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- #!/bin/sh
-
- set -e
-
- imgloop=
- tmpfile=
- tmploop=
- dmname=
- cowlink=
-
- function cleanup () {
- set +e
- [ -n "$cowlink" ] && rm $cowlink
- [ -n "$dmname" ] && dmsetup remove $dmname
- [ -n "$tmploop" ] && losetup -d $tmploop
- [ -n "$tmpfile" ] && rm $tmpfile
- [ -n "$imgloop" ] && losetup -d $imgloop
- }
-
- trap cleanup EXIT
-
- imgfile=$1 ; shift
- command=$1 ; shift
- if [ -z "$imgfile" -o -z "$command" ] ; then
- echo Syntax: $0 /path/to/image/file command [args..]
- exit 1
- fi
-
-
- x=`losetup -f` ; losetup -r $x $imgfile ; imgloop=$x
-
-
- tmpfile=`mktemp $imgfile.XXXXXXXXXX`
- truncate -r $imgfile $tmpfile
- x=`losetup -f` ; losetup $x $tmpfile ; tmploop=$x
-
-
- imgsize=`blockdev --getsz $imgloop`
- x=`basename $imgfile` ; echo 0 $imgsize snapshot $imgloop $tmploop N 16 | \
- dmsetup create $x ; dmname=$x
- chown --reference=$imgfile /dev/mapper/$dmname
- chmod --reference=$imgfile /dev/mapper/$dmname
-
-
- x=$imgfile.cow ; ln -s /dev/mapper/$dmname $x ; cowlink=$x
-
-
- echo "Created $cowlink"
- $command "$@" $cowlink
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