3DSFAT16tool

3DSFAT16tool.py

# -*- coding: utf-8 -*-
# version 1.0

import os
import sys
import argparse
import math
import numpy

if not sys.version_info[:2] == (2, 7):
    print '*****\n!!!!!Warning - Only tested with Python 2.7!!!!!\n*****\n'

parser = argparse.ArgumentParser()
parser.add_argument('nand_file', action='store', help='NAND file (must exist for dumping and injecting)')
parser.add_argument('fat16_file', action='store', help='FAT16 file (only should exist for injecting, fat16 file will be written/overwrite when dumping)')
parser.add_argument('fat16_xorpad', action='store', help='FAT16 xorpad file')
choose = parser.add_mutually_exclusive_group()
choose.add_argument('-d', action='store_true', default=False, dest='dump', help='Dump FAT16 from NAND file')
choose.add_argument('-i', action='store_true', default=False, dest='inject', help='Inject FAT16 into NAND file')
parser.add_argument('-n3ds', action='store_true', default=False, dest='n3ds', help='Use for N3DS NAND dumps')
parser.add_argument('-lowmem', action='store_true', default=False, dest='lowmem', help='Use if you have low RAM available')
arguments = parser.parse_args()

#https://stackoverflow.com/questions/5734691/fastest-bitwise-xor-between-two-multibyte-binary-data-variables
def xor(data, key):
    import numpy, math

    # key multiplication in order to match the data length
    key = (key*int(math.ceil(float(len(data))/float(len(key)))))[:len(data)]

    # Select the type size in bytes       
    for i in (8,4,2,1):
        if not len(data) % i: break

    if i == 8: dt = numpy.dtype('<Q8');
    elif i == 4: dt = numpy.dtype('<L4');
    elif i == 2: dt = numpy.dtype('<H2');
    else: dt = numpy.dtype('B');

    return numpy.bitwise_xor(numpy.fromstring(key, dtype=dt), numpy.fromstring(data, dtype=dt)).tostring()

if (arguments.dump is arguments.inject):
    print 'Please choose -d or -i to dump or inject the fat16 partition'
    exit(0)

print '*******\n3DSFAT16tool\n*******\n'

start = 0x0B930000
size = 0x2F3E3600
chunksize = 0x3200000 #10MB(0XA00000) RAM usage ~77.531MiB, 25MB(0X1900000) RAM usage ~77.531MiB, 50MB(0X3200000) RAM usage ~364.840MiB
fsOffset = 0x2CA00
if(arguments.n3ds):
    size = 0x41D2D200
    fsOffset = 0x2AE00

if not os.path.isfile(arguments.nand_file):
    print 'NAND file cannot be found'
    exit(0)

if (arguments.inject):
    if not os.path.isfile(arguments.fat16_file):
        print 'FAT16 file cannot be found'
        exit(0)
    with open(arguments.fat16_file, 'rb') as r, open(arguments.nand_file, 'rb+') as w, open(arguments.fat16_xorpad, 'rb') as x:
        print 'Injecting... please wait'
        if arguments.lowmem:
            for i in range(0, size, chunksize):
                w.seek(start+fsOffset+i)
                x.seek(fsOffset+i)
                chunksize = size % chunksize if size < chunksize else chunksize 
                fat16 = r.read(chunksize)
                xorpad = x.read(chunksize)
                w.write(xor(fat16, xorpad))
                size -= chunksize
        else:
            w.seek(start+fsOffset)
            x.seek(fsOffset)
            fat16 = r.read(size)
            xorpad = x.read(size)
            w.write(xor(fat16, xorpad))


if (arguments.dump):
    if os.path.isfile(arguments.fat16_file):
        print 'FAT16 with this name and path already exists, file will be overwritten'
    with open(arguments.nand_file, 'rb') as r, open(arguments.fat16_file, 'wb') as w, open(arguments.fat16_xorpad, 'rb') as x:
        print 'Dumping... please wait'
        if arguments.lowmem:
            for i in range(0, size, chunksize):
                r.seek(start+fsOffset+i)
                x.seek(fsOffset+i)
                chunksize = size % chunksize if size < chunksize else chunksize 
                fat16 = r.read(chunksize)
                xorpad = x.read(chunksize)
                w.write(xor(fat16, xorpad))
                size -= chunksize
        else:
            r.seek(start+fsOffset)
            x.seek(fsOffset)
            fat16 = r.read(size)
            xorpad = x.read(size)
            w.write(xor(fat16, xorpad))

print ''

print 'Finished'

works fine with python 3.4. you just need to install numpy and convert the print statements to print functions.