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- import base64
- import string
- import struct
- from ._compat import text_type
- from .exc import BadData
- def want_bytes(s, encoding="utf-8", errors="strict"):
- if isinstance(s, text_type):
- s = s.encode(encoding, errors)
- return s
- def base64_encode(string):
- """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):
- """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):
- raise BadData("Invalid base64-encoded data")
- # The alphabet used by base64.urlsafe_*
- _base64_alphabet = (string.ascii_letters + string.digits + "-_=").encode("ascii")
- _int64_struct = struct.Struct(">Q")
- _int_to_bytes = _int64_struct.pack
- _bytes_to_int = _int64_struct.unpack
- def int_to_bytes(num):
- return _int_to_bytes(num).lstrip(b"\x00")
- def bytes_to_int(bytestr):
- return _bytes_to_int(bytestr.rjust(8, b"\x00"))[0]
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