Edenhofer · June 23, 2018 15:30
diff --git a/downgrade.sh b/downgrade.sh
 #!/usr/bin/bash
 #
 #   downgrade: downgrade packages using pacman's database and system log files
 #
 #   Copyright (c) 2008 locci <carlocci_at_gmail_dot_com>
 #   Copyright (c) 2008-2016 Pacman Development Team <[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 2 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/>.
 #

 shopt -s extglob
 shopt -s nullglob

 declare -r myname='downgrade'
 declare -r myver='5.0.1'
 USE_COLOR='y'
 pac_arg=''
 QUIET=0
 LAST_TRANSACTIONS=10

 # gettext initialization
 export TEXTDOMAIN='pacman'
 export TEXTDOMAINDIR='@localedir@'

 # Determine whether we have gettext; make it a no-op if we do not
 if ! type -p gettext >/dev/null; then
 	gettext() {
 		printf "%s\n" "$*"
 	}
 fi

 plain() {
 	(( QUIET )) && return
 	local mesg=$1; shift
 	printf "${BOLD}    ${mesg}${ALL_OFF}\n" "$@" >&1
 }

 msg() {
 	(( QUIET )) && return
 	local mesg=$1; shift
 	printf "${GREEN}==>${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&1
 }

 msg2() {
 	(( QUIET )) && return
 	local mesg=$1; shift
 	printf "${BLUE}  ->${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&1
 }

 ask() {
 	local mesg=$1; shift
 	printf "${BLUE}::${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}" "$@" >&1
 }

 warning() {
 	local mesg=$1; shift
 	printf "${YELLOW}==> $(gettext "WARNING:")${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&2
 }

 error() {
 	local mesg=$1; shift
 	printf "${RED}==> $(gettext "ERROR:")${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&2
 }

 # getopt-like parser
 parseopts() {
 	local opt= optarg= i= shortopts=$1
 	local -a longopts=() unused_argv=()

 	shift
 	while [[ $1 && $1 != '--' ]]; do
 		longopts+=("$1")
 		shift
 	done
 	shift

 	longoptmatch() {
 		local o longmatch=()
 		for o in "${longopts[@]}"; do
 			if [[ ${o%:} = "$1" ]]; then
 				longmatch=("$o")
 				break
 			fi
 			[[ ${o%:} = "$1"* ]] && longmatch+=("$o")
 		done

 		case ${#longmatch[*]} in
 			1)
 				# success, override with opt and return arg req (0 == none, 1 == required)
 				opt=${longmatch%:}
 				if [[ $longmatch = *: ]]; then
 					return 1
 				else
 					return 0
 				fi ;;
 			0)
 				# fail, no match found
 				return 255 ;;
 			*)
 				# fail, ambiguous match
 				printf "downgrade: $(gettext "option '%s' is ambiguous; possibilities:")" "--$1"
 				printf " '%s'" "${longmatch[@]%:}"
 				printf '\n'
 				return 254 ;;
 		esac >&2
 	}

 	while (( $# )); do
 		case $1 in
 			--) # explicit end of options
 				shift
 				break
 				;;
 			-[!-]*) # short option
 				for (( i = 1; i < ${#1}; i++ )); do
 					opt=${1:i:1}

 					# option doesn't exist
 					if [[ $shortopts != *$opt* ]]; then
 						printf "downgrade: $(gettext "invalid option") -- '%s'\n" "$opt" >&2
 						OPTRET=(--)
 						return 1
 					fi

 					OPTRET+=("-$opt")
 					# option requires optarg
 					if [[ $shortopts = *$opt:* ]]; then
 						# if we're not at the end of the option chunk, the rest is the optarg
 						if (( i < ${#1} - 1 )); then
 							OPTRET+=("${1:i+1}")
 							break
 						# if we're at the end, grab the the next positional, if it exists
 						elif (( i == ${#1} - 1 )) && [[ $2 ]]; then
 							OPTRET+=("$2")
 							shift
 							break
 						# parse failure
 						else
 							printf "downgrade: $(gettext "option requires an argument") -- '%s'\n" "$opt" >&2
 							OPTRET=(--)
 							return 1
 						fi
 					fi
 				done
 				;;
 			--?*=*|--?*) # long option
 				IFS='=' read -r opt optarg <<< "${1#--}"
 				longoptmatch "$opt"
 				case $? in
 					0)
 						# parse failure
 						if [[ $optarg ]]; then
 							printf "downgrade: $(gettext "option '%s' does not allow an argument")\n" "--$opt" >&2
 							OPTRET=(--)
 							return 1
 						# --longopt
 						else
 							OPTRET+=("--$opt")
 						fi
 						;;
 					1)
 						# --longopt=optarg
 						if [[ $optarg ]]; then
 							OPTRET+=("--$opt" "$optarg")
 						# --longopt optarg
 						elif [[ $2 ]]; then
 							OPTRET+=("--$opt" "$2" )
 							shift
 						# parse failure
 						else
 							printf "downgrade: $(gettext "option '%s' requires an argument")\n" "--$opt" >&2
 							OPTRET=(--)
 							return 1
 						fi
 						;;
 					254)
 						# ambiguous option -- error was reported for us by longoptmatch()
 						OPTRET=(--)
 						return 1
 						;;
 					255)
 						# parse failure
 						printf "downgrade: $(gettext "invalid option") '--%s'\n" "$opt" >&2
 						OPTRET=(--)
 						return 1
 						;;
 				esac
 				;;
 			*) # non-option arg encountered, add it as a parameter
 				unused_argv+=("$1")
 				;;
 		esac
 		shift
 	done

 	# add end-of-opt terminator and any leftover positional parameters
 	OPTRET+=('--' "${unused_argv[@]}" "$@")
 	unset longoptmatch

 	return 0
 }


 # Print usage information
 usage() {
 	printf "%s (pacman) %s\n" "$myname" "$myver"
 	echo
 	printf -- "$(gettext "Downgrade packages using pacman's database and system log files")\n"
 	echo
 	printf -- "$(gettext "Usage: %s [options] [package(s)]")\n" "$0"
 	echo
 	printf -- "$(gettext "Options:")\n"
 	printf -- "$(gettext "  -h, --help       Show this help message and exit")\n"
 	printf -- "$(gettext "  -q, --quiet      Silence most of the status reporting; not suitable for interactive use")\n"
 	printf -- "$(gettext "  -m, --nocolor    Disable colorized output messages")\n"
 	printf -- "$(gettext "  -n, --number <n> List the last <n> transactions (defaults to %s)")\n" "$LAST_TRANSACTIONS"
 	printf -- "$(gettext "  --needed         Do not reinstall the targets that are already up-to-date")\n"
 	printf -- "$(gettext "  --noconfirm      Bypass any and all “Are you sure?” messages")\n"
 	echo
 	printf -- "$(gettext "Examples:")"
 	printf -- "    %s --needed\n" "$myname"
 	printf -- "    %s linux linux-headers\n" "$myname"
 	printf -- "    %s --noconfirm binutils\n" "$myname"
 	echo
 }

 # Print version information
 version() {
 	printf "%s %s\n" "$myname" "$myver"
 	echo 'Copyright (C) 2016 Gordian Edenhofer <[email protected]>'
 	echo 'Copyright (C) 2008-2016 Pacman Development Team <[email protected]>'
 }


 # Printing the usage information takes precedence over every other parameter
 for option in "$@"; do
 	[[ $option == "-h" || $option == "--help" ]] && usage && exit 0
 done

 # Parse arguments
 OPT_SHORT='qmn:v'
 OPT_LONG=('quiet' 'nocolor' 'number:' 'needed' 'noconfirm' 'version')
 if ! parseopts "$OPT_SHORT" "${OPT_LONG[@]}" -- "$@"; then
 	usage
 	exit 1
 fi
 set -- "${OPTRET[@]}"
 unset OPT_SHORT OPT_LONG OPTRET

 while :; do
 	case "$1" in
 		-q|--quiet)
 			QUIET=1 ;;
 		-m|--nocolor)
 			USE_COLOR='n' ;;
 		-n|--number)
 			LAST_TRANSACTIONS="$2" ;;
 		--needed)
 			pac_arg="${pac_arg} --needed" ;;
 		--noconfirm)
 			pac_arg="${pac_arg} --nocofirm" ;;
 		-v|--version)
 			version
 			exit 0 ;;
 		--)
 			shift
 			break 2 ;;
 	esac
 	shift
 done

 # Configure colored output
 # check if messages are to be printed using color
 unset ALL_OFF BOLD BLUE GREEN RED YELLOW
 if [[ -t 2 && ! $USE_COLOR = "n" ]]; then
 	# prefer terminal safe colored and bold text when tput is supported
 	if tput setaf 0 &>/dev/null; then
 		ALL_OFF="$(tput sgr0)"
 		BOLD="$(tput bold)"
 		BLUE="${BOLD}$(tput setaf 4)"
 		GREEN="${BOLD}$(tput setaf 2)"
 		RED="${BOLD}$(tput setaf 1)"
 		YELLOW="${BOLD}$(tput setaf 3)"
 	else
 		ALL_OFF="\e[1;0m"
 		BOLD="\e[1;1m"
 		BLUE="${BOLD}\e[1;34m"
 		GREEN="${BOLD}\e[1;32m"
 		RED="${BOLD}\e[1;31m"
 		YELLOW="${BOLD}\e[1;33m"
 	fi
 fi
 readonly ALL_OFF BOLD BLUE GREEN RED YELLOW


 # Source environmental variables and specify fallbacks
 if [[ ! -r /etc/pacman.conf ]]; then
 	error "unable to read /etc/pacman.conf"
 	exit 1
 fi
 eval $(awk '/LogFile/ {print $1$2$3}' /etc/pacman.conf)
 pac_LogFile="${LogFile:-"/var/log/pacman.log"}"
 eval $(awk '/CacheDir/ {print $1$2$3}' /etc/pacman.conf)
 pac_CacheDir="${LogFile:-"/var/cache/pacman/pkg"}"
 if [[ ! -r /etc/makepkg.conf ]]; then
 	error "unable to read /etc/makepkg.conf"
 	exit 1
 fi
 source "/etc/makepkg.conf"
 if [[ -r ~/.makepkg.conf ]]; then
 	source ~/.makepkg.conf
 fi

 # Retrieve the list of packages to be assembled and break if none was specified
 pkg_list=($*)
 if [[ ${#pkg_list[@]} == 0 ]]; then
 	msg "Select one of the following transactions:"

 	# Read in log file as array
 	mapfile -t lines <"${pac_LogFile}"

 	# Query the date to which to downgrade to
 	transaction_count=0
 	transaction_line=("${#lines[@]}")
 	for (( idx=${#lines[@]}-1; idx>=0; idx-- )); do
 		# Print transaction list with their id
 		if [[ "${lines[idx]}" =~ "[ALPM] transaction started" ]]; then
 			for (( n=${transaction_line[-1]}; n>=idx; n-- )); do
 				# Skip transactions which do not qualify as upgrade or downgrade
 				if [[ "${lines[n]}" =~ "[ALPM] "(upgraded|downgraded)" " ]]; then
 					((transaction_count++))
 					transaction_line[transaction_count]="${idx}"
 					QUIET=0 msg2 "${transaction_count}\t: date $(echo "${lines[idx]}" | awk '{ print $1 " " $2 }')\tline ${transaction_line[transaction_count]}"
 					break
 				fi
 			done
 		fi
 		(( "${transaction_count}" == "${LAST_TRANSACTIONS}" )) && break
 	done
 	ask "Transaction number: "
 	read user_input
 	if [[ -z "${user_input##*[!0-9]*}" ]] || (( user_input > LAST_TRANSACTIONS || user_input == 0 )); then
 		error "'${user_input}' is not a valid choice..."
 		exit 1
 	fi

 	# Assemble a list of packages to downgrade
 	downgrade_pkgname=()
 	downgrade_pkgver=()
 	downgrade_pkgfile=()
 	for (( idx=${#lines[@]}-1; idx>=0; idx-- )); do
 		if (( idx == ${transaction_line[user_input]} )); then
 			break
 		elif [[ "${lines[idx]}" =~ "[ALPM] "(upgraded|downgraded)" " ]]; then
 			# Append package to list
 			downgrade_pkgname+=("$(echo "${lines[idx]}" | awk '{ print $5 }')")
 			downgrade_pkgver+=("$(echo "${lines[idx]}" | awk '{ print substr($6,2) }')")
 			if [[ -f "$(find "${pac_CacheDir}" -maxdepth 1 -type f -name "${downgrade_pkgname[-1]}-${downgrade_pkgver[-1]}-*" -print -quit)" ]]; then
 				downgrade_pkgfile+=("$(find "${pac_CacheDir}" -maxdepth 1 -type f -name "${downgrade_pkgname[-1]}-${downgrade_pkgver[-1]}-*" -print -quit)")
 			elif [[ -n "${PKGDEST}" && -f "$(find "${PKGDEST}" -maxdepth 1 -type f -name "${downgrade_pkgname[-1]}-${downgrade_pkgver[-1]}-*" -print -quit)" ]]; then
 				downgrade_pkgfile+=("$(find "${PKGDEST}" -maxdepth 1 -type f -name "${downgrade_pkgname[-1]}-${downgrade_pkgver[-1]}-*" -print -quit)")
 			else
 				downgrade_pkgfile+=("")
 			fi
 		fi
 	done

 	# Safely set duplicates to null in package lists
 	for (( idx=${#downgrade_pkgname[@]}-1; idx>=0; idx-- )); do
 		for (( n=0; n<idx; n++ )); do
 			if [[ "${downgrade_pkgname[n]}" == "${downgrade_pkgname[idx]}" ]]; then
 				downgrade_pkgname[${n}]=""
 				downgrade_pkgver[${n}]=""
 				downgrade_pkgfile[${n}]=""
 			fi
 		done
 	done
 else
 	# Loop over given packages and ask for a version
 	for pkgname in "${pkg_list[@]}"; do
 		# Scan system for available package versions and skip if none were found
 		if [[ -n "${PKGDEST}" ]]; then
 			mapfile -t pkg_versions < <(find "${pac_CacheDir}" "${PKGDEST}" -maxdepth 1 -type f -regextype sed -regex ".*/${pkgname}-[^-]\+-[^-]\+-[^-]\+\.pkg\.tar.*" -print)
 		else
 			mapfile -t pkg_versions < <(find "${pac_CacheDir}" -maxdepth 1 -type f -regextype sed -regex ".*/${pkgname}-[^-]\+-[^-]\+-[^-]\+\.pkg\.tar.*" -print)
 		fi
 		if [[ "${#pkg_versions[@]}" -eq 0 ]]; then
 			error "No package baring the name '${pkgname}' was found... skipping"
 			continue
 		fi
 		# TODO: Add ArchLinuxArchive support

 		# Sort the version array
 		pkg_versions=($(printf '%s\n' "${pkg_versions[@]}" | sort))

 		# Query the version to which to downgrade
 		msg "Select one of the following versions for ${pkgname}:"
 		pkg_count=0
 		for pkgfile in "${!pkg_versions[@]}"; do
 			msg2 "$((pkg_count+1))\t: $(basename "${pkg_versions[pkg_count]}" | sed 's/-[^-]*.pkg.tar..*//g')\tfile ${pkg_versions[pkg_count]}"
 			((pkg_count++))
 		done
 		ask "Item number: "
 		read user_input
 		if [[ -z "${user_input##*[!0-9]*}" ]] || (( user_input > pkg_count || user_input == 0 )); then
 			error "'${user_input}' is not a valid choice..."
 			continue
 		fi
 		downgrade_pkgfile+=("${pkg_versions[$((user_input-1))]}")
 	done
 fi

 # Strip null elements from file array
 for i in "${!downgrade_pkgfile[@]}"; do
 	[[ -z "${downgrade_pkgfile[i]}" ]] && unset "downgrade_pkgfile[$i]"
 done

 # Invoke pacman if matches were found
 if [[ -z "${downgrade_pkgfile[@]}" ]]; then
 	msg "Nothing to downgrade..."
 else
 	msg "Starting pacman..."

 	# Gain privileges using sudo if not running as root
 	if [[ $EUID -eq 0 ]]; then
 		pacman -U ${pac_arg} "${downgrade_pkgfile[@]}"
 	else
 		if ! which sudo &>/dev/null ; then
 			error "Cannot find the sudo binary!"
 			error "${myname} requires root privileges. Either install \"sudo\" or run as root."
 			exit 1
 		else
 			sudo pacman -U ${pac_arg} "${downgrade_pkgfile[@]}"
 		fi
 	fi
 fi
 msg "Done."

 exit 0

 # vim: set noet:
	#!/usr/bin/bash
	#
	# downgrade: downgrade packages using pacman's database and system log files
	#
	# Copyright (c) 2008 locci <carlocci_at_gmail_dot_com>
	# Copyright (c) 2008-2016 Pacman Development Team <[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 2 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/>.
	#

	shopt -s extglob
	shopt -s nullglob

	declare -r myname='downgrade'
	declare -r myver='5.0.1'
	USE_COLOR='y'
	pac_arg=''
	QUIET=0
	LAST_TRANSACTIONS=10

	# gettext initialization
	export TEXTDOMAIN='pacman'
	export TEXTDOMAINDIR='@localedir@'

	# Determine whether we have gettext; make it a no-op if we do not
	if ! type -p gettext >/dev/null; then
	gettext() {
	printf "%s\n" "$*"
	}
	fi

	plain() {
	(( QUIET )) && return
	local mesg=$1; shift
	printf "${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&1
	}

	msg() {
	(( QUIET )) && return
	local mesg=$1; shift
	printf "${GREEN}==>${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&1
	}

	msg2() {
	(( QUIET )) && return
	local mesg=$1; shift
	printf "${BLUE} ->${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&1
	}

	ask() {
	local mesg=$1; shift
	printf "${BLUE}::${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}" "$@" >&1
	}

	warning() {
	local mesg=$1; shift
	printf "${YELLOW}==> $(gettext "WARNING:")${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&2
	}

	error() {
	local mesg=$1; shift
	printf "${RED}==> $(gettext "ERROR:")${ALL_OFF}${BOLD} ${mesg}${ALL_OFF}\n" "$@" >&2
	}

	# getopt-like parser
	parseopts() {
	local opt= optarg= i= shortopts=$1
	local -a longopts=() unused_argv=()

	shift
	while [[ $1 && $1 != '--' ]]; do
	longopts+=("$1")
	shift
	done
	shift

	longoptmatch() {
	local o longmatch=()
	for o in "${longopts[@]}"; do
	if [[ ${o%:} = "$1" ]]; then
	longmatch=("$o")
	break
	fi
	[[ ${o%:} = "$1"* ]] && longmatch+=("$o")
	done

	case ${#longmatch[*]} in
	1)
	# success, override with opt and return arg req (0 == none, 1 == required)
	opt=${longmatch%:}
	if [[ $longmatch = *: ]]; then
	return 1
	else
	return 0
	fi ;;
	0)
	# fail, no match found
	return 255 ;;
	*)
	# fail, ambiguous match
	printf "downgrade: $(gettext "option '%s' is ambiguous; possibilities:")" "--$1"
	printf " '%s'" "${longmatch[@]%:}"
	printf '\n'
	return 254 ;;
	esac >&2
	}

	while (( $# )); do
	case $1 in
	--) # explicit end of options
	shift
	break
	;;
	-[!-]*) # short option
	for (( i = 1; i < ${#1}; i++ )); do
	opt=${1:i:1}

	# option doesn't exist
	if [[ $shortopts != $opt ]]; then
	printf "downgrade: $(gettext "invalid option") -- '%s'\n" "$opt" >&2
	OPTRET=(--)
	return 1
	fi

	OPTRET+=("-$opt")
	# option requires optarg
	if [[ $shortopts = $opt: ]]; then
	# if we're not at the end of the option chunk, the rest is the optarg
	if (( i < ${#1} - 1 )); then
	OPTRET+=("${1:i+1}")
	break
	# if we're at the end, grab the the next positional, if it exists
	elif (( i == ${#1} - 1 )) && [[ $2 ]]; then
	OPTRET+=("$2")
	shift
	break
	# parse failure
	else
	printf "downgrade: $(gettext "option requires an argument") -- '%s'\n" "$opt" >&2
	OPTRET=(--)
	return 1
	fi
	fi
	done
	;;
	--?=\|--?*) # long option
	IFS='=' read -r opt optarg <<< "${1#--}"
	longoptmatch "$opt"
	case $? in
	0)
	# parse failure
	if [[ $optarg ]]; then
	printf "downgrade: $(gettext "option '%s' does not allow an argument")\n" "--$opt" >&2
	OPTRET=(--)
	return 1
	# --longopt
	else
	OPTRET+=("--$opt")
	fi
	;;
	1)
	# --longopt=optarg
	if [[ $optarg ]]; then
	OPTRET+=("--$opt" "$optarg")
	# --longopt optarg
	elif [[ $2 ]]; then
	OPTRET+=("--$opt" "$2" )
	shift
	# parse failure
	else
	printf "downgrade: $(gettext "option '%s' requires an argument")\n" "--$opt" >&2
	OPTRET=(--)
	return 1
	fi
	;;
	254)
	# ambiguous option -- error was reported for us by longoptmatch()
	OPTRET=(--)
	return 1
	;;
	255)
	# parse failure
	printf "downgrade: $(gettext "invalid option") '--%s'\n" "$opt" >&2
	OPTRET=(--)
	return 1
	;;
	esac
	;;
	*) # non-option arg encountered, add it as a parameter
	unused_argv+=("$1")
	;;
	esac
	shift
	done

	# add end-of-opt terminator and any leftover positional parameters
	OPTRET+=('--' "${unused_argv[@]}" "$@")
	unset longoptmatch

	return 0
	}


	# Print usage information
	usage() {
	printf "%s (pacman) %s\n" "$myname" "$myver"
	echo
	printf -- "$(gettext "Downgrade packages using pacman's database and system log files")\n"
	echo
	printf -- "$(gettext "Usage: %s [options] [package(s)]")\n" "$0"
	echo
	printf -- "$(gettext "Options:")\n"
	printf -- "$(gettext " -h, --help Show this help message and exit")\n"
	printf -- "$(gettext " -q, --quiet Silence most of the status reporting; not suitable for interactive use")\n"
	printf -- "$(gettext " -m, --nocolor Disable colorized output messages")\n"
	printf -- "$(gettext " -n, --number <n> List the last <n> transactions (defaults to %s)")\n" "$LAST_TRANSACTIONS"
	printf -- "$(gettext " --needed Do not reinstall the targets that are already up-to-date")\n"
	printf -- "$(gettext " --noconfirm Bypass any and all “Are you sure?” messages")\n"
	echo
	printf -- "$(gettext "Examples:")"
	printf -- " %s --needed\n" "$myname"
	printf -- " %s linux linux-headers\n" "$myname"
	printf -- " %s --noconfirm binutils\n" "$myname"
	echo
	}

	# Print version information
	version() {
	printf "%s %s\n" "$myname" "$myver"
	echo 'Copyright (C) 2016 Gordian Edenhofer <[email protected]>'
	echo 'Copyright (C) 2008-2016 Pacman Development Team <[email protected]>'
	}


	# Printing the usage information takes precedence over every other parameter
	for option in "$@"; do
	[[ $option == "-h" \|\| $option == "--help" ]] && usage && exit 0
	done

	# Parse arguments
	OPT_SHORT='qmn:v'
	OPT_LONG=('quiet' 'nocolor' 'number:' 'needed' 'noconfirm' 'version')
	if ! parseopts "$OPT_SHORT" "${OPT_LONG[@]}" -- "$@"; then
	usage
	exit 1
	fi
	set -- "${OPTRET[@]}"
	unset OPT_SHORT OPT_LONG OPTRET

	while :; do
	case "$1" in
	-q\|--quiet)
	QUIET=1 ;;
	-m\|--nocolor)
	USE_COLOR='n' ;;
	-n\|--number)
	LAST_TRANSACTIONS="$2" ;;
	--needed)
	pac_arg="${pac_arg} --needed" ;;
	--noconfirm)
	pac_arg="${pac_arg} --nocofirm" ;;
	-v\|--version)
	version
	exit 0 ;;
	--)
	shift
	break 2 ;;
	esac
	shift
	done

	# Configure colored output
	# check if messages are to be printed using color
	unset ALL_OFF BOLD BLUE GREEN RED YELLOW
	if [[ -t 2 && ! $USE_COLOR = "n" ]]; then
	# prefer terminal safe colored and bold text when tput is supported
	if tput setaf 0 &>/dev/null; then
	ALL_OFF="$(tput sgr0)"
	BOLD="$(tput bold)"
	BLUE="${BOLD}$(tput setaf 4)"
	GREEN="${BOLD}$(tput setaf 2)"
	RED="${BOLD}$(tput setaf 1)"
	YELLOW="${BOLD}$(tput setaf 3)"
	else
	ALL_OFF="\e[1;0m"
	BOLD="\e[1;1m"
	BLUE="${BOLD}\e[1;34m"
	GREEN="${BOLD}\e[1;32m"
	RED="${BOLD}\e[1;31m"
	YELLOW="${BOLD}\e[1;33m"
	fi
	fi
	readonly ALL_OFF BOLD BLUE GREEN RED YELLOW


	# Source environmental variables and specify fallbacks
	if [[ ! -r /etc/pacman.conf ]]; then
	error "unable to read /etc/pacman.conf"
	exit 1
	fi
	eval $(awk '/LogFile/ {print $1$2$3}' /etc/pacman.conf)
	pac_LogFile="${LogFile:-"/var/log/pacman.log"}"
	eval $(awk '/CacheDir/ {print $1$2$3}' /etc/pacman.conf)
	pac_CacheDir="${LogFile:-"/var/cache/pacman/pkg"}"
	if [[ ! -r /etc/makepkg.conf ]]; then
	error "unable to read /etc/makepkg.conf"
	exit 1
	fi
	source "/etc/makepkg.conf"
	if [[ -r ~/.makepkg.conf ]]; then
	source ~/.makepkg.conf
	fi

	# Retrieve the list of packages to be assembled and break if none was specified
	pkg_list=($*)
	if [[ ${#pkg_list[@]} == 0 ]]; then
	msg "Select one of the following transactions:"

	# Read in log file as array
	mapfile -t lines <"${pac_LogFile}"

	# Query the date to which to downgrade to
	transaction_count=0
	transaction_line=("${#lines[@]}")
	for (( idx=${#lines[@]}-1; idx>=0; idx-- )); do
	# Print transaction list with their id
	if [[ "${lines[idx]}" =~ "[ALPM] transaction started" ]]; then
	for (( n=${transaction_line[-1]}; n>=idx; n-- )); do
	# Skip transactions which do not qualify as upgrade or downgrade
	if [[ "${lines[n]}" =~ "[ALPM] "(upgraded\|downgraded)" " ]]; then
	((transaction_count++))
	transaction_line[transaction_count]="${idx}"
	QUIET=0 msg2 "${transaction_count}\t: date $(echo "${lines[idx]}" \| awk '{ print $1 " " $2 }')\tline ${transaction_line[transaction_count]}"
	break
	fi
	done
	fi
	(( "${transaction_count}" == "${LAST_TRANSACTIONS}" )) && break
	done
	ask "Transaction number: "
	read user_input
	if [[ -z "${user_input##[!0-9]}" ]] \|\| (( user_input > LAST_TRANSACTIONS \|\| user_input == 0 )); then
	error "'${user_input}' is not a valid choice..."
	exit 1
	fi

	# Assemble a list of packages to downgrade
	downgrade_pkgname=()
	downgrade_pkgver=()
	downgrade_pkgfile=()
	for (( idx=${#lines[@]}-1; idx>=0; idx-- )); do
	if (( idx == ${transaction_line[user_input]} )); then
	break
	elif [[ "${lines[idx]}" =~ "[ALPM] "(upgraded\|downgraded)" " ]]; then
	# Append package to list
	downgrade_pkgname+=("$(echo "${lines[idx]}" \| awk '{ print $5 }')")
	downgrade_pkgver+=("$(echo "${lines[idx]}" \| awk '{ print substr($6,2) }')")
	if [[ -f "$(find "${pac_CacheDir}" -maxdepth 1 -type f -name "${downgrade_pkgname[-1]}-${downgrade_pkgver[-1]}-*" -print -quit)" ]]; then
	downgrade_pkgfile+=("$(find "${pac_CacheDir}" -maxdepth 1 -type f -name "${downgrade_pkgname[-1]}-${downgrade_pkgver[-1]}-*" -print -quit)")
	elif [[ -n "${PKGDEST}" && -f "$(find "${PKGDEST}" -maxdepth 1 -type f -name "${downgrade_pkgname[-1]}-${downgrade_pkgver[-1]}-*" -print -quit)" ]]; then
	downgrade_pkgfile+=("$(find "${PKGDEST}" -maxdepth 1 -type f -name "${downgrade_pkgname[-1]}-${downgrade_pkgver[-1]}-*" -print -quit)")
	else
	downgrade_pkgfile+=("")
	fi
	fi
	done

	# Safely set duplicates to null in package lists
	for (( idx=${#downgrade_pkgname[@]}-1; idx>=0; idx-- )); do
	for (( n=0; n<idx; n++ )); do
	if [[ "${downgrade_pkgname[n]}" == "${downgrade_pkgname[idx]}" ]]; then
	downgrade_pkgname[${n}]=""
	downgrade_pkgver[${n}]=""
	downgrade_pkgfile[${n}]=""
	fi
	done
	done
	else
	# Loop over given packages and ask for a version
	for pkgname in "${pkg_list[@]}"; do
	# Scan system for available package versions and skip if none were found
	if [[ -n "${PKGDEST}" ]]; then
	mapfile -t pkg_versions < <(find "${pac_CacheDir}" "${PKGDEST}" -maxdepth 1 -type f -regextype sed -regex "./${pkgname}-[^-]\+-[^-]\+-[^-]\+\.pkg\.tar." -print)
	else
	mapfile -t pkg_versions < <(find "${pac_CacheDir}" -maxdepth 1 -type f -regextype sed -regex "./${pkgname}-[^-]\+-[^-]\+-[^-]\+\.pkg\.tar." -print)
	fi
	if [[ "${#pkg_versions[@]}" -eq 0 ]]; then
	error "No package baring the name '${pkgname}' was found... skipping"
	continue
	fi
	# TODO: Add ArchLinuxArchive support

	# Sort the version array
	pkg_versions=($(printf '%s\n' "${pkg_versions[@]}" \| sort))

	# Query the version to which to downgrade
	msg "Select one of the following versions for ${pkgname}:"
	pkg_count=0
	for pkgfile in "${!pkg_versions[@]}"; do
	msg2 "$((pkg_count+1))\t: $(basename "${pkg_versions[pkg_count]}" \| sed 's/-[^-].pkg.tar..//g')\tfile ${pkg_versions[pkg_count]}"
	((pkg_count++))
	done
	ask "Item number: "
	read user_input
	if [[ -z "${user_input##[!0-9]}" ]] \|\| (( user_input > pkg_count \|\| user_input == 0 )); then
	error "'${user_input}' is not a valid choice..."
	continue
	fi
	downgrade_pkgfile+=("${pkg_versions[$((user_input-1))]}")
	done
	fi

	# Strip null elements from file array
	for i in "${!downgrade_pkgfile[@]}"; do
	[[ -z "${downgrade_pkgfile[i]}" ]] && unset "downgrade_pkgfile[$i]"
	done

	# Invoke pacman if matches were found
	if [[ -z "${downgrade_pkgfile[@]}" ]]; then
	msg "Nothing to downgrade..."
	else
	msg "Starting pacman..."

	# Gain privileges using sudo if not running as root
	if [[ $EUID -eq 0 ]]; then
	pacman -U ${pac_arg} "${downgrade_pkgfile[@]}"
	else
	if ! which sudo &>/dev/null ; then
	error "Cannot find the sudo binary!"
	error "${myname} requires root privileges. Either install \"sudo\" or run as root."
	exit 1
	else
	sudo pacman -U ${pac_arg} "${downgrade_pkgfile[@]}"
	fi
	fi
	fi
	msg "Done."

	exit 0

	# vim: set noet: