Desktop crash on decorations computation

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

https://bugs.launchpad.net/ubuntu/+bug/1910532

Anyway this is how worked around the issue
https://discourse.ubuntu.com/t/testing-unity-session-in-focal-fossa-20-04/13692/158
Basically I've removed the function unity::decoration::Window::Impl::ComputeShapedShadowQuad

This issue affects Android studio also. I fixed the crash via this changes.
```
diff --git a/decorations/DecoratedWindow.cpp b/decorations/DecoratedWindow.cpp
index ed5548f5e..72096765b 100644
--- a/decorations/DecoratedWindow.cpp
+++ b/decorations/DecoratedWindow.cpp
@@ -750,6 +750,9 @@ void Window::Impl::ComputeShapedShadowQuad()
   unsigned int radius = active() ? manager_->active_shadow_radius() : manager_->inactive_shadow_radius();

   Shape shape(win_->id());
+ if (shape.GetRectangles().size() == 0)
+ return;
+
   auto const& border = win_->borderRect();
   auto const& shadow_offset = manager_->shadow_offset();

```
This code avoid invalid shape object.
I tested it in Ubuntu 20.04 virtual machine. Now compiz doesn't crash after `ffmvforce test`.
Thanks you for the easy reproduction way.

Thanks for the hint, there are now MRs for handling this.

Focal PPA package meanwhile: https://launchpad.net/~ci-train-ppa-service/+archive/4693/

Let me know if anything is not going as expected.

The fix for this has been uploaded to jammy-proposed.

Hello Dario, or anyone else affected,

Accepted unity into impish-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unity/7.5.1+21.10.20211026-0ubuntu1 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-impish to verification-done-impish. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-impish. 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.

Hello Dario, or anyone else affected,

Accepted unity into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unity/7.5.1+20.04.20211026.1-0ubuntu1 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-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. 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.

This bug was fixed in the package unity - 7.5.1+22.04.20211026.2-0ubuntu1

---------------
unity (7.5.1+22.04.20211026.2-0ubuntu1) jammy; urgency=medium

  [ Uladzislau Nikalayevich ]
  * DecoratedWindow: Do not try to use shaped shadows on empty quads.
    Windows may have no shaped rectangles, but we're still trying to set
    them. This is because we might not initialize the shape size, leading
    to invalid values. (LP: #1904337)

  [ Marco Trevisan (Treviño) ]
  * DecorationsShape: Initialize parameters on missing rectangles.
    In such case the shape should just be empty, but we didn't really handle
    the case properly.
  * dummy-xorg-test-runner: Use command -v instead of deprecated which
  * TestSwitchController: Do not define FakeApplicationWindow as NiceMock twice.
    It's already used as ::Nice later, no need to define it initially,
    otherwise newer gtest won't compile

 -- Marco Trevisan (Treviño) <mail@3v1n0.net> Tue, 26 Oct 2021 17:36:55 +0000

System: Ubuntu 20.04 focal
Package: Unity 7.5.1+20.04.20211026.1-0ubuntu1

Today I was working in Android Studio. I made a long session (~4 hours) without any crashes. Usually Android Studio randomly crashes my DE every 15 minutes. I didn't see any new additional graphical bugs.
Sometime i saw undercoated Ubuntu error windows "Unable to mount <My phone name>. Couldn't find matching udev device", but it's a old bug, i saw it on unity 7.5.0+20.04.20210409.0-0ubuntu1.
I restarted compiz via command `compiz --replace --debug`. I saw messages in console like this:

```
ERROR 2021-10-28 22:52:59 unity.decoration.shape DecorationsShape.cpp:78 Failed to get shape rectangles
ERROR 2021-10-28 22:52:59 unity.decoration.shape DecorationsShape.cpp:78 Failed to get shape rectangles
```
Unity handles this error property for me now. This happens when you click on menu bar item and fast moves your cursor over menu bar.

System: Ubuntu 21.10.
Package: 7.5.1+21.10.20210601.1-0ubuntu1

Bug doesn't affect this system with the original package from impish repo.
Bug doesn't affect Ubuntu 20.10 with 7.5.1+21.10.20210601.1-0ubuntu1 package also. I've added impish repo in sources.list and updated unity package with dependencies for this.

This bug was fixed in the package unity - 7.5.1+20.04.20211026.1-0ubuntu1

---------------
unity (7.5.1+20.04.20211026.1-0ubuntu1) focal; urgency=medium

  [ Uladzislau Nikalayevich ]
  * DecoratedWindow: Do not try to use shaped shadows on empty quads.
    Windows may have no shaped rectangles, but we're still trying to set
    them. This is because we might not initialize the shape size, leading
    to invalid values. (LP: #1904337)

  [ Marco Trevisan (Treviño) ]
  * DecorationsShape: Initialize parameters on missing rectangles.
    In such case the shape should just be empty, but we didn't really handle
    the case properly. (LP: #1904337)

 -- Marco Trevisan (Treviño) <mail@3v1n0.net> Tue, 26 Oct 2021 12:40:42 +0000

The verification of the Stable Release Update for unity 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.

Assuming the very same change fixed things in focal, I think we can safely mark as verified also for impish (not to regress in case of updates).

I don't think it is safe to mark this as verified without actually following the verification steps, subsequently I'm reverting the tag changes.

Ubuntu 21.10 (Impish Indri) has reached end of life, so this bug will not be fixed for that specific release.