DBus 自省 XML 生成 Qt 代码
各种支持 DBus 的开发框架都能够通过 XML 自动生成代码，例如 Glib 的 gdbus-codegen 和 Qt 的 qdbusxml2cpp。
通过 DBus 对象 org.freedesktop.DBus.Introspectable 接口下的 Introspect 方法可以自省 XML，这样就不需要手写了。
但是 d-feet、dbus-send 等工具会给返回值加上类型标注或者换行符导致需要人工修改。因此需要自己写一个脚本来自省 DBus。
使用示例:
$ ./introspect.py -t system -n org.freedesktop.NetworkManager -p /org/freedesktop/NetworkManager
$ ./introspect.py -t system -n org.freedesktop.NetworkManager -p /org/freedesktop/NetworkManager/Devices/5
$ ls -1
introspect.py
org.freedesktop.NetworkManager.Device.Statistics.xml
org.freedesktop.NetworkManager.Device.WifiP2P.xml
org.freedesktop.NetworkManager.Device.xml
org.freedesktop.NetworkManager.xml
$ qdbusxml2cpp -c NetworkManager -p NetworkManager org.freedesktop.NetworkManager.xml --no-namespaces
$ qdbusxml2cpp -c Device -p Device org.freedesktop.NetworkManager.Device.xml --no-namespaces
$ qdbusxml2cpp -c WifiP2P -p WifiP2P org.freedesktop.NetworkManager.Device.WifiP2P.xml --no-namespaces
$ ls -1
Device.cpp
Device.h
introspect.py
NetworkManager.cpp
NetworkManager.h
org.freedesktop.NetworkManager.Device.Statistics.xml
org.freedesktop.NetworkManager.Device.WifiP2P.xml
org.freedesktop.NetworkManager.Device.xml
org.freedesktop.NetworkManager.xml
WifiP2P.cpp
WifiP2P.h
使用
--no-namespaces选项的原因是，qdbusxml2cpp会把 DBus Name 的最后一项作为类名，而之前项作为命名空间名 即org.freedesktop.NetworkManager生成::org::freedesktop::NetworkManager类。 而org.freedesktop.NetworkManager.Device生成的::org::freedesktop::NetworkManager::Device类。 这两者会发生冲突。前者的NetworkManager是类名，而后者的是命名空间明。
验证生成的代码:
#include <QDebug>
#include "NetworkManager.h"
#include "Device.h"
#include "WifiP2P.h"
int main(void)
{
NetworkManager networkManager{"org.freedesktop.NetworkManager", "/org/freedesktop/NetworkManager", QDBusConnection::systemBus()};
auto devicePathes = networkManager.devices();
for (auto& devicePath : devicePathes)
{
Device device("org.freedesktop.NetworkManager", devicePath.path(), QDBusConnection::systemBus());
qDebug() << "check wifi p2p device" << devicePath.path();
if (device.deviceType() == 30)
{
qDebug() << "found wifi p2p device" << devicePath.path();
break;
}
}
}
17:06:43: Starting /home/planc/miracast/build-wifi-p2p-unknown-Default/wifi-p2p...
check wifi p2p device "/org/freedesktop/NetworkManager/Devices/1"
check wifi p2p device "/org/freedesktop/NetworkManager/Devices/2"
check wifi p2p device "/org/freedesktop/NetworkManager/Devices/5"
found wifi p2p device "/org/freedesktop/NetworkManager/Devices/5"
17:06:43: /home/planc/miracast/build-wifi-p2p-unknown-Default/wifi-p2p exited with code 0
如果看不到日志打印可以参考 Qt 日志模块的使用 进行配置
#! /usr/bin/env python3
import dbus
from dbus.proxies import ProxyObject
import xml.dom.minidom as minidom
from typing import Callable, List, Set, Dict
from argparse import ArgumentParser, Namespace
# 不需要的 Interface
filter:Set[str] = {
"org.freedesktop.DBus.Introspectable",
"org.freedesktop.DBus.Peer",
"org.freedesktop.DBus.Properties",
}
class DBusTypeParser(object):
dbusQtContainerType:Dict[str,str] = {
"<array>": "QList",
"<struct>": "QVariant",
"<dict>": "QMap",
}
dbusQtType:Dict[str,str] = {
"y": "quint8",
"b": "bool",
"n": "qint16",
"q": "quint16",
"i": "qint32",
"u": "quint32",
"x": "qint64",
"t": "quint64",
"d": "double",
"h": "quint32",
"s": "QString",
"o": "QDBusObject",
"g": "QString",
"v": "QVariant",
}
def __init__(self) -> None:
# 状态
self.currentState:str = "<normal>"
self.stateStack:List[str] = []
# dict里的第几个参数
self.currentIndex:int = 0
self.indexStack:List[int] = []
def pushState(self, state:str) -> None:
if state == "<dict>":
self.pushIndex(self.currentIndex)
self.currentIndex = 0
self.stateStack.append(state)
def popState(self) -> str:
state:str = self.stateStack.pop()
if state == "<dict>":
self.currentIndex = self.popIndex()
return state
def pushIndex(self, index:int) -> None:
self.indexStack.append(index)
def popIndex(self) -> int:
return self.indexStack.pop()
def parse(self, signature:str) -> str:
self.currentState = "<normal>"
self.currentIndex = 0
qtype:str = ""
while len(signature) > 0:
ch:str = signature[0]
signature = signature[1:]
if ch in DBusTypeParser.dbusQtType:
if self.currentState == "<normal>":
qtype += self.parseNormal(ch)
elif self.currentState == "<struct>":
qtype += self.parseStruct(ch)
elif self.currentState == "<dict>":
qtype += self.parseDict(ch)
elif self.currentState == "<array>":
qtype += self.parseArray(ch)
elif ch == "a" and signature:
if self.currentState == "<dict>" and self.currentIndex == 0:
qtype += DBusTypeParser.dbusQtContainerType['<dict>'] + "<"
self.pushState(self.currentState)
self.currentState = "<array>"
elif ch == "(":
if self.currentState == "<dict>" and self.currentIndex == 0:
qtype += DBusTypeParser.dbusQtContainerType['<dict>'] + "<"
self.pushState(self.currentState)
self.currentState = "<struct>"
elif ch == "{":
# a{ 开启dict模式，之前为暂态的array模式，不push
self.currentState = "<dict>"
elif ch == ")":
qtype += self.parseStruct(ch)
if self.currentState == "<dict>" and self.currentIndex == 0:
qtype += ", "
self.currentIndex += 1
elif ch == "}":
self.currentState = self.popState()
qtype += self.parseDict(ch)
if self.currentState == "<dict>" and self.currentIndex == 0:
qtype += ", "
self.currentIndex += 1
else:
print(f"{ch}")
raise f"Unknown signature '{ch}'"
return qtype
def parseNormal(self, ch:str) -> str:
return DBusTypeParser.dbusQtType[ch]
def parseArray(self, ch:str) -> str:
self.currentState = self.popState()
return f"{DBusTypeParser.dbusQtContainerType['<array>']}<{DBusTypeParser.dbusQtType[ch]}>"
def parseStruct(self, ch:str) -> str:
if ch != ")":
return ""
self.currentState = self.popState()
if self.currentState == "<struct>":
return ""
if self.currentState == "<normal>":
return DBusTypeParser.dbusQtContainerType["<struct>"]
if self.currentState == "<dict>":
return DBusTypeParser.dbusQtContainerType["<struct>"]
if self.currentState == "<array>":
self.currentState = self.popState()
return f"{DBusTypeParser.dbusQtContainerType['<array>']}<{DBusTypeParser.dbusQtContainerType['<struct>']}>"
def parseDict(self, ch:str) -> str:
if ch == "}":
return ">"
self.currentIndex += 1
if self.currentIndex == 1:
return DBusTypeParser.dbusQtContainerType['<dict>'] + "<" + DBusTypeParser.dbusQtType[ch] + ", "
else:
return DBusTypeParser.dbusQtType[ch]
dbusTypeParser = DBusTypeParser()
parser:ArgumentParser = ArgumentParser(description='DBus Introspect XML')
parser.add_argument("-t", "--type", default="session", help="bus type, system or session")
parser.add_argument("-n", "--name", help="bus namae")
parser.add_argument("-p", "--path", help="object path")
args:Namespace = parser.parse_args()
bus:dbus.Bus = dbus.SystemBus() if args.type == "system" else dbus.SessionBus()
proxy:ProxyObject = bus.get_object(args.name, args.path)
xmlString:str = proxy.Introspect(dbus_interface='org.freedesktop.DBus.Introspectable')
root:minidom.Document = minidom.parseString(xmlString)
interfaces:List[minidom.Element] = root.getElementsByTagName("interface")
neededInterfaces:List[minidom.Element] = []
for interface in interfaces:
name:str = interface.getAttribute("name")
if name in filter:
continue
methods:List[minidom.Element] = interface.getElementsByTagName("method")
for method in methods:
inIndex:int = 0
outIndex:int = 0
methodArgs:List[minidom.Element] = method.getElementsByTagName("arg")
for arg in methodArgs:
sign:str = arg.getAttribute("type")
qtype:str = dbusTypeParser.parse(sign)
annotation:minidom.Element = root.createElement("annotation")
if arg.getAttribute("direction") == "in":
annotation.setAttribute("name", f"org.qtproject.QtDBus.QtTypeName.In{inIndex}")
inIndex += 1
if arg.getAttribute("direction") == "out":
annotation.setAttribute("name", f"org.qtproject.QtDBus.QtTypeName.Out{outIndex}")
outIndex += 1
annotation.setAttribute("value", qtype)
method.appendChild(annotation)
properties = interface.getElementsByTagName("property")
for property in properties:
sign:str = property.getAttribute("type")
qtype:str = dbusTypeParser.parse(sign)
annotation:minidom.Element = root.createElement("annotation")
annotation.setAttribute("name", "org.qtproject.QtDBus.QtTypeName")
annotation.setAttribute("value", qtype)
property.appendChild(annotation)
neededInterfaces.append(interface)
for interface in neededInterfaces:
with open(interface.getAttribute("name") + ".xml", "w") as fp:
fp.write(interface.toprettyxml())