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Re: Check SHA vs Content (was: RE: svn commit: r1759233 - /subversion/trunk/subversion/libsvn_wc/questions.c)

From: Stefan Sperling <stsp_at_elego.de>
Date: Tue, 4 Apr 2017 11:33:18 +0200

On Mon, Feb 20, 2017 at 09:05:25AM +0100, Bert Huijben wrote:
> This code is still in trunk without any of the discussed improvements, so
> this change is currently part of 1.10.0-alpha1.
> If we don't implement the improvements I think we should check if we want
> to revert to the 1.0-1.9 behavior before we really look at releasing 1.10.
> See discussion below
> Bert

I think the proposed approach as implemented on trunk can no longer be
considered viable, unfortunately, because of this step:

> > >>> 4. Calculate SHA-1 checksum of detranslated contents of working file
> > >>> and compare it with pristine's checksum stored in wc.db.

Given that the SHA1 collision problem is real, we are now trying to stop
relying on hashes to compare content. So it does not make sense to add
new code which relies on hashes in this way, in my opinion.

It seems that using SHA1 to compare content is key to the proposed approach.
If that is correct, then I don't agree with releasing 1.10 with this feature
and I would be in favour of reverting this change.

Ivan, do you have any further comments on this thread? You have remained
silent for quite some time now :(
Received on 2017-04-04 11:33:35 CEST

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