def pack_object_at(data, offset, as_stream):
"""
:return: Tuple(abs_data_offset, PackInfo|PackStream)
an object of the correct type according to the type_id of the object.
If as_stream is True, the object will contain a stream, allowing the
data to be read decompressed.
:param data: random accessable data containing all required information
:parma offset: offset in to the data at which the object information is located
:param as_stream: if True, a stream object will be returned that can read
the data, otherwise you receive an info object only"""
data = buffer(data, offset)
type_id, uncomp_size, data_rela_offset = pack_object_header_info(data)
total_rela_offset = None # set later, actual offset until data stream begins
delta_info = None
# OFFSET DELTA
if type_id == OFS_DELTA:
i = data_rela_offset
c = ord(data[i])
i += 1
delta_offset = c & 0x7f
while c & 0x80:
c = ord(data[i])
i += 1
delta_offset += 1
delta_offset = (delta_offset << 7) + (c & 0x7f)
# END character loop
delta_info = delta_offset
total_rela_offset = i
# REF DELTA
elif type_id == REF_DELTA:
total_rela_offset = data_rela_offset + 20
ref_sha = data[data_rela_offset:total_rela_offset]
delta_info = ref_sha
# BASE OBJECT
else:
# assume its a base object
total_rela_offset = data_rela_offset
# END handle type id
abs_data_offset = offset + total_rela_offset
if as_stream:
stream = DecompressMemMapReader(buffer(data, total_rela_offset), False,
uncomp_size)
if delta_info is None:
return abs_data_offset, OPackStream(offset, type_id, uncomp_size,
stream)
else:
return abs_data_offset, ODeltaPackStream(offset, type_id,
uncomp_size, delta_info,
stream)
else:
if delta_info is None:
return abs_data_offset, OPackInfo(offset, type_id, uncomp_size)
else:
return abs_data_offset, ODeltaPackInfo(offset, type_id,
uncomp_size, delta_info)
def pack_object_at(data, offset, as_stream): """ :return: Tuple(abs_data_offset, PackInfo|PackStream) an object of the correct type according to the type_id of the object. If as_stream is True, the object will contain a stream, allowing the data to be read decompressed. :param data: random accessable data containing all required information :parma offset: offset in to the data at which the object information is located :param as_stream: if True, a stream object will be returned that can read the data, otherwise you receive an info object only""" data = buffer(data, offset) type_id, uncomp_size, data_rela_offset = pack_object_header_info(data) total_rela_offset = None # set later, actual offset until data stream begins delta_info = None # OFFSET DELTA if type_id == OFS_DELTA: i = data_rela_offset c = ord(data[i]) i += 1 delta_offset = c & 0x7f while c & 0x80: c = ord(data[i]) i += 1 delta_offset += 1 delta_offset = (delta_offset << 7) + (c & 0x7f) # END character loop delta_info = delta_offset total_rela_offset = i # REF DELTA elif type_id == REF_DELTA: total_rela_offset = data_rela_offset+20 ref_sha = data[data_rela_offset:total_rela_offset] delta_info = ref_sha # BASE OBJECT else: # assume its a base object total_rela_offset = data_rela_offset # END handle type id abs_data_offset = offset + total_rela_offset if as_stream: stream = DecompressMemMapReader(buffer(data, total_rela_offset), False, uncomp_size) if delta_info is None: return abs_data_offset, OPackStream(offset, type_id, uncomp_size, stream) else: return abs_data_offset, ODeltaPackStream(offset, type_id, uncomp_size, delta_info, stream) else: if delta_info is None: return abs_data_offset, OPackInfo(offset, type_id, uncomp_size) else: return abs_data_offset, ODeltaPackInfo(offset, type_id, uncomp_size, delta_info)
def _object(self, sha, as_stream, index=-1):
""":return: OInfo or OStream object providing information about the given sha
:param index: if not -1, its assumed to be the sha's index in the IndexFile"""
# its a little bit redundant here, but it needs to be efficient
if index < 0:
index = self._sha_to_index(sha)
if sha is None:
sha = self._index.sha(index)
# END assure sha is present ( in output )
offset = self._index.offset(index)
type_id, uncomp_size, data_rela_offset = pack_object_header_info(
buffer(self._pack._data, offset))
if as_stream:
if type_id not in delta_types:
packstream = self._pack.stream(offset)
return OStream(sha, packstream.type, packstream.size,
packstream.stream)
# END handle non-deltas
# produce a delta stream containing all info
# To prevent it from applying the deltas when querying the size,
# we extract it from the delta stream ourselves
streams = self.collect_streams_at_offset(offset)
buf = streams[0].read(512)
offset, src_size = msb_size(buf)
offset, target_size = msb_size(buf, offset)
streams[0].stream.seek(
0) # assure it can be read by the delta reader
dstream = DeltaApplyReader.new(streams)
return OStream(sha, dstream.type, target_size, dstream)
else:
if type_id not in delta_types:
return OInfo(sha, type_id_to_type_map[type_id], uncomp_size)
# END handle non-deltas
# deltas are a little tougher - unpack the first bytes to obtain
# the actual target size, as opposed to the size of the delta data
streams = self.collect_streams_at_offset(offset)
buf = streams[0].read(512)
offset, src_size = msb_size(buf)
offset, target_size = msb_size(buf, offset)
# collect the streams to obtain the actual object type
if streams[-1].type_id in delta_types:
raise BadObject(sha, "Could not resolve delta object")
return OInfo(sha, streams[-1].type, target_size)
def _object(self, sha, as_stream, index=-1): """:return: OInfo or OStream object providing information about the given sha :param index: if not -1, its assumed to be the sha's index in the IndexFile""" # its a little bit redundant here, but it needs to be efficient if index < 0: index = self._sha_to_index(sha) if sha is None: sha = self._index.sha(index) # END assure sha is present ( in output ) offset = self._index.offset(index) type_id, uncomp_size, data_rela_offset = pack_object_header_info(buffer(self._pack._data, offset)) if as_stream: if type_id not in delta_types: packstream = self._pack.stream(offset) return OStream(sha, packstream.type, packstream.size, packstream.stream) # END handle non-deltas # produce a delta stream containing all info # To prevent it from applying the deltas when querying the size, # we extract it from the delta stream ourselves streams = self.collect_streams_at_offset(offset) buf = streams[0].read(512) offset, src_size = msb_size(buf) offset, target_size = msb_size(buf, offset) streams[0].stream.seek(0) # assure it can be read by the delta reader dstream = DeltaApplyReader.new(streams) return OStream(sha, dstream.type, target_size, dstream) else: if type_id not in delta_types: return OInfo(sha, type_id_to_type_map[type_id], uncomp_size) # END handle non-deltas # deltas are a little tougher - unpack the first bytes to obtain # the actual target size, as opposed to the size of the delta data streams = self.collect_streams_at_offset(offset) buf = streams[0].read(512) offset, src_size = msb_size(buf) offset, target_size = msb_size(buf, offset) # collect the streams to obtain the actual object type if streams[-1].type_id in delta_types: raise BadObject(sha, "Could not resolve delta object") return OInfo(sha, streams[-1].type, target_size)
