Xubuntu lightdm: Wrong wallpaper at login screen.

[Kenneth Wrede]

This bug is about the background image/wallpaper in xubuntu's lightdm. The login screen.

The wallpaper is supposed to be the same as the wallpaper for the marked user. If I higlight my name, it should show my wallpaper, and if I highlight my brothers namne, it should change to his wallpaper.

But it doesn't. It is stuck with the wallpaper I had when I uppgraded from saucy to trusty. No user have that wallpaper today, but it still shows up at the login page.

1 Using Xubuntu Trusty, uppgraded from Saucy. (Saucy was a clean install.)
2 lightdm version 1.9.8-0ubuntu1

[Later edit = spelling corrections. English is not my native.]

[Sebastien Bacher (seb128)]

Thank you for your bug report, xubuntu isn't using the unity-greeter but the gtk one, which doesn't feature changing wallpaper with the user. How did you change you wallpaper image?

[Kenneth Wrede (kennethwrede)]

I don't know what greeter it is using, or have been using.

But I do know that saucy is showing the users wallpaper. (Well, maybee wallpaper of the last one who have been loged in?) One of the more elegant changes since Precis.

AÍ also know that I'm stuck with the old wallpaper, wich was the correct one then. It just doesn't seem to update it.

How I changed the wallpaper image? I right-clicked on the desktop and choosed desktop settings. And from there another picture of my liking. (We are jsut talking jpg-pictures, if it matters.) No funny hacking of the system files so far.

[Sebastien Bacher (seb128)]

could you take a photo of your login screen so we are sure we are talking about the same greeter?

some data points:

- whatever you use to set your user background needs to write its config in accountsservice (the service the greeter uses), nautilus and gnome-control-center do it in Unity, not sure if xfce does it

- the image you set must be readable by other users, otherwise the greeter can't access it (e.g the directory where it's storing needs to be world readable), that's bug #928553

[Kenneth Wrede (kennethwrede)]

Sebastian: Picture of login screen attached!

I have done some more research.
1) It does not affect newly created accounts. (Created today.)
2) Of the two older accounts, I can only try with my own. Missing the password for the other one.

I tried again, and I was not mistaken. Xubuntu does change wallpaper in lightdm when another user is highlighted, whatever greeter it might be. (Wasn't that change made between quantal and raring?)

In both cases of my and the new account, all pictures as in jpg-format and saved in the accounts homefolders. I havn't been bothering about the reading rights, and have therefore not been activly changing them eigther. They are all downloaded with FF from google image search.

lightdm doesn't look the after the upgrade to trusty. Did any config-files change as well? Or does the update script mess around with reading rights as well? I guess the explanaition/solotion is somewere here.

[Sebastien Bacher (seb128)]

thanks for the screenshot, that's indeed no unity-greeter, I didn't know the gtk greeter had that feature

if you connect with another user, can you access the background from your normal user? it might be that /home/<user> has different permission for that old user? can you "ls -ld /home/$USER" (same on the directory including the backgroud image)

[Kenneth Wrede (kennethwrede)]

If use my own user can browse everyones files! (Ugh! Shouldn't that be impossible by default of security reasons?)

If I browse with a new user, I can read some of my own files, others are locked. But all pictures in my wallpapers filder could be read. /home/username/Pictures/1920x1080 Benq/*.jpg

I can not say why some files are avilable and others are not. I have not changed any permissions on purpose what so ever. (Beliving it stayed private as long I didn't put it in the 'public' folder.) I might be files that have been changed since upgrade to trusty?

Just a thougt!
I have no idea how the greeters works. But would it not be possible and easy to keep copies of all active wallpapers somewhere else in the system, and then use them as the actual ones? (in /var?) Then anyone can use any picture, and they can always be read by other users and the system services? Then we don't need to bother about reading rights in oters users home folders.

[Gunnar Hjalmarsson (gunnarhj)]

lightdm-gtk-greeter does query accountsservice for the background property, but I don't think it tries with /home.

@Kenneth:
You may want to check

/var/lib/AccountsService/users/[username]

For the greeter to know which wallpaper to pick, respective user config file needs to include the Background property with the path to the image. Probably you won't wind any Background setting for the users where it does not work.

An idea is to use whatever tool you use for creating and modifying users and change the background to something else and then back to the desired background. That way the accountsservice settings might be properly updated.

[Kenneth Wrede (kennethwrede)]

Gunnar

I'm checking here as requested: /var/lib/AccountsService/users/[username]

I do find a file for every account that have been used. Inside them I find similar information, and a path to the wallpaper that is showing up at login. My file is pointing to the old wallpaper. And if I change the wallpaper again, tha path doesn't change at all. (The path contains spaces, but it should probably not matter. It didn't matter in saucy.)

I don't have have any special tool for the user accounts, except the one that is included with the controll panel. (Don't know package name.) And can't do such detaild changes from it.

[Gunnar Hjalmarsson (gunnarhj)]

As Sebastien stated above: "whatever you use to set your user background needs to write its config in accountsservice (the service the greeter uses)"

Sounds like the program you use does not tell accountsservice about the changes.

As a workaround for now you can simply edit the files in /var/lib/AccountsService/users manually.

[Kenneth Wrede (kennethwrede)]

Seems like Gunnar is right. The greeter does read the files correctly. It is just not updated proparly.

I think it is time to se if it is reproducable on another machine. If nobody is doing it before me, I can probably manage in a few days. I'm in a lack of time. The steps should be.

1) Install a clean xubuntu saucy 64-bit. (Don't know if arch matters. Probably not.) When asked questions, always choose default when possible,
2) The installer creates a user. Login and download 2 new wallpapers and save them somwhere in you home folder.
3) Set one of the new wallpapers the recomended way. (Leftclick on desktop, choose desktop settings, locate de folder with the files. Pick one.)
4) Check! Log out and in again to see if it works. The wallpaper in your session and lightdm shall be the same. Reboot if nessecary.
5) Update it with security and recomended enabled.

6) In terminal, run "sudo update-manager -d". It will tell you that the system is updated but a new version is avaliable.
7) Update to Trusty. Choose default if asked anything.

8) The login screen have a new design with your wallpaper as a background. Login and change it to the other you downloaded in step 2.
9) Logout/reboot.
10) You should now be stuck with the old wallpaper at the login screen. The new one will show up in session. No matter how you are trying to change it.

[Thaddaeus Tintenfisch (thad-fisch-deactivatedaccount)]

xfdesktop draws the user desktop in the actual session and comes with accountsservice support (custom patch for Xubuntu).

However, the patch was updated and re-added just recently. Is your system up-to-date? What does "apt-cache policy xfdesktop4" return?

[Kenneth Wrede (kennethwrede)]

It was uppdated when I opened this report, and since then I have updated once. But I'm using a mirror, so it depends on it.

I can change to main server if it helps?

xfdesktop4:
  Installed: 4.11.3-2ubuntu1
  Candidate: 4.11.3-2ubuntu1
  Version table:
 *** 4.11.3-2ubuntu1 0
        500 http://ubuntu.trumpetti.atm.tut.fi/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status

[Thaddaeus Tintenfisch (thad-fisch-deactivatedaccount)]

The latest version is installed. According to your comments, new user accounts are not affected by this problem, correct?

[Kenneth Wrede (kennethwrede)]

Thaddäus:

"new user accounts are not affected by this problem, correct?"

That's correct!

And I can only try with one old account on one machine. If nobody else have done it first, I will try to reproduce it on a new install in virtualbox. I will publish the results here whatever they are. But it might take some days before I can take time for it.

I have not messed with the settings or have been using any special tools. But there is still no guarantee that it is not my particular install that is messy. Especially as trusty still was a late alfa when I upgraded. We can't trust such systems. :)

[Alistair Buxton (a-j-buxton)]

Could you try to run lightdm in test mode:

lightdm --test-mode --debug

For me, this will show the right wallpaper, but the real login session won't. That makes me suspect the problem is not in xfdesktop.

[Alistair Buxton (a-j-buxton)]

You probably need to install xserver-xephyr to make test mode work.

[Kenneth Wrede (kennethwrede)]

Alistair

I tried your test and debug mode. It also showed the wrong wallpaper.

(But before I try that again, I need to know how to get rid of the window. It did not accept to be closed and a shutdown killed far more then the window itself... *lol* )

[Kenneth Wrede (kennethwrede)]

I need some help by someone clever.

I've installed saucy in virtualbox (ubuntu version) and updated it to trusty. But the resolution of the screen then went so smal that I can't fit the nettings diaolg that I need. It is just 640x480. Useless!

I installed the additions, but it didn't help. Suggestions?

[Kenneth Wrede (kennethwrede)]

Ok, I solved the problem with Virtualbox and could complete the test according to comment #10

I'm happy to tell that is was NOT reproducable, in that way anyway. That must mean that it is my system that is broken, not the xfce or lightdm components. And of there where problems with the packages I installed during the upgrade, they seems to have been patched already.

I will thank you for taking your time.

[Kenneth Wrede (kennethwrede)]

The bug seems only to appear on one particular system. Probably broken by unknown reason.

[Yanpas (yanpaso)]

Met with this bug just right now. Xubuntu stopped (after reinstalling lightdm and lightdm gtk greeter) to update icon. I was manually to edit /var/lib/AccountsService/users/[username]

[Yanpas (yanpaso)]

update background*

[Yanpas (yanpaso)]

Sorry, invalid.
I was using xfdesktop from git, which is not patched with accountsservice (accounts-daemon), so my background wan't changing