ntfsuuid

#!/bin/bash
#
# ntfsuuid - Tools for manipulating UUIDs in NTFS filesystems
#
#    Copyright (C) 2011 Rodrigo Silva - <linux@rodrigosilva.com>
#
#    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/>.
#
# Huge thanks to all the gurus and friends in irc://irc.freenet.org/#bash
# and the contributors of http://mywiki.wooledge.org/
#
# TODO: Integrate with common/common lib (SELF, _Confirm, _TestRoot)
# TODO: Test avaliability of tools (xxd, blkid, dd)
# TODO: Document error messages
# TODO: Allow volume LABEL instead of /dev/sdxy
# TODO: reconsider getopts http://mywiki.wooledge.org/BashFAQ/035

exec 3> /dev/null # to avoid harcoding /dev/null everywhere. For tools' stderr.

SELF="${0##*/}" # builin $(basename $0)

COMMAND=
VERBOSE=
LOWER=
FORCE=
TEST=
DEBUG=
BINARY=
DEVICE=
NTFSUUID=

usage ()
{
	local explicit="$1"

    cat <<EOF
Usage: $SELF [OPTIONS] --generate
       $SELF [OPTIONS] --read     DEVICE
       $SELF [OPTIONS] --set      DEVICE [--uuid UUID] [--binary]
       $SELF [OPTIONS] --copy     INPUT_DEVICE OUTPUT_DEVICE
EOF
	if [[ -z "$explicit" ]] ; then
	    cat <<EOF
Try '$SELF --help' for more information.
EOF
	else
	    cat <<EOF

Tools for reading, setting and generating UUIDs suitable for NTFS filesystems (8 bytes)

Options:
  -h, --help            print this message and exit
  -v, --verbose         verbose output (displays extra information)
  -l, --lower           use lower case for displaying UUIDs
  -f, --force           do not prompt before changes, assumes Yes for all questions
  -t, --test            simulation test, do not write any data on disk (affects --set and --copy only)
  -d, --debug           displays debug information on parsed options and arguments
  -b, --binary          interprets UUID as 8-byte binary data (rather than hexadecimal string)
                        --binary is only used with --uuid, otherwise it is ignored
  -u, --uuid UUID       uses the specified UUID. Must be a 16 chars ASCII string, case-insensitive, [0-9,A-F]
                        if --binary is used, UUID must be 8 bytes long
                        --uuid is only used with --set, otherwise it is ignored

Commands:
  --generate            output a random UUID suitable for an NTFS device (8 bytes)
  --read DEVICE         output the current UUID of the specified NTFS device
  --set  DEVICE         sets the UUID for the specified NTFS device (uses a random one if --uuid is ommited)
  --copy DEV_IN DEV_OUT copy (clone) the UUID from an NTFS device to another

Examples:
  $SELF --generate
  $SELF --read /dev/sdx1
  $SELF --set  /dev/sdx1
  $SELF --set  /dev/sdx1 --uuid 2AE2C85D31835048
  $SELF --set  /dev/sdx1 --uuid rodrigo1 --binary
  $SELF --copy /dev/sdx1 /dev/sdx2

Author: Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
License: GPLv3 <http://www.gnu.org/licenses/>
EOF
	fi
}

#######################################  Auxiliary Functions

_NTFSUuid()
{
	local device="$1"
	local lower="$2"

	local uuid=$(
		sudo xxd -plain -s 72 -len 8 "$device" |
		grep -o .. |
		tac |
		tr -d '\n'
	)

	if [[ "$lower" ]]; then
		echo "${uuid,,}"
	else
		echo "${uuid^^}"
	fi
}

_RandomUuid()
{
	local lower=""

	if [[ -z "$LOWER" ]] ; then lower="-u" ; fi
	NTFSUUID=$(xxd "$lower" -plain -l 8 /dev/urandom)
}

_TestNTFS()
{
	local device="$1"

	if [[ -n "$device" ]] ; then
		if [[ -b "$device" ]] ; then
			if sudo blkid -p  "$device" | grep -q "TYPE=\"ntfs\"" ; then
				return 0
			else
				echo "error: $device: permission denied or not an NTFS device"
				return 13
			fi
		else
			echo "error: $device: not found or not a device"
			return 12
		fi
	else
		# Redundant, since DEVICE is mandatory, enforced by getopts
		echo "error: this operation requires a device"
		return 11
	fi
}

_Confirm()
{
	local message="$1"
	local confirm

	if [[ -z "$FORCE" ]] ; then
		# can be improved with smarter setting of default value
		read -p "$message (y/n, default YES): " confirm
		case "x$confirm" in
			x[Yy]*|x) return 0;;
			*)
				if [[ -n "$VERBOSE" ]] ; then
					echo "$SELF: $COMMAND: cancelled by user"
				fi
				return 2
			;;
		esac
	fi
}

_PrintFlags()
{
	# Echoing $DEBUG value is redundant, since this will only be printed if = 1
	# The missing space before $GETOPT is intentional, as getopt output
	#   contains a leading space
	cat <<EOF
Parsed Options  =$GETOPT
Debug           = $DEBUG
Verbose         = $VERBOSE
Lower case      = $LOWER
Non-Interactive = $FORCE
Simulation Test = $TEST
Binary          = $BINARY
Command         = $COMMAND
Device          = $DEVICE
Uuid            = $NTFSUUID
EOF
}


#######################################  Main Functions


Uuid_Generate()
{
	_RandomUuid

	# All input data is set, print debug info
	if [[ -n "$DEBUG" ]] ; then _PrintFlags ; fi

	if [[ -n "$VERBOSE" ]] ; then
		echo "Random UUID: $NTFSUUID"
	else
		echo "$NTFSUUID"
	fi
}

Uuid_Read()
{
	_TestNTFS "$DEVICE" || return $?

	NTFSUUID=$(_NTFSUuid "$DEVICE" "$LOWER")

	# All input data is set, print debug info
	if [[ -n "$DEBUG" ]] ; then _PrintFlags ; fi

	if [[ -n "$VERBOSE" ]] ; then
		echo "UUID of $DEVICE is $NTFSUUID"
	else
		echo "$NTFSUUID"
	fi
}

Uuid_Set()
{
	local binary_uuid
	local result=0

	# Handle UUID: Calculate a random one if not given
	if [[ -z "$NTFSUUID" ]] ; then
		_RandomUuid
	else
		if [[ -z "$BINARY" ]] ; then
			# Hexadecimal String format
			if ! [[ "$NTFSUUID" =~ ^[0-9A-Fa-f]{16}$ ]] ; then
				echo "error: $NTFSUUID: invalid UUID. Must be 16 hexadecimal characters [0-9,A-F]. Ex: 2AE2C85D31835048"
				return 21
			fi
		else
			# Binary format
			if [[ ${#NTFSUUID} -ne 8 ]] ; then
				echo "error: $NTFSUUID: invalid UUID. Binary format must be 8 bytes long"
				return 22
			fi

			# Save original UUID
			binary_uuid="$NTFSUUID"

			# Convert to hexadecimal string
			NTFSUUID=$(echo "$NTFSUUID" | xxd -len 8 -plain)
		fi

	fi

	# Adjust UUID case, for display messages purposes only
	if [[ "$LOWER" ]]; then
		NTFSUUID="${NTFSUUID,,}"
	else
		NTFSUUID="${NTFSUUID^^}"
	fi

	# Test device
	_TestNTFS "$DEVICE" || return $?

	# All input data is set, print debug info
	if [[ -n "$DEBUG"  ]] ; then _PrintFlags ; fi
	if [[ -n "$BINARY" ]] ; then echo "Binary UUID     = $binary_uuid" ; fi

	# Confirm with user
	_Confirm "Set $DEVICE UUID to $NTFSUUID?" || return $?

	# Set the UUID
	if [[ -z "$TEST" ]] ; then
		echo "$NTFSUUID" |
		grep -o .. |
		tac |
		xxd -r -plain |
		sudo dd of="$DEVICE" bs=8 count=1 seek=9 \
			conv=notrunc status=noxfer 2>&3
		result=$?
	fi

	if [[ $result -eq 0 ]] ; then
		# Verbose message
		if [[ -n "$VERBOSE" ]] ; then echo "UUID of $DEVICE set to $NTFSUUID" ; fi
		return 0
	else
		echo "error: $COMMAND: $result (permission denied?)"
		return $result
	fi
}

Uuid_Copy()
{
	local input="$DEVICE"
	local output="$1"
	local result=0
	local lower

	# Check DEVICE_OUTPUT (getopt only handle 1 mandatory argument per option)
	if [[ -z "$output" ]] ; then
		echo "error: output device not specified"
		usage
		exit 31
	fi

	# Test Input and Output devices
	_TestNTFS "$input" && _TestNTFS "$output" || return $?

	# Read input device's UUID
	NTFSUUID=$(_NTFSUuid "$input" "$LOWER")

	# All input data is set, print debug info (with additional DEVICE_OUTPUT parameter)
	if [[ -n "$DEBUG" ]] ; then _PrintFlags ; echo "Output          = $1" ; fi

	# Confirm with user
	_Confirm "Copy UUID $NTFSUUID from $input to $output ?" || return $?

	# Copy the UUID
	if [[ -z "$TEST" ]] ; then
		sudo dd if="$input" of="$output" bs=8 count=1 seek=9 skip=9 conv=notrunc /
		        status=noxfer 2>&3
		result=$?
	fi

	if [[ $result -eq 0 ]] ; then
		# Verbose message
		if [[ -n "$VERBOSE" ]] ; then echo "UUID $NTFSUUID copied from $input to $output" ; fi
		return 0
	else
		echo "error: $COMMAND ended with status $result (permission denied?)"
		return $result
	fi
}

#######################################  Command Line parsing


# Print usage if no parameter passed
if [[ $# -eq 0 ]] ; then
	usage
	exit 1
fi

GETOPT=$(getopt --alternative --options "vlftbd" --longoptions "verbose,lower,force,test,binary,debug,uuid:,help,generate,read:,set:,copy:" --name "$SELF" -- "$@")
if [[ $? -gt 0 ]] ; then usage ; exit 1 ; fi  # error in getopt
eval set -- "$GETOPT"

while true ; do
	case "$1" in
		-v|--verbose ) shift ; VERBOSE="1"                          ;; # Set verbose
		-l|--lower   ) shift ; LOWER="1"                            ;; # Set lower case
		-f|--force   ) shift ; FORCE="1"                            ;; # Set non-interactive
		-t|--test    ) shift ; TEST="1"                             ;; # Set simulation test
		-b|--binary  ) shift ; BINARY="1"                           ;; # Set binary mode
		-d|--debug   ) shift ; DEBUG="1"                            ;; # Set debug mode
		--uuid       ) shift ; NTFSUUID="$1"                ; shift ;; # Set UUID
		--help       ) shift ; COMMAND="help"                       ;; # Help requested
		--generate   ) shift ; COMMAND="generate"                   ;; # Prints random UUID
		--read       ) shift ; COMMAND="read" ; DEVICE="$1" ; shift ;; # Reads UUID from dev
		--set        ) shift ; COMMAND="set"  ; DEVICE="$1" ; shift ;; # Sets UUID of dev
		--copy       ) shift ; COMMAND="copy" ; DEVICE="$1" ; shift ;; # Copy UUID from dev
		--           ) shift ; break ;;
		*            ) break ;;
	esac
done

case "$COMMAND" in
	help     ) usage "HELP"   ; exit 0  ;;
	generate ) Uuid_Generate  ; exit $? ;;
	read     ) Uuid_Read      ; exit $? ;;
	set      ) Uuid_Set       ; exit $? ;;
	copy     ) Uuid_Copy "$@" ; exit $? ;;
	*        ) usage          ; exit 1  ;;
esac