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|
#!/bin/sh
DEPENDENCIES='tune2fs parted lsblk blkid'
READ_ONLY=y
die()
{
echo "Error: $*" >&2
exit 1
}
parted()
{
if [ "$READ_ONLY" ]
then
echo parted "$@"
else
(set -x; command parted "$@")
fi
}
check_deps()
{
for dep in $DEPENDENCIES
do
command -v "$dep" >/dev/null || die "Missing dependency: $dep"
done
}
filesystem_size()
{
[ "$1" ] || return
fstype=$(blkid -o value -s TYPE "$1") || die "blkid could not determine FS type"
case "$fstype" in
ext[234]) filesystem_size_e2fs "$1";;
*) die "Unsupported filesystem type: $FSTYPE";;
esac
}
filesystem_size_e2fs()
{
tune2fs -l "$1" | {
unset block_count block_size
while read line
do
case "$line" in
'Block count:'*) block_count=${line#*:} ;;
'Block size:'*) block_size=${line#*:} ;;
esac
done
[ "$block_count" -a "$block_size" ] || return
echo $((block_count * block_size))
}
}
get_block_device_names() # Outputs: $PARTNAME $DEVNAME
{
[ -b "$1" ] || die "Not a block device: $1"
PARTNAME=/dev/$(lsblk -no KNAME "$1") || die "lsblk failed to get kernel device name for $1"
[ -b "$PARTNAME" ] || die "Not a block device: $PARTNAME"
DEVNAME=/dev/$(lsblk -no PKNAME "$PARTNAME") || die "lsblk failed to get parent device name for $PARTNAME"
[ -b "$DEVNAME" ] || die "Not a block device: $DEVNAME"
}
shrink_partition()
{
get_block_device_names "$1"
partnum=${PARTNAME#$DEVNAME}
[ "$PARTNAME" = "$DEVNAME$partnum" ] || die "Cannot compute partition number; (partname, devname) = ($PARTNAME, $DEVNAME)"
partsize=$(filesystem_size "$PARTNAME") || die "Failed to obtain fs size"
parted "$DEVNAME" resizepart "$partnum" $((partsize))B
}
check_deps
shrink_partition "$1"
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