obmc/dbuslib/introspection.py

# Contributors Listed Below - COPYRIGHT 2016
# [+] International Business Machines Corp.
#
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied. See the License for the specific language governing
# permissions and limitations under the License.

import xml.etree.ElementTree as ET
import dbus


class IntrospectionNodeParser:
    def __init__(self, data, tag_match=bool, intf_match=bool):
        self.data = data
        self.cache = {}
        self.tag_match = tag_match
        self.intf_match = intf_match

    def parse_args(self):
        return [x.attrib for x in self.data.findall('arg')]

    def parse_children(self):
        return [x.attrib['name'] for x in self.data.findall('node')]

    def parse_method_or_signal(self):
        name = self.data.attrib['name']
        return name, self.parse_args()

    def parse_interface(self):
        iface = {}
        iface['method'] = {}
        iface['signal'] = {}

        for node in self.data:
            if node.tag not in ['method', 'signal']:
                continue
            if not self.tag_match(node.tag):
                continue
            p = IntrospectionNodeParser(
                node, self.tag_match, self.intf_match)
            n, element = p.parse_method_or_signal()
            iface[node.tag][n] = element

        return iface

    def parse_node(self):
        if self.cache:
            return self.cache

        self.cache['interfaces'] = {}
        self.cache['children'] = []

        for node in self.data:
            if node.tag == 'interface':
                p = IntrospectionNodeParser(
                    node, self.tag_match, self.intf_match)
                name = p.data.attrib['name']
                if not self.intf_match(name):
                    continue
                self.cache['interfaces'][name] = p.parse_interface()
            elif node.tag == 'node':
                self.cache['children'] = self.parse_children()

        return self.cache

    def get_interfaces(self):
        return self.parse_node()['interfaces']

    def get_children(self):
        return self.parse_node()['children']

    def recursive_binding(self):
        return any('/' in s for s in self.get_children())


class IntrospectionParser:
    def __init__(self, name, bus, tag_match=bool, intf_match=bool):
        self.name = name
        self.bus = bus
        self.tag_match = tag_match
        self.intf_match = intf_match

    def _introspect(self, path):
        try:
            obj = self.bus.get_object(self.name, path, introspect=False)
            iface = dbus.Interface(obj, dbus.INTROSPECTABLE_IFACE)
            data = iface.Introspect()
        except dbus.DBusException:
            return None

        return IntrospectionNodeParser(
            ET.fromstring(data),
            self.tag_match,
            self.intf_match)

    def _discover_flat(self, path, parser):
        items = {}
        interfaces = list(parser.get_interfaces().keys())
        if interfaces:
            items[path] = {}
            items[path]['interfaces'] = interfaces

        return items

    def introspect(self, path='/', parser=None):
        items = {}
        if not parser:
            parser = self._introspect(path)
        if not parser:
            return {}
        items.update(self._discover_flat(path, parser))

        if path != '/':
            path += '/'

        if parser.recursive_binding():
            callback = self._discover_flat
        else:
            callback = self.introspect

        for k in parser.get_children():
            parser = self._introspect(path + k)
            if not parser:
                continue
            items.update(callback(path + k, parser))

        return items