Quantron backup script, 3rd generation
Posted by Anonymous on Wed 15th Jan 2020 07:19
raw | new post
modification of post by Anonymous (view diff)

#!/bin/bash

export PATH='/sbin:/usr/sbin:/bin:/usr/bin'
typeset -r usbstick_mountpoint='/media/usb0'

typeset -r backupscript_version='V2.0.6'

printf '#\n'
printf '# Quantron backup script STARTING...\n'

# stop codesys application
# we assume this returns only after codesys is no longer running
systemctl stop 'codesys3-rt.service'

# send all output to the quantron framebuffer console
export TERM='linux'
exec 0<>'/dev/tty0' 1>&0 2>&0
clear

# NASTY HACK:
# systemd/udev has a timeout running which will send SIGKILL to
# all processes in a cggroup. Since this backup script is interactive
# the only way to avoid getting killed by that timeout is to move
# the current shell process into another cggroup.
# This hack is WRONG on so many levels that it hurts, but given
# the time constraints and the stupidity how our system is currently
# designed there was to other way.
# We do this here, after redirecting output to the framebuffer terminal,
# so that we can see whether this fails or not.
printf '%d' $$ >'/sys/fs/cgroup/systemd/system/cgroup.procs'

color_printf()
{
        typeset color=$1
        shift
        typeset ttycmd=''

        case "$color" in
                'black')        ttycmd=$'\E[30m' ;;
                'red')          ttycmd=$'\E[31m' ;;
                'green')        ttycmd=$'\E[32m' ;;
                'yellow')       ttycmd=$'\E[33m' ;;
                'blue')         ttycmd=$'\E[34m' ;;
                'magenta')      ttycmd=$'\E[35m' ;;
                'cyan')         ttycmd=$'\E[36m' ;;
                'white')        ttycmd=$'\E[37m' ;;
        esac

        printf '%s' "$ttycmd"
        printf "$@"
        printf '%s' $'\E[0m'
}


is_usbstick_mounted()
{
        grep -q -E \
                "[[:space:]]+${usbstick_mountpoint}[[:space:]]+(fat|vfat|ntfs|ext4)[[:space:]]+(rw|ro)," \
                '/proc/self/mounts'
        return $?
}

disable_console_screensaver()
{
        # make sure the framebuffer console screenblanker is NOT active
        printf '0\n' >'/sys/devices/platform/imx21-fb.0/graphics/fb0/blank'

        # disable screen blanking (we have to do this via terminal codes
        # since /sys/module/kernel/parameters/consoleblank is read-only)
        printf '\E[9;0]'

        return 0
}

do_menu()
{
        typeset key

        #
        # main menu
        #
        printf '\n#\n'
        printf '# Welcome to the '
        color_printf 'red' 'QUANTRON'
        printf ' /var/dyn\n# backup tool (version %s)!\n' "${backupscript_version}"
        printf '#\n\n'

        color_printf 'yellow' ' * Menu:\n'
        color_printf 'yellow' ' - Press <ESC> key for abort\n\t(system shutdown)\n'     # key="A"
        color_printf 'yellow' ' - Press <T> key for backup\n'                           # key="C"
        color_printf 'yellow' ' - Press <L%%/R%%> key for restore\n'                    # key="D"

        for ((;;)) ; do
                disable_console_screensaver

                key=''

                #
                # wait for a key press...
                #
                # (warning: Quantron V3.1.9 has bash3.2.48 which does
                # NOT support -N, only -n is supported!)
                #
                IFS='' read -e -r -u0 -n1 key

                case "$key" in
                        'A')
                                color_printf 'cyan' '#### Aborting, system shutting down...\n'
                                sleep 3
                                reboot -p
                                exit 0
                                ;;
                        'C')
                                color_printf 'cyan' '#### Starting backup...\n'
                                sleep 3
                                do_backup
                                exit 0
                                ;;
                        'D')
                                color_printf 'cyan' '#### Starting restore...\n'
                                sleep 3
                                do_restore
                                exit 0
                                ;;
                        *)
                                # beep ?
                                ;;
                esac
        done

        # notreached
}

do_backup()
{
        typeset -i backuperr=0

        if ! is_usbstick_mounted ; then
                color_printf 'red' '# ERROR: No USB stick mounted, aborting\n'
                return 1
        fi

        if ! /sbin/eag_usbstick mount_writeable ; then
                color_printf 'red' '# ERROR: Cannot mount stick writeable, aborting\n'
                return 1
        fi

        mkdir -p "${usbstick_mountpoint}/quantron_backup"
        rm -f "${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2.md5sum"

        color_printf 'cyan' '\n# Saving files...\n'
        set -o pipefail

        (cd / && tar -cvf - var/dyn/* ) | \
                bzip2 -9 | \
                tee \
                        >(md5sum '/dev/stdin' | sed 's/\/dev\/stdin/quantron_var_dyn_backup.tar.bz2/' >"${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2.md5sum") \
                        >"${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2"
        (( backuperr+=$? ))

        sync ; sync # UNIX tradition!

        /sbin/eag_usbstick mount_readonly
        (( backuperr+=$? ))

        # verifying backup
        color_printf 'cyan' '\n# Verifying backup data...\n'
        (cd "${usbstick_mountpoint}/quantron_backup" && md5sum -c 'quantron_var_dyn_backup.tar.bz2.md5sum')
        if (( $? != 0 )) ; then
                (( backuperr++ ))
                color_printf 'red' '# ERROR: Wrong MD5 hash sum of written data\n'

                # remove backup archive so the user cannot restore broken data
                /sbin/eag_usbstick mount_writeable >'/dev/null' 2>&1
                rm -f \
                        "${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2" \
                        "${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2.md5sum"
                /sbin/eag_usbstick mount_readonly >'/dev/null' 2>&1
        fi

        if (( backuperr == 0 )) ; then
                color_printf 'green' '\n#\n# Backup success.\n#\n'
        else
                color_printf 'red' '\n#\n# Backup FAILED!!\n#\n'
        fi

        disable_console_screensaver

        color_printf 'yellow' '\n\nPlease remove USB stick and reboot...\n'
        return $(( backuperr?1:0 ))
}

do_restore()
{
        typeset -i restoreerr=0

        if [[ ! -r "${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2" ]] ; then
                color_printf 'red' '# ERROR: Cannot read backup file %s\n' "${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2"
                return 1
        fi

        color_printf 'cyan' '\n# Verifying backup data...\n'
        (cd "${usbstick_mountpoint}/quantron_backup" && md5sum -c 'quantron_var_dyn_backup.tar.bz2.md5sum')
        if (( $? != 0 )) ; then
                color_printf 'red' '# ERROR: Backup archive does not have the correct hash sum.\n'
                color_printf 'red' '\n#\n# Restore FAILED!!\n#\n'
                return 1
        fi

        color_printf 'cyan' '\n# Restoring files...\n'
        set -o pipefail
        bunzip2 -c <"${usbstick_mountpoint}/quantron_backup/quantron_var_dyn_backup.tar.bz2" |
                (cd / && tar -xvf -)
        (( restoreerr+=$? ))

        sync ; sync # UNIX tradition!

        if (( restoreerr == 0 )) ; then
                color_printf 'green' '\n#\n# Restore success.\n#\n'
        else
                color_printf 'red' '\n#\n# Restore FAILED!!\n#\n'
        fi

        disable_console_screensaver

        color_printf 'yellow' '\n\nPlease remove USB stick and reboot...\n'
        return $(( restoreerr?1:0 ))
}

# main
do_menu

# EOF.