[.NET] Would it be possible to add support for MacCatalyst?

[MartyIX]

I have tried to create a PR on https://github.com/ektrah/libsodium-core side to add support for Apple MacCatalyst (net7.0-maccatalyst runtime identifier in .NET).

Now it turns out that the dylib for MacCatalyst is not in the nuget package of jedisct1/libsodium

So I wonder whether a modification of

• https://github.com/jedisct1/libsodium/blob/master/dist-build/macos.sh, and

• libsodium/packaging/dotnet-core/libsodium.pkgproj

  Line 37 in 01c237f

  <Content Include="runtimes/osx-arm64/native/libsodium.dylib" PackagePath="runtimes/osx-arm64/native/" />

would do the job to add the support for the platform?

I would give a hand but I'm not sure how to add the target x86_64-apple-ios-macabi to the makefiles (at least that's what I understand is required to do basically).

What do you think please?

Thanks

Resources:

• https://developer.apple.com/forums/thread/122571?answerId=675312022#675312022 clang -target x86_64-apple-ios-macabi
• Add target x86_64-apple-ios13.0-macabi (Mac Catalyst) Instabug/Instabug-iOS#444
• https://stackoverflow.com/questions/70770314/autotools-says-its-building-for-macos-although-i-specified-maccatalyst-as-the

[jedisct1]

The xcframework includes Catalyst (as well as all iOS, macOS, watchOS and TVOS versions + simulators).

It can be built with dist-build/apple-xcframework.sh, or you can simply download pre-built files from swift-sodium, that are frequently updated.

Since xcframework is the standard way to distribute multi-platform Apple libraries, there has to be a way to use them in .NET projects.
If not, you can still get files for individual architectures from it.

[ektrah]

Thanks a lot for the explanation, @rolfbjarne!

A few follow-up questions:

• Since all these RIDs import the unix RID, would it be an option to place a Clibsodium.xcframework.zip in runtimes/unix/native/ to avoid the duplication?

• Does macos still need a .dylib or is the .a from Clibsodium.xcframework fine? Is there a best practice?

• Is [DllImport("__Internal")] still needed or is it now fine to use [DllImport("libsodium")] across all platforms?

[rolfbjarne]

• Since all these RIDs import the unix RID, would it be an option to place a Clibsodium.xcframework.zip in runtimes/unix/native/ to avoid the duplication?

I'm not entirely sure, but I don't think that will work.

• Does macos still need a .dylib or is the .a from Clibsodium.xcframework fine? Is there a best practice?

For macos either way works, it doesn't really matter.

• Is [DllImport("__Internal")] still needed or is it now fine to use [DllImport("libsodium")] across all platforms?

__Internal is required for every platform that uses the static (*.a) library.

[MartyIX]

Based on the great feedback of @rolfbjarne and @ektrah, I succeeded in making libsodium work in a maccatalyst app on my mac arm64 machine. More specifically, I don't observe DllNotFoundException anymore.

Please clone the sample app and follow the following instructions if you want to test it too:

git clone https://github.com/jedisct1/libsodium.git
cd libsodium

# Add the following line to the `packaging/dotnet-core/libsodium.pkgproj` file:
# <Content Include="runtimes/maccatalyst-arm64/native/libsodium.a" PackagePath="runtimes/maccatalyst-arm64/native/" />
#
# Also modify version to "1.0.18.6" (any non-yet-released version is fine for testing but please stick with this one so 
# https://github.com/MartyIX/libsodium-maccatalyst-sample works for you).

# Folder where we're going to pack a .NET NuGet package.
mkdir .libsodium-pack
cp AUTHORS ChangeLog LICENSE packaging/dotnet-core/libsodium.pkgproj .libsodium-pack/

# Compilation requires an Apple machine as far as I know.
dist-build/apple-xcframework.sh

# My machine is an ARM64 one.
mkdir -p .libsodium-pack/runtimes/maccatalyst-arm64/native
cp libsodium-apple/catalyst/lib/libsodium.a .libsodium-pack/runtimes/maccatalyst-arm64/native # You can see that I just copy the static library and then I use `[DllImport("__Internal")]` in the sample app. That's easy for me to understand. 

## If you have x64 mac machine. Use this, I guess.
# mkdir -p .libsodium-pack/runtimes/maccatalyst-x64/native
# cp libsodium-apple/catalyst/lib/libsodium.a .libsodium-pack/runtimes/maccatalyst-x64/native

# Pack the NuGet package.
# The result is located in '.libsodium-pack/bin/Release/libsodium.1.0.18.6.nupkg'
dotnet pack -c Release .libsodium-pack/libsodium.pkgproj

# Copy libsodium.1.0.18.6.nupkg to your https://github.com/MartyIX/libsodium-maccatalyst-sample/tree/main/LocalNugetCache folder.
# Start https://github.com/MartyIX/libsodium-maccatalyst-sample/tree/main/LocalNugetCache using: dotnet build && dotnet run
# You should observe a MacCatalyst app which does not crash and displays the testing output.

This is really an attempt to make it work and the goal is to move forward (even if the direction is not correct) so we can get to some final solution. Best effort really.

One notable question is how to test that a MacCatalyst application works because there is no exit code as console applications have. That's maybe something that @rolfbjarne possibly know -- any pointer here would be greatly appreciated.

[rolfbjarne]

One notable question is how to test that a MacCatalyst application works because there is no exit code as console applications have. That's maybe something that @rolfbjarne possibly know -- any pointer here would be greatly appreciated.

You can execute the executable inside the .app directly instead of the app bundle:

$ path/to/MyTest.app/Contents/MacOS/MyTest

and then you'll get an exit code.

This works for macOS apps as well btw.

[MartyIX]

Wow! Exciting. Thanks!

[jedisct1]

But can't we remove all the Apple targets we have and ship the xcframework file instead?

[MartyIX]

That's a good question. I understand Rolf's comment this way: You can have a single xcframework file (the compiled library) but one needs to duplicate it to several folders (i.e. platforms RIDs) in the NuGet package. So the final NuGet file size will be larger than one would like/want.

@rolfbjarne Is that correct?

[rolfbjarne]

That's a good question. I understand Rolf's comment this way: You can have a single xcframework file (the compiled library) but one needs to duplicate it to several folders (i.e. platforms RIDs) in the NuGet package. So the final NuGet file size will be larger than one would like/want.

@rolfbjarne Is that correct?

That is correct.

It's also likely possible to shrink each xcframework copy by removing files for other platforms, but that would be a manual and possibly error-prone process.

[MartyIX]

With Rolf's big help, I tested the following approach using libsodium.a from libsodium-apple/Clibsodium.xcframework/ios-arm64_x86_64-maccatalyst folder:

Please clone the sample app and follow the following instructions if you want to test it too:

git clone https://github.com/jedisct1/libsodium.git
cd libsodium

# Add the following line to the `packaging/dotnet-core/libsodium.pkgproj` file:
# <Content Include="runtimes/maccatalyst-x64/native/libsodium.a" PackagePath="runtimes/maccatalyst-x64/native/" />
# <Content Include="runtimes/maccatalyst-arm64/native/libsodium.a" PackagePath="runtimes/maccatalyst-arm64/native/" />
#
# Also modify version to "1.0.18.6" (any non-yet-released version is fine for testing but please stick with this one so 
# https://github.com/MartyIX/libsodium-maccatalyst-sample works for you).

# Folder where we're going to pack a .NET NuGet package.
mkdir .libsodium-pack
cp AUTHORS ChangeLog LICENSE packaging/dotnet-core/libsodium.pkgproj .libsodium-pack/

# Compilation requires an Apple machine as far as I know.
dist-build/apple-xcframework.sh

mkdir -p .libsodium-pack/runtimes/maccatalyst-arm64/native
cp libsodium-apple/Clibsodium.xcframework/ios-arm64_x86_64-maccatalyst/libsodium.a .libsodium-pack/runtimes/maccatalyst-arm64/native

mkdir -p .libsodium-pack/runtimes/maccatalyst-x64/native
cp libsodium-apple/Clibsodium.xcframework/ios-arm64_x86_64-maccatalyst/libsodium.a .libsodium-pack/runtimes/maccatalyst-x64/native

# Pack the NuGet package.
# The result is located in '.libsodium-pack/bin/Release/libsodium.1.0.18.6.nupkg'
dotnet pack -c Release .libsodium-pack/libsodium.pkgproj

# Copy libsodium.1.0.18.6.nupkg to your https://github.com/MartyIX/libsodium-maccatalyst-sample/tree/main/LocalNugetPackages folder.
# Start https://github.com/MartyIX/libsodium-maccatalyst-sample sample app using: `dotnet build && dotnet run`
# You should observe a MacCatalyst app which does not crash and displays the testing output.

and it works for me with the sample app with arm64 arch and even x64 (emulated on my machine using Rosetta).

[MartyIX]

@jedisct1 What is a good next step please?