#! /bin/bash
#
# xpack -  simple tool for handling self-extracting archives
#
# Author: Michael Towers <gradgrind[at]online[dot]de>
#
#    xpack 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.
#
#    xpack is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with xpack; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
#----------------------------------------------------------------------------
#
# version 1.1

# This script serves both as packer and extracter, according to the name used
# to invoke it. When invoked as 'xpack', it will copy itself to the archive
# file (passed on the command line) and then append a tar.gz archive of the
# source directory (passed on the command line). E.g.
#     ./xpack path/to/archive xarchive
# To extract the archive, simply run the resulting archive file, passing a
# directory into which it should be unpacked on the command line. E.g.
#          ./xarchive newpath/to/directory
# or,      bash xarchive newpath/to/directory

if [ "$( basename "$0" )" != "xpack" ]; then
    # extract archive
    if [ ! -d "$1" ]; then
        echo "ERROR: Destination directory not found"
        echo "Usage:"
        echo "  ${APP}  <directory>  - Unpack this archive to <directory> (which must exist)"
        exit 1
    fi

# The following lines allow the implementation of the '-r' option to xpack.
# The version of this script which is copied to the generated archive file will,
# in that case, have the '#+#' removed.
#+#    # test if the script is started by root user. If not, exit
#+#    if [ $UID -ne 0 ]; then
#+#        echo "Only root can run $0"; exit 1
#+#    fi

    echo "Extracting archive to $1"
    let "SKIP = $( grep --binary-files=text -n -m 1 "^#__ARCHIVE__" "$0" | cut -d ':' -f 1 ) + 1"

    tail -n +$SKIP "$0" | tar -xzC "$1"
    exit 0
fi

usage () {
    echo
    echo "Usage:"
    echo "  ${APP}  [-dr] <directory> <archive file>"
    echo "             Create self-extracting archive from <directory>"
    echo
    echo "          -d    Don't include the base directory"
    echo "          -r    Require root permissions for extracting"
    echo
    exit 1
}

NOBASE=""
ROOT=""
while getopts ":dr" Option
do
  case ${Option} in
    d ) NOBASE="-d" ;;
    r ) ROOT="-r" ;;
    * ) usage ;;
  esac
done
shift $((${OPTIND} - 1))

if [ ! -d "$1" ]; then
    echo "ERROR: Source directory not found"
    usage
fi

if [ -e "$2" ]; then
    echo "ERROR: Destination file exists"
    usage
fi

cp $0 $2
if [ $? -ne 0 ]; then
    echo "ERROR: Cannot write to destination file"
    usage
fi

if [ -n "${ROOT}" ]; then
    if [ $UID -ne 0 ]; then
        echo "Only root can use the -r opton"
        exit 1
    fi
    sed -i 's|^#+#||g' $2
fi

DIR="$( readlink -f $1 )"
BASE="."
if [ -z "${NOBASE}" ]; then
    DIR="$( dirname ${DIR} )"
    if [ $? -ne 0 ]; then echo "dirname -f ${DIR} ... failed"; usage; fi
    BASE="$( basename $1 )"
fi

# tar to standard output adds a load of nulls to the output,
# which is a bit untidy and results in warnings, so do it this way:
tar czf $2_ -C ${DIR} ${BASE}
cat $2_ >> $2
rm $2_

# DO NOT delete the next line, which MUST be the last line of 'xpack'
#__ARCHIVE__