RCS file corruption.

[Richard Gribble]

I have experienced this problem several times.  In my case it seemed
to be a problem between 'Unix' and 'DOS' files.  In each case, I have
been able to fix it by editing the RCS file using vim and deleting all
the extraneous carriage returns - :%s/^M$//<enter>  Sometimes I've had
to do it twice.  Once I do that, it seems to work.

The interesting thing is that it doesn't happen every time there is a
Unix/DOS file type change, so I don't know if it will work for you or
not.  While I have not dug into the source code (for this problem,
anyway), the fact that my files tend to truncate at 65536 bytes seems
suggestive of a line-length limitation.


Hope this helps,

Richard.

On Tue, Jun 19, 2012 at 9:16 AM, Wagemans, Peter <peter.wagemans@kpn.com> wrote:
>
>
> For many years I have been using Emacs and RCS version control for
> individual simple notes and org-mode text files, with a habit of
> frequent check-in and check-out to save units of work. On Windows the
> RCS implementation is from Cygwin.
>
> Over the last months I have encountered several cases where check-in,
> check-out resulted in a work file truncated at exactly 64kiB and an
> inconsistent RCS file. Recovery from backup was necessary. Since both
> files were destroyed, I was unable to reproduce the problem.
>
> Now I seem to have found an example with a reconstructed work file
> that seems to systematically show the error (on my system) when
> checked in to an older backup RCS file.
>
> Problem aspects:
>
>  - The check-in reduces the size of the RCS file. It maintains the
>   version history and delta scripts, but the content of the latest
>   version is truncated to 64kiB (in the cases I encountered). [The
>   size of the latest version as stored within the RCS file is a bit
>   bigger since '@'-characters are doubled.]
>
>  - This makes the RCS file inconsistent: the edit scripts to recreate
>   older versions refer to line numbers that no longer exist.
>
>  - Since the problem also occurs on the command line, Emacs is not
>   part of the problem, just the way I encountered it.
>
>  - In my problem cases, the RCS files were not very small, up to
>   several MiB in size, usually also with modifications "in the
>   middle", not just extra content at the end. This is just for
>   information; I have no evidence whether any of this is relevant to
>   the problem.
>
>  - On Windows 7 64-bit and Vista 32-bit, I have seen the problem with
>   Cygwin rcs-5.8-1, so far not with rcs-5.7-11 (switching back and
>   forth several times with Cygwin setup.exe).
>
>  - On the example files, the GNU rcs 5.8.1 distribution compiled on
>   OpenSuSE 11.4 64-bit does the check-in OK. The same code base
>   configured and built on Windows 7, 64-bit under Cygwin produces an
>   inconsistent RCS file upon check-in. So it is probably not a pure
>   RCS bug; it seems dependent on the Cygwin environment.
>
> Attached is an archive with a template directory with a checked out
> work file and two directories after check-in, one successful (rcs
> package 5.7-11) and one not (rcs package 5.8-1). To reproduce the
> problem, copy the template directory tree, place your user name in the
> lock section of the RCS file blind.org,v:
>
>        xxxxxxxxx:1.100; strict;
>
> instead of 'xxxxxxxxx' and then do a check-in with ci.
>
> The attached cygcheck output is for Windows 7 64-bit, edited for
> confidentiality.
>
> Alphanumeric content characters in the example files have been
> replaced with the character 'x'.
>
> Now I'm wondering how to proceed with this problem (apart from
> reverting to rcs 5.7):
>
>  - Have other people encountered this kind of problem?
>
>  - Can other people reproduce the problem with my example file?
>
>  - Is there a known solution?
>
>  - If not, how can the problem be tracked down and solved?
>
>
> Regards,
>
> Peter Wagemans
>
>
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