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Move compressed header info constants/classes to .compress.common
This allows the constants/classes to be accessed from the individual decompressor submodules.
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dgelessus
parent
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commit
9dbdf5b827
@ -1,99 +1,14 @@
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import struct
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from . import dcmp0
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from . import dcmp1
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from . import dcmp2
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from .common import DecompressError
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from .common import DecompressError, CompressedApplicationHeaderInfo, CompressedHeaderInfo, CompressedSystemHeaderInfo
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__all__ = [
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"DecompressError",
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"decompress",
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]
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# The signature of all compressed resource data, 0xa89f6572 in hex, or "®üer" in MacRoman.
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COMPRESSED_SIGNATURE = b"\xa8\x9fer"
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# The compression type commonly used for application resources.
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COMPRESSED_TYPE_APPLICATION = 0x0801
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# The compression type commonly used for System file resources.
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COMPRESSED_TYPE_SYSTEM = 0x0901
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# Common header for compressed resources of all types.
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# 4 bytes: Signature (see above).
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# 2 bytes: Length of the complete header (this common part and the type-specific part that follows it). (This meaning is just a guess - the field's value is always 0x0012, so there's no way to know for certain what it means.)
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# 2 bytes: Compression type. Known so far: 0x0901 is used in the System file's resources. 0x0801 is used in other files' resources.
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# 4 bytes: Length of the data after decompression.
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# 6 bytes: Remainder of the header. The exact format varies depending on the compression type.
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STRUCT_COMPRESSED_HEADER = struct.Struct(">4sHHI6s")
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# Remainder of header for an "application" compressed resource.
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# 1 byte: "Working buffer fractional size" - the ratio of the compressed data size to the uncompressed data size, times 256.
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# 1 byte: "Expansion buffer size" - the maximum number of bytes that the data might grow during decompression.
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# 2 bytes: The ID of the 'dcmp' resource that can decompress this resource. Currently only ID 0 is supported.
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# 2 bytes: Reserved (always zero).
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STRUCT_COMPRESSED_APPLICATION_HEADER = struct.Struct(">BBhH")
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# Remainder of header for a "system" compressed resource.
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# 2 bytes: The ID of the 'dcmp' resource that can decompress this resource. Currently only ID 2 is supported.
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# 4 bytes: Decompressor-specific parameters.
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STRUCT_COMPRESSED_SYSTEM_HEADER = struct.Struct(">h4s")
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class CompressedHeaderInfo(object):
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@classmethod
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def parse(cls, data: bytes) -> "CompressedHeaderInfo":
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try:
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signature, header_length, compression_type, decompressed_length, remainder = STRUCT_COMPRESSED_HEADER.unpack_from(data)
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except struct.error:
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raise DecompressError(f"Invalid header")
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if signature != COMPRESSED_SIGNATURE:
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raise DecompressError(f"Invalid signature: {signature!r}, expected {COMPRESSED_SIGNATURE}")
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if header_length != 0x12:
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raise DecompressError(f"Unsupported header length: 0x{header_length:>04x}, expected 0x12")
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if compression_type == COMPRESSED_TYPE_APPLICATION:
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working_buffer_fractional_size, expansion_buffer_size, dcmp_id, reserved = STRUCT_COMPRESSED_APPLICATION_HEADER.unpack(remainder)
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if reserved != 0:
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raise DecompressError(f"Reserved field should be 0, not 0x{reserved:>04x}")
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return CompressedApplicationHeaderInfo(header_length, compression_type, decompressed_length, dcmp_id, working_buffer_fractional_size, expansion_buffer_size)
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elif compression_type == COMPRESSED_TYPE_SYSTEM:
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dcmp_id, parameters = STRUCT_COMPRESSED_SYSTEM_HEADER.unpack(remainder)
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return CompressedSystemHeaderInfo(header_length, compression_type, decompressed_length, dcmp_id, parameters)
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else:
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raise DecompressError(f"Unsupported compression type: 0x{compression_type:>04x}")
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def __init__(self, header_length: int, compression_type: int, decompressed_length: int, dcmp_id: int) -> None:
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super().__init__()
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self.header_length: int = header_length
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self.compression_type: int = compression_type
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self.decompressed_length: int = decompressed_length
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self.dcmp_id: int = dcmp_id
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class CompressedApplicationHeaderInfo(CompressedHeaderInfo):
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def __init__(self, header_length: int, compression_type: int, decompressed_length: int, dcmp_id: int, working_buffer_fractional_size: int, expansion_buffer_size: int) -> None:
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super().__init__(header_length, compression_type, decompressed_length, dcmp_id)
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self.working_buffer_fractional_size: int = working_buffer_fractional_size
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self.expansion_buffer_size: int = expansion_buffer_size
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def __repr__(self):
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return f"{type(self).__qualname__}(header_length={self.header_length}, compression_type={self.compression_type:>04x}, decompressed_length={self.decompressed_length}, dcmp_id={self.dcmp_id}, working_buffer_fractional_size={self.working_buffer_fractional_size}, expansion_buffer_size={self.expansion_buffer_size})"
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class CompressedSystemHeaderInfo(CompressedHeaderInfo):
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def __init__(self, header_length: int, compression_type: int, decompressed_length: int, dcmp_id: int, parameters: bytes) -> None:
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super().__init__(header_length, compression_type, decompressed_length, dcmp_id)
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self.parameters: bytes = parameters
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def __repr__(self):
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return f"{type(self).__qualname__}(header_length={self.header_length}, compression_type={self.compression_type:>04x}, decompressed_length={self.decompressed_length}, dcmp_id={self.dcmp_id}, parameters={self.parameters!r})"
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def _decompress_application(data: bytes, header_info: CompressedApplicationHeaderInfo, *, debug: bool=False) -> bytes:
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if header_info.dcmp_id == 0:
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@ -1,3 +1,4 @@
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import struct
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import typing
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@ -5,6 +6,90 @@ class DecompressError(Exception):
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"""Raised when resource data decompression fails, because the data is invalid or the compression type is not supported."""
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# The signature of all compressed resource data, 0xa89f6572 in hex, or "®üer" in MacRoman.
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COMPRESSED_SIGNATURE = b"\xa8\x9fer"
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# The compression type commonly used for application resources.
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COMPRESSED_TYPE_APPLICATION = 0x0801
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# The compression type commonly used for System file resources.
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COMPRESSED_TYPE_SYSTEM = 0x0901
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# Common header for compressed resources of all types.
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# 4 bytes: Signature (see above).
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# 2 bytes: Length of the complete header (this common part and the type-specific part that follows it). (This meaning is just a guess - the field's value is always 0x0012, so there's no way to know for certain what it means.)
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# 2 bytes: Compression type. Known so far: 0x0901 is used in the System file's resources. 0x0801 is used in other files' resources.
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# 4 bytes: Length of the data after decompression.
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# 6 bytes: Remainder of the header. The exact format varies depending on the compression type.
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STRUCT_COMPRESSED_HEADER = struct.Struct(">4sHHI6s")
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# Remainder of header for an "application" compressed resource.
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# 1 byte: "Working buffer fractional size" - the ratio of the compressed data size to the uncompressed data size, times 256.
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# 1 byte: "Expansion buffer size" - the maximum number of bytes that the data might grow during decompression.
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# 2 bytes: The ID of the 'dcmp' resource that can decompress this resource. Currently only ID 0 is supported.
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# 2 bytes: Reserved (always zero).
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STRUCT_COMPRESSED_APPLICATION_HEADER = struct.Struct(">BBhH")
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# Remainder of header for a "system" compressed resource.
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# 2 bytes: The ID of the 'dcmp' resource that can decompress this resource. Currently only ID 2 is supported.
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# 4 bytes: Decompressor-specific parameters.
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STRUCT_COMPRESSED_SYSTEM_HEADER = struct.Struct(">h4s")
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class CompressedHeaderInfo(object):
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@classmethod
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def parse(cls, data: bytes) -> "CompressedHeaderInfo":
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try:
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signature, header_length, compression_type, decompressed_length, remainder = STRUCT_COMPRESSED_HEADER.unpack_from(data)
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except struct.error:
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raise DecompressError(f"Invalid header")
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if signature != COMPRESSED_SIGNATURE:
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raise DecompressError(f"Invalid signature: {signature!r}, expected {COMPRESSED_SIGNATURE}")
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if header_length != 0x12:
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raise DecompressError(f"Unsupported header length: 0x{header_length:>04x}, expected 0x12")
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if compression_type == COMPRESSED_TYPE_APPLICATION:
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working_buffer_fractional_size, expansion_buffer_size, dcmp_id, reserved = STRUCT_COMPRESSED_APPLICATION_HEADER.unpack(remainder)
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if reserved != 0:
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raise DecompressError(f"Reserved field should be 0, not 0x{reserved:>04x}")
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return CompressedApplicationHeaderInfo(header_length, compression_type, decompressed_length, dcmp_id, working_buffer_fractional_size, expansion_buffer_size)
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elif compression_type == COMPRESSED_TYPE_SYSTEM:
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dcmp_id, parameters = STRUCT_COMPRESSED_SYSTEM_HEADER.unpack(remainder)
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return CompressedSystemHeaderInfo(header_length, compression_type, decompressed_length, dcmp_id, parameters)
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else:
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raise DecompressError(f"Unsupported compression type: 0x{compression_type:>04x}")
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def __init__(self, header_length: int, compression_type: int, decompressed_length: int, dcmp_id: int) -> None:
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super().__init__()
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self.header_length: int = header_length
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self.compression_type: int = compression_type
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self.decompressed_length: int = decompressed_length
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self.dcmp_id: int = dcmp_id
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class CompressedApplicationHeaderInfo(CompressedHeaderInfo):
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def __init__(self, header_length: int, compression_type: int, decompressed_length: int, dcmp_id: int, working_buffer_fractional_size: int, expansion_buffer_size: int) -> None:
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super().__init__(header_length, compression_type, decompressed_length, dcmp_id)
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self.working_buffer_fractional_size: int = working_buffer_fractional_size
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self.expansion_buffer_size: int = expansion_buffer_size
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def __repr__(self):
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return f"{type(self).__qualname__}(header_length={self.header_length}, compression_type={self.compression_type:>04x}, decompressed_length={self.decompressed_length}, dcmp_id={self.dcmp_id}, working_buffer_fractional_size={self.working_buffer_fractional_size}, expansion_buffer_size={self.expansion_buffer_size})"
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class CompressedSystemHeaderInfo(CompressedHeaderInfo):
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def __init__(self, header_length: int, compression_type: int, decompressed_length: int, dcmp_id: int, parameters: bytes) -> None:
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super().__init__(header_length, compression_type, decompressed_length, dcmp_id)
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self.parameters: bytes = parameters
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def __repr__(self):
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return f"{type(self).__qualname__}(header_length={self.header_length}, compression_type={self.compression_type:>04x}, decompressed_length={self.decompressed_length}, dcmp_id={self.dcmp_id}, parameters={self.parameters!r})"
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def _read_variable_length_integer(data: bytes, position: int) -> typing.Tuple[int, int]:
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"""Read a variable-length integer starting at the given position in the data, and return the integer as well as the number of bytes consumed.
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