unpack.py

import sys
import mmap
import struct
import zlib
fi = open(sys.argv[1], "rb")
mm = mmap.mmap(fi.fileno(), 0, prot=mmap.PROT_READ)

last_inode = 0x6d08

ofs = 0x50
while ofs <= last_inode :
    name_len = mm[ofs+9]
    if name_len :
        ty = mm[ofs+1]
        if ty == 0x81 :
            s = struct.unpack("IIII", mm[ofs:ofs+0x10])
            size = s[1]&((1<<26)-1)
            n_blocks = (size - 1) // 4096 + 1
            blockptr_offset = s[3]<<2
            name = mm[ofs+0x10:ofs+0x10+4*name_len].strip(b"\0").decode()
            print("name", name, hex(blockptr_offset), size, n_blocks)
            block_start = blockptr_offset+(n_blocks*4)
            try :
                print("name")
                with open("ex/%s"%name, "wb") as ofi:
                    for i in range(n_blocks) :
                        block_end = struct.unpack("I", mm[blockptr_offset+4*i:blockptr_offset+4*(i+1)])[0]
                        ofi.write(zlib.decompress(mm[block_start:block_end]))
                        block_start = block_end
            except zlib.error:
                print("error", name)

    ofs += 0x10+name_len*4