Class BytesIO

Lib/_pyio.py:872–1031

Buffered I/O implementation using an in-memory bytes buffer.

class BytesIO(BufferedIOBase):

    """Buffered I/O implementation using an in-memory bytes buffer."""

    # Initialize _buffer as soon as possible since it's used by __del__()
    # which calls close()
    _buffer = None

    def __init__(self, initial_bytes=None):
        # Use to keep self._buffer and self._pos consistent.
        self._lock = Lock()

        buf = bytearray()
        if initial_bytes is not None:
            buf += initial_bytes

        with self._lock:
            self._buffer = buf
            self._pos = 0

    def __getstate__(self):
        if self.closed:
            raise ValueError("__getstate__ on closed file")
        with self._lock:
            state = self.__dict__.copy()
        del state['_lock']
        return state

    def __setstate__(self, state):
        self.__dict__.update(state)
        self._lock = Lock()

    def getvalue(self):
        """Return the bytes value (contents) of the buffer
        """
        if self.closed:
            raise ValueError("getvalue on closed file")
        return bytes(self._buffer)

    def getbuffer(self):
        """Return a readable and writable view of the buffer.
        """
        if self.closed:
            raise ValueError("getbuffer on closed file")
        return memoryview(self._buffer)

    def close(self):
        if self._buffer is not None:
            self._buffer.clear()
        super().close()

    def read(self, size=-1):
        if self.closed:
            raise ValueError("read from closed file")
        if size is None:
            size = -1
        else:
            try: