cnmt de-struct-or

cnmt_destructor.py

# cnmt de-struct-or
# SocraticBliss (R)

from struct import unpack as up
from binascii import hexlify as hx

'''
CNMT HEADER
title_id = up('<Q', cnmt[:0x8])
title_version = up('<I', cnmt[0x8:0xC])
title_type = up('<B', cnmt[0xC:0xD])
unk1 = up('<s', cnmt[0xD:0xE])
unk2 = up('<4s', cnmt[0xE:0x12])
entries = up('<H', cnmt[0x12:0x14])
padding = up('<12s', cnmt[0x14:0x20])

CNMT META ENTRIES
entry_id_1 = up('<Q', cnmt[0x20:0x28])
entry_version_1 = up('<I', cnmt[0x28:0x2C])
entry_type_1 = up('<B', cnmt[0x2C:0x2D])
unk1 = up('<s', cnmt[0x2D:0x2E])
unk2 = up('<2s', cnmt[0x2E:0x30])

CNMT CONTENT ENTRIES
hash_1 = cnmt[0x20:0x40]
ncaid_1 = cnmt[0x40:0x50]
size_1 = up('<6s', cnmt[0x50:0x56])
type_1 = up('<B', cnmt[0x56:0x57])
padding = up('<s' cnmt[0x57:0x58])

So much fun... but no performance increase
titles = {'%016x' % up('<Q', cnmt[0x20+(0x10*i):0x28+(0x10*i)]): '%s' % up('<I', cnmt[0x28+(0x10*i):0x2C+(0x10*i)]) for i in xrange(up('<H', cnmt[0x12:0x14])[0])}
'''

def parse_meta(cnmt):
    titles = {}
    offset = 0x20
    entries = up('<H', cnmt[0x12:0x14])[0]
    for i in xrange(entries):
        entry_id, entry_version = up('<QI', cnmt[offset:offset+0xC])
        offset += 0x10
        titles['%016x' % entry_id] = '%s' % entry_version
    return titles

def read(title):
    try:
        with open('%s' % title, 'rb') as file:
            cnmt = file.read()
    except IOError:
        raise SystemExit('Error: Failed to read %s!' % title)
    return cnmt
    
def main():
    cnmt = read('SystemUpdate_0100000000000816/SystemUpdate_0100000000000816.cnmt')
    print('System Update ContentMeta Dictionary: %s' % parse_meta(cnmt))
    
    cnmt = read('SystemData_0100000000000814/SystemData_0100000000000814.cnmt')
    print('ContentMeta Dictionary: %s' % {'%016x' % up('<Q', cnmt[:0x8]): hx(cnmt[0x40:0x50])})

if __name__=='__main__':
    main()