Re: [Bug-tar] ACL support in git version of GNU tar

[Markus Steinborn]

I have rebased my patches to GNU tar 1.28 - clone the git repository 
git://gitorious.org/tar-fcaps/tar-fcaps.git to access them and look in 
the branch pu (ACL patches) and pu2 (Capabilities patch).

If you wonder: I am using the version in branch "msteinborn-1.28".


Greetings from Germany

Markus Steinborn



Markus Steinborn wrote:
> I've still no decision about the following - let me add one note to it:
>
> Patch 2 of the series contained a bug - take the attached file as a 
> replacement.
>
>
>
> Markus Steinborn wrote:
> > What about the following patches?
> >
> > Markus Steinborn wrote
> > > Hi,
> > >
> > > I'd like to remember of the following bug report and to announce 
> > > that I have finished patches for all these issues.
> > >
> > > I have submitted my patches to redhat (as they currently apply clean 
> > > on a redhat patched tar 1.27.1). See 
> > > https://bugzilla.redhat.com/show_bug.cgi?id=1052876 for them.
> > >
> > > If you are ready to accept that patches (and only then, currently I 
> > > have quite limited time) I would rebase the patches to tar master.
> > >
> > >
> > > I also want to remind of 
> > > http://lists.gnu.org/archive/html/bug-tar/2013-04/msg00024.html: 
> > > where "Paul Eggert" writes "That sort of thing all sounds 
> > > reasonable, I guess. I'd like Sergey's opinion though.". What is 
> > > your opinion to this, Sergey?
> > >
> > >
> > > Greetings from Germany
> > >
> > > Markus Steinborn
> > > GNU gv maintainer
> > >
> > >
> > >
> > > Markus Steinborn schrieb:
> > > > Hi everybody,
> > > >
> > > > Today I noticed that GNU tar (git master) now supports XATTRs, ACLs 
> > > > and SELINUX-Attributes. I am really pleased to read this in "git 
> > > > log". Congratualtions for this improvement. The improvements do not 
> > > > break star und redhat tar compatibility.
> > > >
> > > > Having used Redhats patch for many years now (and an improved 
> > > > version which I made), I am able to enumerate a few points that 
> > > > IMHO need improvement:
> > > >
> > > >
> > > > (1) tar archive creation with "--numeric-owner" option:
> > > >
> > > > In this case, users are expectiing that the archive does not 
> > > > contain any symbolic owner name, so it can be extracted to an emoty 
> > > > hard disc on a system bootet e. g. by a rescue cd from Redhat. 
> > > > Current sitation is that ACLs still include the symbolic owner and 
> > > > not the numeric owner.
> > > >
> > > > This is quite trivial to fix:
> > > >
> > > > Replace all ocurences of "val = acl_to_text(acl, &len);" by "val = 
> > > > acl_to_any_text(acl, 0, ',', ( 
> > > > numeric_owner_option?TEXT_NUMERIC_IDS:0));" and followed by 
> > > > "len=strlen(val);" after the "if (!val)" error-handling.
> > > >
> > > >
> > > > Effect: Numeric owner is stored.
> > > >
> > > > I'd like to note that this improvement is essential to me.
> > > >
> > > >
> > > >
> > > > (2a) tar archive creation without "--numeric-owner" option:
> > > >
> > > > In GNU tar 1.26, for every file the owner is stored both, symbolic 
> > > > and numeric. I would expect that ACLs are stored in both ways, too. 
> > > > star shows us how to do that:
> > > >
> > > > star stores the numeric owner in a forth field of an acl: (e.g. 
> > > > "u:msteinbo:rwx:500").
> > > >
> > > >
> > > >
> > > > (2b) tar extract should use the 4th field (discussed in point 2) in 
> > > > presence of "-numeric-owner".
> > > >
> > > > This together with point (2) enabled users to restore an backup 
> > > > created without numeric owner option on a clean hard disc without 
> > > > passwd entries for the users (let's assume that /etc/passwd is 
> > > > contained in the archive so the operation makes sense).
> > > >
> > > > I'd like to mention that this point would increase star 
> > > > compatibility a lot.
> > > >
> > > >
> > > >
> > > > Optional (3): Do not store ACLs iff ACL contains just the normal 
> > > > user, group and other permissions, i. .e. the ACL is an 
> > > > compatibility ACL.
> > > >
> > > >
> > > > What is your opinion on these points?
> > > >
> > > >
> > > > Greetings from Germany
> > > >
> > > > Markus Steinborn
> > > > GNU gv maintainer
> > > >
> > > >
> > > >
> > > > PS: "iff" is the usual abbreviation for "if and only if" and not a 
> > > > typo.