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Re: UTF-8 NFC/NFD paths issue

From: Greg Stein <gstein_at_gmail.com>
Date: Fri, 17 Sep 2010 07:22:12 -0400

On Thu, Sep 16, 2010 at 19:26, Daniel Shahaf <d.s_at_daniel.shahaf.name> wrote:
> Greg Stein wrote on Thu, Sep 16, 2010 at 00:59:59 -0400:
>> On Wed, Sep 15, 2010 at 23:35, Daniel Shahaf <d.s_at_daniel.shahaf.name> wrote:
>...
>> > If yes, then we infer that no two in-repository paths (which are
>> > bytewise different) canonicalize to the same byte sequence. Which is
>> > pretty useful precondition to have, i.e., what /can/ svn do on a legacy
>> > repository where some two paths are bytewise-different yet Unicode-equal?
>>
> (I assume you're replying to my second paragraph)
>> This will be *very* difficult to manage. Even if a given repository
>> somehow manages to rewrite history to "fix" the paths, then you may
>> have an unknown number of downstream synchronized repositories to
>> similarly fix.
>>
>> I think an answer might be to rely on the upcoming obliterate
>> feature's "out of band" change descriptions. For example, a repository
>> might tell a working copy, "hey: file XYZ was obliterated since you
>> last talked to me. if you happen to have it, then get rid of it. I
>> won't recognize it henceforth." You can see a similar descriptor sent
>> to working copies or repositories that says "I recoded XYZ. update to
>> the new encoding."
>>
>
> I don't see why this needs to be special-cased? The server can simply
> send "rename(NFD(), NFC())" and the wc library can figure for itself
> that it's inoperative for her in the same place she determines that
> "rename('foo','FOO')" is inoperative for her (when the filesystem is
> case-insensitive).

When does the server send that? If the wc is at r1000, and the server
is at r1000, then the standard update response is nil.

Yet if an administrator comes along and renames the repository paths
to NFC, then *something* needs to return in an update response. I see
it as "not part of the update request", and that there is an
out-of-band response that details such changes. ie. changes that occur
outside the revision numbering flow.

Cheers,
-g
Received on 2010-09-17 13:22:51 CEST

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