https://twitter.com/aoirint/status/1637366346592952322

decode_utf8_bytestream.py

def decode_utf8_bytestream(byte_stream):
    i = 0
    decoded_strings = []
    decoded_string = b''
    while i < len(byte_stream):
        byte = byte_stream[i]
        if byte == 0x00:
            decoded_strings.append(decoded_string)
            decoded_string = b''
            i += 1
        elif byte <= 0x7F:
            decoded_string += byte_stream[i:i+1]
            i += 1
        elif byte <= 0xDF:
            decoded_string += byte_stream[i:i+2]
            i += 2
        elif byte <= 0xEF:
            decoded_string += byte_stream[i:i+3]
            i += 3
        else:
            decoded_string += byte_stream[i:i+4]
            i += 4
    if len(decoded_string) != 0:
        decoded_strings.append(decoded_string)
    return [s.decode('utf-8') for s in decoded_strings]


byte_str = b'\xe3\x81\x82\xe3\x81\x84\xe3\x81\x86\x00\xe3\x81\x8a\xe3\x81\x86\xe3\x81\x8c\xe3\x81\x84\x00'
decoded_strings = decode_utf8_bytestream(byte_str)
print(decoded_strings[0]) # 'あいう'
print(decoded_strings[1]) # 'おうがい'

https://twitter.com/aoirint/status/1637375030031179779

のことがわかったので、このプログラムはゴミです