwin@cygwin.com Subject: Re: Extended attributes Message-ID: <20140116091600.GC26205@calimero.vinschen.de> Reply-To: cygwin@cygwin.com Mail-Followup-To: cygwin@cygwin.com References: <006e01cf1066$c5f0e080$51d2a180$%fedin@samsung.com> <20140113141041.GC21977@calimero.vinschen.de> <002f01cf11ba$df28b550$9d7a1ff0$%fedin@samsung.com> <20140115091530.GH10212@calimero.vinschen.de> <001701cf1281$5fc57150$1f5053f0$%fedin@samsung.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="O3RTKUHj+75w1tg5" Content-Disposition: inline In-Reply-To: <001701cf1281$5fc57150$1f5053f0$%fedin@samsung.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-SW-Source: 2014-01/txt/msg00192.txt.bz2 --O3RTKUHj+75w1tg5 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Content-length: 2571 On Jan 16 10:08, Pavel Fedin wrote: > Hello! >=20 > > > What do you think about adding other possible namespaces (system, > > > security, and... don't remember the 3rd one) ? So that when > > > manipulating UNIX archives etc these attributes could be kept along > > > with files ? At least we have one use case now. > >=20 > > That doesn't make sense. Extended attributes as implemented by Windows > > are user attributes, not system attributes. The non-user attributes on > > Linux have a very special meaning to the kernel and/or are restricted > > to privileged users only. Their functionality is already provided by > > other OS functions (as for system.posix_acl_access) or not at all (as > > for security.selinux). >=20 > I know they have special meaning. At the other hand, if we allow > them, we will allow to store them on a filesystem. Wouldn't it be > nice ? This is useful at least for SquashFS image preparation. > I guess for similar reasons we have support e. g. for device nodes > (/dev) with their major/minor numbers. They are also ignored by > Cygwin, and just stored on the filesystem (or do i miss something ?). Yes, the history. The device nodes were a start to implement actual loadable device handler code (application level, not actual device drivers), but for some reason it was never fully implemented. I'm really not inclined to add this. As it is, the NTFS xattr are always treated as user attributes. An NTFS attr "foo.bar" is returned as "user.foo.bar" and when writing, a "user.foo.bar" is written as "foo.bar". Adding other attribute types requires to add some special casing and parsing code to differ user attributes from other attributes without breaking backward compatibility. Also, it will never work correctly on a Samba share, because Samba will always treat the incoming attribute as above. So, if you write an attribute "trusted.md5sum" on a samba share, it will actually be converted to "user.trusted.md5sum" by Samba. Another point is stuff like system.posix_acl_access. It's the underlying implementation of POSIX ACLs on Linux, so an application with sufficient access rights could read and write the content directly, rather than using the system calls. But the surprise from the application point of view is, the "system.posix_acl_access" xattrs will have no effect in terms of permissions. Having said that, http://cygwin.com/acronyms/#PTC. Corinna --=20 Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat --O3RTKUHj+75w1tg5 Content-Type: application/pgp-signature Content-length: 819 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJS16NQAAoJEPU2Bp2uRE+gEjcP/1Tti95fN90QaP0fBjK5tW0x xbdDasodJdIYrfxx2RCSwJfNeZkYYEuFAWd31BaSnWO9yv5gnL4PDEGG1HI5R4E2 iuNVyTrdI2i+Hzj/mXVVzQRhK4ZGI9YqsaZraer/f8duAAR+QK9EHWJRt22Ijo75 wlt7ORKI5fPSDsBYFiT0373F5r+ciXXHy6bImBXTQ0xmEgWpRvHMlpKCD5F3pZ/4 ODWGogvMOsbrpsFVZgBGjaSoI6urUEAdme2JFg7XqrdzP55yRRJEvXSEy31AV9W+ W9j+SkV+JVKSnMOaB1nI8+NghMlWNSNsUaO+nvGzPcvAHBZAtWjZGBAajdj14e+G e2A01nl+rauwq4KfDXLbc2eBzYIOjEoJ0Ntf0N2BQdZG/gm862pmzHOHRA9LJp28 kdhkRG9j1I2qZF/52+wHmumxAy9uTOuJPreCBJrmLUB/7bI5MUU6y2Ma5sL7Vgwh 4ErGDoEmbFVvK5eBKveNWDpypfatkLOSClZ4GbUaF2Y8/35RLlvd1GvpOlUztjOH FDAsC66KTsx6NR5KmEiTZi8oSYIDNT97vbP1Tb/LnJ9RS7RQqCuWaaVWsQh2TnBO DikvjPEFTwAJwp+6MkXh4yqTm3dnbDzl7Qwa8ly3yw6AoSJkiio2iu19gt9dMaUb 2fSDYxsEtfS5h3/+1H97 =4mf6 -----END PGP SIGNATURE----- --O3RTKUHj+75w1tg5--