Debugging dbus communication

[László Monda]

Hi List,

I'm on the quest of tracing a longstanding bug that involves dbus.

I use the following script to lock my screen upon leaving my laptop:

#!/bin/bash
gnome-screensaver-command -l
sleep 1
xset dpms force off

The problem is that after a random amount of time screen backlight
gets enabled for some reason without me touching the keyboard or
moving the mouse.  Based on what I read and experienced there are
certain dbus messages that trigger this bug, such as wifi or HDD SMART
dbus messages.

Let me show you such an example:

2013-05-04 18:17:00  signal sender=:1.85 -> dest=(null destination)
serial=158 path=/org/freedesktop/UDisks/devices/sda;
interface=org.freedesktop.UDisks.Device; member=Changed
2013-05-04 18:17:00  signal sender=:1.85 -> dest=(null destination)
serial=159 path=/org/freedesktop/UDisks;
interface=org.freedesktop.UDisks; member=DeviceChanged
2013-05-04 18:17:00     object path "/org/freedesktop/UDisks/devices/sda"
2013-05-04 18:17:00  signal sender=:1.85 -> dest=(null destination)
serial=160 path=/org/freedesktop/UDisks/devices/sdb;
interface=org.freedesktop.UDisks.Device; member=Changed
2013-05-04 18:17:00  signal sender=:1.85 -> dest=(null destination)
serial=161 path=/org/freedesktop/UDisks;
interface=org.freedesktop.UDisks; member=DeviceChanged
2013-05-04 18:17:00     object path "/org/freedesktop/UDisks/devices/sdb"
2013-05-04 18:20:03  signal sender=:1.59 -> dest=(null destination)
serial=148 path=/org/freedesktop/UDisks2/drives/INTEL_SSDSA2M080G2GC_CVPO01140280080JGN;
interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
2013-05-04 18:20:03     string "org.freedesktop.UDisks2.Drive.Ata"
2013-05-04 18:20:03     array [
2013-05-04 18:20:03        dict entry(
2013-05-04 18:20:03           string "SmartUpdated"
2013-05-04 18:20:03           variant             uint64 1367684403
2013-05-04 18:20:03        )
2013-05-04 18:20:03     ]
2013-05-04 18:20:03     array [
2013-05-04 18:20:03     ]
2013-05-04 18:20:03  signal sender=:1.59 -> dest=(null destination)
serial=149 path=/org/freedesktop/UDisks2/drives/WDC_WD5000BEVT_22ZAT0_WD_WXE0A89R3145;
interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
2013-05-04 18:20:03     string "org.freedesktop.UDisks2.Drive.Ata"
2013-05-04 18:20:03     array [
2013-05-04 18:20:03        dict entry(
2013-05-04 18:20:03           string "SmartPowerOnSeconds"
2013-05-04 18:20:03           variant             uint64 62006400
2013-05-04 18:20:03        )
2013-05-04 18:20:03        dict entry(
2013-05-04 18:20:03           string "SmartUpdated"
2013-05-04 18:20:03           variant             uint64 1367684403
2013-05-04 18:20:03        )
2013-05-04 18:20:03     ]
2013-05-04 18:20:03     array [
2013-05-04 18:20:03     ]

Basically I'd like to be able to list the subscribers of such
messages.  How is this possible?

Thanks in advance.

--
László Monda <http://monda.hu>