Converting Mercurial repo to Subversion

Had a small-ish project that the developers used Mercurial as there repository, and since we use Subversion for everything else. Now that the project is more or less done (for the initial launch anyways), I need to get it setup in our main subversion repository.

I found this great post, with an included bash script, that got me pretty close. I spent a couple of days tweaking it (background tasks as I did other more pressing work). And ended up with this

#!/bin/bash

# DANGER: written as a once-off script, not suitable for naive consumption. Use at
# your own peril. It has been tested on one case only.
#
# Potential issues for reuse:
# * no sanity checks anywhere (don't call it with the wrong parameters)
# * no handling of branches
# * certain layout of the results of hg commands is assumed
# * all commits come from the user running the script
# * move operations probably won't appear in the history as such
# * we assume the SVN side doesn't change
#

HG_SOURCE=$1   # the source is a normal hg repository
SVN_TARGET=$2  # the target is a folder within a SVN working copy (e.g. /trunk)

export QUIET_FLAG= # -q for quiet, empty for verbose

echo Converting Mercurial repository at $HG_SOURCE into Subversion working copy at $SVN_TARGET

# Turn the SVN location into a mercurial one
pushd $SVN_TARGET
hg init .

# Get the revision counts (Overridable with START_REV, STOP_REV so you can restart if something bad happens)
pushd $HG_SOURCE
TIP_REV=`hg tip | head -1 | sed -e "s/[^ ]* *\([^:]*\)/\1/g"`
STOP_REV=$TIP_REV
START_REV=0
popd # out of $HG_SOURCE

# Pull all the changes from the mercurial repo, don't update though (helps with 
hg $QUIET_FLAG pull -r $TIP_REV $HG_SOURCE

for i in `seq $START_REV $STOP_REV`
do
    echo "Fetching Mercurial revision $i/$TIP_REV"
    hg $QUIET_FLAG update -C -r $i
    # Parse out the incoming log message
    HG_LOG_MESSAGE=`hg -R $HG_SOURCE -v log -r $i | grep -A10 ^description:$ | grep -v ^description:$ | head --lines=-2` 
    HG_LOG_CHANGESET=`hg -R $HG_SOURCE -v log -r $i | grep ^changeset: | head -1`
    HG_LOG_USER=`hg -R $HG_SOURCE -v log -r $i | grep ^user: | head -1`
    HG_LOG_DATE=`hg -R $HG_SOURCE -v log -r $i | grep ^date: | head -1`
    
    echo "- removing deleted files"
    svn status | grep '^!' | sed -e 's/^! *\(.*\)/\1/g' | while read fileToRemove
    do
        svn remove $QUIET_FLAG "$fileToRemove"
    done
    
    echo "- removing empty directories" # needed since Mercurial doesn't manage directories
    find . -name '.svn' -prune -o -type d -printf '%p+++' -exec ls -am {} \; | grep '., .., .svn$' | sed -e 's/^\(.*\)+++.*/\1/g' | while read dirToRemove
    do
        rm -rf "$dirToRemove" # remove first, otherwise working copy is broken for some reason only SVN knows
        svn remove $QUIET_FLAG "$dirToRemove"
    done
    
    echo "- adding files to SVN control"
    # 'svn add' recurses and snags .hg* files, we are pulling those out, so do our own recursion (slower but more stable)
    #   This is mostly important if you have sub-sites, as they each have a large .hg file in them
    while [ `svn status | grep '^\?' | grep -v '[ /].hg\(tags\|ignore\|sub\|substate\)\?\b' | wc -l` -gt 0 ]
    do
        svn status | grep '^\?' | grep -v '[ /].hg\(tags\|ignore\|sub\|substate\)\?\b' | sed -e 's/^\? *\(.*\)/\1/g' | while read fileToAdd
        do
            if [ -d "$fileToAdd" ]
            then
                # Mercurial seems to copy existing directories on moves or something like that -- we
                # definitely get some .svn subdirectories in newly created directories if the original
                # action was a move. New directories should never contain a .svn folder since that breaks
                # SVN 
                find "$fileToAdd" -type d -name ".svn" | while read accidentalSvnFolder
                do
                    rm -rf "$accidentalSvnFolder"
                done
            fi
            # Using --depth empty here, so we don't recurisivly add, we are taking care of that ourselves.
            svn add $QUIET_FLAG --depth empty "$fileToAdd"
        done
    done
    
    echo "- committing"
    # This section is here to specificly fix symlinks that get swapped between symlinks and real files
    #  But could be extended to catch any commit errors you can't know about until you try to submit
    # NOTE: This is a "done << EOF" style while loop so we can have a controlling variable to exit the loop
    #       otherwise NEED_COMMIT can't be modified in the body of the loop (bash pipe thingie)
    NEED_COMMIT=true
    while $NEED_COMMIT
    do
        NEED_COMMIT=false
        SVN_COMMIT_RESULT=`svn ci $QUIET_FLAG -m "$HG_LOG_CHANGESET
$HG_LOG_USER
$HG_LOG_DATE
$HG_LOG_MESSAGE" 2>&1`
        echo $SVN_COMMIT_RESULT
        
        while read needFixin;
        do
            if [ "$needFixin" != "" ]
            then
                svn pd svn:special $needFixin
                NEED_COMMIT=true
            fi
        done << EOF
$(echo "$SVN_COMMIT_RESULT" | grep "has unexpectedly changed special status" | sed -e 's/^svn: Entry \x27\(.*\)\x27 has unexpectedly .*$/\1/g')
EOF
    done
    echo "- done"
done

popd # out of $SVN_TARGET