FSKit Extension

[BernhardGlueck]

Apple platform

macOS

Framework version

net9.0-*

Affected platform version

Any

Description

The FsKit Api binding was reintroduced a few months ago. After going through it, the api has been bound but as far as i can see there basic Extension Protocol ( UnaryFileSystemExtension ) is not included, thus making it impossible to build such an FSKit extension ...

Steps to Reproduce

Did you find any workaround?

No response

Build logs

No response

[rolfbjarne]

UnaryFileSystemExtension is Swift-only, so we haven't bound it yet.

That said, it seems FSUnaryFileSystem is the Objective-C equivalent, which we have bound. Would that work for you?

[BernhardGlueck]

Hi !
Sorry that it took so long to get back to you.

The problem i am facing is that UnaryFileSystemExtension != FSUnaryFileSystem.

Let me elaborate:
FSKit implementations are App Extensions in the MACOS Ecosystem, and such are normal applications.
For FSKIT extensions we have the base protocol/class UnaryFileSystemExtension that when implemented in a swift struct acts a a kind of mixin, so that the implementer only needs to implement the one abstract member of it and return an FSUnaryFileSystem instance. THe protocol mixin will then handle the task of taking this instance and exposing it as a file system to the OS ...

Sadly this base protocol ( UnaryFileSystemExtension ) is closed source and in swift...

I have already implemented FSUnaryFIleSystem which is the actual workhorse of a custom file system, and the bindings seem to cover all cases for that.. Its just impossible to actually expose it to the os ...

Let me explain a bit further via C# Pseudcode what is ( in my opinion going on )

public interface IFSVolume // = FSVolume, ObjC and bound by dotnet/macos, can be implemented
{
    // Operations omitted for brevity 
}

public interface IFsUnaryFileSystem  // = FsUnaryFileSystem, ObjC, and bound by dotnet/macos, can be implemented
{
    
   IFSVolume Mount(string url);
}

public interface IUnaryFileSystemExtension  //  = UnaryFileSystemExtension, SWIFT not bound and thus not implementable
{
    IFsUnaryFileSystem FileSystem { get;}

    void ExtensionMain(string[] arguments)
    {
        var fileSystem = FileSystem;

        // Do some stuff to expose this to the OS, and start some sort of main loop.
        // Closed source, don't know whats happening here, thus cannot replicate.

        // And this is my exact issue, as I cannot use the "Swift" way below, i have 
// to figure out how to duplicate this logic.
    }
}

public class EntryPoint : IUnaryFileSystemExtension 
{

    public IFsUnaryFileSystem FileSystem => // Return my implementation of IFSUnaryFileSystem.

    // This main function is synthesized by the swift @main infrastructure.
    public void Main(string[] arguments)
    {
        // Of course this is an instance method, and not really callable here, but in the swift world
        // protocols can have static mixins... so just take this code as pseudo code.
        ExtensionMain(arguments);
    }
}

[rolfbjarne]

I see. I just tried to create the extension in Xcode, and even you select Objective-C as the language, Xcode adds a single swift file.

So I tried to come up with a workaround. Addd this to your extension's csproj: https://gist.github.com/rolfbjarne/03d95d53c774e9277dcc8cd5327f0c53

It's completely untested, but the idea is to create that single swift file, compile it, and link it into the extension's native executable.

Change the FSExtensionObjectiveCClassName property to the name of your class that implements IFSUnaryFileSystem.

You might also have to set this property in your csproj:

<PropertyGroup>
    <Registrar>managed-static</Registrar>
</PropertyGroup>

Can you try this and see how it goes?

[dotnet-policy-service]

Hi @@BernhardGlueck. 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.