Review Android AssemblyReader

[bruno-garcia]

Came up on Discord:

Our current version of Android AssemblyReader was taken from this sha:

• sentry-dotnet/src/Sentry.Android.AssemblyReader/ATTRIBUTION.txt

  Line 2 in cbe1af4

  https://github.com/xamarin/xamarin-android/blob/c92702619f5fabcff0ed88e09160baf9edd70f41/tools/assembly-store-reader/AssemblyStoreExplorer.cs

Upstream, as the history shows:

• https://github.com/dotnet/android/commits/main/tools/assembly-store-reader/AssemblyStoreExplorer.cs

A change was done to it since:

• https://github.com/dotnet/android/pull/8694/files#diff-d705beccc7479fb87d9203224767b0bd417e49e3b8de238ec0cd0811179d1de6

I didn't look into it but might be related to making assemblies RID specific, changing the internal layout of the apk:

• Make all assemblies RID-specific dotnet/android#8478

[bruno-garcia]

@jamescrosswell @bricefriha one way to test if things are working, is getting a Release built Android app built on .NET 9, and see if we still get all C# line numbers in exceptions and crashes

[jamescrosswell]

@jamescrosswell @bricefriha one way to test if things are working, is getting a Release built Android app built on .NET 9, and see if we still get all C# line numbers in exceptions and crashes

Argh... this obviously slipped through the cracks.

.NET 9 does introduced a new AssemblyStore format for APK files. Reading the new format is demonstrated in assembly-store-reader-mk2 (which is a newer version of the store reader to the one we vendored in).

The relvant commits appear to be:

• Make all assemblies RID-specific dotnet/android#8478
• [native] Real shared libraries in APK /lib directories dotnet/android#9154

Unfortunately the code for assembly-store-reader-mk2 isn't yet complete and the functionality to read v1 store formats hasn't yet been implemented. As such, we're going to have to:

1. Vendor in the code to read v2 stores from assembly-store-reader-mk2
2. Find some way to determine whether the store is a v1 or v2 store and instantiate the appropriate reader (we already have an AndroidAssemblyReaderFactory that creates either a directory reader or a store reader)... hopefully we can extend this so it returns v1 or v2 as appropriate

Additionally, the current code we've got gets the apk path as so:

sentry-dotnet/src/Sentry/Platforms/Android/AndroidHelpers.cs

Line 27 in 1928a48

var apkPath = Application.Context.ApplicationInfo?.SourceDir;

I'm not sure if that actually works in .NET 8 (needs to be tested). In .NET 9 at least, this returns /somepath/base.apk and, whilst that apk does exist in net9.0, it doesn't contain any of the .NET assemblies that we need to load. Instead, these appear to be in /somepath/split_config.[arch].apk (e.g. /somepath/split_config.arm64_v8a.apk on an arm64 v8a device).

It is possible to get a list of all the source dirs via Application.Context.ApplicationInfo?.SplitSourceDirs so we'll have to identify the appropriate path in that array based on the current architecture and then open that file in our new v2 store reader.

I tested this on a Release build of the Sentry.Samples.Maui application, using assembly-store-reader-mk2 tool from the dotnet/android repo and it works. So now all we have to do is vendor in that code as a new reader and find a way to instanciate the appropriate reader.