patchnso.py + sample patches for SMO 1.2.0

info.md

patchnso.py: a simple script to patch the .text sections of nso files and reassemble them

Python 2.7, requires lz4 module to be installed

Usage Instructions:

1. Using hactool, extract the exefs of your game
2. Within the exefsdir, there should be "main" and "main.npdm" and possibly a few others
3. "main" is the game's main nso, you can load it into IDA and create your own patches or go out and find some
4. When you have your patches put them all in a file in this format: (all values should be in hex) location:codepatch Example: 2E8:21008052
5. Then run "python patchnso.py main patch-file-here output-file-here"
6. Your patched file will appear and you can put it under /atmosphere/titles/title-id/exefs/ on your sd card, renamed back to "main", with the other files from your extracted exefs and you have now patched your game!

Sample Patches

With this script, I included some sample patches I made for Super Mario Odyssey Version 1.2.0, try them out (on the correct version) and have fun!

patchnso.py

import binascii, struct, hashlib, sys
import lz4.block as block


if len(sys.argv) != 4:
	print "patchnso.py: simple script to patch the .text sections of nso files and reassemble them"
	print "by tesnos6921, thanks to switchbrew.org for docs and the atmosphere team for exefs patching so early"
	print "Usage: patchnso.py nso-file patch-file out-file"
	print "patch-file should contain lines formatted like so, with values in hex."
	print "location:codepatch, Example: 2E8:21008052"
	print "Empty lines or lines beginning with pound signs are ignored."

def padding(padlength):
	pad = ""
	for i in range(padlength):
		pad += "\x00"
	return pad

def patchtext(source, patchlist):
	patchedsource = source
	
	for patch in patchlist:
		if "#" in patch or patch.strip() == "":
			continue
	
		patchlocation, patchcode = patch.split(":")
		
		patchlocation = int(patchlocation, 16)
		patchcode = binascii.unhexlify(patchcode.strip())
		
		patchedsource = patchedsource[:patchlocation] + patchcode + patchedsource[patchlocation+len(patchcode):]
		
	return patchedsource

main_f = open(sys.argv[1], "rb")
mainsource = main_f.read()
main_f.close()

header = mainsource[:0x100]

textloc = struct.unpack("<I", header[0x10:0x14])[0]
dectextsize = struct.unpack("<I", header[0x18:0x1C])[0]

rodataloc = struct.unpack("<I", header[0x20:0x24])[0]
dataloc = struct.unpack("<I", header[0x30:0x34])[0]
oldtextsize = rodataloc - textloc
rodatasize = dataloc - rodataloc

textsource = mainsource[textloc:textloc+oldtextsize]
textsource = block.decompress(textsource, uncompressed_size=dectextsize)

patch_f = open(sys.argv[2], "r")
patches = patch_f.readlines()
patch_f.close()

textsource = patchtext(textsource, patches)
texthash = hashlib.sha256(textsource).digest()

compressedtext = block.compress(textsource, mode='fast', acceleration=2)
compressedtext = compressedtext[0x4:]
compressedtextsize = len(compressedtext)

rodata = mainsource[rodataloc:rodataloc+rodatasize]
data = mainsource[dataloc:]

newrodataloc = textloc + compressedtextsize

header = header[:0x20] + struct.pack("<I", newrodataloc) + header[0x24:]
newdataloc = newrodataloc + rodatasize
header = header[:0x30] + struct.pack("<I", newdataloc) + header[0x34:]

header = header[:0x60] + struct.pack("<I", compressedtextsize) + header[0x64:]
header = header[:0xA0] + texthash + header[0xC0:]

newmain = header + padding(textloc - len(header)) + compressedtext + rodata + data

newmain_f = open(sys.argv[3], "wb")
newmain_f.write(newmain)
newmain_f.close()

samplepatches

TO BE UPDATED SOON