Mailing-List: contact users-help@subversion.apache.org; run by ezmlm
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Date: Sat, 23 Jul 2016 18:03:17 +0000
From: Daniel Shahaf <d.s@daniel.shahaf.name>
To: Eric Johnson <eric@tibco.com>
Cc: "Krueger, Lars (CQSE)" <lars.krueger@carmeq.com>,
	users@subversion.apache.org
Subject: Re: securing of correct transmit
Message-ID: <20160723180317.GA6269@tarsus.local2>
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 <b2a37556-52a8-da65-9e6c-0c9c67fc2e98@tibco.com>
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Eric Johnson wrote on Fri, Jul 22, 2016 at 09:27:50 -0700:
> Hi Lars,
> 
> On 7/22/16 1:56 AM, Krueger, Lars (CQSE) wrote:
> >Hello together,
> >I need to know how SVN ensures that each item (comminting or updateing) is
> >correctly transmitted from/ to a repository. If I use ‘svn info’ command I
> >can see a ‘Checksum’ for a file. Do you use this Checksum?
> 
> I have not examined the code. I can say, however, in the years that I've
> been lurking on this list, I've *never* seen anyone report an issue with a
> file being corrupted in transit to the server. I assume that is because the
> answer to your question is emphatically, "yes".
> 

Yes, we use checksums in both directions.  The checksum is usually sha1
although it may be md5 for old data [written by 1.5(?) and older].

> Of course, it is open source, so you can go look at the code. I was curious
> whether I could find it. This seems like the right file. I see references to
> "checksum" in their, so that's promising.
> https://svn.apache.org/repos/asf/subversion/trunk/subversion/libsvn_client/commit.c
> 

My answer would be the open_file/apply_textdelta/close_file sequence
from the svn_delta_editor_t type.  These three are the interface that
transmits a versioned file across the wire.

Cheers,

Daniel