mergemaster -U overwriting modified files

Mel Flynn mel.flynn+fbsd.questions at
Fri May 15 14:59:39 UTC 2009

On Sunday 26 April 2009 11:12:12 Frederique Rijsdijk wrote:
> Bruce Cran wrote:
> > On Sat, 25 Apr 2009 12:10:42 +0200
> >
> > Peter Schuller <peter.schuller at> wrote:
> >> I recently began testing mergemaster -U since the perpetual "review
> >> diff of file I never touched" grows annoying real quick.
> >>
> >> Unfortunately I recently discovered that it does not seem to do what
> >> you might expect. For example it nuked my mailer.conf on one machine,
> >> and my /etc/namedb/named.conf (!!!) on another machine.
> >>
> >> Is this a bug or intended? What is the intended functionality of -U?
> >
> > I noticed this recently too: after using mergemaster -U without
> > problems for a long time it suddenly went and overwrote named.conf on
> > a recently upgrade of 7-STABLE.
> I've seen this happen as well with named.conf.

I think I know the cause, not entirely the problem yet, as I just got hit by 
this too and right at the point where I upgraded source tree from cvs to svn 
so *all* files had different idents.

Before running mergemaster -iU I checked /var/db/mergemaster.mtree and it was 
zero-sized. Why, is not entirely clear, (hence, I don't know the real problem) 
but I thought I noticed mergemaster saving mtree database on the pre-world 
run. Looking at the code though, this should be impossible, so the more I 
think about it, the more I start to doubt. At the time I was thinking why is 
mergemaster saving the mtree and that's when I checked it's size.

Whatever the cause, this is where mergemaster fails:
if [ -n "${AUTO_UPGRADE}" -a -f "${DESTDIR}${MTREEFILE}" ]; then
        for file in `mtree -eq -f ${DESTDIR}${MTREEFILE} -p ${DESTDIR}/ \
                2>/dev/null | awk '($2 == "changed") {print $1}'`; do
                if [ -f "${DESTDIR}/$file" ]; then
                        CHANGED="${CHANGED} ${DESTDIR}/$file"

Because ${MTREEFILE} is empty, the mtree command will not produce output and 
CHANGED will not be populated. For things like this, it would be nice if mtree 
supported a 'lint' mode to check syntax, but at the very least could 
mergemaster test for -s rather then or in addition to -f?


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