#!/bin/sh
#
# Version 0.2
#
# etcdiff (deb-etcdiff?) shows how your current /etc dir
# diverges from the debian distribution standard one.
#
# Copyright (C) 2008,2009 Antonio Ospite <ospite@studenti.unina.it>
# License: GPLv2 or later


# TODO:
#   Add per package etcdiff, using dpkg -L
#   Add per distro etcdiff using dpkg --get-selections
#
# Note that the first method can't consider files not in original packages,
# unless some smart trick is used (new files could be in same /etc subdir of
# the provided configuration files)
#
# The second one could even speedup the whole etcdiffing by recreating an etc
# dir as per packages defaults, and do one big diff.

set -x

#PROMPT_RM=-i

DEBIANMIRROR="http://ftp.it.debian.org/debian"

rm $PROMPT_RM -rf temp     && mkdir temp
rm $PROMPT_RM -rf archives && mkdir archives
rm $PROMPT_RM -rf conf     && mkdir conf

# Examples of file query

# by list
#FILES="/etc/sysctl.conf /etc/init.d/procps /etc/passwd-"

# by command
FILES=$(find /etc/apache2 -type f $USERMODE | grep -v '.dpkg-')

# by command, public files, limited
#USERMODE="-perm /o+r"
#MAXDEPTH="-maxdepth 1"
#FILES=$(find /etc/ $MAXDEPTH -type f $USERMODE | grep -v '.dpkg-')

# by package name
#FILES=$(dpkg -L apache2.2-common | grep '^/etc')

for file in ${FILES};
do
  if [ ! -e $file ];
  then
    echo "ERROR, file $file does not exist."
    exit 1;
  fi
  echo "-> $file"

  # Find out which installed package provides the config file
  PACKAGE=$(dpkg-query -S "$file" | cut -d ':' -f 1 | uniq 2> /dev/null)

  # Copy the whole file if it is not provided by default
  if [ "x$PACKAGE" == "x" ];
  then
    DESTDIR=`dirname $file`
    # strip trailing slash
    [ ${DESTDIR:0:1} == '/' ] && DESTDIR=${DESTDIR:1}

    # RECREATE the destination dir 
    [ -d conf/$DESTDIR ] || mkdir -p conf/$DESTDIR
    cp "$file" conf/$DESTDIR

    continue
  fi

  # Get the package from the repository and diff

  FILENAME=$(apt-cache show $PACKAGE | grep ^Filename | cut -d ' ' -f 2-)
  ARCHIVE=$(basename $FILENAME)

  if [ ! -f archives/$ARCHIVE ];
  then
    ( cd archives &&
        wget -q -nc -c $DEBIANMIRROR/$FILENAME &&
        mkdir ../temp/$PACKAGE
        dpkg -x $ARCHIVE ../temp/$PACKAGE
    )
  fi

  # Check for file existence before diffing, the file is not provided in
  # package archive, but it could have been generated by package installation
  # scripts
  if [ ! -f temp/$PACKAGE/$file ];
  then
    echo "Warning: '$file' can't be found in package!"
  fi


  # TODO: diff only once and check filesize
  TMPDIFF_FILE=`mktemp /tmp/etcdiff.XXXXXXXXXX`
  diff -u temp/$PACKAGE/$file $file > $TMPDIFF_FILE
  if [ `stat -c '%s' $TMPDIFF_FILE` -eq 0 ];
  then
    echo "$file: not changed"
    rm -f $TMPDIFF_FILE
  else
    DESTDIR=`dirname $file`
    # strip trailing slash
    [ ${DESTDIR:0:1} == '/' ] && DESTDIR=${DESTDIR:1}

    # RECREATE the destination dir 
    [ -d conf/$DESTDIR ] || mkdir -p conf/$DESTDIR
    cp $TMPDIFF_FILE conf/$DESTDIR/$(basename $file).patch

    rm -f $TMPDIFF_FILE
  fi

done