xcramfs.py

#!/usr/bin/env python3
# SPDX-License-Identifier: MIT

import sys
import struct
import os

cramfs_known = []

with open(sys.argv[1], "rb") as f:
	f.seek(0x440000)
	cramfs_known.append(f.read(0x8000))
	f.seek(0xD28000)
	cramfs_known.append(f.read(0x8000))
	f.seek(0x3028000)
	cramfs_known.append(f.read(0x8000))
	f.seek(0x6740000)
	cramfs_known.append(f.read(0x8000))

for blk in cramfs_known:
	super_magic = int.from_bytes(blk[0:4], byteorder="big")
	super_size = int.from_bytes(blk[4:8], byteorder="big")
	super_flags = int.from_bytes(blk[8:12], byteorder="big")
	super_future = int.from_bytes(blk[12:16], byteorder="big")
	super_signature = blk[16:32]
	super_fsid_crc = int.from_bytes(blk[32:36], byteorder="big")
	super_fsid_edition = int.from_bytes(blk[36:40], byteorder="big")
	super_fsid_blocks = int.from_bytes(blk[40:44], byteorder="big")
	super_fsid_files = int.from_bytes(blk[44:48], byteorder="big")
	super_name = blk[48:64]
	print("super_magic: %08x" % (super_magic))
	print("super_size: %08x" % (super_size))
	print("super_flags: %08x" % (super_flags))
	print("super_future: %08x" % (super_future))
	print("super_signature: ", super_signature)
	print("super_fsid_crc: %08x" % (super_fsid_crc))
	print("super_fsid_edition: %08x" % (super_fsid_edition))
	print("super_fsid_blocks: %08x" % (super_fsid_blocks))
	print("super_fsid_files: %08x" % (super_fsid_files))
	print("super_name: ", super_name)
	offs = 64
	for i in range(super_fsid_files):
		inode_mode_uid = int.from_bytes(blk[offs + 0:offs + 4], byteorder="big")
		inode_mode = (inode_mode_uid & 0xFFFF0000) >> 16
		inode_uid = inode_mode_uid & 0xFFFF
		inode_size_gid = int.from_bytes(blk[offs + 4:offs + 8], byteorder="big")
		inode_size = (inode_size_gid & 0xFFFFFF00) >> 8
		inode_gid = inode_size_gid & 0xFF
		inode_namelen_offset = int.from_bytes(blk[offs + 8:offs + 12], byteorder="big")
		inode_namelen = (inode_namelen_offset & 0xFC000000) >> 26
		inode_offset = inode_namelen_offset & 0x3FFFFFF
		offs += 12
		print("inode: ", hex(inode_mode), hex(inode_uid), hex(inode_size), hex(inode_gid), hex(inode_namelen), hex(inode_offset))
		print("inode name: ", blk[offs:offs + (inode_namelen * 4)].rstrip(b"\x00"))
		offs += inode_namelen * 4