Create gcmtool.py

Tool for unpack and pack GCM/ISO files.
This tool don't save random bytes written in non-mapped DVD intervals that's why the resulting ISO file will be different from initial ISO
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tmpz23 2021-12-18 11:58:21 +01:00 committed by GitHub
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#!/usr/bin/env python3
from pathlib import Path
__version__ = "0.0.1"
__author__ = "rigodron, algoflash, GGLinnk"
__license__ = "MIT"
__status__ = "developpement"
DVD_MAGIC = b"\xC2\x33\x9F\x3D"
FST_TYPE_FILE = 0
FST_TYPE_DIR = 1
######################################################################
# Todo : add logging ; add extension check ; add --verbose ; add --disable-ignore
# -> test it on random iso and check that it's the same than dolphin extract
# -> test it !!!!
# Add FST rebuild ;
# add info on unused randoms bytes on initial DVD iso file
# -> that's why repack iso is different from initial iso
######################################################################
class Dol:
# Get total length using the sum of the 18 sections length and dol header length (0x100)
def getDolLen(self, dolheader_data:bytes):
dol_len = 0x100
for i in range(18):
dol_len += int.from_bytes(dolheader_data[0x90+i*4:0x90+(i+1)*4], "big", signed=False)
return dol_len
# https://sudonull.com/post/68549-Gamecube-file-system-device
class GCM:
def unpack(self, iso_path:Path):
with iso_path.open("rb") as iso_file:
bootbin_data = iso_file.read(0x440)
if bootbin_data[0x1c:0x20] != DVD_MAGIC:
raise Exception("Invalid DVD format - this tool is for ISO/GCM files")
bi2bin_data = iso_file.read(0x2000)
# https://www.gc-forever.com/wiki/index.php?title=Apploader
# -> Full apploader size is sum of size and trailerSize, rounded up to 32 bytes.
iso_file.seek(0x2454)
size = int.from_bytes(iso_file.read(4), "big", signed=False)
trailerSize = int.from_bytes(iso_file.read(4), "big", signed=False)
# Dolphin Emulator add 32 Null bytes at the end of the extracted apploader.img
apploader_size = size + trailerSize + 32
iso_file.seek(0x2440)
apploaderimg_data = iso_file.read(apploader_size)
print( 0x2440 + apploader_size )
print("fst.bin :", int.from_bytes(bootbin_data[0x424:0x428],"big", signed=False), int.from_bytes(bootbin_data[0x428:0x42c],"big", signed=False))
iso_file.seek( int.from_bytes(bootbin_data[0x424:0x428],"big", signed=False) )
fstbin_data = iso_file.read( int.from_bytes(bootbin_data[0x428:0x42c],"big", signed=False) )
dol_offset = int.from_bytes(bootbin_data[0x420:0x424],"big", signed=False)
iso_file.seek( dol_offset )
dol = Dol()
dolheader_data = iso_file.read(0x100)
bootdol_data = dolheader_data + iso_file.read( dol.getDolLen( dolheader_data ) - 0x100 )
print("dol :", dol_offset, dol.getDolLen( dolheader_data ))
base_path = Path(f"{bootbin_data[:4].decode('utf-8')}-{int.from_bytes(bootbin_data[6:7], 'little', signed=False):02}")
sys_path = base_path / "sys"
sys_path.mkdir(parents=True, exist_ok=True)
with (sys_path / "boot.bin").open("wb") as bootbin_file, \
(sys_path / "bi2.bin" ).open("wb") as bi2bin_file, \
(sys_path / "fst.bin").open("wb") as fstbin_file, \
(sys_path / "apploader.img").open("wb") as apploaderimg_file,\
(sys_path / "boot.dol").open("wb") as bootdol_file :
bootbin_file.write(bootbin_data)
bi2bin_file.write(bi2bin_data)
fstbin_file.write(fstbin_data)
apploaderimg_file.write(apploaderimg_data)
bootdol_file.write(bootdol_data)
root_path = base_path / "root"
root_path.mkdir(exist_ok=True)
# And now we parse FST data to unpack all files in the GCM iso file
dir_index_path = {0: root_path}
currentdir_path = root_path
# root: index=0 so nextdir is the end
nextdir = int.from_bytes(fstbin_data[8:12], "big", signed=False)
# offset of filenames block
base_names = nextdir * 12
# go to parent when index reach next dir
nextdir_arr = [ nextdir ]
for index in range(1, base_names // 12):
i = index * 12
file_type = int.from_bytes(fstbin_data[i:i+1], "big", signed=False)
name = fstbin_data[base_names + int.from_bytes(fstbin_data[i+1:i+4], "big", signed=False):].split(b"\x00")[0].decode("utf-8")
while index == nextdir_arr[-1]:
currentdir_path = currentdir_path.parent
nextdir_arr.pop()
if file_type == FST_TYPE_DIR:
nextdir = int.from_bytes(fstbin_data[i+8:i+12], "big", signed=False)
parentdir = int.from_bytes(fstbin_data[i+4:i+8], "big", signed=False)
nextdir_arr.append( nextdir )
currentdir_path = dir_index_path[parentdir] / name
dir_index_path[index] = currentdir_path
currentdir_path.mkdir(exist_ok=True)
else:
fileoffset = int.from_bytes(fstbin_data[i+4:i+8], "big", signed=False)
filesize = int.from_bytes(fstbin_data[i+8:i+12], "big", signed=False)
with (currentdir_path / name).open("wb") as new_file:
iso_file.seek(fileoffset)
new_file.write( iso_file.read(filesize) )
print("file :", fileoffset, filesize)
def pack(self, folder_path:Path, iso_path:Path = None):
if iso_path == None:
iso_path = folder_path.parent / Path(folder_path.name).with_suffix(".iso")
with iso_path.open("wb") as iso_file, \
(folder_path / "sys" / "boot.bin").open("rb") as bootbin_file, \
(folder_path / "sys" / "bi2.bin" ).open("rb") as bi2bin_file, \
(folder_path / "sys" / "fst.bin").open("rb") as fstbin_file, \
(folder_path / "sys" / "apploader.img").open("rb") as apploaderimg_file,\
(folder_path / "sys" / "boot.dol").open("rb") as bootdol_file :
bootbin_data = bootbin_file.read()
iso_file.write( bootbin_data )
iso_file.write(bi2bin_file.read())
iso_file.write(apploaderimg_file.read())
fstbin_offset = int.from_bytes(bootbin_data[0x424:0x428],"big", signed=False)
fstbin_len = int.from_bytes(bootbin_data[0x428:0x42c],"big", signed=False)
if (folder_path / "sys" / "fst.bin").stat().st_size != fstbin_len:
raise Exception("Invalid fst.bin size in boot.bin offset 0x428:0x42c!")
iso_file.seek( fstbin_offset )
fstbin_data = fstbin_file.read()
iso_file.write( fstbin_data )
dol_offset = int.from_bytes(bootbin_data[0x420:0x424],"big", signed=False)
iso_file.seek( dol_offset )
iso_file.write( bootdol_file.read() )
# Now parse fst.bin for writing files in the iso
dir_index_path = {0: folder_path / "root"}
currentdir_path = folder_path / "root"
# root: index=0 so nextdir is the end
nextdir = int.from_bytes(fstbin_data[8:12], "big", signed=False)
# offset of filenames block
base_names = nextdir * 12
# go to parent when index reach next dir
nextdir_arr = [ nextdir ]
for index in range(1, base_names // 12):
i = index * 12
file_type = int.from_bytes(fstbin_data[i:i+1], "big", signed=False)
name = fstbin_data[base_names + int.from_bytes(fstbin_data[i+1:i+4], "big", signed=False):].split(b"\x00")[0].decode("utf-8")
while index == nextdir_arr[-1]:
currentdir_path = currentdir_path.parent
nextdir_arr.pop()
if file_type == FST_TYPE_DIR:
nextdir = int.from_bytes(fstbin_data[i+8:i+12], "big", signed=False)
parentdir = int.from_bytes(fstbin_data[i+4:i+8], "big", signed=False)
nextdir_arr.append( nextdir )
currentdir_path = dir_index_path[parentdir] / name
dir_index_path[index] = currentdir_path
currentdir_path.mkdir(exist_ok=True)
else:
fileoffset = int.from_bytes(fstbin_data[i+4:i+8], "big", signed=False)
filesize = int.from_bytes(fstbin_data[i+8:i+12], "big", signed=False)
print(fileoffset, filesize)
with (currentdir_path / name).open("rb") as new_file:
iso_file.seek(fileoffset)
iso_file.write( new_file.read(filesize) )
def get_argparser():
import argparse
parser = argparse.ArgumentParser(description='ISO/GCM packer & unpacker - [GameCube] v' + __version__)
parser.add_argument('--version', action='version', version='%(prog)s ' + __version__)
parser.add_argument('input_path', metavar='INPUT', help='')
parser.add_argument('output_path', metavar='OUTPUT', help='', nargs='?', default="")
group = parser.add_mutually_exclusive_group(required=True)
group.add_argument('-p', '--pack', action='store_true', help="-p source_folder (dest_file.iso) : Pack source_folder in new file source_folder.iso or dest_file.iso if specified")
group.add_argument('-u', '--unpack', action='store_true', help='-u source_iso.iso (dest_folder) : Unpack the GCM/ISO in new folder source_iso or dest_folder if specified')
return parser
if __name__ == '__main__':
args = get_argparser().parse_args()
p_input = Path(args.input_path)
p_output = Path(args.output_path)
gcm = GCM()
if args.pack:
logging.info("### Pack")
if(p_output == Path(".")):
p_output = Path(p_input.with_suffix(".iso"))
gcm.pack( p_input, p_output )
elif args.unpack:
logging.info("### Unpack")
if(p_output == Path(".")):
p_output = Path(p_input.name)
gcm.unpack( p_input, p_output )