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Re: wildcard authz docs question

From: Doug Robinson <doug.robinson_at_wandisco.com>
Date: Mon, 01 May 2017 14:20:16 +0000

Daniel:

On Mon, Apr 17, 2017 at 21:13 Daniel Shahaf <d.s_at_daniel.shahaf.name> wrote:

> Stefan Fuhrmann wrote on Mon, Apr 17, 2017 at 22:22:33 +0200:
> > On 15.03.2017 10:55, Daniel Shahaf wrote:
> > >>From the 1.10 draft release notes:
> > >
> > >>All wildcards apply to full path segments only, i.e. * never matches
> > >>/, except for the case where /**/ matches zero or more path segments.
> > >>For example, /*/**/* will match any path which contains at least
> > >>2 segments and is equivalent to /**/*/* as well as /*/*/**.
> > >Are «/*/**/*» «/**/*/*» «/*/*/**» really equivalent? I would have
> > >expected the first two to match any node except / and /'s immediate
> > >children, but I wouldn't expect the third form to match /trunk/iota
> > >where iota is a file, since the pattern has a trailing slash after the
> > >non-optional second component.
> > How do you know that /trunk/iota is a file?
>
> I was reviewing the API docs as a black box, i.e., from a user
> (repository admin) perspective, not from an implementation perspective.
>
> From that perspective, I would say that having a [/trunk/iota/**]
> stanza to apply to a /trunk/iota file violates the principle of least
> surprise.

From a very critical point of view I agree.

However, the point of wildcards is to easily reserve a complete namespace.
If we do not apply that stanza apply to the file means requiring 2 stanzas
to cover the space entirely. That's both expensive and brittle (2X stanzas
and requires remembering to treat them in pairs - both when adding and when
removing).

And I think the "surprise" will be very short-lived if at all.

From a cost/benefit standpoint I think it is extremely positive.

Doug

>
> > The problem is that the authz callback does not provide
> > enough context information to make that distinction.
> > We might extend the interface in the future - allowing
> > to restrict rules to exclusively match files or dirs only.
>
> Are you referring to svn_repos_authz_check_access()? [which doesn't
> have an svn_fs_t handle or the information to open one]
>
> > But making that backward compatible adds quite a bit
> > of complexity that I don't want to pile on there in 1.10.
>
> I don't understand this sentence at all. Why do we need to be backwards
> compatible (this is a new feature), and why is being back compat in
> this case necessarily expensive?
>
> Moreover, implementation considerations aside, there is still the
> question of what the documentation should say about this situation.
>
> Cheers,
>
> Daniel
>

-- 
*DOUGLAS B ROBINSON* SENIOR PRODUCT MANAGER
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*E* doug.robinson_at_wandisco.com
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Received on 2017-05-01 16:20:34 CEST

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