recompress

#!/bin/bash

# A simple script to checkout or update a svn or git repo as source service
#  
# (C) 2010 by Adrian Schröter <adrian@suse.de>
#  
# This program is free software; you can redistribute it and/or  
# modify it under the terms of the GNU General Public License  
# as published by the Free Software Foundation; either version 2  
# of the License, or (at your option) any later version.  
# See http://www.gnu.org/licenses/gpl-2.0.html for full license text.  

# defaults
MYCOMPRESSION=""
FILES=""

while test $# -gt 0; do
  case $1 in
    *-compression)
      MYCOMPRESSION="$2"
      shift
    ;;
    *-file)
      FILES="$FILES ${2##*/}"
      shift
    ;;
    *-outdir)
      MYOUTDIR="$2"
      shift
    ;;
    *)
      echo Unknown parameter $1.
      echo 'Usage: recompress --compression $COMPRESSION --file $FILE --outdir $OUT'
      exit 1
    ;;
  esac
  shift
done

if [ -z "$MYCOMPRESSION" ]; then
  MYCOMPRESSION="bz2"
fi
if [ -z "$FILES" ]; then
  echo "ERROR: no inputs files are given via --file parameter!"
  exit 1
fi
if [ -z "$MYOUTDIR" ]; then
  echo "ERROR: no output directory is given via --outdir parameter!"
  exit 1
fi

for i in $FILES; do
  FILE=`ls -1 "$i" || ls -1 "_service:*:$i"`
  if [ ! -f "$FILE" ]; then
    echo "Unknown file $i"
    exit 1
  fi
  UNCOMPRESS="cat"
  BASENAME="$FILE"
  if [ "${FILE%.gz}" != "$FILE" ]; then
    UNCOMPRESS="gunzip -c"
    BASENAME="${FILE%.gz}"
  elif [ "${FILE%.tgz}" != "$FILE" ]; then
    UNCOMPRESS="gunzip -c"
    BASENAME="${FILE%.tgz}.tar"
  elif [ "${FILE%.bz2}" != "$FILE" ]; then
    UNCOMPRESS="bunzip2 -c"
    BASENAME="${FILE%.bz2}"
  elif [ "${FILE%.xz}" != "$FILE" ]; then
    UNCOMPRESS="xz -dc"
    BASENAME="${FILE%.xz}"
  fi

  if [ "$MYCOMPRESSION" == "gz" ]; then
    COMPRESS="gzip -c -n --rsyncable -"
    NEWFILE="${BASENAME#_service:}.gz"
  elif [ "$MYCOMPRESSION" == "bz2" ]; then
    COMPRESS="bzip2 -c -"
    NEWFILE="${BASENAME#_service:}.bz2"
  elif [ "$MYCOMPRESSION" == "xz" ]; then
    COMPRESS="xz --threads=0 -c -"
    NEWFILE="${BASENAME#_service:}.xz"
  elif [ "$MYCOMPRESSION" == "none" ]; then
    COMPRESS="cat -"
    NEWFILE="${BASENAME#_service:}"
  else
    echo "ERROR: Unknown compression"
    exit 1
  fi

  # do the real work
  $UNCOMPRESS -- "$FILE" | $COMPRESS > "$MYOUTDIR/$NEWFILE" || exit 1

  # Check if the (compressed) target file already exists in the directory where
  # the service is invoked and drop the newly generated one. Avoids overwriting
  # otherwise identical files which only have different timestamps. Note that
  # zdiff and co all fail to do that properly...
  if [ -f $NEWFILE ] ; then
    DIFF_TMPDIR=$(mktemp -d)
    SRC_DIR="$PWD"
    cd $DIFF_TMPDIR
    mkdir new old
    $(cd new ; tar -xf "$MYOUTDIR/$NEWFILE" 2> /dev/null || mv -- "$MYOUTDIR/$NEWFILE" .)
    $(cd old ; tar -xf "$SRC_DIR/$NEWFILE" 2> /dev/null || mv -- "$SRC_DIR/$NEWFILE" .)
    if diff -r new old > /dev/null ; then
      echo "Identical target file $NEWFILE already exists, skipping.."
      rm -r -- "$MYOUTDIR/$NEWFILE"
    else
      echo "Compressed $FILE to $NEWFILE"
    fi
    cd $SRC_DIR
    rm -rf -- "$DIFF_TMPDIR"
  else
    echo "Compressed $FILE to $NEWFILE"
  fi

  # we can remove service files, no need to store them twice
  rm -f -- "$FILE"
done

exit 0