Spare Image To RAW Image

Usage:
mkdir system

./simg2img.py system.img.ext4 system.raw

sudo mount -t ext4 -o loop system.raw system/

sudo chown -R USERNAME:USERNAME $pwd {To Have Write Access}

simg2img.py

@@ -0,0 +1,151 @@
+#!/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 sys
+import struct
+
+class 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 "Usage: simg2img.py input_file output_file"
+	sys.exit(1)
+
+if len(sys.argv) > 2:
+	outfile = sys.argv[2]
+else:
+	print "No output file specified!"
+	print "Usage: simg2img.py input_file output_file"
+	sys.exit(1)
+
+ifd = open(filename, "rb")
+
+buf=""
+
+# get filelen
+ifd.seek(0, 2)
+file_len = ifd.tell()
+print file_len
+
+EXT4_FILE_HEADER_MAGIC = 0xED26FF3A
+EXT4_CHUNK_HEADER_SIZE = 12
+
+magic_found=False
+max_offs=min(file_len, 50*1024*1024) # don't look into the file more than 20Mb
+
+# Very inefficient way to find the magic... but it's not too slow in practice so it's ok ;)
+for k in xrange((file_len+3)/4):
+	offs = k*4 # assumption: the magic value is aligned to 4 bytes
+	ifd.seek(offs, 0)
+
+	buf = ifd.read(28)
+	#print repr(buf)
+	file_header = ext4_file_header(buf)
+
+	if file_header.magic == EXT4_FILE_HEADER_MAGIC:
+		print "Found magic at offs=%(offs)d (0x%(offs)X)" % {'offs': offs}
+		magic_found=True
+		break
+
+if not magic_found:
+	print "Not a compressed ext4 file!!"
+	sys.exit(1)
+
+print "file_header chunks:%X"%(file_header.total_chunks)
+
+total_chunks = file_header.total_chunks
+print("total chunk = %d "%(total_chunks))
+
+ofd = open(outfile, "wb")
+
+sector_base = 82528
+output_len = 0
+
+while 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_size
+	else:
+		if chunk_header.type == 0xCAC2:  # TYPE_FILL
+			data = '\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_size
+		else:
+			if chunk_header.type == 0xCAC3:  # TYPE_DONT_CARE
+				print "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_size
+			else:
+				data = '\0' * (sector_size << 9);
+				ofd.write(data)
+				print "unknown type!!"
+				output_len += len(data)
+				print("output len:%x"%(output_len))
+				sector_base += sector_size
+
+	total_chunks -= 1 
+	print("remain chunks = %d "%(total_chunks));
+
+print "write done"
+
+ifd.close()
+ofd.close()
+
+