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#!/bin/sh
# resize-cloud-image
Usage() {
cat <<EOF
Usage: ${0##*/} image size [output]
Resize a UEC image to a new size.
if output is given, do not modify 'image', but create new file 'output'
New size is specified per resize2fs(8), e.g. "1G" for 1 gigabyte
EOF
return 0
}
error() { echo "$@" 1>&2; }
fail() { [ $# -eq 0 ] || error "$@"; exit 1; }
human2bytes() {
# converts size suitable for input to resize2fs to bytes
# s:512 byte sectors, K:kilobytes, M:megabytes, G:gigabytes
# none: block size of the image
local input=${1} defunit=${2:-1024}
local unit count;
case "$input" in
*s) count=${input%s}; unit=512;;
*K) count=${input%K}; unit=1024;;
*M) count=${input%M}; unit=$((1024*1024));;
*G) count=${input%G}; unit=$((1024*1024*1024));;
*) count=${input} ; unit=${2:-1024};;
esac
_RET=$((${count}*${unit}))
}
xtruncate() {
if which truncate >/dev/null 2>&1; then
truncate "${@}"
else
local size=${1} file=${2} blk=""
size=${size#--size=}
# this is a poor mans truncate supporting whatever human2bytes supports
human2bytes "${size}" && blk=$((${_RET}/512)) &&
dd if=/dev/zero of="${file}" obs=512 seek=${blk} count=0 2>/dev/null
fi
}
[ "$1" = "-h" -o "$1" = "--help" ] && { Usage; exit 0; }
[ $# -eq 3 -o $# -eq 2 ] || { Usage 1>&2; exit 1; }
old="$1"
size="$2"
new="${3:-${old}}"
[ -f "${old}" ] || fail "${old}: does not exist"
human2bytes "${size}" && new_size=${_RET} ||
fail "failed to understand ${size}"
if [ ! "${old}" -ef "${new}" ]; then
file_out=$(file "${old}") || fail "failed to read ${old} with 'file'"
case "${file_out}" in
*gzip\ compressed*)
file_out_z=$(file -z "${old}")
case "${file_out_z}" in
*tar\ archive*)
: > "${new}" && newd=$(dirname "${new}") ||
fail "failed to get full path for ${new}"
tmpd=$(mktemp -d "${newd}/.${0##*/}.XXXXXX") &&
( cd "${tmpd}" && tar -S --wildcards -xzf - "*.img" &&
mv *.img "../${new}" ) < "${old}" || {
rm -Rf "${tmpd}";
fail "failed to extract image from ${old}"
}
rm -Rf "${tmpd}"
;;
*)
zcat -f "$old" | cp --sparse=always /dev/stdin "$new";;
esac
;;
*) cp --sparse=always "${old}" "${new}";;
esac
[ $? -eq 0 ] || fail "failed to cp ${old} -> ${new}"
else
# if old=new (in place), it must be a simple image file
case "${old}" in
*.gz) fail "refusing work in place compressed or archive file: ${old}";;
esac
fi
ls_out=$(ls -l "${new}") &&
old_size=$(echo "${ls_out}" | awk '{print $5}') ||
fail "failed to get size of ${new}"
out=$(e2fsck -fp "$new" 2>&1) || {
error "${out}"
fail "failed to fsck ${new}"
}
if [ "${old_size}" -lt "${new_size}" ]; then
xtruncate "--size=$size" "$new" || fail "failed to change size of ${new}"
fi
out=$(resize2fs "$new" "$size" 2>&1) || {
error "${out}"
fail "failed to resize ${new} -> ${size}"
}
if [ "${old_size}" -gt "${new_size}" ]; then
xtruncate "--size=$size" "$new" || fail "failed to change size of ${new}"
fi
exit 0
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