sdm-cmdsubs

#!/bin/bash
#
# This file is sourced by sdm for the burn and shrink commands
# It is not callable by anything other than sdm
# because it needs access to a bazillion variables defined
# in sdm, so can only run in the context of sdm. 
#
function write_burnmsg() {
    #
    # $1 has the message to write
    # It's written to the terminal and added to burnmsg
    #
    burnmsg+=("$(thisdate) $1")
    echo "$1"
    return 0
}    

function ddctrlc() {
    printf "\n%% Caught CTRL/C during burn. Cleaning up...\n"
    if [ "$ddpid" != "" ]
    then
	#echo "killing $ddpid"
	kill -HUP $ddpid > /dev/null 2>&1
	wait $ddpid > /dev/null 2>&1
	exit 1
    fi
}

errifrc() {
    [ $1 -ne 0 ] && errexit "$2 $1"
}

function setdiskid() {
    local dev="$1" diskid="$2"
    sfdisk --disk-id $dev 0x${diskid}
    if [ $? -ne 0 ]    # Assume it's an older version of sfdisk without --disk-id if it fails
    then
	write_burnmsg "% sfdisk failed; Trying fdisk to set Disk ID"
        fdisk "$dev" > /dev/null <<EOF
x
i
0x$diskid
r
w
EOF
        errifrc $? "? fdisk error "
	write_burnmsg "> Disk ID $diskid set successfully with fdisk"
    else
	write_burnmsg "> Disk ID $diskid set successfully with sfdisk"
    fi
}

function expandpartition() {
    # $1: devicename (/dev/sdX)
    local fulldevname=$1
    local dev=${fulldevname##/dev/}
    local part="${dev}2"           # RasPiOS Ext 4 partition is always partition 2
    local gb=$((1024*1024*1024)) gib=$((1000*1000*1000))

    while read line
    do
        if [[ "$line" =~ "msdos" ]]
        then
            fsize=$(IFS=":" read fs bytes file n1 n2 fs <<< $line ; echo $bytes)
            fsize=${fsize%B}     #Fsize is file system size in bytes
        elif [[ "$line" =~ "ext4" ]]
        then
            IFS=":;" read partnum partstart partend partsize fstype etc etc2 etc3 <<< $line
            partstart=${partstart%B}
            partend=${partend%B}
            partsize=${partsize%B}
        fi
    done < <(parted -ms /dev/$dev unit B print)
    #
    #   https://alioth-lists.debian.net/pipermail/parted-devel/2006-December/000573.html
    # $l1: BYT;  ** error if not BYT 
    # $l2: filespec:bytesB:file:512:512:msdos::;
    # $l3: partnum:startB:endB:sizeB:fstype:::;
    # $l4: partnum:startB:endB:sizeB:fstype:::;

    devsize=$(cat /sys/block/$dev/size)   # 512byte blocks
    newsize=$((devsize - 1 ))             # 512byte blocks
    partsize=$(cat /sys/block/$dev/$part/size)  # 512byte blocks

    pbytes=$((partsize*512))
    nbytes=$(((devsize*512)-$partend+$pbytes))
    pgbytes=$(python3 -c "print(\"{:.1f}\".format(round($pbytes/$gb, 2)))")
    pgibytes=$(python3 -c "print(\"{:.1f}\".format(round($pbytes/$gib, 2)))")
    ngbytes=$(python3 -c "print(\"{:.1f}\".format(round($nbytes/$gb, 2)))")
    ngibytes=$(python3 -c "print(\"{:.1f}\".format(round($nbytes/$gib, 2)))")
    write_burnmsg "> Expand Root: Expand partition from ${pgbytes}GB (${pgibytes}GiB) to ${ngbytes}GB (${ngibytes}GiB)"
    parted -m /dev/$dev u s resizepart 2 $newsize
    errifrc $? "? parted resizepart failed with status"
    #echo ",+" | sfdisk -N 2 $fulldevname
    #errifrc $? "? sfdisk expand last partition failed with status"
}

function checkupdsdm() {
    #
    # Loop through sdm files and plugins and check for any newer ones on host
    # Warn or update if so
    # $1: 'check' to report, or 'update' to check and update
    # $2: bupdate (sdm, plugin, or sdm+plugin (--bupdate))
    local copt=$1 bup=$2

    #
    # Check sdm components if --bupdate sdm
    # Really for sdm dev work only
    #
    if [[ "$bup" =~ "sdm" ]]
    then
	for fsdm in $sdmflist
	do
	    case "$copt" in
		check)
		    checkifnewer $sdmdir/$fsdm $SDMPT/$sdmdir/$fsdm && logtoboth "% sdm file '$fsdm' on host is newer"
		    ;;
		update)
		    [[ "$bup" =~ "sdm" ]] && copyifnewer $sdmdir/$fsdm $SDMPT/$sdmdir/$fsdm && logtoboth "% Update sdm module '$fsdm' from host to '$SDMPT$sdmdir"
		    ;;
	    esac
	done
    fi
    #
    # For plugins:
    # Loop through plugin list from command line
    # if has path always then copy to local-plugins in the img
    # else if newer in plugins or local-plugins, copy into img if --bupdate plugin
    if [ "$plugins" != "" ]
    then
	IFS="~" read -a plugs <<< "$plugins"
        for p in "${plugs[@]}"
        do
	    p="${p%:*}"
	    pn="$(basename $p)"
            if [ "$p" != "$pn" ]
	    then
		# plugin with path specified; copy into IMG if newer regardless of --bupdate
		copyifnewer $p $SDMPT/$sdmdir/local-plugins && logtoboth "% Update (or add) Plugin '$p' to $sdmdir/local-plugins"
	    else
		# no path on plugin. if find in plugins or local-plugins copy into img if --bupdate plugin else mention
		# this code doesn't report if plugin not found. That will happen later when it gets run
		for d in $sdmdir/local-plugins $sdmdir/plugins
		do
		    if [ -f $d/$pn ]
		    then
			case "$copt" in
			    check)
				checkifnewer $d/$pn $SDMPT/$d/$pn && logtoboth "% Plugin '$p' on the host is newer"
				;;
			    update)
				if [[ "$bup" =~ "plugin" ]]
				then
				    copyifnewer $d/$pn $SDMPT/$sdmdir/local-plugins && logtoboth "% Update Plugin '$pn' from '$d/$pn' to '$sdmdir/local-plugins'"
				else
				    logtoboth "% Plugin '$pn' on the host is newer"
				fi
				;;
			esac
			break
		    fi
		done
	    fi
        done
    fi
}

function sdm_burndevfile() {

    # Stash burn messages in an array until log on SD Card is mounted and available 
    declare -x SDMNSPAWN="Burn0"
    declare -a burnmsg
    declare -x SDMPT=$(makemtpt)
    newdiskid="$(printf  "%x" "$(((RANDOM*RANDOM*RANDOM*RANDOM+RANDOM)&0xFFFFFFFF))")"
    [ "$hname" == "" ] && echo "% hostname not specified with --host; will not be written"
    if [ $burn -eq 1 ]
    then
	#
	# Burning to a device
	#
	[ "$burndev" == "" ] && errexit "? No storage device specified"
	perr=0
	for p in 1 2 3 4
	do
	    [[ "$burndev" =~ "mmcblk" ]] && pn="p${p}" || pn=$p
	    pdev="${burndev}${pn}"
	    ismounted $pdev && echo "? Partition $pdev is mounted" && perr=1
	done
	[ $perr -eq 1 ] && errexit "? Use 'sudo umount' to unmount each mounted partition, then redo the burn command"
	ismounted $burndev && errexit "? Device '$burndev' is mounted"
	[ ! -b $burndev ] && errexit "? '$burndev' is not a block device"
	write_burnmsg "* Burn '$dimg' to '$burndev'..."
	burnmsg+=("$(thisdate) > Burn command line: $cmdline")
	ddcmd="dd if=$dimg of=$burndev status=progress $ddsw"
	burnmsg+=("$(thisdate) > dd command: $ddcmd")
	# Burn the IMG to the device
	echo "$ddcmd"
	trap "ddctrlc" SIGINT
	$ddcmd &
	ddpid=$!
	wait $ddpid > /dev/null 2>&1
	[ $? -ne 0 ] && errexit "? Exiting due to dd error"
	trap SIGINT
	burnmsg+=("$(thisdate) > dd Copy completed")
	# Prevent mount errors
	sync ; sync ; sleep 1
	p1="1" ; p2="2"
	[[ "$burndev" =~ "mmcblk" ]] && p1="p1" && p2="p2"
	if [ $expandroot -eq 1 ]
	then
	    expandpartition $burndev
	fi
	olddiskid="$((blkid -o value $burndev) | (read id ; echo $id))"
	write_burnmsg "> Set new disk ID '$newdiskid' on '$burndev'"
	setdiskid $burndev $newdiskid
	sync ; sync ; sleep 1
	mount -v ${burndev}${p2} $SDMPT
	mount -v ${burndev}${p1} $SDMPT/boot
	! ismounted ${burndev}${p2} && errexit "? Unable to mount ${burndev}${p2}"
    else
	#
	# Burning to a file
	#
	[ "$burnfilefile" == "" ] && errexit "? No Output IMG file specified"
	[ -f $burnfilefile ] && errexit "? Output IMG file '$burnfilefile' exists"
	write_burnmsg "* Burn '$dimg' to Output IMG '$burnfilefile'..."
	burnmsg+=("$(thisdate) > Burn IMG command line: $cmdline")
	ddcmd="dd if=$dimg of=$burnfilefile status=progress $ddsw"
	burnmsg+=("$(thisdate) > dd command: $ddcmd")
	# Burn the IMG to the file
	echo "$ddcmd"
	trap "ddctrlc" SIGINT
	$ddcmd &
	ddpid=$!
	wait $ddpid > /dev/null 2>&1
	[ $? -ne 0 ] && errexit "? Exiting due to dd error"
	trap SIGINT
	burnmsg+=("$(thisdate) > Image copy completed")
	olddiskid="$((blkid -o value $burnfilefile) | (read id ; echo $id))"
	loopdev=$(losetup --show -P -f $burnfilefile)
	setdiskid $loopdev $newdiskid
	losetup -d $loopdev
	domount "$burnfilefile"
	expandroot=1           # Force Expand Root into the newly written IMG so it will happen when burned to something with sdm
    fi
    write_burnmsg "> Set new Disk ID '$newdiskid' in /etc/fstab and /boot/cmdline.txt"
    sed -i "s/${olddiskid}/${newdiskid}/g" $SDMPT/etc/fstab
    # init_resize disappeared in 2022-09-06 build, but keep this here for older IMGs
    sed -i 's| init=/usr/lib/raspi-config/init_resize\.sh||' $SDMPT/boot/cmdline.txt
    sed -i 's| sdhci\.debug_quirks2=4||' $SDMPT/boot/cmdline.txt
    ! grep -q splash $SDMPT/boot/cmdline.txt && sed -i "s/ quiet//g" $SDMPT/boot/cmdline.txt # Remove 'quiet' if Lite (no splash)
    sed -i "s/${olddiskid}/${newdiskid}/" $SDMPT/boot/cmdline.txt
    #
    # Write out the accumulated messages into mounted image if image has been customized
    #
    if [ -d $SDMPT/etc/sdm ]
    then
	write_burnmsg "> Flush accumulated burn log messages"
	for (( i=0 ; i < ${#burnmsg[@]} ; i++ ))
	do
	    echo "${burnmsg[$i]}" >> $SDMPT/etc/sdm/history
	done
	#
	# Burn messages are written, all further messages written with logtoboth, which will write them to the terminal
	# and to $SDMPT/etc/sdm/history in the mounted image or image file
	#
	xsettings="apip apssid autologin b0script b1script bootsetpairs bootscripts dhcpcd disables domain expandroot exports keymap locale myuser myuid noreboot"
	xsettings="$xsettings nowaittimesync passwordpi passwordroot passworduser plugindebug plugins redact rclocal reboot rebootwait regensshkeys"
	xsettings="$xsettings svcdisable svcenable sysctl timezone wificountry wpaconf"
	# Save settings made with the --burn command
	# Define variable b<varname> for each <varname>
	for e in $xsettings
	do
	    eval b$e=\${!e}
	done
	source $SDMPT/etc/sdm/sdm-readparams                   # Read settings from the SD card
	initvirt logtoboth
	# Update settings with settings from cmd line as appropriate
	[ "$bb0script" != "$b0script" ] && b0script=$bb0script
	[ "$bb1script" != "$b1script" ] && b1script=$bb1script
	[ "$bdomain" != "" ] && domain=$bdomain
	[ $breboot -eq 1 ] && reboot=1
	[ $bnoreboot -eq 1 ] && reboot=0 && noreboot=1
	[ $bbootscripts -eq 1 ] && bootscripts=$bbootscripts
	[ "$bbootsetpairs" != "" ] && bootsetpairs="$bbootsetpairs"
	[ $brebootwait -ne $drebootwait ] && rebootwait=$brebootwait
	[ "$bapip" != "10.1.1.1" ] && apip=$bapip
	[ "$bapssid" != "sdm" ] && apssid=$bapssid
	[ "$bwificountry" != "" ] && wificountry="$bwificountry"
	[ "$bplugins" != "" ] && plugins="$bplugins" || plugins=""
	[ "$bmyuser" != "" ] && myuser=$bmyuser && myuid=$bmyuid
	[ "$bsvcenable" != "" ] && svcenable="$bsvcenable"
	[ "$bsvcdisable" != "" ] && svcdisable="$bsvcdisable"
	[ "$bdisables" != "" ] && disables="$bdisables"
	[ $bautologin -eq 1 ] && autologin=1
	expandroot=$((bexpandroot|expandroot))
	regensshkeys=$((bregensshkeys|regensshkeys))
	nowaittimesync=$((bnowaittimesync|nowaittimesync))
	plugindebug=$((bplugindebug|plugindebug))
	redact=$((bredact|redact))
	# --bupdate must specified on the burn command line
	[ "$bupdate" != "" ] && checkupdsdm update "$bupdate" || checkupdsdm check "$bupdate"
	if [ $expandroot -eq 1 -a $regensshkeys -eq 1 ]
	then
	    logtoboth "> Disable unneeded RasPiOS firstboot service in cmdline.txt; both --expand-root and --regen-ssh-host-keys set"
	    sed -i 's| init=/usr/lib/raspberrypi-sys-mods/firstboot||' $SDMPT/boot/cmdline.txt
	else
	    logtoboth "> RasPiOS firstboot service not disabled; at least one of --expand-root and --regen-ssh-host-keys not set"
	fi
	#
	# Set hostname into the image
	#
	if [ "$hname" != "" -a -f $SDMPT/etc/hostname ]
	then
	    # don't include domain name. Leave that to user
	    # [ "$domain" != "" ] && hnd="${hname}.${domain}" || hnd=$hname
	    # [ "$domain" != "" ] && shn=$hnd || shn=""
	    hnd=$hname
	    [ "$domain" != "" ] && shn="${hname}.${domain}" || shn=""
	    logtoboth "> Set hostname '$hnd'"
	    echo $hnd > $SDMPT/etc/hostname
	    sed -i "s/127.0.1.1.*raspberrypi/127.0.1.1\t$hname $shn/g" $SDMPT/etc/hosts
	fi

	if [[ "$loadllocal" =~ "|wifi|" ]]
	then
	    [ "$wificountry" == "" ] && logtoboth "% No --wifi-country specified with --loadlocal wifi; Using 'US' for a short time" && wificountry="US"
	fi
	[ "$bkeymap" != "" ] && keymap=$bkeymap && echo "keymap=$bkeymap" >> $SDMPT/etc/sdm/auto-1piboot.conf
	[ "$btimezone" != "" ] && timezone=$btimezone && echo "timezone=$btimezone" >> $SDMPT/etc/sdm/auto-1piboot.conf
	[ "$blocale" != "" ] && local=$blocale && echo "locale=$blocale" >> $SDMPT/etc/sdm/auto-1piboot.conf
	if [ "$b1script" != "" ]
	then
	    if [ -f $b1script ]
	    then
		if [ ! -f $SDMPT/etc/sdm/assets/$(basename $b1script) ]
		then
		    logtoboth "> Copy '$b1script' to /etc/sdm/assets"
		    cp $b1script $SDMPT/etc/sdm/assets
		    chmod 755 $SDMPT/etc/sdm/assets/$(basename $b1script)
		fi
	    else
		if [ ! -f $SDMPT/etc/sdm/assets/$(basename $b1script) ]
		then
		   logtoboth "? --b1script '$b1script' not found"
		   b1script=""
		fi
	    fi
	fi
	if [ "$bdhcpcd" != "" ]
	then
	    cat $bdhcpcd >> $SDMPT/etc/dhcpcd.conf
	    logtoboth "> Append '$bdhcpcd' to /etc/dhcpcd.conf"
	    dhcpcd=$bdhcpcd
	fi
	if [ "$bexports" != "" ]
	then
	    cp $bexports $SDMPT/etc/exports
	    logtoboth "> Copy '$bexports' to /etc/exports"
	    exports=$bexports
	fi
	if [ "$bsysctl" != "" ]
	then
	    cp $bsysctl $SDMPT/etc/sysctl.d
	    logtoboth "> Copy '$bsysctl' to /etc/sysctl.d/$(basename $bsysctl)"
	    sysctl=$bsysctl
	fi
	if [ "$bwpaconf" != "" ] # was --wpa specified on the burn command?
	then
	    [ ! -f $bwpaconf ] && echo "% --wpa config file '$bwpaconf' not found; Skipping"
	    [ $burn -eq 1 ] && state="'$burndev'" || state="$'burnfilefile'"
	    logtoboth "> Copy WPA Supplicant configuration '$bwpaconf' to '$burndev'"
	    [ -f $bwpaconf ] && cp $bwpaconf $SDMPT/etc/wpa_supplicant/wpa_supplicant.conf
	    wpaconf="$bwpaconf"   # Write updated wpaconf to SD Card params
	fi
	if [ "$brclocal" != "" ]
	then
	    logtoboth "> Add commands to /etc/rc.local per --rclocal"
	    grep -v 'exit 0' $SDMPT/etc/rc.local > $SDMPT/tmp/rc.local
	    IFS="~" read -a citems <<< "$brclocal"
	    for c in "${citems[@]}"
	    do
		logtoboth "   $c"
		echo "$c" >> $SDMPT/tmp/rc.local
	    done
	    echo "exit 0" >> $SDMPT/tmp/rc.local
	    mv $SDMPT/etc/rc.local $SDMPT/etc/rc.local.sdm.burn
	    mv $SDMPT/tmp/rc.local $SDMPT/etc
	    chmod 755 $SDMPT/etc/rc.local
	    [ "$rclocal" == "" ] && rclocal="$brclocal" || rclocal="${rclocal}|$brclocal"
	fi
	hostname="$hname"         # So it gets written to updated params on SD card
	[ "$bbootsetpairs" != "" -o "$bsvcdisable" != "" -o "$bsvcenable" != "" ] &&  setbootset  # Process --bootset settings
	[ $bootscripts -eq 1 ] && state="enabled" || state="disabled"
	logtoboth "> First System Boot Custom Boot Scripts $state"
	[ $rebootwait -ne $drebootwait ] && wmsg=" with a $rebootwait second wait" || wmsg=""
	[ $reboot -eq 1 ] && state="enabled${wmsg}" || state="disabled"
	logtoboth "> First System Boot automatic restart $state"
	bcp=""
	if [ "$bmyuser" != "" -a "$bpassworduser" == "" ]
	then
	    # Not in container so can't use getent
	    if grep -q ^$myuser: $SDMPT/etc/passwd
	    then
		logtoboth "% User $myuser already exists; Skipping..."
		bmyuser=""
	    else
		while [ 1 ]
		do
		    echo -n "** Enter password for user '$myuser': "
		    bpassworduser=$(getpwd)
		    echo ""
		    [ "$bpassworduser" != "" ] && break
		done
	    fi
	fi
	if [ "$bmyuser" != "" -o "$bpasswordpi" != "" -o "$bpasswordroot" != "" -o "$bpassworduser" != "" ]
	then
	    bcp="$SDMPT/etc/sdm/assets/ucp-run-script"
	    echo "#!/bin/bash" > $bcp
	    echo "source /etc/sdm/sdm-readparams" >> $bcp
	    [ "$bpasswordpi" != "" ] && echo "changepwd pi \"$bpasswordpi\"" >> $bcp && passwordpi=$bpasswordpi
	    [ "$bpasswordroot" != "" ] && echo "changepwd root \"$bpasswordroot\"" >> $bcp && passwordroot=$bpasswordroot
	    if [ "$bmyuser" == "" ]
	    then
		[ "$bpassworduser" != "" ] && echo "changepwd $myuser \"$bpassworduser\"" >> $bcp && passworduser=$bpassworduser
	    else
		echo "sdm_adduser $bmyuser \"$bmyuid\" \"$bpassworduser\"" >> $bcp && passworduser=$bpassworduser
	    fi
	    chmod 755 $bcp
	fi
	writeconfig               # Write updated params to the SD card so they are available in the following
	if [ "$b0script" != "" ]
	then
	    logtoboth "> Execute function 'do_b0script' in --b0script '$b0script'"
	    source $b0script
	    ftype=$(type -t do_b0script)
	    [ "$ftype" == "function" ] && do_b0script || logtoboth "% Function 'do_b0script' not found in '$b0script'; Skipping..."
	fi
	if [ "$plugins" != "" ]
	then
	    runplugins 0
	fi
	#declare -x SDMNSPAWN="Burn1"
	if [ -d $SDMPT/etc/lightdm ]
	then
	    if [ $breboot -eq 1 ]
	    then
		sdm_spawn "$sdmdir/sdm-phase1 burn-enable-lightdm-delay" "" Burn1
	    else
		[ $bautologin -eq 1 ] && sdm_spawn "$sdmdir/sdm-phase1 burn-enable-lightdm-autologin" "" Burn1
	    fi
	fi
	if [ "$bdisables" != "" ]
	then
	    logtoboth "> Process --disable $bdisables"
	    sdm_spawn "$sdmdir/sdm-phase1 do-disables" "" Burn1
	fi
	if [ "$bcp" != "" ]
	then
	    logtoboth "> Change passwords or add user per --user, --password-pi, --password-user, and/or --password-root"
	    sdm_spawn "$sdmdir/sdm-phase1 b1script $(basename $bcp)" "" Burn1
	fi
	if [ "$b1script" != "" ]
	then
	    logtoboth "> Run --b1script '$b1script'"
	    sdm_spawn "$sdmdir/sdm-phase1 b1script $b1script" "" Burn1
	fi
	if [ "$plugins" != "" ]
	then
	    sdm_spawn "$sdmdir/sdm-phase1 run-all-plugins 1" "" Burn1
	    sdm_spawn "$sdmdir/sdm-phase1 run-all-plugins post-install" "" Burn1
	fi
	#
	# Redact passwords if requested
	#
	if [ $redact -eq 1 ]
	then
	    logtoboth "> Redact passwords from /etc/sdm/cparams and /etc/sdm/history"
	    for pwd in "$passworduser" "$passwordroot" "$passwordpi"
	    do
		if [ "$pwd" != "" ]
		then
		    sed -i "s/$pwd/REDACTED/" $SDMPT/etc/sdm/cparams
		    sed -i "s/$pwd/REDACTED/" $SDMPT/etc/sdm/history
		fi
	    done
	fi
	declare -x SDMNSPAWN="Burn0"
	logtoboth "* Burn Completed"
    else
	echo $"% IMG '$dimg' is not sdm-enhanced
  Logs and configuration updates will not be written"
	[ "$b0script" != "" ] && echo "  and b0script '$b0script' will not be processed"
	[ "$b1script" != "" ] && echo "  and b1script '$b1script' will not be processed"
	if [ "$hname" != "" ]
	then
	    hnd=$hname
	    [ "$domain" != "" ] && shn="${hname}.${domain}" || shn=""
	    logtoboth "> Set hostname '$hnd'"
	    echo $hnd > $SDMPT/etc/hostname
	    sed -i "s/127.0.1.1.*raspberrypi/127.0.1.1\t$hname $shn/g" $SDMPT/etc/hosts
	fi
    fi
}
#
# Print partitions in IMG 
#
sdm_ppart() {
    echo "* Human-readable partition list"
    parted -s $dimg unit B print
    echo ""
    echo "* Machine-readable partition list"
    parted -ms $dimg unit B print
    #echo "0: filespec:bytesB:file:512:512:msdos::;"
    #echo "1: partnum:startB:endB:sizeB:fstype:::;"
    #echo "2 partnum:startB:endB:sizeB:fstype:::;"
}
#
# Shrink IMG file
#
sdm_shrink() {
    local gb=$((1024*1024*1024)) gib=$((1000*1000*1000))

    [ $dimgdev -eq 1 ] && errexit "? --shrink only operates on IMG files"
    loopdev=""
    fstype=""
    fsize=""
    bsize=$(stat --printf %s $dimg)
    rc=0
    echo "* Start shrink on IMG '$dimg'"
    while read line
    do
	if [[ "$line" =~ "msdos" ]]
	then
	    fsize=$(IFS=":" read fs bytes file n1 n2 fs <<< $line ; echo $bytes)
	    fsize=${fsize%B}
	elif [[ "$line" =~ "ext4" ]]
	then
	    IFS=":;" read partnum partstart partend partsize fstype etc etc2 etc3 <<< $line
	    partstart=${partstart%B}
	    partend=${partend%B}
	    partsize=${partsize%B}
	fi
    done < <(parted -ms $dimg unit B print)
    #
    #   https://alioth-lists.debian.net/pipermail/parted-devel/2006-December/000573.html
    # $l1: BYT;  ** error if not BYT 
    # $l2: filespec:bytesB:file:512:512:msdos::;
    # $l3: partnum:startB:endB:sizeB:fstype:::;
    # $l4: partnum:startB:endB:sizeB:fstype:::;
    #
    [ "$fstype" != "ext4" -o "$fsize" == "" ] && errexit "? IMG '$dimg' does not appear to be a RasPiOS IMG with two partitions"
    if [ $fsize -ne $bsize ]
    then
	errexit "? Discrepancy between stat and parted on file size; parted size: $fsize  stat size: $bsize"
    fi
    # Get partition type information for the 2nd partition (ext4)
    # ** Is this needed? it will fail miserably later which might be OK
#    pline=$(parted -s $dimg unit B print | grep ext4)     # Slightly different than parted done above (no -m)
#    if [[ "$pline" =~ "ext4" ]]
#    then
#	IFS=" " read p1 p2 p3 p4 parttype p6 <<< $pline
#	[ "$parttype" != "primary" ] && errexit "Partition type '$parttype' not supported"
#    else
#	errexit "? No ext4 partition found"
#    fi

    # Create loop device to the partition
    # Commented-out loggers and echos for debugging kernel log messages
    #logger "Create loop device"
    loopdev=$(losetup -f --show -o "$partstart" "$dimg")
    # bx is a dummy due to leading ",". Other 2 can be in either order
    IFS="," read bx b1 b2 <<< $(tune2fs -l $loopdev | while read aline ;\
				do \
				    # If one we want, strip the text and all spaces, then echo it for consumption outside this subshell
				    [[ "$aline" =~ "Block count" ]] && (bc=${aline##Block count: } ; bc=${bc// } ; echo -n ",bc${bc}");\
					[[ "$aline" =~ "Block size" ]] && (bs=${aline##Block size: } ; bs=${bs// } ; echo -n ",bs${bs}");\
					done) ; rc=${PIPESTATUS[0]}
    [ $rc -ne 0 ] && errexit "? tune2fs failed with status $rc"
    # Set bc=block count, bs=blocksize. Handle both orderings: <nn>bc,<nn>bs or <nn>bs,<nn>bc
    [ "${b1#bc}" != "$b1" ] && bc=${b1#bc}
    [ "${b2#bs}" != "$b2" ] && bs=${b2#bs}
    [ "${b1#bs}" != "$b1" ] && bc=${b1#bs}  #In case in other order
    [ "${b2#bc}" != "$b2" ] && bs=${b2#bc}  #...
    [ "$bc" == "" -o "$bs" == "" ] && errexit "? tune2fs failed to read the file system"

    #logger "Check the file system"
    echo "> Check the file system"
    e2fsck -pf $loopdev
    rc=$?
    [ $rc -ge 4 ] && errexit "? e2fsck reports that file system is corrupt $rc"

    #logger "Get new partition size"
    oresize=$(resize2fs -P $loopdev)
    errifrc $? "? resize2fs problem"
    # Strip everything before ": " leaving only the new partition size, then up it a bit
    newsize=${oresize##*: }
    newsize=$((newsize+8))

    # uncomment for debug
    #echo "> Shrink data"
    #echo "  Partition Start: $partstart"
    #echo "  Partition End:   $partend"
    #echo "  Partition Size:  $partsize"
    #echo "  New size: $newsize"
    #echo "  bc: $bc"
    #echo "  bs: $bs"

    [ $bc -le $newsize ] && errexit "% Image cannot be shrunk any further"

    # Shrink the file system
    #logger "Shrink the file system"
    echo "> Shrink the file system to $newsize"
    resize2fs -p $loopdev $newsize
    errifrc $? "? resize2fs shrink exited with status"

    # have not made resizepart work yet, so do a rm/mkpart on the partition
    #parted -s $dimg resizepart 2 $partnewend
    # Shrink the partition by removing and recreating it
    #logger "Remove old partition"
    echo "> Remove old partition"
    parted -s -a minimal $dimg rm $partnum
    errifrc $? "? parted rm partition failed with status"

    #logger "Make new partition"
    echo "> Make new partition"
    partnewsize=$((newsize*bs))
    partnewend=$((partstart+partnewsize-1))
    parttype="primary"
    parted -s $dimg unit B mkpart $parttype $partstart $partnewend
    errifrc $? "? parted mkpart failed with status"
    #
    # Shrink the IMG
    #
    #logger "Shrink the IMG"
    endsize=$((partstart+partnewsize))
    echo "> Shrink the image by truncating to $endsize"
    truncate -s ${endsize%B} $dimg
    errifrc $? "? Truncate failed with status "
    echo "* Shrink complete"
    asize=$(stat --printf %s $dimg)
    pgbytes=$(python3 -c "print(\"{:.1f}\".format(round($bsize/$gb, 2)))")
    pgibytes=$(python3 -c "print(\"{:.1f}\".format(round($bsize/$gib, 2)))")
    ngbytes=$(python3 -c "print(\"{:.1f}\".format(round($asize/$gb, 2)))")
    ngibytes=$(python3 -c "print(\"{:.1f}\".format(round($asize/$gib, 2)))")
    echo "  IMG '$dimg' was ${pgbytes}GB (${pgibytes}GiB) now ${ngbytes}GB (${ngibytes}GiB)"
    return
}