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From Greg Stein <>
Subject Re: Why do we check the base checksum so often?
Date Mon, 06 Feb 2012 22:55:29 GMT
On Mon, Feb 6, 2012 at 17:39, Daniel Shahaf <> wrote:
> 1. Third-parties who use Ev1 interface would lose the integrity check.
> 2. Subversion 1.7 uses, and will use, Ev1 interfaces.
> Therefore:
> 3. Subversion 1.7 would lose the integrity check.
> Correct?

Nope. 'svn' is not considered a third-party, to begin with. Further,
internally, it only uses the Ev1 interfaces. No shims get inserted.
When we deploy Ev2 within the svn libraries and tools (in the 1.8 or
1.9 release), we aren't going to use the shims, so we aren't going to
lose the integrity check.

Third party clients, linked to Ev2-using libraries, and which continue
to use the old Ev1 APIs will have a shim inserted, and (thus) lose the
base_checksum integrity check.

IOW, when we release an Ev2-based Subversion, and third-party clients
that were built against the 1.0 through 1.7 APIs... those clients will
have shims inserted, and lose the check. It *is* possible that our
backwards-compat code could fetch the checksum and pass it along to
those third-party Ev1 users. But in the current dual-shim setup that
Hyrum is developing/testing with, there is no such mechanism for
fetching (hard to do, compared to just disabling the check in the
first place).

Does that make sense?


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