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Re: Checksum mismatch after canceling conflict resolution

From: David Glasser <glasser_at_davidglasser.net>
Date: 2007-11-02 22:29:51 CET

I took this to a new thread: Re: Flushing directory log accumulator
during pool cleanup (Re: svn commit: r23342 -
trunk/subversion/libsvn_wc)

There's even a patch to review!

--dave

On 11/2/07, David Glasser <glasser@davidglasser.net> wrote:
> On 11/2/07, David Glasser <glasser@davidglasser.net> wrote:
> > On 11/2/07, Hyrum K. Wright <hyrum_wright@mail.utexas.edu> wrote:
> > > Hyrum K. Wright wrote:
> > > > David Glasser wrote:
> > > >> On 11/2/07, Hyrum K. Wright <hyrum_wright@mail.utexas.edu> wrote:
> > > >>> I've been spending some time this morning playing around with
> > > >>> interactive conflict resolution, and ran across this little gem:
> > > >>>
> > > >>> hwright@spock:~/test/greek.wc$ svn up
> > > >>> Conflict discovered in 'iota'.
> > > >>> Select: (p)ostpone, (d)iff, (e)dit, (h)elp for more options : h
> > > >>> (p)ostpone - mark the conflict to be resolved later
> > > >>> (d)iff - show all changes made to merged file
> > > >>> (e)dit - change merged file in an editor
> > > >>> (i)nteractive - prompt for each conflicting hunk
> > > >>> (r)esolved - accept merged version of file
> > > >>> (m)ine - accept my version of file
> > > >>> (t)heirs - accept their version of file
> > > >>> (l)aunch - use third-party tool to resolve conflict
> > > >>> (h)elp - show this list
> > > >>>
> > > >>> Select: (p)ostpone, (d)iff, (e)dit, (h)elp for more options : d
> > > >>> --- .svn/text-base/iota.svn-base Fri Nov 2 09:35:14 2007
> > > >>> +++ .svn/tmp/tempfile.tmp Fri Nov 2 09:35:20 2007
> > > >>> @@ -1 +1,5 @@
> > > >>> -This is the file 'iota'.
> > > >>> +<<<<<<< .mine
> > > >>> +This is the file 'iota'. asdf
> > > >>> +=======
> > > >>> +This is the file 'iota'. 1234
> > > >>> +>>>>>>> .r2
> > > >>> Select: (p)ostpone, (d)iff, (e)dit, (r)esolved, (h)elp for more options
> > > >>> : subversion/svn/main.c:934: (apr_err=200015)
> > > >>> svn: Caught signal
> > > >
> > > > This is where I hit ctrl-C.
> > > >
> > > >>> hwright@spock:~/test/greek.wc$ svn up
> > > >>> At revision 2.
> > > >>> hwright@spock:~/test/greek.wc$ svn up -r1
> > > >>> subversion/libsvn_wc/update_editor.c:2032: (apr_err=155017)
> > > >>> svn: Checksum mismatch for '.svn/text-base/iota.svn-base'; expected:
> > > >>> '0a18339a4d1bddab170f4811a8ef6384', actual:
> > > >>> '2d18c5e57e84c5b8a5e9a6e13fa394dc'
> > > >>> hwright@spock:~/test/greek.wc$ ls
> > > >>> A iota
> > > >>> hwright@spock:~/test/greek.wc$ svn up -r0
> > > >>> D A
> > > >>> D iota
> > > >>> Updated to revision 0.
> > > >>>
> > > >>> As a result of canceling the conflict resolver in operation, it appears
> > > >>> that some metadata in the wc wasn't updated correctly. I couldn't
> > > >>> update to r1, but I could update to r0 and then back to r1.
> > > >>>
> > > >>> Is this intended behavior?
> > > >> Absolutely not. The wc should never be corrupted.
> > > >>
> > > >> Do you have an automated reproduction script (perhaps one that at one
> > > >> point echoes "hit ctrl-C during the next prompt")?
> > > >
> > > > Sure, I can create such a script. In the mean time, I've noted above
> > > > where I hit ctrl-C.
> > >
> > > This triggers the problem without using ctrl-C:
> > > [Assumes greek.wc and greek-2.wc are checked out greek trees from the
> > > same repository.]
> > >
> > > echo "asdf" >> greek.wc/iota
> > > svn ci greek.wc/iota -m 'asdf'
> > > echo "1243" >> greek-2.wc/iota
> > >
> > > # This causes a premature abort
> > > echo "d\n" | svn up greek-2.wc
> > >
> > > # WC-corruption here
> > > svn up greek-2.wc -r 1
> >
> > Want to know something hilarious?
> >
> > If you give an EOF or a SIGINT to the "svn up greek-2.wc" during the
> > conflict prompt, you end up with a corrupted wc. (In this case, the
> > entries file believes that iota is at r2 even though both its
> > text-base and checksum are still for r1.)
> >
> > If you just kill -9, though, everything is happy; the wc is locked,
> > but "svn cleanup" fixes that. And no corruption :)
> >
> > So somewhere in our error handling or pool cleanup chain there is a
> > "helpful" function that loggily bumps the revnum on iota. Now to find
> > it...
>
> My good friend GDB tells me that, at the time that the conflict
> handler is called, the following is in the parent directory's log
> accumulation buffer:
>
> <modify-entry
> name="iota"
> present-props=""
> cachable-props="svn:special svn:externals svn:needs-lock"
> has-prop-mods="false"
> has-props="false"/>
> <modify-entry
> committed-rev="2"
> committed-date="2007-11-02T18:31:36.166516Z"
> name="iota"
> last-author="glasser"
> uuid="d6c9db28-8971-11dc-b25b-3577afaf3c19"/>
> <modify-entry
> text-time="1970-01-01T00:00:00.000000Z"
> name="iota"
> url="file:///tmp/x/repos/trunk/iota"
> kind="file"
> deleted="false"
> working-size="-1"
> absent="false"
> revision="2"/>
>
> So it's already committed to updating the file entry, without having
> dealt with the text-base yet...
>
> --dave
>
> --
> David Glasser | glasser_at_davidglasser.net | http://www.davidglasser.net/
>

-- 
David Glasser | glasser_at_davidglasser.net | http://www.davidglasser.net/
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Received on Fri Nov 2 22:30:03 2007

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