58 lines
2.0 KiB
Python
58 lines
2.0 KiB
Python
"""
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Utility functions to deal with binary structs.
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"""
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# Copyright (C) 2020 The Psycopg Team
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import struct
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from typing import Callable, cast, Optional, Tuple
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from typing_extensions import TypeAlias
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from .abc import Buffer
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from . import errors as e
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from ._compat import Protocol
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PackInt: TypeAlias = Callable[[int], bytes]
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UnpackInt: TypeAlias = Callable[[Buffer], Tuple[int]]
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PackFloat: TypeAlias = Callable[[float], bytes]
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UnpackFloat: TypeAlias = Callable[[Buffer], Tuple[float]]
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class UnpackLen(Protocol):
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def __call__(self, data: Buffer, start: Optional[int]) -> Tuple[int]:
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...
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pack_int2 = cast(PackInt, struct.Struct("!h").pack)
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pack_uint2 = cast(PackInt, struct.Struct("!H").pack)
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pack_int4 = cast(PackInt, struct.Struct("!i").pack)
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pack_uint4 = cast(PackInt, struct.Struct("!I").pack)
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pack_int8 = cast(PackInt, struct.Struct("!q").pack)
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pack_float4 = cast(PackFloat, struct.Struct("!f").pack)
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pack_float8 = cast(PackFloat, struct.Struct("!d").pack)
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unpack_int2 = cast(UnpackInt, struct.Struct("!h").unpack)
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unpack_uint2 = cast(UnpackInt, struct.Struct("!H").unpack)
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unpack_int4 = cast(UnpackInt, struct.Struct("!i").unpack)
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unpack_uint4 = cast(UnpackInt, struct.Struct("!I").unpack)
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unpack_int8 = cast(UnpackInt, struct.Struct("!q").unpack)
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unpack_float4 = cast(UnpackFloat, struct.Struct("!f").unpack)
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unpack_float8 = cast(UnpackFloat, struct.Struct("!d").unpack)
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_struct_len = struct.Struct("!i")
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pack_len = cast(Callable[[int], bytes], _struct_len.pack)
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unpack_len = cast(UnpackLen, _struct_len.unpack_from)
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def pack_float4_bug_304(x: float) -> bytes:
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raise e.InterfaceError(
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"cannot dump Float4: Python affected by bug #304. Note that the psycopg-c"
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" and psycopg-binary packages are not affected by this issue."
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" See https://github.com/psycopg/psycopg/issues/304"
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)
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# If issue #304 is detected, raise an error instead of dumping wrong data.
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if struct.Struct("!f").pack(1.0) != bytes.fromhex("3f800000"):
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pack_float4 = pack_float4_bug_304
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