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- import base64
- import string
- import struct
- import typing as _t
- from .exc import BadData
- _t_str_bytes = _t.Union[str, bytes]
- def want_bytes(
- s: _t_str_bytes, encoding: str = "utf-8", errors: str = "strict"
- ) -> bytes:
- if isinstance(s, str):
- s = s.encode(encoding, errors)
- return s
- def base64_encode(string: _t_str_bytes) -> bytes:
- """Base64 encode a string of bytes or text. The resulting bytes are
- safe to use in URLs.
- """
- string = want_bytes(string)
- return base64.urlsafe_b64encode(string).rstrip(b"=")
- def base64_decode(string: _t_str_bytes) -> bytes:
- """Base64 decode a URL-safe string of bytes or text. The result is
- bytes.
- """
- string = want_bytes(string, encoding="ascii", errors="ignore")
- string += b"=" * (-len(string) % 4)
- try:
- return base64.urlsafe_b64decode(string)
- except (TypeError, ValueError) as e:
- raise BadData("Invalid base64-encoded data") from e
- # The alphabet used by base64.urlsafe_*
- _base64_alphabet = f"{string.ascii_letters}{string.digits}-_=".encode("ascii")
- _int64_struct = struct.Struct(">Q")
- _int_to_bytes = _int64_struct.pack
- _bytes_to_int = _t.cast("_t.Callable[[bytes], _t.Tuple[int]]", _int64_struct.unpack)
- def int_to_bytes(num: int) -> bytes:
- return _int_to_bytes(num).lstrip(b"\x00")
- def bytes_to_int(bytestr: bytes) -> int:
- return _bytes_to_int(bytestr.rjust(8, b"\x00"))[0]
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