debextract - wrapper to dpkg-deb -x for multiple filenames

#!/bin/bash
#
# debextract - Wrapper to "dpkg-deb -x" for multiple files
#
#    Copyright (C) 2012 Rodrigo Silva (MestreLion) <[email protected]>
#
#    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 3 of the License, or
#    (at your option) any later version.
#
#    This program 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 this program. If not, see <http://www.gnu.org/licenses/gpl.html>
#
# Wrapper to extract multiple debian packages (*.deb). It automatically chooses
# a destination directory based on the deb's filename and also extracts the
# control information files (the DEBIAN directory inside the package)

usage() {
cat <<- USAGE
    Usage: $self [${main} options] [options] FILE...
USAGE
if [[ "$1" ]] ; then
    cat <<- USAGE
        Try '$self --help' for more information.
    USAGE
    exit 1
fi
cat <<-USAGE

    Extracts Debian Package files (.deb) to a directory matching their filenames

    Options:
    -h|--help     - show this page.
    -v|--verbose  - print more details about what is being done. Also enables
                     verbosity for ${main}. Use -X/+X to enable or disable this
    -X|--vextract - turns ON  verbosity for ${main}. Useful if -v is not set
    +X            - turns OFF verbosity for ${main}. Useful if -v is set
    --destdir DIR - sets a directory for extraction of all packages. If ommited
                     or blank, destination will be each package's current
                     directory. In all cases, package filename will be appended
                     to the final destination path.
    --nocontrol      - do not extract the control files. (DEBIAN directory)
    --controldir DIR - set the destination directory for the control files,
                        relative to the extracted package directory. Ignored if
                        --nocontrol is set. Default is DEBIAN.
    --onerror ACTION - What to do if an error occur when executing $main for a
                        given file. Valid ACTION values are:
              skip     - skip error and continue with next file, if any
              quit     - quit immediately, do not extract any further files
              ask      - if not last file, ask user what to do. Default action
                       Regardless of the action chosen, in case of any error
                       $self will always exit with ${main}'s last unsucessfull
                       exit code
    ${main} options:
                  - see ${main} --help or man ${main}

    FILE...       - package file(s) to extract, multiple files accepted

    The destination directory for extraction of each package will be the package
    filename without its extension (usually .deb). If the filename  has no
    extension, an error will occur, since this would be the same as executing
    ${main} -x file file

    Copyright (C) 2012 Rodrigo Silva (MestreLion) <[email protected]>
    License: GPLv3 or later. See <http://www.gnu.org/licenses/gpl.html>
USAGE
exit 0
}

opterror() { echo "$self: $1" ; usage 1 ; }
missing()  { opterror "missing ${1:+$1 }operand" ; }

testaction() {
    [[ "$1" ]] || missing "action"
    actions=( skip quit ask )
    for action in "${actions[@]}"; do [[ "$action" == "$1" ]] && return ; done
    opterror "invalid action '$1'. valid options are: ${actions[*]}"
}

handleerror() {
    code=$1
    (( verbose )) && echo "$self: error $code in $main"
    (( $2 > 1 )) || return 0 # Noting to handle if this is the last file
    case "$action" in
    skip) return 0 ;;
    quit) return 1 ;;
    ask )
        local choice
        read -rp "(Q)uit, (S)kip, or Skip (A)ll ? " choice
        case "$choice" in
        [Aa]*) action="skip" ; return 0 ;;
        [Ss]*) return 0 ;;
            *) return 1 ;; # Educating users not to blindly hit Enter :)
        esac
    esac
}

declare -a opts=()
self="${0##*/}"
main="dpkg-deb"
action="ask"
destdir=""
control=1
controldir="DEBIAN"
verbose=0
dverb=0
dquiet=0
code=0
ext="--extract"

# Loop options
while (( $# )); do
    case "$1" in
    -h|--help     ) usage                   ;;
    -v|--verbose  ) verbose=1               ;;
    -X|--vextract ) dverb=1                 ;;
    +X            ) dquiet=1                ;;
    -x|--extract  )                         ;; #I'm not so naive.Silently ignore
    --nocontrol   ) control=0               ;;
    --controldir=*) controldir="${1#*=}"    ;;
    --controldir  ) shift ; controldir="$1" ;;
    --destdir=*   ) destdir="${1#*=}"       ;;
    --destdir     ) shift ; destdir="$1"    ;;
    --onerror=*   ) testaction "${1#*=}"    ;;
    --onerror     ) shift ; testaction "$1" ;;
    --            ) shift ; break           ;;
    -*            ) opts+=( "$1" )          ;;
    *             ) break                   ;;
    esac
    shift
done

# Basic parser tests
[[ "$controldir" ]] || missing "control directory"

# Handle dpkg verbosity (done via extract command)
if ((verbose && !dquiet)) || (( !verbose && dverb )); then ext="--vextract"; fi

# Loop file arguments
(( $# )) || missing "file"
while (( $# )); do
    #FIXME: extremely unlikely corner-case flaw: filename without extension, in
    #       a path that contains a dot.  /etc/dir.d/no-deb-ext
    filetitle="${1%.*}"
    if [[ "$destdir" ]] ; then
        path="${destdir}/${filetitle##*/}"
    else
        path="$filetitle"
    fi
    mkdir -p "$path" # make it easy for dpkg
    cmd1=("$main" "${opts[@]}" "$ext"    -- "$1" "${path//\/\///}"            )
    cmd2=("$main" "${opts[@]}" --control -- "$1" "${path//\/\///}/$controldir")
    if (( control )) ; then
        (( verbose )) && echo "$self: executing ${cmd1[@]} && ${cmd2[@]}"
        "${cmd1[@]}" && "${cmd2[@]}" || handleerror $? $# || break
    else
        (( verbose )) && echo "$self: executing ${cmd1[@]}"
        "${cmd1[@]}"                 || handleerror $? $# || break
    fi
    shift
done

(( verbose )) && (( code )) &&
    echo "$self: error(s) occurred, exiting with $main last error's code, $code"

exit $code