Create Amiga CD32/CTDV ISO image (Python/JSON)

build_cd.json

{
    "iso": {
        "volume": "SUPERGAME",
        "application": "Super Game",
        "publisher": "Supersoft",
        "preparer": "Supersoft",
        "copyright": "(C) 2023 Supersoft"
    },
    "files": [
        {
            "path": "CDTV.TM",
            "iso": {
                "path": "/CDTV.TM"
            }
        },

        {
            "path": "content/S/Startup-Sequence",
            "iso": {
                "path": "/S/Startup-Sequence"
            }
        },

        {
            "path": "content/C/RMTM",
            "iso": {
                "path": "/C/RMTM"
            }
        },

        {
            "path": "SuperGame",
            "iso": {
                "path": "/SUPERGAM.EXE",
                "rr_name": "SuperGame"
            }
        },
        {
            "path": "DATA.BIN",
            "iso": {
                "path": "/DATA.BIN"
            }
        },

        {
            "path": "content/Disk.info",
            "iso": {
                "path": "/DISK.INF",
                "rr_name": "Disk.info"
            }
        },
        {
            "path": "content/SuperGame.info",
            "iso": {
                "path": "/SUPERGAM.INF",
                "rr_name": "SuperGame.info"
            }
        },
    ]
}

build_cd.py

import sys
import json
import os
from io import BytesIO

import pycdlib

MODE_CDTV = 1
MODE_CD32 = 32
MODE = MODE_CDTV

# List of CDFS options normally set by ISOCD.
# Stored one byte into the Application Data field of the ISO9660 Primary Volume Descriptor.
# 0x4653 FS     = Fast Search option enabled
# 0x0000        = Size of Fast Search option data
# 0x544d TM     = TradeMark option
# 0x0014        = Size of TradeMark option data
# 0x00000000    = Size of trademark file
# 0x00000012    = Sector number (2048 byte sectors) of start of trademark file
# 0x00000000
# 0x00000000
# 0x00000000
#               NB: CD32.TM file always has zero length and offset 0x12 in the TM option field

#                               F   S           T   M   TMOSIZE TMSIZE          TMSEC1          TMSEC2          TMSEC3          TMSEC4
#                                                               9               13
CDFS_APPDATA = bytearray(b'\x00\x46\x53\x00\x00\x54\x4d\x00\x14\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
CDFS_APPDATA = CDFS_APPDATA.ljust(512, b'\x00')

CDFS_APPDATA_TMSIZE = 9
CDFS_APPDATA_TMSEC1 = 13

def tolong(i, signed=False):
    try:
        return int(i).to_bytes(4, 'big', signed=signed)
    except OverflowError:
        print('tolong OverflowError', i)


def poke_long(l, i, v, signed=False):
    vl = tolong(v, signed)
    l[i + 0] = vl[0]
    l[i + 1] = vl[1]
    l[i + 2] = vl[2]
    l[i + 3] = vl[3]


def rr_dir(file_desc_iso):
    if 'rr_dir' in file_desc_iso:
        return file_desc_iso['rr_dir']
    return os.path.basename(os.path.split(file_desc_iso['path'])[0])


def rr_name(file_desc_iso):
    if 'rr_name' in file_desc_iso:
        return file_desc_iso['rr_name']
    return os.path.basename(file_desc_iso['path'])


# parse args
if len(sys.argv) != 4:
    print('Usage: {} <workpath> <out.iso> <manifest.json> '.format(sys.argv[0]))
    sys.exit(20)

FN_WORK = sys.argv[1]
FN_DISK = sys.argv[2].upper()
FN_JSON = sys.argv[3]

# load json disk description
with open(FN_JSON, 'r') as f:
    cd_desc = json.load(f)

# generate iso file
iso = pycdlib.PyCdlib()
iso.new(
    rock_ridge='1.09',
    interchange_level=3,
    sys_ident='CDTV',
    copyright_file=cd_desc['iso']['copyright'],
    vol_ident=cd_desc['iso']['volume'],
    vol_set_ident=cd_desc['iso']['volume'],
    set_size=1,
    seqnum=1,
    app_ident_str=cd_desc['iso']['application'],
    pub_ident_str=cd_desc['iso']['publisher'],
    preparer_ident_str=cd_desc['iso']['preparer'],
)

# add files from manifest to the image
iso_dirs = []
for file_desc in cd_desc['files']:
    # load file
    with open(os.path.join(FN_WORK, file_desc['path']), 'rb') as f:
        file_data = bytearray(f.read())

    # add dir first if the file has a path
    iso_path = os.path.split(file_desc['iso']['path'])

    iso_dir = iso_path[0]
    if iso_dir != '/' and iso_dir not in iso_dirs:
        iso_dirs.append(iso_dir)
        # print(rr_dir(file_desc['iso']))
        iso.add_directory(iso_dir, rr_name=rr_dir(file_desc['iso']))

    # add file
    iso.add_fp(
        BytesIO(file_data),
        len(file_data),
        iso_path=file_desc['iso']['path'],
        rr_name=rr_name(file_desc['iso'])
    )

iso.write(FN_DISK)
iso.close()

# patch iso file with appropriate cd copyright parts
with open(FN_DISK, 'rb') as f:
    iso_data = bytearray(f.read())

if MODE == MODE_CDTV:
    # CDTV
    with open(os.path.join(FN_WORK, 'CDTV.TM'), 'rb') as f:
        tm_data = bytearray(f.read())

    iso.open(FN_DISK)
    tm_rec = iso.get_record(iso_path='/CDTV.TM')
    tm_ofs = tm_rec.extent_location()
    iso.close()

    poke_long(CDFS_APPDATA, CDFS_APPDATA_TMSIZE, len(tm_data))
    poke_long(CDFS_APPDATA, CDFS_APPDATA_TMSEC1, tm_ofs)
else:
    # CD32
    with open(os.path.join(FN_WORK, 'CD32.TM'), 'rb') as f:
        tm_data = bytearray(f.read())

    poke_long(CDFS_APPDATA, CDFS_APPDATA_TMSIZE, 0)
    poke_long(CDFS_APPDATA, CDFS_APPDATA_TMSEC1, 0x12)
    iso_data[0x9000:0x9000+len(tm_data)] = tm_data

iso_data[0x8373:0x8373+len(CDFS_APPDATA)] = CDFS_APPDATA
with open(FN_DISK, 'wb') as f:
    f.write(iso_data)