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e00e534f2c
Unfortunately the history from before this commit is lost to time. And that's probably for the best.
96 lines
2.5 KiB
Python
96 lines
2.5 KiB
Python
#!/usr/bin/env python
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# coding: utf-8
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import struct
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import zlib
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from io import BytesIO
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# ToDo do some reworking to make this more memory efficient
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class Chunk:
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header_magic = 0xB1FE3AA2
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def __init__(self):
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self.header_version = 0
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self.header_size = 0
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self.compressed_size = 0
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self.hash = 0
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self.stored_as = 0
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self.guid = []
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self.hash_type = 0
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self.sha_hash = None
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self.uncompressed_size = 1024 * 1024
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self._guid_str = ''
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self._guid_num = 0
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self._bio = None
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self._data = None
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@property
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def data(self):
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if self._data:
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return self._data
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if self.compressed:
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self._data = zlib.decompress(self._bio.read())
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else:
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self._data = self._bio.read()
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# close BytesIO with raw data since we no longer need it
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self._bio.close()
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self._bio = None
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return self._data
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@property
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def guid_str(self):
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if not self._guid_str:
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self._guid_str = '-'.join('{:08x}'.format(g) for g in self.guid)
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return self._guid_str
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@property
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def guid_num(self):
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if not self._guid_num:
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self._guid_num = self.guid[3] + (self.guid[2] << 32) + (self.guid[1] << 64) + (self.guid[0] << 96)
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return self._guid_num
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@property
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def compressed(self):
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return self.stored_as & 0x1
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@classmethod
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def read_buffer(cls, data):
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_sio = BytesIO(data)
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return cls.read(_sio)
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@classmethod
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def read(cls, bio):
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head_start = bio.tell()
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if struct.unpack('<I', bio.read(4))[0] != cls.header_magic:
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raise ValueError('Chunk magic doesn\'t match!')
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_chunk = cls()
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_chunk._bio = bio
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_chunk.header_version = struct.unpack('<I', bio.read(4))[0]
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_chunk.header_size = struct.unpack('<I', bio.read(4))[0]
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_chunk.compressed_size = struct.unpack('<I', bio.read(4))[0]
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_chunk.guid = struct.unpack('<IIII', bio.read(16))
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_chunk.hash = struct.unpack('<Q', bio.read(8))[0]
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_chunk.stored_as = struct.unpack('B', bio.read(1))[0]
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if _chunk.header_version >= 2:
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_chunk.sha_hash = bio.read(20)
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_chunk.hash_type = struct.unpack('B', bio.read(1))[0]
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if _chunk.header_version >= 3:
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_chunk.uncompressed_size = struct.unpack('<I', bio.read(4))[0]
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if bio.tell() - head_start != _chunk.header_size:
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raise ValueError('Did not read entire chunk header!')
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return _chunk
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