Linux desktop support - crashpad

[vaind]

Edit: crashpad won't work, see below in comments

---

closes #694, replaces #699

TODOs

• symbol upload
• integration test

[github-actions]

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- Linux desktop support - crashpad ([#733](https://github.com/getsentry/sentry-unity/pull/733))

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[vaind]

Crashpad integration doesn't seem to work properly - after starting the game, it gets stuck with high CPU usage and no scene loaded. The game can only be killed with 9 - SIGKILL - doesn't respond to standard close or sigterm

Default vsync count 1
requesting resize 1024 x 768
resizing window to 1024 x 768
Desktop is 3840 x 2160 @ 60 Hz
UnloadTime: 0.351288 ms
Sentry: (Debug) Logging enabled with 'UnityLogger' min level: Debug
SmokeTester.Configure() called but skipped because this is not a SmokeTest (no arg)
Sentry: (Debug) Setting Release: [email protected]
Sentry: (Debug) Setting Environment: production
Sentry: (Debug) Setting Debug: True
Sentry: (Debug) Disabling native auto session tracking
Sentry: (Debug) Setting CacheDirectoryPath: /home/ivan/.config/unity3d/DefaultCompany/unity-of-bugs/SentryNative
Sentry: (Debug) Setting a native logger
Sentry: (Debug) Initializing sentry native
Sentry: (Info) Native: using database path "/home/ivan/.config/unity3d/DefaultCompany/unity-of-bugs/SentryNative"
Sentry: (Debug) Native: starting transport
Sentry: (Debug) Native: starting background worker thread
Sentry: (Debug) Native: starting backend
Sentry: (Debug) Native: background worker thread started
Sentry: (Debug) Native: starting crashpad backend with handler "/mnt/c/dev/sentry-unity/temp/linux/crashpad_handler"
Sentry: (Debug) Native: using minidump url "https://o447951.ingest.sentry.io:443/api/5439417/minidump/?sentry_client=sentry.native/0.4.17&sentry_key=94677106febe46b88b9b9ae5efd18a00"
Sentry: (Info) Native: started crashpad client handler
Sentry: (Debug) Native: processing and pruning old runs
Sentry: (Debug) Native SDK reported: 'crashedLastRun': 'False'
Sentry: (Debug) Native: starting crashpad backend with handler "/mnt/c/dev/sentry-unity/temp/linux/crashpad_handler"
Sentry: (Debug) Native: using minidump url "https://o447951.ingest.sentry.io:443/api/5439417/minidump/?sentry_client=sentry.native/0.4.17&sentry_key=94677106febe46b88b9b9ae5efd18a00"
Sentry: (Info) Native: started crashpad client handler

another run, with htop

yet another run, htop, show thread names

[vaind]

So, it turns out Crashpad cannot be used because it forks the process on Linux and that's not working well with Unity.
I've tried by investigating the sentry-native source and commenting out/adding return false at some appropriate places. The good thing is I can recompile the library and swap it in the compiled game folder at app_Data/Plugins/libsentry.so

1. CrashpadClient::StartHandler() calls DoubleForkAndExec(). If I return false (i.e. say the current function failed) before the fork() call inside DoubleForkAndExec(), everything works fine (of course no native crash handling). If I do it right after fork(), the UI stops rendering, turns out as a black screen, while you can still click around and in the log I can see the button actions (send dotnet errors) are still triggered) - but no UI, see the image above: Linux desktop support - crashpad #733 (comment)

2. Additionally, there seems to be another error, related to log forwarding from native to c# in SentryNativeBridge.cs, I assume it has something to do with the fork() as well because it only has issues after the call.

Therefore, I'm dropping this approach and we're going to breakpad, see #734