#!/bin/sh
# 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 [ $# -eq 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

threads="$(nproc)"
for package in "$@" ; do
  printf "%s\n" "Exploding package: '$package' into current directory:"

  unset uses_threads

  # Determine compression utility.
  case "$(printf "%s" "${package##*.}" | tr A-Z a-z)" in
    tgz | gz)
      compressor=gzip
      ;;
    tbz | bz2)
      if command -v lbzip2 1> /dev/null 2> /dev/null ; then
        compressor=lbzip2
      else
        compressor=bzip2
      fi
      ;;
    tlz | lz)
      if command -v plzip 1> /dev/null 2> /dev/null ; then
        compressor=plzip
        uses_threads=yes
      elif command -v lzip 1> /dev/null 2> /dev/null ; then
        compressor=lzip
      else
        printf "%s\n" "ERROR:  lzip compression utility not found in \$PATH." 1>&2
        exit 3
      fi
      ;;
    lzma)
      compressor=lzma
      ;;
    txz | xz)
      compressor=xz
      uses_threads=yes
      ;;
    *)
      printf "%s\n" "ERROR:  Unknown compression type: '${package##*.}'" 1>&2
      exit 4
      ;;
  esac

  if ! ( umask 000 ; cat -- "$package" | "$compressor" ${uses_threads:+"--threads=$threads"} -dc | tar --xattrs --xattrs-include='*' --keep-directory-symlink -xpvf - 2> /dev/null ) ; then
    printf "%s\n" "ERROR:  Failed to explodepkg because of cat, $compressor or tar." 1>&2
    exit 5
  fi

  if [ -r install/doinst.sh ] ; then
    printf "\n%s\n%s\n" "An installation script was detected in ./install/doinst.sh, but" "was not executed."
  fi
done