xdg-screensaver doesn't lock screen with light-locker

[Paul Battley]

When a screen-locking method is available, 'xdg-screensaver lock' should always lock the screen.

Steps to reproduce:

On a fresh installation of Lubuntu 14.04, run:

$ xdg-screensaver lock

Expected:
[screen locks]

Actual:
ERROR: Unknown command 'lock'

However, it is possible to lock the screen via:

$ light-locker-command -l

The xdg-screensaver script uses one of several external utilities, depending on the desktop environment. It falls through to screensaver_xserver() at line 697 (or 740, because the function is duplicated!), which does not include a lock function, even though one is available.

This is a problem because xfce4-power-manager (part of lubuntu-desktop) uses xdg-screensaver to lock the screen on suspend under Lubuntu, but this has no effect. This may represent a security risk as a computer configured to (and reasonably assumed to) lock on suspend will actually resume straight to the desktop.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: xdg-utils 1.1.0~rc1-2ubuntu7.1
ProcVersionSignature: Ubuntu 3.13.0-35.62-generic 3.13.11.6
Uname: Linux 3.13.0-35-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.3
Architecture: amd64
CurrentDesktop: LXDE
Date: Fri Sep 5 18:55:04 2014
InstallationDate: Installed on 2014-08-31 (5 days ago)
InstallationMedia: Lubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
PackageArchitecture: all
SourcePackage: xdg-utils
UpgradeStatus: No upgrade log present (probably fresh install)

[Thaddaeus Tintenfisch (thad-fisch-deactivatedaccount)]

Starting with version 1.5.0 and up, light-locker can be controlled via org.freedesktop.ScreenSaver DBus calls. This makes it compatible with xdg-screensaver.

https://github.com/the-cavalry/light-locker/commit/dfcfc9834241225c4bd9fccc9a77714a183b805c

[Paul Battley (pbattley)]

The current revision of xdg-screensaver (22) only uses org.freedesktop.ScreenSaver DBus calls if the desktop environment is KDE.

[Simon Steinbeiß (ochosi)]

@pbattley: Indeed, which is why xdg-screensaver will have to be patched for light-locker as soon as version 1.5.x is in the repositories.

[Simon Steinbeiß (ochosi)]

This bug has been adressed upstream meanwhile and will land as part of the 1.5 or 1.6 series of light-locker: https://github.com/the-cavalry/light-locker/commit/cbddddff9bd5e5a3d16f7208f259934b097c4b06