cardconvert.py

#!/usr/bin/env python3
import os
import sys
import struct
import binascii
import argparse

MB = 0x100000

parser = argparse.ArgumentParser(description='Edit CCI card type for 3DS flashcarts')
parser.add_argument('--trim', action='store_true', help='trim to fit (will break pokemon games)')
parser.add_argument('--type', type=int, choices=[1, 2], required=True, help='card type to set')
parser.add_argument('file', type=argparse.FileType('rb+'), nargs='+', help='CCIs (.3ds/3dz) to edit')
args = parser.parse_args()

print('-=-                           -=-')
print('CCI card type converter by Void')
print('   Original code by snailface')
print('   Pkm-breaking trim by Jdbye')
print('-=-                           -=-')
print()

# Creates matching unmodified checksum when converting back to original type
# (Unless you have a bad dump that had not properly cleared the untrimmed area)

def num2string(n, size):
	ret = b''
	for i in range(size):
		ret += bytes([n & 0xFF])
		n >>= 8
	return ret
	
def byteSwap(n):
	return n[::-1]

def hex2value(n):
	return int(binascii.hexlify(n), 16)

def grabData(off, size):
	f.seek(off)
	offset = f.read(size)
	return offset

def isFlag(f, off):
	f.seek(off)
	byte = ord(f.read(1))
	return byte and byte < 3

def process(f, type, trim):
	print("[-] Flags", ord(grabData(0x18B, 1)), ord(grabData(0x18D, 1)), ord(grabData(0x18F, 1)), hex2value(byteSwap(grabData(0x300, 4))), grabData(0x200, 4), '\n')

	if ord(grabData(0x18D, 1)) == type:
		print('[!] Skipping "%s" as already type %d' % (f.name, type))
		return

	print('[!] Converting "%s"' % f.name)

	if isFlag(f, 0x18B):
		f.seek(0x18B)
		f.write(bytes([type]))
		
	f.seek(0x18D)
	f.write(bytes([type]))
	
	if isFlag(f, 0x18F):
		f.seek(0x18F)
		f.write(bytes([type]))
	
	dataSize = hex2value(byteSwap(grabData(0x300, 4)))
	saveOffset = int(dataSize / MB) * MB + MB
	mediaUnitOffset = int(saveOffset / 0x200)
	
	f.seek(0x200)
	f.write(num2string(mediaUnitOffset, 4) if type == 2 else b'\xff\xff\xff\xff')
	
	# Format type 2 save
	f.seek(0, 2)
	clearSize = f.tell() - saveOffset
	f.seek(saveOffset)
	f.write(b'\xff' * clearSize)

	if trim:
		print('[*] Trimming')
		# TODO: Are all type 2 saves 16M or is this just the max?
		f.truncate(saveOffset + (MB * 16))
		
for f in args.file:
	process(f, args.type, args.trim)
	print()

print('[~] Done processing %d files' % len(args.file))