SSL.py 文件源码

def recv_into(self, buffer, nbytes=None, flags=None):
        """
        Receive data on the connection and store the data into a buffer rather
        than creating a new string.

        :param buffer: The buffer to copy into.
        :param nbytes: (optional) The maximum number of bytes to read into the
            buffer. If not present, defaults to the size of the buffer. If
            larger than the size of the buffer, is reduced to the size of the
            buffer.
        :param flags: (optional) The only supported flag is ``MSG_PEEK``,
            all other flags are ignored.
        :return: The number of bytes read into the buffer.
        """
        if nbytes is None:
            nbytes = len(buffer)
        else:
            nbytes = min(nbytes, len(buffer))

        # We need to create a temporary buffer. This is annoying, it would be
        # better if we could pass memoryviews straight into the SSL_read call,
        # but right now we can't. Revisit this if CFFI gets that ability.
        buf = _ffi.new("char[]", nbytes)
        if flags is not None and flags & socket.MSG_PEEK:
            result = _lib.SSL_peek(self._ssl, buf, nbytes)
        else:
            result = _lib.SSL_read(self._ssl, buf, nbytes)
        self._raise_ssl_error(self._ssl, result)

        # This strange line is all to avoid a memory copy. The buffer protocol
        # should allow us to assign a CFFI buffer to the LHS of this line, but
        # on CPython 3.3+ that segfaults. As a workaround, we can temporarily
        # wrap it in a memoryview, except on Python 2.6 which doesn't have a
        # memoryview type.
        try:
            buffer[:result] = memoryview(_ffi.buffer(buf, result))
        except NameError:
            buffer[:result] = _ffi.buffer(buf, result)

        return result