Re: RCS file corruption.

[Richard Gribble <richard at gandalfwizard dot us>]

On Thu, Jun 21, 2012 at 5:05 AM, Wagemans, Peter <peter.wagemans@kpn.com> wrote:
>
>
> Richard Gribble wrote:
>
> > 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
>
> RCS should be able to handle carriage returns without problems and
> indeed, my Linux build of the same code works correctly on the example
> files.
>
> In this case at some point the RCS code copies the work file content
> to the new RCS file as the latest version and unexpectedly gets an EOF
> after exactly 65536 bytes.
>
> [The file copy loop is the code under "/* Copy the file. ?*/" in
> putdftext in rcsgen.c in the GNU rcs 5.8.1 code. At the lowest level
> in the RCS code the EOF comes from the getc(stream) in the
> GETBYTE_BODY macro used in the function fro_try_getbyte in b-fro.c.]
>
> But you may be on to something with the carriage returns. In my
> example file there is a carriage return linefeed pair just on the 64kB
> boundary:
>
> Output from od -t x1z -Ad:
>
> 0065520 78 20 78 78 20 78 78 78 78 78 78 78 78 78 2e 0d ?>x xx xxxxxxxxx..<
> 0065536 0a 0d 0a 2a 2a 2a 2a 2a 2a 20 78 78 78 78 78 78 ?>...****** xxxxxx<
>
> Perhaps this is not a coincidence. It makes me wonder whether some
> underlying layer is seeing the carriage return at the end of the
> buffer, looks ahead for a linefeed (data that is not available in the
> current buffer) and causes the EOF in some way.
>
> How can we find out why getc is incorrectly returning EOF in this
> situation?
>
> Regards,
>
> Peter Wagemans
>
>

One thing I may have failed to mention is that (anecdotaly - I didn't
take copious notes) the problem usually appeared when I had lines with
two "^M"s at the end.? I suspect this happens because sometimes I edit
the files on my Linux box and sometimes on my Windows box.


Later,

Richard.


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