Xamarin-android: DirectBoot execution fails with java.lang.UnsatisfiedLinkError

[mungojam]

When trying to use any Xamarin tool in the DirectBoot pre-login session I get:

08-18 22:54:33.644 2722 2722 E AndroidRuntime: FATAL EXCEPTION: main
08-18 22:54:33.644 2722 2722 E AndroidRuntime: Process: com.xamarin.directboot, PID: 2722
08-18 22:54:33.644 2722 2722 E AndroidRuntime: java.lang.UnsatisfiedLinkError: No implementation found for void mono.android.Runtime.register(java.lang.String, java.lang.Class, java.lang.String) (tried Java_mono_android_Runtime_register and Java_mono_android_Runtime_register__Ljava_lang_String_2Ljava_lang_Class_2Ljava_lang_String_2)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at mono.android.Runtime.register(Native Method)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at md511db93b05d0fbee144be45ad6fb54d50.BootBroadcastReceiver.(BootBroadcastReceiver.java:15)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at java.lang.Class.newInstance(Native Method)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at android.app.ActivityThread.handleReceiver(ActivityThread.java:3671)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at android.app.ActivityThread.-wrap18(Unknown Source:0)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1979)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:108)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at android.os.Looper.loop(Looper.java:166)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:7425)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
08-18 22:54:33.644 2722 2722 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)

Steps to Reproduce

1. Make sure your phone has Nougat+ file based encryption enabled
2. Download this Xamarin sample (though I get same error with my own attempts to implement DirectBoot)
3. Build in release mode
4. Deploy to phone
5. Set an alarm in the app
6. Reboot and wait for alarm time without logging on
7. Nothing happens
8. Check logcat and you'll find the error above

Also raised this issue against the sample https://github.com/xamarin/monodroid-samples/issues/277, but it looks more like a Xamarin bug to me.

https://developer.xamarin.com/samples/monodroid/android-n/DirectBoot/DirectBoot.zip

Expected Behavior

To be able to use DirectBoot like other apps can. I've been able to use native apps like google clock and they work fine.

Actual Behavior

Xamarin actions such as simple notifications do not fire and an error is logged

Device

My phone is a Huawei Honor 9 with Android 8.0.0

Version Information

Microsoft Visual Studio Enterprise 2017
Version 15.8.1
VisualStudio.15.Release/15.8.1+28010.2003
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[rihadavid]

I am having the same issue, on Huawei P20 Lite. Did you find some workaround?

[mungojam]

No, nothing. just waiting for any response before I can implement the feature that I want to add

[rihadavid]

Ok, so after digging deeper, I've discovered that the mono stuff defined in AndroidManifest.xml during build (e.g. <provider android:name="mono.MonoRuntimeProvider" ... >) needs the android:directBootAware="true" attribute and then it works as expected.

So basically to fix this, Xamarin.Android project properties should offer some DirectBootAware option and when activated, all those providers/receivers etc. should use the android:directBootAware="true".
Or maybe even better, xamarin could automatically detect that the project manifest contains android:directBootAware="true" and add what is needed automatically.

This seems to be mostly related to a file src/Xamarin.Android.Build.Tasks/Utilities/ManifestDocument.cs, which I can see has been recently edited by @dellis1972 or @jonpryor , so maybe you could be able to provide a fix? 🙏

Meanwhile, would you be able to help us with some workaround? I tried to add <provider android:name="mono.MonoRuntimeProvider" android:directBootAware="true"> to my AndroidManifest.xml in the project, but found out that manifest merging is not supported in xamarin, so instead of adding the directBootAware to the provider, the final manifest ends with two definitions of the same provider.
So eventually, I needed to decompile the built apk using apktool, edit the manifest manually, build it again using apktool, sign it using jarsigner, zipalign it and manually install on the device to test it. This is something that I could probably do on my release apk, but I would also like to debug it. There is one workaround for merging the manifest, but it seems quite complicated.

So please, would you know of any other way how to force the android:directBootAware="true" into the final manifest? Thank you 🙏

[rihadavid]

And just to explain why all of this matter - since Android 7.0, an alarm clock app needs to use DirectBootAware, because if user sets an alarm and the device restarts itself (for whatever reason) during the night, the alarm will fail to go off, because the device is booted in a locked state and only DirectBootAware apps can do anything in this state.

About 50% Android users are on 7.0+, so this might affect a lot of people who use Xamarin-built alarm clock apps. Of course, the DirectBootAware does not apply only to alarm clocks, other types of apps might use it as well.

[dellis1972]

Here is a simpler workaround until we can get some code into a release.

  <UsingTask  
    TaskName="PatchManifest"  
    TaskFactory="CodeTaskFactory"  
    AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll" >  
    <ParameterGroup>  
      <Path ParameterType="System.String" Required="true" />  
      <Token ParameterType="System.String" Required="true" />  
      <Replacement ParameterType="System.String" Required="true" />  
    </ParameterGroup>  
    <Task>  
      <Code Type="Fragment" Language="cs"><![CDATA[  
string content = File.ReadAllText(Path);  
content = content.Replace(Token, Replacement);  
File.WriteAllText(Path, content);  
]]></Code> 
    </Task> 
  </UsingTask>  

  <Target Name="_FixupDirectBootProviders" AfterTargets="_GenerateJavaStubs">
    <PatchManifest Path="$(IntermediateOutputPath)android\AndroidManifest.xml"
      Token="&lt;provider android:name=&quot;mono.MonoRuntimeProvider&quot;" Replacement="&lt;provider android:directBootAware=&quot;true&quot; android:name=&quot;mono.MonoRuntimeProvider&quot;"
    />
  </Target>

Just drop this xml into the bottom of your csproj just above the final </Project> element. It just does a simple text replace so its not that intelligent.

[dellis1972]

@rihadavid a quick question. I'm in favour of the automatic detection of the directBootAware attribute and have it add the required attributes to the providers we auto generate.

The question is, is searching for the directBootAware attribute on the application element good enough? Or will there be instances where you only really want it on a service element and not on the application? It seems that you can add the attribute on a bunch of different elements like application, activity, service etc. to make matters more complicated those attributes can be set in code via class attributes.

[Activity (DirectBootAware=true)]

[1] https://developer.android.com/guide/topics/manifest/application-element

[rihadavid]

@dellis1972

_"You can pick the subset of your app components that need to be Direct Boot aware, but if you are using a custom Application class, it is assumed to be Direct Boot aware if any component inside your app is marked as Direct Boot aware."_
Source: googleblog.com

So, unless the directBootAware is added automatically to a custom Application class during build time (which I am not sure), it should not rely on the application element because developer might read this and do not add the directBootAware to the custom Application class.