#!/bin/sh

# This script injects a "test-mode" file into a copy of the main disk image. 
# It begins by parsing the partition table of the disk image to identify the
# 'aux' partition, which is then extracted. An empty 'test-mode' file is 
# injected into the extracted partition, and the modified partition is written
# back to the output image. The output image can subsequently be used as a 
# backing image for Copy-on-Write (QCOW) images utilized by Qeneth.

set -e

while getopts "b:o:" opt; do
  case $opt in
    b) base_img="$OPTARG" ;;  # Base image (Original image)
    o) output_img="$OPTARG" ;;  # Output image (Backing image for QCoW images)
    *) echo "Usage: $0 -b <BASE-IMAGE> -o <OUTPUT-IMAGE>" ; exit 1 ;;
  esac
done

if [ -z "$base_img" ] || [ -z "$output_img" ]; then
  echo "Both -b (base image) and -o (output image) parameters are required."
  exit 1
fi

rm -f "$output_img"
if ! cp "$base_img" "$output_img"; then
  echo "Error: Failed to copy $base_img to $output_img"
  exit 1
fi

if ! part_table=$(fdisk -l "$output_img" 2>/dev/null); then
  echo "Error: Failed to read partition table from $output_img"
  exit 1
fi

aux_line=$(echo "$part_table" | grep 'aux')
if [ -z "$aux_line" ]; then
  echo "Error: 'aux' partition not found in $output_img"
  exit 1
fi

start=$(echo "$aux_line" | awk '{print $2}')
end=$(echo "$aux_line" | awk '{print $3}')
count=$(($end - $start + 1))
block_size=$(echo "$part_table" | grep "Logical sector size" | awk '{print $4}')

dd if="$output_img" of="tmpaux" skip="$start" count="$count" bs="$block_size" status=none

touch tmp-empty-file
e2cp tmp-empty-file tmpaux:/test-mode
rm tmp-empty-file

dd of="$output_img" if="tmpaux" seek="$start" count="$count" bs="$block_size" status=none conv=notrunc
rm tmpaux