35 lines
979 B
Python
35 lines
979 B
Python
 
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"""The MyIni2CK container: magic, XOR scrambling, A2F compression.
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Boxsim uses one container for project files (`.bpj`) and driver files (`.bch`).
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"""
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from __future__ import annotations
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from . import a2f
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from .krypt import unscramble
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MAGIC = b"MyIni2CK"
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class ContainerError(ValueError):
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pass
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def is_container(raw: bytes) -> bool:
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return raw[: len(MAGIC)] == MAGIC
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def decode(raw: bytes) -> bytes:
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"""Decode a Boxsim container to its raw INI payload."""
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if not is_container(raw):
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raise ContainerError(
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f"not a MyIni2CK file (magic {raw[:8]!r}, expected {MAGIC!r})"
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)
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# The compressed layer reads its own 8 byte header back, so hand it the
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# magic followed by the descrambled body exactly as Boxsim does.
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return a2f.expand(MAGIC + unscramble(raw[len(MAGIC) :]))
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def decode_text(raw: bytes) -> str:
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"""Decode to text. Boxsim writes Windows-1252 with CRLF line ends."""
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return decode(raw).decode("cp1252")
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