[SRU] REGRESSION: ubuntustudio-default-settings 22.04.26.1 breaks Ubuntu Studio login

[Bill Miller]

[ Impact ]

 * The update to ubuntustudio-default-settings 22.04.26.1 caused an unforeseen regression in which the SDDM theme failes reproducibly. This is due to the replacement of a symlink of Main.qml in the SDDM theme that should point to the Breeze SDDM theme no longer existing and being replaced by a physical file when it should not have been.

 * It is notable that this did *not* show up in the debdiff of the upload [1], nor does it show up anywhere in the git history. This does seem like a strange anomaly, to which the cause is unknown.

 * To resolve, a new version of this is uploaded and needs expedited approval to fix this regression.

[ Test Case ]

 * Install Ubuntu Studio 22.04

 * Completely upgrade

 * Restart

 * SDDM theme will be broken

[ Where things could go wrong ]

 * At this point, I have little faith in the .debdiff to show if the symlinks have been replaced with physical files, so I suppose this could happen. However, I have checked the source tarball prior to upload to make sure, and all 0kb symlinks seem to be in-place.

[ Other Information ]

[1] https://launchpadlibrarian.net/623379853/ubuntustudio-default-settings_22.04.26_22.04.26.1.diff.gz

====
Original bug report:

Steps to reproduce

1) Install Ubuntu Studio 22.04. Completely default install (whole disk, etc)
2) Boot into new install
3) Install all updates and reboot
You get an unfamiliar looking login screen and an error message "The current theme cannot be loaded due to the errors below, please select another theme"
file:///usr/share/sddm/themes/ubuntu-theme/Main.qml:204:17: Cannot assign to non-existent property "actionItemsVisible"

Through process of elimination, determined that of the 345 packages installed in step 3, ubuntustudio-default-settings causes the problem.

See also https://askubuntu.com/questions/1450991/sddm-error-cannot-assign-to-non-existent-property-actionitemsvisible

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: ubuntustudio-default-settings 22.04.26.1
ProcVersionSignature: Ubuntu 5.15.0-58.64-lowlatency 5.15.74
Uname: Linux 5.15.0-58-lowlatency x86_64
ApportVersion: 2.20.11-0ubuntu82.3
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
Date: Thu Jan 19 18:18:16 2023
InstallationDate: Installed on 2023-01-19 (0 days ago)
InstallationMedia: Ubuntu-Studio 22.04.1 LTS "Jammy Jellyfish" - Release amd64 (20220809)
PackageArchitecture: all
SourcePackage: ubuntustudio-default-settings
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Aaron Rainbolt (arraybolt3)]

Pretty sure this has been affecting me lately, I assumed that something went wrong with my upgrade and it would fix itself, but I'm guessing not.

[Erich Eickmeyer (eeickmeyer)]

/usr/share/sddm/themes/ubuntustudo/Main.qml is merely a symlink to /usr/share/sddm/themes/breeze/Main.qml, which comes from the sddm-theme-breeze, whose source package is plasma-workspace. This means this is not a bug with ubuntustudio-default-settings, but rather a bug with plasma-workspace.

[Rik Mills (rikmills)]

> /usr/share/sddm/themes/ubuntustudo/Main.qml is merely a symlink to /usr/share/sddm/themes/breeze/Main.qml

No it is not. It is a real file shipped in ubuntustudio-default-settings 22.04.26.1

[Ross Gammon (rosco2)]

Yes - this is also affecting me. Ubuntu Studio 22.04.

The error is about a file in ubuntu-theme, not ubuntustudio:
rossg@ross-ixtremem5120:/usr/share/sddm/themes/ubuntu-theme$ ls -la
totalt 240
drwxr-xr-x 3 root root 4096 jan 14 12:52 .
drwxr-xr-x 7 root root 4096 jan 11 2022 ..
lrwxrwxrwx 1 root root 24 jul 9 2022 Background.qml -> ../breeze/Background.qml
lrwxrwxrwx 1 root root 29 jul 9 2022 BreezeMenuStyle.qml -> ../breeze/BreezeMenuStyle.qml
drwxr-xr-x 3 root root 4096 jan 14 12:52 components
-rw-r--r-- 1 root root 4876 mar 19 2022 default-logo.svg
lrwxrwxrwx 1 root root 15 sep 22 2020 faces -> ../breeze/faces
lrwxrwxrwx 1 root root 28 jul 9 2022 KeyboardButton.qml -> ../breeze/KeyboardButton.qml
lrwxrwxrwx 1 root root 19 jul 9 2022 Login.qml -> ../breeze/Login.qml
-rw-r--r-- 1 root root 23070 jul 9 2022 Main.qml
-rw-r--r-- 1 root root 388 mar 19 2022 metadata.desktop
-rw-r--r-- 1 root root 189788 jul 9 2022 preview.png
lrwxrwxrwx 1 root root 27 jul 9 2022 SessionButton.qml -> ../breeze/SessionButton.qml
-rw-r--r-- 1 root root 218 mar 19 2022 theme.conf

According to dpkg, this file does not exist:
rossg@ross-ixtremem5120:/usr/share/sddm/themes/ubuntu-theme$ dpkg -S usr/share/sddm/themes/ubuntu-theme/Main.qml
dpkg-query: ingen pakker fundet der matcher mønster *usr/share/sddm/themes/ubuntu-theme/Main.qml*

This is a bug, so I will change the status back to "new". But we need to find the right package to asign it to.

[Ross Gammon (rosco2)]

Eric & Rik seem to be referring to the wrong file. I am seeing the same issue, but it is usr/share/sddm/themes/ubuntu-theme/Main.qml that is the problem file.

At some point I had changed from the default UbuntuStudio themes (for the first time ever), because I could not login due to the sddm screen being mostly blank, and some applications being totally unusable.

rossg@ross-ixtremem5120:/usr/share/sddm/themes/ubuntu-theme$ ls -la
totalt 240
drwxr-xr-x 3 root root 4096 jan 14 12:52 .
drwxr-xr-x 7 root root 4096 jan 11 2022 ..
lrwxrwxrwx 1 root root 24 jul 9 2022 Background.qml -> ../breeze/Background.qml
lrwxrwxrwx 1 root root 29 jul 9 2022 BreezeMenuStyle.qml -> ../breeze/BreezeMenuStyle.qml
drwxr-xr-x 3 root root 4096 jan 14 12:52 components
-rw-r--r-- 1 root root 4876 mar 19 2022 default-logo.svg
lrwxrwxrwx 1 root root 15 sep 22 2020 faces -> ../breeze/faces
lrwxrwxrwx 1 root root 28 jul 9 2022 KeyboardButton.qml -> ../breeze/KeyboardButton.qml
lrwxrwxrwx 1 root root 19 jul 9 2022 Login.qml -> ../breeze/Login.qml
-rw-r--r-- 1 root root 23070 jul 9 2022 Main.qml
-rw-r--r-- 1 root root 388 mar 19 2022 metadata.desktop
-rw-r--r-- 1 root root 189788 jul 9 2022 preview.png
lrwxrwxrwx 1 root root 27 jul 9 2022 SessionButton.qml -> ../breeze/SessionButton.qml
-rw-r--r-- 1 root root 218 mar 19 2022 theme.conf

rossg@ross-ixtremem5120:/usr/share/sddm/themes/ubuntu-theme$ dpkg -S usr/share/sddm/themes/ubuntu-theme/Main.qml
dpkg-query: ingen pakker fundet der matcher mønster *usr/share/sddm/themes/ubuntu-theme/Main.qml*

Hmmm. How else can I find out who owns this file?

[Ross Gammon (rosco2)]

This is a bug, so I am changing it to "new" from "invalid". I agree we need to find the right package though.

[Ross Gammon (rosco2)]

rossg@ross-ixtremem5120:/usr/share/sddm/themes/ubuntu-theme$ apt-file search /usr/share/sddm/themes/ubuntu-theme/Main.qml
rossg@ross-ixtremem5120:/usr/share/sddm/themes/ubuntu-theme$

[Rik Mills (rikmills)]

/usr/share/sddm/themes/ubuntu-theme/ is a symlink set up by 'alternatives' system by sddm package install scripts

On all flavours that use sddm it links as: ubuntu-theme -> /etc/alternatives/sddm-ubuntu-theme/

Each flavour with its sddm theme config then makes /etc/alternatives/sddm-ubuntu-theme/ point to their sddm theme folder.

So on studio that points to /usr/share/sddm/themes/ubuntustudo/

That means that the file /usr/share/sddm/themes/ubuntu-theme/Main.qml in question is actually physically on disk the real file /usr/share/sddm/themes/ubuntustudo/Main.qml which is shipped in ubuntustudio-default-settings package.

Hope that clears things up.

[Ross Gammon (rosco2)]

Thanks Rik.

For those that would like a work-around. In the SDDM Theme chooser (from the menu), choose any of the Materia and Breeze themes, and they are fine.

[Erich Eickmeyer (eeickmeyer)]

Hi Ross and Rik,

Aaron and I discussed this extensively on IRC. Yes, we did determine that Main.qml is a physical file on disk, but it should not have been, and we don't know why. Per the debdiff [1] it should not have been, and per the git history, it never has been more than a symlink in the branch. In fact, if you look at the source at the tag for 22.04.26.1, it is still a symlink [2].

I have found the source of the problem though. It seems as though during my upload, that file did, in fact, sneak in [3], but why it didn't show up in the debdiff, I'll never know. Either way, this will be triggering the regression process of the original SRU in LP: #1965439.

[1] https://launchpadlibrarian.net/623379853/ubuntustudio-default-settings_22.04.26_22.04.26.1.diff.gz
[2] https://git.launchpad.net/ubuntustudio-default-settings/tree/usr/share/sddm/themes/ubuntustudio/Main.qml?h=ubuntu/22.04.26.1
[3] https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/ubuntustudio-default-settings/22.04.26.1/ubuntustudio-default-settings_22.04.26.1.tar.xz

[Steve Langasek (vorlon)]

Hello Bill, or anyone else affected,

Accepted ubuntustudio-default-settings into jammy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/ubuntustudio-default-settings/22.04.26.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-jammy to verification-done-jammy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-jammy. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Robie Basak (racb)]

> I have found the source of the problem though. It seems as though during my upload, that file did, in fact, sneak in [3], but why it didn't show up in the debdiff, I'll never know.

FWIW, the debdiff is blind to symlinks. For example, if you make a change to file that is symlinked from elsewhere in the same package, then debdiff will present that as both files changed. Similarly, if a file is dereferenced and replaced by an equivalent real file, debdiff won't see that. So debdiffs don't round trip correctly in the case of symlinks. This makes use of debdiff to perform reviews dangerous, too.

[Erich Eickmeyer (eeickmeyer)]

> FWIW, the debdiff is blind to symlinks. For example, if you make a
> change to file that is symlinked from elsewhere in the same package,
> then debdiff will present that as both files changed. Similarly, if a
> file is dereferenced and replaced by an equivalent real file, debdiff
> won't see that. So debdiffs don't round trip correctly in the case of
> symlinks. This makes use of debdiff to perform reviews dangerous, too.

Thanks, Robie. That was my suspicion, and also why I 1) Verified in a PPA prior
to upload, 2) Verified the tarball was correct prior to upload, and 3) Verified
the tarball was correct after upload. Everything looks correct this time
around.

It would be nice if debdiffs weren't blind to symlinks and that they could see
if there was a change from a symlink to an actual file, but I'm not sure how
that would get implemented.

[Bill Miller (wbmilleriii)]

I downloaded and installed the package from https://launchpad.net/ubuntu/jammy/amd64/ubuntustudio-default-settings/22.04.26.2

Then I restarted and I got back to the default login screen.

To me, this appears to have fixed it. Great work!

$ apt policy ubuntustudio-default-settings
ubuntustudio-default-settings:
  Installed: 22.04.26.2
  Candidate: 22.04.26
  Version table:
 *** 22.04.26.2 100
        100 /var/lib/dpkg/status
     22.04.26.1 500
        500 http://us.archive.ubuntu.com/ubuntu jammy-updates/universe amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu jammy-updates/universe i386 Packages
     22.04.26 1001
        500 http://us.archive.ubuntu.com/ubuntu jammy/universe amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu jammy/universe i386 Packages

[Aaron Rainbolt (arraybolt3)]

Enabled -proposed on a VM affected by this bug. Installed the new ubuntustudio-default-settings, then rebooted. SDDM theme appears to be working correctly again.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ubuntustudio-default-settings - 22.04.26.2

---------------
ubuntustudio-default-settings (22.04.26.2) jammy; urgency=medium

  * Fix for SDDM theme regression (LP: #2003388)

 -- Erich Eickmeyer <email address hidden> Fri, 20 Jan 2023 08:15:19 -0800

[Steve Langasek (vorlon)]

The verification of the Stable Release Update for ubuntustudio-default-settings has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.