dehydrate-fs/dehydrate.sh
2022-07-29 18:50:42 +00:00

26 lines
863 B
Bash
Executable File

#!/usr/bin/env bash
set -eo pipefail
image="$1"; [ -z "$1" ] && { echo "No image file specified!" >&2; exit 1; }
mfile="$2"; [ -z "$2" ] && { echo "No mapfile specified!" >&2; exit 1; }
[ -z "$3" -a -t 1 ] && { echo "The output of this script is unsafe for raw display." >&2
exit 1; } \
|| ofile=${3:-/dev/stdout}
BLOCKSIZE=`sed -nE 's/^#BLOCKSIZE=([0-9]+)$/\1/p' "$mfile"`
[ -z "$BLOCKSIZE" ] && { echo "Mapfile does not specify blocksize!" >&2; exit 1; }
shopt -s expand_aliases
alias dd="dd bs=$BLOCKSIZE status=none"
{
i=0
while read -r -d$'\n' _ block lengt _; do
#Leaves the remainder block for convenience
dd if="$image" skip=$i count=$((block-i))
dd if=/dev/zero count=$((lengt-1))
i=$((block+lengt-1))
done < <(grep -v ^\# "$mfile" | sed -En '/[a-f0-9]{64}/!p' | sort -unk2)
dd if="$image" skip=$i
} > "$ofile"