[lubuntu-devel] Fwd: xfce4-power-manager BUG + possible FIX

[Simon Quigley]

This message appeared and it affects Lubuntu, so I'm forwarding it here.


-------- Forwarded Message --------
Subject: xfce4-power-manager BUG + possible FIX
Date: Sat, 23 Jul 2016 02:17:33 +0200
From: Bernd <s1237382 at gmail.com>
To: ubuntu-devel-discuss at lists.ubuntu.com
CC: pkg-xfce-devel at lists.alioth.debian.org

Dear maintainer(s),

first time I try to give some feedback, so please don't feel offended,
or even beat me, if this is not the right place to report.


PACKAGE
=======
Package: xfce4-power-manager
Version: 1.4.4-4ubuntu2


PROBLEM DESCRIPTION
===================
Running xfce4-power-manager on a lubuntu 16.04 system using a laptop
running on battery I kept receiving the following notification
'GDBus.Error:org.freedesktop.DBus.Error.AccessDenied:Permission denied'

Investigating further it turned out, there was a discrepancy between
'xfce4-power-manger-settings' GUI reporting the sleep mode on battery to
be "Suspend" and 'dbus-monitor --system' reporting the real action
taking place to be an attempt to go into "Hibernate" mode (relevant part
cited below), which in turn is disabled via polkit-1 on my system.

---
method call time=1469228622.268937 sender=:1.62 ->
destination=org.freedesktop.login1 serial=25
path=/org/freedesktop/login1; interface=org.freedesktop.login1.Manager;
member=Hibernate
   boolean true
---


STEPS TO REPRODUCE
==================
1. reset/remove xfce-power-manager.xml configuration
2. disable action "org.freedesktop.login1.hibernate" via polkit-1
3. unplug laptop from power source
4. keep doing nothing for 15 minutes


INVESTIGATION
=============
Digging the sources I found the problem to be split between
src/xfpm-xfconf.c:489 setting the default value of the property
"inactivity-sleep-mode-on-battery" to XFP_DO_HIBERNATE and
'xfpm_settings_on_battery()' in settings/xfpm-settings.c:863 narrowing
down possible ComboBox options down to those actually supported by
system policy.

Given an empty/default xfce4-power-manager.xml configuration and via
system policy disabled hibernate this leads to the funny fact that
'xfce4-power-manager-settings' GUI will not only wrongly "report" the
selected sleep mode to be "Suspend".
But even worse never never never ever allow the user to really switch
sleep mode on battery to "Suspend", as to fire the necessary callback it
would be necessary to actually change the ComboBox selection, which
given a single choice is impossible.

I managed to circumvent the problem manually adding: <property
name="inactivity-sleep-mode-on-battery" type="uint" value="1"/> to the
configuration file, but probably this might not be the most obvious i.e.
user friendly way to handle such situations.


SUGGESTED FIX
=============
To handle scenarios like the one described with either "Suspend",
"Hibernate", or even both unavailable imho it wouldn't be too painful to
allow XFPM_DO_NOTHING as another option for both properties
"inactivity-sleep-mode-on-battery" and "inactivity-sleep-mode-on-ac".

This would not only allow to select either "Suspend" or "Hibernate" even
if the other one isn't available still firing the necessary callback in
'xfce4-power-manager-settings', but also allow to still show a
meaningful value in the GUI in case both of them are unavailable.

I put a patch just doing this in the attachment.


BTW
===
imho lowering the "magic" never timeout value from 14 to 0 and allowing
a range starting from 0 wouldn't be to painful, especially for testing
purposes. :) I know it is already possible to use lower values manually
hacking the config file, but again probably this is not the most obvious
and user-friendly way.


Best regards
  Bernd.


-- 
Bernd <s1237382 at gmail.com>



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