Piotr Kucharski
2003-02-15

CVS: How to make it send you diffs of committed work?
=====================================================

'CVSROOT/loginfo' file is used to control where "cvs commit" log
information is sent. (Read more about it inside the file itself)

As we work on ircd project, we commit to irc tree. Hence such an entry:

^irc.*  $CVSROOT/CVSROOT/dolog %{sVv}

'dolog' script is a kind of a go-between -- as I wanted mails to be sent
not every commit, but every hour, with possibly accumulated content.

Script itself is very simple:

#!/bin/sh
cd /home/chopin/.cvs
umask 002;
echo $* >> commits.prep
(echo ""; echo $USER; date; cat) >> commits

What it does, is
a) recording changed filenames (%s) along with their previous (%V)
and current (%v) versions in 'commits.prep' file; it might look like this:

irc/doc ChangeLog,1.187,1.188 2.11-New,1.8,1.9
irc/ircd s_bsd.c,1.94,1.95

b) recording log message (yes, it is piped to stdin) to 'commits' file;
it might look like (series of) this:

chopin
Sat Feb 15 21:02:32 EST 2003
Update of /usr/local/repository/irc/doc
In directory oink:/tmp/cvs-serv23473

Modified Files:
        2.11-New
Log Message:
minor doc change

Now, I have a cron job, executing 'rotate' script every hour. This one
does the magic of diffing, here:

#!/bin/sh
PATH=/usr/bin:/usr/local/bin
WDIR=/home/chopin/.cvs
cd $WDIR
if [ ! -f commits.old ]; then
        if [ ! -s commits ]; then
                exit
        fi
        mv commits commits.old
        cat commits.prep >> commits.prep.old && rm commits.prep
fi
if [ -s commits.old ]; then
        CVSROOT=/usr/local/repository
        export CVSROOT
        # local copy of checked out irc CVS
        cd /home/chopin/CVS
        cvs -Q co irc
        cat $WDIR/commits.prep.old | \
        awk -F'[ ,]' '{D=$1; for (i=2;i<NF;i+=3)
        {printf "cvs diff -uN -r %s -r %s %s/%s\n", $(i+1), $(i+2), D, $i}}' \
        | /usr/bin/ksh >> $WDIR/commits.old
        cd $WDIR
        mailx -s"master IRC CVS commits" irc-changes < commits.old && \
        rm -f commits.old commits.prep.old
else
        rm -f commits.old
fi

As you can see, the script uses local directory (here: /home/chopin/CVS)
to do checkout of irc tree (this means you have to set this dir up, set
up cvs to allow such checkouts etc.) and then some awk to change 
'commits.prep' (taking the example from above) to series of:
cvs diff -uN -r 1.187 -r 1.188 irc/doc/ChangeLog
cvs diff -uN -r 1.8 -r .19 irc/doc/2.11-New
cvs diff -uN -r 1.94 -r 1.95 irc/ircd/s_bsd.c
which then are piped to ksh for execution and their output appended to the
'commits' log file, which then is simply mailed to whoever you want (here:
local distrubution list 'irc-changes').

Of course this can be improved; it probably does not work well with
different trees (or maybe not at all), I should take into the account
the adding and removing of files, I could send every diff as separate
attachment (using metamail perhaps), etc. etc.

But it works and you can modify it to suit your needs.

Happy coding!