wingolog

A couple of weeks ago I was hacking on a GStreamer element from gst-plugins-bad and realized that I needed a way to record my changes in pieces, but not commit to the repository. GStreamer uses CVS, which does not support this workflow.

Bazaar to the rescue, then. I created a new local repository, in the plugin directory. It's as simple as typing bzr init, adding the files you want to track, and then committing as you make changes. I ended up committing a dozen patches or so.

Of course, when I was finished I wanted to push the changes upstream. Thus the point of this writing product, a script to turn a bzr repository into a series of patch files on disk:

#!/bin/bash
set -e
patchbase=$(basename `pwd`)
outputdir=$1
if test -z "$outputdir"; then outputdir=.; fi

revno=`bzr version-info | grep revno | cut -d: -f2`
echo "exporting $(($revno)) patches..."
for ((i=0; $i<$revno; i=$i+1)); do
    file="$patchbase.diff.$(($i+1))"
    echo "exporting $i..$(($i+1)) to $file"
    # dunno why bzr always returns $? != 0
    bzr log -r$(($i+1))..$(($i+1)) > $file || true
    bzr diff -r$i..$(($i+1)) >> $file || true
done

I then reverted my tree, applying and committing the patches one-by-one with e.g. patch -u -p0 < foo.diff.4. I'm sure there's some kind of more integrated plugin to do this, but a 10-minute shell script was easiest to hack out.

As an aside, bzr uncommit is quite useful for producing a readable history -- I often go back and modify the committed patches so that they are more understandable on their own.

Happy hacking!