使用python從dbus獲取'state'

Question

我想在python中做一個非常簡單的事情-通過dbus從firewalld讀取狀態-“ org.freedesktop.DBus.Properties”。

根據https://firewalld.org/documentation/man-pages/firewalld.dbus.html

state - s - (ro)
firewalld state. This can be either INIT or RUNNING. In INIT state, firewalld is starting up and initializing.

我找到了如何使用linux的dbus-send來做到這一點，但是我只是無法在python中實現它。

這是最接近我的問題的答案，但我仍然無法弄清楚。 [ dbus_to_python（）正好接受1個參數？

Here's how to do it in shell:
firewall-cmd --state
running 

And with dbus-send:
dbus-send --system --print-reply --dest=org.fedoraproject.FirewallD1 /org/fedoraproject/FirewallD1 org.freedesktop.DBus.Properties.Get string:"org.fedoraproject.FirewallD1" string:"state"
method return time=1563593597.133270 sender=:1.2 -> destination=:1.116 serial=691 reply_serial=2
   variant       string "RUNNING"

# Here's my incorrect code:
import dbus
Bus = dbus.SystemBus()
Proxy = Bus.get_object('org.fedoraproject.FirewallD1', '/org/fedoraproject/FirewallD1')
Proxy.Get('state', dbus_interface='org.freedesktop.DBus.Properties')

這是我從python得到的錯誤消息：

ERROR:dbus.connection:Unable to set arguments ('state',) according to signature 'ss': <class 'TypeError'>: More items found in D-Bus signature than in Python arguments
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 70, in __call__
    return self._proxy_method(*args, **keywords)
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 145, in __call__
    **keywords)
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 641, in call_blocking
    message.append(signature=signature, *args)
TypeError: More items found in D-Bus signature than in Python arguments
>>> 

Answer 1

解決方法如下：

Proxy.Get('org.fedoraproject.FirewallD1', 'state', dbus_interface='org.freedesktop.DBus.Properties')

Answer 2

問題是org.freedesktop.DBus.Properties接口的Get方法實際上接受兩個參數，該接口用於訪問的屬性和該屬性的名稱：

org.freedesktop.DBus.Properties.Get (in STRING interface_name,
                                     in STRING property_name,
                                     out VARIANT value);

來自https://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-properties

import dbus
Bus = dbus.SystemBus()
Proxy = Bus.get_object('org.fedoraproject.FirewallD1', '/org/fedoraproject/FirewallD1')
Proxy.Get('org.fedoraproject.FirewallD1', 'state', dbus_interface='org.freedesktop.DBus.Properties')

由於沒有特定的DBus服務或對象，因此使用了不同的常量進行了測試。