def guess_oob_offset(image, headers, oob_size):
oobs_bytes = YaffsParser.get_oob_bytes(image, headers, oob_size)
best_parsed = []
# We use -16 because we are looking for 16 bytes in the tag
# for parsing
for offset in xrange(0, oob_size-16):
parsed = []
for bytes in oobs_bytes:
parsed_oob = YaffsOobTag(bytes, offset)
if not parsed_oob.isHeaderTag:
continue
else:
parsed.append(parsed_oob)
if len(parsed) > len(best_parsed):
best_offset = offset
best_parsed = parsed
object_ids = set([o.object_id for o in best_parsed])
if len(object_ids) > 0:
print "OOB tag offset is %d" % best_offset
print "with %d valid header tags" % len(best_parsed)
print "Object id: %s" % str(object_ids)
return best_offset
print "Unable to determine OOB tag offset."
return None
def guess_block_size(image, chunk_size, oob_size, oob_offset):
chunk_pairs = YaffsParser.extract_chunks(image, chunk_size, oob_size)
chunks = [c for c, o in chunk_pairs[:1024]]
oobs_bytes = YaffsParser.get_oob_bytes(image, chunks, oob_size)
oobs = [YaffsOobTag(b, oob_offset) for b in oobs_bytes]
prev = -1
counts = []
count = 0
for oob in oobs:
if oob.block_seq != prev:
if count > 0:
counts.append(count)
count = 1
prev = oob.block_seq
else:
count += 1
import collections
size, freq = collections.Counter(counts).most_common(1)[0]
if freq == 1:
print "Unable to determine block size."
return None
print "Most likely block size: %d" % size
return size
def main():
"""
Assume we pass this script the image file path as an argument on the
command line.
"""
usage = 'usage: %prog [options] imagefile'
parser = OptionParser(usage=usage)
parser.add_option('--chunksize', action='store', type='int',
dest='chunk_size', default=2048)
parser.add_option('--oobsize', action='store', type='int',
dest='oob_size', default=64)
options, args = parser.parse_args()
if len(args) != 1:
print "Incorrect command line arguments. Missing (or too many) image files"
return 1
image = args[0]
headers = Scanner.get_anchor_headers(image, options.chunk_size,
options.oob_size, 'contacts2.db')
oobs = YaffsParser.get_oob_bytes(image, headers, options.oob_size)
for oob in oobs:
sys.stdout.write(oob)
#Separate each oob with 16 'X' Bytes.
sys.stdout.write('X'*16)
def count_constant_oobs(image, chunks, oobsize):
oobs = YaffsParser.get_oob_bytes(image, chunks, oobsize)
constants_count = 0
constant = '\xff' * oobsize
for oob in oobs:
if oob == constant:
constants_count += 1
return constants_count
