tools: ynl: allow setting recv() size

    return f"Netlink error: {os.strerror(-self.nl_msg.error)}\n{self.nl_msg}"

class ConfigError(Exception):

    pass

class NlAttr:

    ScalarFormat = namedtuple('ScalarFormat', ['native', 'big', 'little'])

    type_formats = {

class YnlFamily(SpecFamily):

    def __init__(self, def_path, schema=None, process_unknown=False):

    def __init__(self, def_path, schema=None, process_unknown=False,

                 recv_size=0):

        super().__init__(def_path, schema)

        self.include_raw = False

        except KeyError:

            raise Exception(f"Family '{self.yaml['name']}' not supported by the kernel")

        # Note that netlink will use conservative (min) message size for

        # the first dump recv() on the socket, our setting will only matter

        # from the second recv() on.

        self._recv_size = recv_size if recv_size else 131072

        # Netlink will always allocate at least PAGE_SIZE - sizeof(skb_shinfo)

        # for a message, so smaller receive sizes will lead to truncation.

        # Note that the min size for other families may be larger than 4k!

        if self._recv_size < 4000:

            raise ConfigError()

        self.sock = socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, self.nlproto.proto_num)

        self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)

        self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_EXT_ACK, 1)

    def check_ntf(self):

        while True:

            try:

                reply = self.sock.recv(128 * 1024, socket.MSG_DONTWAIT)

                reply = self.sock.recv(self._recv_size, socket.MSG_DONTWAIT)

            except BlockingIOError:

                return

        done = False

        rsp = []

        while not done:

            reply = self.sock.recv(128 * 1024)

            reply = self.sock.recv(self._recv_size)

            nms = NlMsgs(reply, attr_space=op.attr_set)

            for nl_msg in nms:

                if nl_msg.extack: