#!/bin/bash
# Copyright 1994, 1998, 2000  Patrick Volkerding, Concord, CA, USA
# Copyright 2001, 2003  Slackware Linux, Inc., Concord, CA, USA
# Copyright 2007, 2009, 2017, 2018  Patrick Volkerding, Sebeka, MN, USA
# All rights reserved.
#
# Redistribution and use of this script, with or without modification, is
# permitted provided that the following conditions are met:
#
# 1. Redistributions of this script must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
#
#  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
#  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
#  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
#  EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
#  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
#  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
#  OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
#  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
#  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
#  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

if [ $# = 0 ]; then
  cat << EOF
Usage: explodepkg package_name [package_name2, ...]

Explodes a Slackware compatible software package
(or any tar+{gzip,bzip2,lz,xz archive) in the current directory.
Equivalent to (for each package listed):

  ( umask 000 ; cat package_name | COMPRESSOR -dc | tar xpvf package_name )

Note: This should only be used for debugging or examining packages, not for
installing them. It doesn't execute installation scripts or update the package
indexes in /var/lib/pkgtools/packages and /var/lib/pkgtools/scripts.

EOF
fi

# Set maximum number of threads to use. By default, this will be the number
# of CPU threads:
THREADS="$(nproc)"

# Main loop:
for PKG in $* ; do
  echo "Exploding package $PKG in current directory:"
  # Determine extension:
  packageext="$( echo $PKG | rev | cut -f 1 -d . | rev)"
  # Determine compression utility:
  case $packageext in
  'tgz' )
    packagecompression=gzip
    ;;
  'gz' )
    packagecompression=gzip
    ;;
  'tbz' )
    if which lbzip2 1> /dev/null 2> /dev/null ; then
      packagecompression=lbzip2
    else
      packagecompression=bzip2
    fi
    ;;
  'bz2' )
    if which lbzip2 1> /dev/null 2> /dev/null ; then
      packagecompression=lbzip2
    else
      packagecompression=bzip2
    fi
    ;;
  'tlz' )
    if which plzip 1> /dev/null 2> /dev/null ; then
      packagecompression="plzip --threads=${THREADS}"
    elif which lzip 1> /dev/null 2> /dev/null ; then
      packagecompression=lzip
    else
      echo "ERROR:  lzip compression utility not found in \$PATH."
      exit 3
    fi
    ;;
  'lz' )
    if which plzip 1> /dev/null 2> /dev/null ; then
      packagecompression="plzip --threads=${THREADS}"
    elif which lzip 1> /dev/null 2> /dev/null ; then
      packagecompression=lzip
    else
      echo "ERROR:  lzip compression utility not found in \$PATH."
      exit 3
    fi
    ;;
  'lzma' )
    packagecompression=lzma
    ;;
  'txz' )
    packagecompression="xz --threads=${THREADS}"
    ;;
  'xz' )
    packagecompression="xz --threads=${THREADS}"
    ;;
  esac
  ( umask 000 ; cat $PKG | $packagecompression -dc | tar --xattrs --xattrs-include='*' --keep-directory-symlink -xpvf - 2> /dev/null )
  if [ -r install/doinst.sh ]; then
    echo
    echo "An installation script was detected in ./install/doinst.sh, but"
    echo "was not executed."
  fi
done