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