Viewing file:  encoding.py (1.39 KB) -rw-r--r--
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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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