Support .blend files saved with large bhead
This is mostly the same as blender/blender!140195. The header parsing code has been updated to be able to read old and new .blend file headers. There is a new test file which is the same as the existing `basic_file.blend`, but saved with the new header format. A new unit test has been added to check that this file is read correctly as well. Pull Request: https://projects.blender.org/blender/blender-asset-tracer/pulls/92893
This commit is contained in:
Jacques Lucke
Jacques Lucke
parent
eb69ca5632
commit
f1ee7980b2
@ -135,7 +135,7 @@ class BlendFile:
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self.block_from_addr = {} # type: typing.Dict[int, BlendFileBlock]
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self.header = header.BlendFileHeader(self.fileobj, self.raw_filepath)
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self.block_header_struct = self.header.create_block_header_struct()
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self.block_header_struct, self.block_header_fields = self.header.create_block_header_struct()
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self._load_blocks()
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def _open_file(self, path: pathlib.Path, mode: str) -> typing.IO[bytes]:
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@ -455,23 +455,13 @@ class BlendFileBlock:
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self.code = b"ENDB"
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return
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# header size can be 8, 20, or 24 bytes long
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# 8: old blend files ENDB block (exception)
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# 20: normal headers 32 bit platform
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# 24: normal headers 64 bit platform
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if len(data) <= 15:
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self.log.debug("interpreting block as old-style ENB block")
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blockheader = self.old_structure.unpack(data)
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self.code = self.endian.read_data0(blockheader[0])
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return
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blockheader = header_struct.unpack(data)
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self.code = self.endian.read_data0(blockheader[0])
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blockheader = bfile.block_header_fields(*header_struct.unpack(data))
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self.code = self.endian.read_data0(blockheader.code)
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if self.code != b"ENDB":
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self.size = blockheader[1]
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self.addr_old = blockheader[2]
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self.sdna_index = blockheader[3]
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self.count = blockheader[4]
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self.size = blockheader.len
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self.addr_old = blockheader.old
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self.sdna_index = blockheader.SDNAnr
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self.count = blockheader.nr
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self.file_offset = bfile.fileobj.tell()
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def __repr__(self) -> str:
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@ -19,6 +19,8 @@
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# (c) 2009, At Mind B.V. - Jeroen Bakker
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# (c) 2014, Blender Foundation - Campbell Barton
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# (c) 2018, Blender Foundation - Sybren A. Stüvel
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from dataclasses import dataclass
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import logging
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import os
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import pathlib
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@ -30,58 +32,151 @@ from . import dna_io, exceptions
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log = logging.getLogger(__name__)
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@dataclass
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class BHead4:
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code: bytes
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len: int
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old: int
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SDNAnr: int
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nr: int
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@dataclass
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class SmallBHead8:
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code: bytes
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len: int
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old: int
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SDNAnr: int
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nr: int
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@dataclass
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class LargeBHead8:
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code: bytes
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SDNAnr: int
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old: int
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len: int
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nr: int
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class BlendFileHeader:
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"""
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BlendFileHeader represents the first 12 bytes of a blend file.
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BlendFileHeader represents the first 12-17 bytes of a blend file.
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It contains information about the hardware architecture, which is relevant
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to the structure of the rest of the file.
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"""
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structure = struct.Struct(b"7s1s1s3s")
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magic: bytes
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file_format_version: int
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pointer_size: int
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is_little_endian: bool
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endian: typing.Type[dna_io.EndianIO]
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endian_str: bytes
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def __init__(self, fileobj: typing.IO[bytes], path: pathlib.Path) -> None:
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log.debug("reading blend-file-header %s", path)
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fileobj.seek(0, os.SEEK_SET)
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header = fileobj.read(self.structure.size)
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values = self.structure.unpack(header)
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self.magic = values[0]
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bytes_0_6 = fileobj.read(7)
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if bytes_0_6 != b'BLENDER':
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raise exceptions.BlendFileError("invalid first bytes %r" % bytes_0_6, path)
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self.magic = bytes_0_6
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pointer_size_id = values[1]
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if pointer_size_id == b"-":
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byte_7 = fileobj.read(1)
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is_legacy_header = byte_7 in (b'_', b'-')
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if is_legacy_header:
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self.file_format_version = 0
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if byte_7 == b'_':
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self.pointer_size = 4
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elif byte_7 == b'-':
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self.pointer_size = 8
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else:
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raise exceptions.BlendFileError("invalid pointer size %r" % byte_7, path)
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byte_8 = fileobj.read(1)
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if byte_8 == b'v':
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self.is_little_endian = True
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elif byte_8 == b'V':
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self.is_little_endian = False
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else:
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raise exceptions.BlendFileError("invalid endian indicator %r" % byte_8, path)
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bytes_9_11 = fileobj.read(3)
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self.version = int(bytes_9_11)
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else:
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byte_8 = fileobj.read(1)
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header_size = int(byte_7 + byte_8)
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if header_size != 17:
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raise exceptions.BlendFileError("unknown file header size %d" % header_size, path)
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byte_9 = fileobj.read(1)
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if byte_9 != b'-':
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raise exceptions.BlendFileError("invalid file header", path)
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self.pointer_size = 8
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elif pointer_size_id == b"_":
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self.pointer_size = 4
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else:
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raise exceptions.BlendFileError(
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"invalid pointer size %r" % pointer_size_id, path
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)
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byte_10_11 = fileobj.read(2)
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self.file_format_version = int(byte_10_11)
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if self.file_format_version != 1:
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raise exceptions.BlendFileError("unsupported file format version %r" % self.file_format_version, path)
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byte_12 = fileobj.read(1)
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if byte_12 != b'v':
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raise exceptions.BlendFileError("invalid file header", path)
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self.is_little_endian = True
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byte_13_16 = fileobj.read(4)
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self.version = int(byte_13_16)
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endian_id = values[2]
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if endian_id == b"v":
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if self.is_little_endian:
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self.endian_str = b'<'
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self.endian = dna_io.LittleEndianTypes
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self.endian_str = b"<" # indication for struct.Struct()
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elif endian_id == b"V":
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self.endian = dna_io.BigEndianTypes
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self.endian_str = b">" # indication for struct.Struct()
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else:
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raise exceptions.BlendFileError(
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"invalid endian indicator %r" % endian_id, path
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)
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self.endian_str = b'>'
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self.endian = dna_io.BigEndianTypes
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version_id = values[3]
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self.version = int(version_id)
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def create_block_header_struct(self) -> typing.Tuple[struct.Struct, typing.Type[typing.Union[BHead4, SmallBHead8, LargeBHead8]]]:
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"""
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Returns a Struct instance for parsing data block headers and a corresponding
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Python class for accessing the right members. Ddepending on the .blend file,
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the order of the data members in the block header may be different.
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"""
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assert self.file_format_version in (0, 1)
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if self.file_format_version == 1:
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header_struct = struct.Struct(b''.join((
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self.endian_str,
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# LargeBHead8.code
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b'4s',
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# LargeBHead8.SDNAnr
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b'i',
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# LargeBHead8.old
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b'Q',
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# LargeBHead8.len
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b'q',
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# LargeBHead8.nr
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b'q',
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)))
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return header_struct, LargeBHead8
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def create_block_header_struct(self) -> struct.Struct:
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"""Create a Struct instance for parsing data block headers."""
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return struct.Struct(
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b"".join(
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(
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self.endian_str,
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b"4sI",
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b"I" if self.pointer_size == 4 else b"Q",
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b"II",
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)
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)
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)
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if self.pointer_size == 4:
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header_struct = struct.Struct(b''.join((
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self.endian_str,
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# BHead4.code
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b'4s',
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# BHead4.len
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b'i',
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# BHead4.old
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b'I',
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# BHead4.SDNAnr
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b'i',
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# BHead4.nr
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b'i',
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)))
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return header_struct, BHead4
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assert self.pointer_size == 8
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header_struct = struct.Struct(b''.join((
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self.endian_str,
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# SmallBHead8.code
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b'4s',
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# SmallBHead8.len
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b'i',
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# SmallBHead8.old
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b'Q',
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# SmallBHead8.SDNAnr
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b'i',
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# SmallBHead8.nr
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b'i',
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)))
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return header_struct, SmallBHead8
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BIN
tests/blendfiles/basic_file_large_bhead8.blend
Normal file
BIN
tests/blendfiles/basic_file_large_bhead8.blend
Normal file
Binary file not shown.
@ -13,6 +13,7 @@ class BlendFileBlockTest(AbstractBlendFileTest):
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def test_loading(self):
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self.assertFalse(self.bf.is_compressed)
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self.assertEqual(0, self.bf.header.file_format_version)
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def test_some_properties(self):
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ob = self.bf.code_index[b"OB"][0]
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@ -154,6 +155,23 @@ class BlendFileBlockTest(AbstractBlendFileTest):
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self.assertEqual("OBümlaut", ob.id_name.decode())
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class BlendFileLargeBhead8Test(AbstractBlendFileTest):
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def setUp(self):
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self.bf = blendfile.BlendFile(self.blendfiles / "basic_file_large_bhead8.blend")
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def test_loading(self):
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self.assertFalse(self.bf.is_compressed)
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self.assertEqual(1, self.bf.header.file_format_version)
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def test_some_properties(self):
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ob = self.bf.code_index[b"OB"][0]
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self.assertEqual("Object", ob.dna_type_name)
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# Try high level operation to read the object location.
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loc = ob.get(b"loc")
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self.assertEqual([2.0, 3.0, 5.0], loc)
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class PointerTest(AbstractBlendFileTest):
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def setUp(self):
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self.bf = blendfile.BlendFile(self.blendfiles / "with_sequencer.blend")
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