python-rsrcfork/rsrcfork/compress/__init__.py

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import io
import typing
from . import dcmp0
from . import dcmp1
from . import dcmp2
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from .common import DecompressError, CompressedHeaderInfo
__all__ = [
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"CompressedHeaderInfo",
"DecompressError",
"decompress",
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"decompress_parsed",
"decompress_stream",
"decompress_stream_parsed",
]
# Maps 'dcmp' IDs to their corresponding Python implementations.
# Each decompressor has the signature (header_info: CompressedHeaderInfo, stream: typing.BinaryIO, *, debug: bool=False) -> typing.Iterator[bytes].
DECOMPRESSORS = {
0: dcmp0.decompress_stream,
1: dcmp1.decompress_stream,
2: dcmp2.decompress_stream,
}
def decompress_stream_parsed(header_info: CompressedHeaderInfo, stream: typing.BinaryIO, *, debug: bool=False) -> typing.Iterator[bytes]:
"""Decompress compressed resource data from a stream, whose header has already been read and parsed into a CompressedHeaderInfo object."""
try:
decompress_func = DECOMPRESSORS[header_info.dcmp_id]
except KeyError:
raise DecompressError(f"Unsupported 'dcmp' ID: {header_info.dcmp_id}")
decompressed_length = 0
for chunk in decompress_func(header_info, stream, debug=debug):
decompressed_length += len(chunk)
yield chunk
if decompressed_length != header_info.decompressed_length:
raise DecompressError(f"Actual length of decompressed data ({decompressed_length}) does not match length stored in resource ({header_info.decompressed_length})")
def decompress_parsed(header_info: CompressedHeaderInfo, data: bytes, *, debug: bool=False) -> bytes:
"""Decompress the given compressed resource data, whose header has already been removed and parsed into a CompressedHeaderInfo object."""
return b"".join(decompress_stream_parsed(header_info, io.BytesIO(data), debug=debug))
def decompress_stream(stream: typing.BinaryIO, *, debug: bool=False) -> typing.Iterator[bytes]:
"""Decompress compressed resource data from a stream."""
header_info = CompressedHeaderInfo.parse_stream(stream)
if debug:
print(f"Compressed resource data header: {header_info}")
yield from decompress_stream_parsed(header_info, stream, debug=debug)
def decompress(data: bytes, *, debug: bool=False) -> bytes:
"""Decompress the given compressed resource data."""
return b"".join(decompress_stream(io.BytesIO(data), debug=debug))