Contents of /cryptsetup/trunk/debian/scripts/decrypt_derived

#!/bin/sh

# WARNING: If you use the decrypt_derived keyscript for devices with
# persistent data (i.e. not swap or temp devices), then you will lose
# access to that data permanently if something damages the LUKS header
# of the LUKS device you derive from. The same applies if you luksFormat
# the device, even if you use the same passphrase(s). A LUKS header 
# backup, or better a backup of the data on the derived device may be 
# a good idea. See the Cryptsetup FAQ on how to do this right.

countlines() {
        local IFS input count tmp
        input="$1"
        count=0
        IFS='
'
        for tmp in $input; do
                count=$(( $count + 1 ))
        done
        echo $count
}

if [ -z "$1" ]; then
        echo "$0: must be executed with a crypto device as argument" >&2
        exit 1
fi

if ! device=$(dmsetup --showkeys table 2>/dev/null | grep "^$1:"); then
        echo "$0: failed to find $1 in dmtable" >&2
        exit 1
fi

if [ -z "$device" ]; then
        echo "$0: device $1 doesn't exist" >&2
        exit 1
fi

count=$(countlines "$device")
if [ $count -ne 1 ]; then
        echo "$0: more than one device match $1" >&2
        exit 1
fi

eval set -- $device
type="$4"
key="$6"

if [ "$type" != "crypt" ]; then
        echo "$0: device $1 is not a crypto device" >&2
        exit 1
fi

echo -n "$key"
exit 0
1	#!/bin/sh
2
3	# WARNING: If you use the decrypt_derived keyscript for devices with
4	# persistent data (i.e. not swap or temp devices), then you will lose
5	# access to that data permanently if something damages the LUKS header
6	# of the LUKS device you derive from. The same applies if you luksFormat
7	# the device, even if you use the same passphrase(s). A LUKS header
8	# backup, or better a backup of the data on the derived device may be
9	# a good idea. See the Cryptsetup FAQ on how to do this right.
10
11	countlines() {
12	local IFS input count tmp
13	input="$1"
14	count=0
15	IFS='
16	'
17	for tmp in $input; do
18	count=$(( $count + 1 ))
19	done
20	echo $count
21	}
22
23	if [ -z "$1" ]; then
24	echo "$0: must be executed with a crypto device as argument" >&2
25	exit 1
26	fi
27
28	if ! device=$(dmsetup --showkeys table 2>/dev/null \| grep "^$1:"); then
29	echo "$0: failed to find $1 in dmtable" >&2
30	exit 1
31	fi
32
33	if [ -z "$device" ]; then
34	echo "$0: device $1 doesn't exist" >&2
35	exit 1
36	fi
37
38	count=$(countlines "$device")
39	if [ $count -ne 1 ]; then
40	echo "$0: more than one device match $1" >&2
41	exit 1
42	fi
43
44	eval set -- $device
45	type="$4"
46	key="$6"
47
48	if [ "$type" != "crypt" ]; then
49	echo "$0: device $1 is not a crypto device" >&2
50	exit 1
51	fi
52
53	echo -n "$key"
54	exit 0