upfile.py

import struct
import os
from collections import namedtuple

HEADER_FMT = "<4s7L"
HeaderTuple = namedtuple("Header", ["magic", "unknown1", "size1", "offset1", 
    "size3", "names_ofs", "names_len", "offset3"])

binary = open("data.up", "rb")
header_bytes = binary.read(32)
header = HeaderTuple(*struct.unpack(HEADER_FMT, header_bytes))
print(header)
print(hex(header[3]), hex(header[5]), hex(header[7]), 
    hex(os.path.getsize("data.up")))
if not header.magic == b"UDSP":
    print("File not UpPackage")

binary.seek(header.names_ofs)
names_bytes = binary.read(header.names_len)
names = names_bytes.split(b"\0")
print("names len", len(names))