Created attachment 1608124 [details]
patch

Changes in Python 3.8 implementation of __str__ method for object class cause lvmdbusd to produce invalid lvm commands.

Error example:

Failed to call the 'LvCreate' method on the '/com/redhat/lvmdbus1/Vg/0' object: GDBus.Error:org.freedesktop.DBus.Python.dbus.exceptions.DBusException: ('com.redhat.lvmdbus1.Vg', 'Exit code 3, stderr =   Invalid argument for --stripes: dbus.Int32(2, variant_level=1)\n  Error during parsing of command line.\n')

The problem is with converting dbus.UInt types to string lvmdbusd:

On Python 3.8:

>>> str(dbus.Int64(1))
'dbus.Int64(1)'

On Python 3.7 (and older):
>>> str(dbus.UInt64(1))
'1'

I have created a simple patch to fix this, it fixes errors discovered by libblockdev test suite.

This might be something that should be fixed in python-dbus, but I also think that lvmdbusd shouldn't rely on dbus __str__ functions to produce a valid string and explicitly converting dbus.UInt types to integer first is a safer solution.

LVM version:

  LVM version:     2.03.05(2) (2019-06-15)
  Library version: 1.02.163 (2019-06-15)
  Driver version:  4.40.0