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Re: Building perl-5.10.0


On Apr  1 18:38, Eric Blake wrote:
> According to Corinna Vinschen on 4/1/2008 7:44 AM:
> |  Shouldn't the "nobody" entry
> | disappear when calling chmod?  That's how I understand the statement in
> | the POSIX docs:
> |
> |  "An alternate file access control mechanism shall [...] be disabled for
> |   a file after the file permission bits are changed for that file with
> |   chmod( ).  The disabling of the alternate mechanism need not disable
> |   any additional mechanisms supported by an implementation."
> |
> | Either the ACLs of a file are not an "alternate" access mechanism,
> | but an "additional" access mechanism.  But that doesn't match the
> | description either:
> |
> |  "An additional access control mechanism shall only further restrict
> |   the access permissions defined by the file permission bits."
>
> Yes, those were the two paragraphs I was noticing when I made my claim
> that cygwin's chmod(2) wasn't obeying POSIX.
>
> ACLs can serve as both "alternate" (give more rights to some users than
> what is implied by the traditional stat bits) and "additional" (restrict
> rights to certain users outside of what is shown in the traditional stat
> bits).
>
> | Or, Linux doesn't follow POSIX here, which seems unlikely to me.
>
> Actually, it seems highly likely to me - after all, at one point, POSIX
> considered standardizing a form of ACLs, but it never went anywhere (and
> in the meantime, several competing styles of how to implement ACLs cropped
> up; Solaris and Linux tackle the issue noticably different, and Selinux
> security descriptors are yet another wrinkle in the picture).

In the meantime I tested this scenario on Solaris 9 as well and I found
that it behaves exactly as Linux and Cygwin.  It's nice to see that
both, Linux and Solaris, are following Cygwin's lead here <cough, cough>.
Just for the records (again), Cygwin's ACL support is modeled on the
Solaris ACL API.

>   Maybe it's
> worth asking on the Austin Group mailing list?

I think so, yes.  It looks somewhat unusual if two important OSes
seem to contradict what's in the specs.  Are you going to ask?


Corinna

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

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