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Bug 5361

Summary: RFC: Automatically fall back to non-udev joystick detection in Flatpak or pressure-vessel container
Product: SDL Reporter: Simon McVittie <smcv>
Component: joystickAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: HG 2.1   
Hardware: x86_64   
OS: Linux   
Attachments: joystick: Don't use udev in Flatpak or pressure-vessel container

Description Simon McVittie 2020-11-19 17:42:55 UTC 
Another follow-up for Bug #5337.

We can't expect udev change-notification to work reliably in containers, for the reasons discussed on Bug #5337.

Flatpak provides an official way to detect that you're inside a Flatpak container (test whether the file /.flatpak-info exists), so perhaps it would make sense for SDL to move to the inotify code path automatically in that case?

Similarly, Steam's pressure-vessel container tool, as used for the Steam Linux Runtime containers, can be detected by probing /run/pressure-vessel.
Comment 1 Simon McVittie 2020-11-19 17:43:39 UTC 
Created attachment 4530 [details]
joystick: Don't use udev in Flatpak or pressure-vessel container


Flatpak[1] and pressure-vessel[2] are known to use user namespaces,
therefore udev event notification via netlink won't work reliably.
Both frameworks provide a filesystem API that libraries can use to
detect them. Do that, and automatically fall back from udev-based
device discovery to the inotify-based fallback introduced in Bug #5337.

[1] <https://flatpak.org/>
[2] <https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/tree/master/pressure-vessel>
Comment 2 Sam Lantinga 2020-11-24 05:11:10 UTC 
Looks good, thanks!
https://hg.libsdl.org/SDL/rev/5a0fa9b6d4bf