simg2img.py

#!/usr/bin/env python#encoding:utf8#===============================================================================##          FILE:  simg2img.py# #         USAGE:  ./simg2img.py system.img # #   DESCRIPTION:  # #        AUTHOR: Karl Zheng #       COMPANY: Meizu#       CREATED: 2011年10月18日 15时25分15秒 CST#      REVISION:  ---#===============================================================================import sysimport structclass ext4_file_header:def __init__(self, buf):self.magic, \self.major, \self.minor, \self.file_header_size, \self.chunk_header_size, \self.block_size, \self.total_blocks, \self.total_chunks, \self.crc32, \= struct.unpack('<IHHHHIIII', buf)class ext4_chunk_header:def __init__(self, buf):self.type,\self.reserved,\self.chunk_size,\self.total_size,\= struct.unpack('<HHII', buf)if len(sys.argv) > 1:filename = sys.argv[1]else:print "No file is designated!!"sys.exit(1)ifd = open(filename, "rb")buf=""# get filelenifd.seek(0, 2)file_len = ifd.tell()print file_lenifd.seek(0, 0)buf = ifd.read(28)#print repr(buf)file_header = ext4_file_header(buf)EXT4_FILE_HEADER_MAGIC = 0xED26FF3AEXT4_CHUNK_HEADER_SIZE = 12if file_header.magic != EXT4_FILE_HEADER_MAGIC:print "Not a compressed ext4 file!!"sys.exit(1)print "file_header chunks:%X"%(file_header.total_chunks)total_chunks = file_header.total_chunksprint("total chunk = %d "%(total_chunks))ofd = open("tmp.img", "wb")sector_base = 82528output_len = 0while total_chunks > 0:buf = ifd.read(EXT4_CHUNK_HEADER_SIZE)chunk_header = ext4_chunk_header(buf)sector_size = (chunk_header.chunk_size * file_header.block_size) >> 9;#print "ct:%X, cs:%X, ts:%X, ss:%X"%(chunk_header.type, chunk_header.chunk_size, chunk_header.total_size, sector_size)data = ""if chunk_header.type == 0xCAC1:  # raw type data = ifd.read(chunk_header.total_size - EXT4_CHUNK_HEADER_SIZE)if len(data) != (sector_size << 9):print("len data:%d, sector_size:%d"%(len(data), (sector_size << 9)))sys.exit(1)else:print ("len data:%d, sector_size:%d"%(len(data), sector_size << 9))ofd.write(data)output_len += len(data)print("raw_chunk ")print("write raw data in %d size %d \n"%(sector_base, sector_size))print("output len:%x"%(output_len))sector_base += sector_sizeelse:if chunk_header.type == 0xCAC2:  # TYPE_FILLdata = '\0' * (sector_size << 9);ofd.write(data) output_len += len(data)print("fill_chunk \n")print("chunk_size:%x"%(chunk_header.chunk_size))print("output len:%x"%(output_len))sector_base += sector_sizeelse:if chunk_header.type == 0xCAC3:  # TYPE_DONT_CAREprint "none chunk at chunk:%d"%(file_header.total_chunks - total_chunks)print("data_size:0x%x, chunk_size:%d, block_size:%d"%(sector_size << 9, chunk_header.chunk_size, file_header.block_size))data = '\0' * (sector_size << 9);ofd.write(data) output_len += len(data)sector_base += sector_sizeelse:data = '\0' * (sector_size << 9);ofd.write(data)print "unknown type!!"output_len += len(data)print("output len:%x"%(output_len))sector_base += sector_sizetotal_chunks -= 1 print("remain chunks = %d "%(total_chunks));print "write done"ifd.close()ofd.close()