Regression: Runtime errors with IL stripped assemblies

[jxbrenner]

Android application type

Classic Xamarin.Android (MonoAndroid12.0, etc.)

Affected platform version

Xamarin.Android 12.3

Description

Mono runtime error, app hangs and crashes. See device log output below.

Sample project attached for reference. MSBuild configured to match what I'm using in VS 2019 for app distribution.
XamarinAndroidApp.zip

Steps to Reproduce

1. New Android App (Xamarin) - Blank App
2. Configure MSBuild for static compilation, IL stripping, and target arm64-v8a
3. Build and run

Did you find any workaround?

Build with Xamarin.Android 12.0.

Relevant log output

Time	Device Name	Type	PID	Tag	Message
	Sonimtech XP8800	Info	1785	ActivityManager	Process com.companyname.xamarinandroidapp (pid 14562) has died: fore TOP 
	Sonimtech XP8800	Error	14562	mono-rt	
  at Java.Interop.JniRuntime.GetRegisteredRuntime (System.IntPtr invocationPointer) <0x720f10ff0c + 0x0007c> in <4be0212dda1448dbbb5bcb78bcd13cf4>:0 
  at Java.Interop.JniEnvironmentInfo.set_EnvironmentPointer (System.IntPtr value) <0x720f12534c + 0x0008b> in <4be0212dda1448dbbb5bcb78bcd13cf4>:0 
  at Java.Interop.JniRuntime..ctor (Java.Interop.JniRuntime+CreationOptions options) <0x720f110234 + 0x005b7> in <4be0212dda1448dbbb5bcb78bcd13cf4>:0 
  at Android.Runtime.AndroidRuntime..ctor (System.IntPtr jnienv, System.IntPtr vm, System.Boolean allocNewObjectSupported, System.IntPtr classLoader, System.IntPtr classLoader_loadClass, System.Boolean jniAddNativeMethodRegistrationAttributePresent) <0x720f4c15b0 + 0x0008b> in <97754039425649c180140cd9408a4bd2>:0 
  at Android.Runtime.JNIEnv.Initialize (Android.Runtime.JnienvInitializeArgs* args) [0x000f3] in <97754039425649c180140cd9408a4bd2>:0 
	Sonimtech XP8800	Error	14562	mono-rt	
	Sonimtech XP8800	Error	14562	mono-rt	[ERROR] FATAL UNHANDLED EXCEPTION: System.InvalidProgramException: Invalid IL code in System.Collections.Generic.Dictionary`2<intptr, Java.Interop.JniRuntime>:TryGetValue (intptr,Java.Interop.JniRuntime&): IL_0000: ret       

[jonathanpeppers]

This setting is not supported in .NET 6, does it help to remove it?

<BundleAssemblies>True</BundleAssemblies>

Likewise, we don't have support for this "experimental" setting either:

<AndroidAotMode>Hybrid</AndroidAotMode>

Which is what would use cil-strip. Can you give some more info on why you'd like to use it? Thanks!

Hi @jxbrenner. We have added the "need-info" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

[jxbrenner]

Hi @jonathanpeppers, thanks for the response! I opened the issue for a regression I've observed when building with VS 2022 against Xamarin TFMs, specifically MonoAndroid12.0. I would very much like to see IL stripping work with .net6.0-android as well, as I can't migrate to a unified framework and MAUI until it does.

Regarding assembly bundling, no removing that from the build process doesn't help.

Regarding the whole "experimental hybrid setting", I'd like to focus more on the fact that I can't execute the Mono CIL Stripper tool on my statically compiled assemblies anymore, and less on what MSBuild properties are experimental. I appreciate that the example I gave included that property as a means to strip the IL as that's how it's triggered from the project file; however, regardless of how I run the Mono CIL Stripper against my assemblies, I still get the same fatal runtime error about invalid IL code when building with VS 2022. This is not the case with VS 2019.

I personally don't care what IL remains in any of the assemblies except for my shared and head project. Unfortunately, I can't even IL strip these assemblies when building with VS 2022 (same fatal runtime error). So to put a finer point on the issue here, I just want to be able to continue to execute the Mono CIL Stripper against my shared and head project assemblies when building against MonoAndroid. However, a fix that applies to .net-android would be even better since this gives my app a path forward to MAUI.

Regarding motivation for IL stripping, see dotnet/runtime#44855 and #1218. TLDR on that is reducing assemblies to metadata protects IP and improves security of closed-source projects. Decompiling obfuscated IL back to C# is trivial.

[jonathanpeppers]

@jxbrenner cil-strip is located here:

https://github.com/mono/mono/tree/main/mcs/tools/cil-strip

Should you file an issue there instead?

[jxbrenner]

@jonathanpeppers hey what gives, now you're making me think! I don't think so. I spent some time comparing the output of stripped assemblies produced when I build the example project with VS 2019 and VS 2022, and so far I believe cil-strip is still producing the same output for the given input (go figure, it's version 0.6.9.0 in both versions of VS). Definitely the case with XamarinAndroidApp and System.Collections.Generic.Dictionary (what I'm getting the runtime error on in the example).

While I was doing that I found that the packages built with VS 2022 keep all the managed assemblies in assemblies/assemblies.blob instead of directly in the assemblies folder (or bundled). That's something different from VS 2019, I'm wondering if there's an easy fix here. Is there a build property I can set to disable the assembly store task?

[jonathanpeppers]

Yes, you might try this for your Release configuration:

<AndroidUseAssemblyStore>false</AndroidUseAssemblyStore>

And if that solves the issue, there might be a problem with this combination of settings. Let us know, thanks!

[jxbrenner]

Unfortunately if there's an easy fix, that's not it, still the same runtime error.

To help you help me I've attached a diff report of the build properties from the MSBuild logs of the example project (VS 2019 on the left, VS 2022 on the right). Does anything jump off the page at you? How about the runtime error? Invalid IL code in the BCL, I mean there shouldn't be any since we stripped it, and why would we need it since it's all statically compiled? As mentioned, mscorlib output from cil-strip appears exactly the same, ex. all methods in the method table have their bodies stripped and are patched NoInlining.

I'm wondering about the differences in the AndroidAotEnableLazyLoad, AndroidAotStripLibraries properties. They're both false in the VS2019 build, but I can't seem to override them in VS2022 with the project file.

BuildPropDiffs.zip