gist-3793a40dd0c7930f12b79ca1931a3296/extract-gigaleak-csu.sh

#   extract-gigaleak-csu
#   Lillian Skinner
#   Last modified 2023/08/19
# Extracts firmware CIAs from the RomFS of "SystemUpdater-0_13-0927-UnFixedKey.csu". This can't be done with other tools as 0.13.0 doesn't use the normal RomFS format.
# So far this only gets the start/end addresses of the CIAs.

echo "Finding CIA headers in file..."
od -t x -A d romfs.bin | grep "00002020 00000000 00000a00 00000350" | sed 's/ .*//' | sed 's/^0*//' > romfs-dir.txt
# Get start address of every CIA header and store to file
echo "Found all headers!"
echo "================================================="

declare -i x=0
declare -i i=1

echo "Extracting odd CIAs..."
echo "================================================="
sed 1d romfs-dir.txt | while IFS=, read -r START_HEADER; read NEXT_HEADER
do
    echo "CIA $i header at         ${START_HEADER}"
    echo "Next header at           ${NEXT_HEADER}"
    echo "Finding CIA $i end from CIA $((i + 1)) header... "
    y="00"
    x=0
    z="00"
    while [ "$y" = "00" ]; do
        x+=1
        y=$(od -j $((NEXT_HEADER - x)) -N 1 -x -A n romfs.bin | sed 's|[ ,]||g' | sed 's/^..//');
        # Get bytes one backwards from next header
        # printf '%x\n' $((NEXT_HEADER - x))
        # echo $y
        # echo $x
    done
    echo "End found!"
    echo "Non-zerobyte ($y) at $((NEXT_HEADER - x))"
    echo "Padding from CIA $i to $((i + 1)) is $((x - 1)) bytes."
    echo "CIA $i done!"
    echo "================================================="
    i+=2
done < romfs-dir.txt

echo "Extracting even CIAs..."
echo "================================================="
sed 1d romfs-dir.txt | while IFS=, read -r START_HEADER; read NEXT_HEADER
do
    echo "CIA $i header at         ${START_HEADER}"
    echo "Next header at           ${NEXT_HEADER}"
    echo "Finding CIA $i end from CIA $((i + 1)) header... "
    y="00"
    x=0
    z="00"
    while [ "$y" = "00" ]; do
        x+=1
        y=$(od -j $((NEXT_HEADER - x)) -N 1 -x -A n romfs.bin | sed 's|[ ,]||g' | sed 's/^..//');
        # Get bytes one backwards from next header
        # printf '%x\n' $((NEXT_HEADER - x))
        # echo $y
        # echo $x
    done
    echo "End found!"
    echo "Non-zerobyte ($y) at $((NEXT_HEADER - x))"
    echo "Padding from CIA $i to $((i + 1)) is $((x - 1)) bytes."
    echo "CIA $i done!"
    echo "================================================="
    i+=2
done