[Bug 1877806] [NEW] [SRU] ardour crashes when saving lv2 plugin preset - bug discovered in lilv

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You have been subscribed to a public bug by Erich Eickmeyer (eeickmeyer):

[Impact]

 * Users of Ardour who wish to use LV2 audio plugins and make settings
   presets are running into an issue where they are unable to save changes
   to their presets. Attempts simply crash the application.

 * This has been only been observed in Ubuntu 20.04 LTS. Attempts to
   reproduce the behavior on 18.04, 19.10, and Groovy Gorilla proved
   fruitless.

 * Upon investigation, the bug was a regression in lilv 0.24.6 which was
   corrected in 0.24.8 per https://github.com/lv2/lilv/issues/32 and its 
   attached commit.

[Test Case]

 * In Ardour, start a new project, go to the Mixer view.

 * Add a track to the project

 * Add any LV2 plugin to the track

 * Open the LV2 plugin interface via a double-click on the plugin

 * Save a "New" preset, use any name.

 * Make a change to the plugin state (any parameter), click "Save".
   Ardour will crash.

[Regression Potential]

 * This library (lilv) affects LV2 plugins and only LV2 plugins. Version 
   0.24.8 contains a number of bugfixes to enhance the stability of LV2
   plugins, including the bugfix mentioned.

 * Even though this version contains a number of bug fixes, there is always
   potential for some regression in LV2 plugins to occur, such as 
   misbehavior or other regressions similar to this particular bug.

[Other Info]
 
 * The diff in this case is quite large due to the number of bugs fixed. 
   While it is possible for a simple cherry pick of the commit in question,
   I believe there is an even greater risk of regression or bugs appearing 
   if the full bugfix release is not used.

 * The full bugfix release (0.24.8) fixes many bugs and does not contain
   any new features as far as I can tell.


Original bug follows:

The few lv2 plugins I have tried all crash ardour when I click on "save"
to save the preset. Clicking Add to create a new plugin doesn't crash,
but it also does not save the preset.  If you load a plugin preset
already created and then click save, you end up wiping out the contents
of the preset direcoty in ~/.lv2.  The .ttl files are deleted and you
end up with an empty directoy.  The only thing printed on the console
when this happens is this:

CALF DEBUG: instance 0x55c00d102860 data 0x55c01ca1cf10
CALF DEBUG: calf 0x7f8d31f7b0f0 cpi 0x7f8d31783ca0
Segmentation fault (core dumped)

AFAIK, teh preset add and save functions work for ladspa plugins.

-Don

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ardour 1:5.12.0-3ubuntu4
ProcVersionSignature: Ubuntu 5.4.0-29.33-lowlatency 5.4.30
Uname: Linux 5.4.0-29-lowlatency x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
Date: Sat May  9 21:39:09 2020
InstallationDate: Installed on 2020-04-26 (13 days ago)
InstallationMedia: Ubuntu-Studio 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: ardour
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: ardour (Ubuntu)
     Importance: Undecided
         Status: Triaged

** Affects: lilv (Ubuntu)
     Importance: Undecided
         Status: Fix Released

** Affects: ardour (Ubuntu Focal)
     Importance: Undecided
         Status: Triaged

** Affects: lilv (Ubuntu Focal)
     Importance: High
     Assignee: Erich Eickmeyer (eeickmeyer)
         Status: In Progress

** Affects: lilv (Ubuntu Groovy)
     Importance: Undecided
         Status: Fix Released


** Tags: amd64 apport-bug focal
-- 
[SRU] ardour crashes when saving lv2 plugin preset - bug discovered in lilv
https://bugs.launchpad.net/bugs/1877806
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