[svn.haxx.se] · SVN Dev · SVN Users · SVN Org · TSVN Dev · TSVN Users · Subclipse Dev · Subclipse Users · this month's index

Re: Merkle trees in svn [was: Quick question about the sha1-checksum for directories in svn.]

From: Branko Čibej <brane_at_apache.org>
Date: Thu, 5 Oct 2017 18:44:00 +0200

On 05.10.2017 16:46, Julian Foad wrote:
> Branko Čibej wrote:
>> On 05.10.2017 16:19, Paul Hammant wrote:
>>> Not that my vote counts for much, but I'd prefer w/o props, obeying
>>> read permissions.
>>
>> "Obeying read permissions" means that the directory hashes would have to
>> be computed dynamically for each user.
>
> Correct, but let's not imply that's a showstopper.

I never said it was.

> Calculation of a directory's hash would have to happen for each
> directory where the user has mixed access to the immediate children,
> and for all parents of such a directory up to the root.

And /that/ is the painful part: the fact that you need a depth-first
traversal of the tree in order to calculate the hash for the root
directory. And the reason why we're not exposing the directory hash,
even if the FS stores it.

> For any subtree where the user has full access, we can use a stored
> value.

Assuming we know that said user has full access ... which we might,
depending on where the hash calculation would take place, i.e., whether
it would have useful access to the authz info.

-- Brane
Received on 2017-10-05 18:44:04 CEST

This is an archived mail posted to the Subversion Dev mailing list.