from struct import unpack
from os import makedirs
from os.path import exists
import os

with open("dvdroot.dat", "rb") as f:
    # "SONICHEROESDAT\x00\x00", file count, section 1 (filenames), section 2 (pathnames,
    # has "dvdroot" at the start so no need to append foldername), section 3 (data block,
    # offsets table is relative)
    header = unpack("<16s4I", f.read(0x20))
    offsets = [(header[4] + unpack("<I", f.read(4))[0]) for i in range(header[1])]
    #extract     ^^^ absolute offset
    f.seek(0, 2)
    offsets.append(f.tell())
    # append EOF so we don't have an off-by-one
    for i in range(header[1]):
        f.seek(header[3] + (i * 0x20)) #section 2 = folder names
        folder = f.read(0x20).rstrip("\x00") #padded to 0x20, just read whole thing
        folder = folder.replace("/", "\\")
        folder = folder.split("\\")
        folder = os.sep.join(folder) #work for all OSes
        f.seek(header[2] + (i * 0x20)) #section 1 = filenames
        filename = f.read(0x20).rstrip("\x00")
        if not exists(folder):
            makedirs(folder) #make folder to extract to
        with open(folder + filename, "wb") as o:
            f.seek(offsets[i])
            o.write(f.read(offsets[i+1] - offsets[i])) #no off by one ^^^