#!/bin/bash
# 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; version 2 of the License.
#
# 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.

ignore_error() {
	"$@" 2>/dev/null
	return 0
}

parse_fstab(){
	echo $(perl -ane 'printf("%s:%s\n", @F[0,1]) if $F[0] =~ m#^UUID=#;' $1/etc/fstab)
# 	perl -ane 'printf("%s:%s\n", @F[0,1]) if $F[0] =~ m#^/dev#;' $1/etc/fstab
# 	perl -ane 'printf("%s:%s\n", @F[0,1]) if $F[0] =~ m#^LABEL=#;' $1/etc/fstab
}

detect(){
	local detected="$(os-prober | tr ' ' '_' | paste -s -d ' ')"
	echo ${detected}
}

# $1: os-prober array
get_os_name(){
	local str=$1
	str="${str#*:}"
	str="${str#*:}"
	str="${str//:/}"
	echo "$str"
}

get_chroot_arch(){
	local elf=$(file $1/usr/bin/file)
	elf=${elf//*executable,}
	echo ${elf%%,*}
}

chroot_part_mount() {
	mount "$@" && CHROOT_ACTIVE_PART_MOUNTS=("$2" "${CHROOT_ACTIVE_PART_MOUNTS[@]}")
	msg2 "mounted: ${CHROOT_ACTIVE_PART_MOUNTS[@]}"
}

select_os(){
        os_list=( $(detect) )
	local count=${#os_list[@]}
	if [[ ${count} > 0 ]];then
                msg "List of found systems:"
                local i=0
                for os in ${os_list[@]};do
                        msg3 "$i) $(get_os_name ${os})"
                        i=$((i+1))
                done
                i=0
		msg "Please enter your choice [0-$count] : "
                read selection
        else
		selection=0
	fi
	local root=${os_list[$selection]}
	root=${root%%:*}
	local type=${os_list[$selection]}
	type=${type##*:}
        if [[ "${type##*:}" == 'linux' ]];then
		chroot_mount_partitions "${chrootdir}" "$root"
        else
                die "You can't mount $type!"
        fi
}

chroot_mount_partitions(){

	CHROOT_ACTIVE_PART_MOUNTS=()
	CHROOT_ACTIVE_MOUNTS=()

	[[ $(trap -p EXIT) ]] && die 'Error! Attempting to overwrite existing EXIT trap'
	trap 'trap_handler' EXIT

	chroot_part_mount $2 $1

	local mounts=$(parse_fstab "$1")

	for entry in ${mounts[@]}; do
		entry=${entry//UUID=}
		local dev=${entry%:*}
		local mp=${entry#*:}
		case "${entry#*:}" in
			'/'|'swap'|'none') continue ;;
			*) chroot_part_mount "/dev/disk/by-uuid/${dev}" "$1${mp}" ;;
		esac
	done

	local chroot_arch=$(get_chroot_arch $1)
	[[ ${chroot_arch} == x86-64 ]] && chroot_arch=${chroot_arch/-/_}
	case ${arch} in
		i686)
			if [[ ${chroot_arch} == x86_64 ]];then
				die "You can't chroot from ${arch} host into ${chroot_arch}!"
			fi
		;;
	esac

	chroot_mount_conditional "! mountpoint -q '$1'" "$1" "$1" --bind &&
	chroot_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
	chroot_mount sys "$1/sys" -t sysfs -o nosuid,noexec,nodev,ro &&
# 	ignore_error chroot_mount_conditional "[[ -d '$1/sys/firmware/efi/efivars' ]]" \
# 	efivarfs "$1/sys/firmware/efi/efivars" -t efivarfs -o nosuid,noexec,nodev &&
	chroot_mount udev "$1/dev" -t devtmpfs -o mode=0755,nosuid &&
	chroot_mount devpts "$1/dev/pts" -t devpts -o mode=0620,gid=5,nosuid,noexec &&
	chroot_mount shm "$1/dev/shm" -t tmpfs -o mode=1777,nosuid,nodev &&
	chroot_mount run "$1/run" -t tmpfs -o nosuid,nodev,mode=0755 &&
	chroot_mount tmp "$1/tmp" -t tmpfs -o mode=1777,strictatime,nodev,nosuid
	chroot_mount /etc/resolv.conf "$1/etc/resolv.conf" --bind
}

chroot_mount() {
	mount "$@" && CHROOT_ACTIVE_MOUNTS=("$2" "${CHROOT_ACTIVE_MOUNTS[@]}")
	#msg2 "mounted: ${CHROOT_ACTIVE_MOUNTS[@]}"
}

chroot_mount_conditional() {
	local cond=$1; shift
	if eval "$cond"; then
		chroot_mount "$@"
	fi
}

chroot_api_mount() {
	CHROOT_ACTIVE_MOUNTS=()
	[[ $(trap -p EXIT) ]] && die 'Error! Attempting to overwrite existing EXIT trap'
	trap 'chroot_api_umount' EXIT

	chroot_mount_conditional "! mountpoint -q '$1'" "$1" "$1" --bind &&
	chroot_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
	chroot_mount sys "$1/sys" -t sysfs -o nosuid,noexec,nodev,ro &&
# 	ignore_error chroot_mount_conditional "[[ -d '$1/sys/firmware/efi/efivars' ]]" \
# 	   efivarfs "$1/sys/firmware/efi/efivars" -t efivarfs -o nosuid,noexec,nodev &&
	chroot_mount udev "$1/dev" -t devtmpfs -o mode=0755,nosuid &&
	chroot_mount devpts "$1/dev/pts" -t devpts -o mode=0620,gid=5,nosuid,noexec &&
	chroot_mount shm "$1/dev/shm" -t tmpfs -o mode=1777,nosuid,nodev &&
	chroot_mount run "$1/run" -t tmpfs -o nosuid,nodev,mode=0755 &&
	chroot_mount tmp "$1/tmp" -t tmpfs -o mode=1777,strictatime,nodev,nosuid
}

chroot_part_umount() {
	umount "${CHROOT_ACTIVE_PART_MOUNTS[@]}"
	unset CHROOT_ACTIVE_PART_MOUNTS
}

chroot_api_umount() {
	umount "${CHROOT_ACTIVE_MOUNTS[@]}"
	unset CHROOT_ACTIVE_MOUNTS
}

trap_handler(){
	chroot_api_umount
	chroot_part_umount
}