cbindgen VS jni-rs

Golang uses cgo to communicate with external C libraries and Rust uses FFI (Foreign function interfaces) to export C functions. Additionally, a library for automatically generating bindings can be used to generate the header files (.h). In our case, we'll only be exporting two C functions, so using cbindgen is overkill but we'll use it regardless because why not?  Firstly, we'll write the rust functions we want to export. We'll start by creating a new rust library:

[1]: https://github.com/mozilla/cbindgen

As a 2-step approach, you could also probably use https://github.com/mozilla/cbindgen and then Nim's native C FFI.

The tooling for the first kind -- calling Rust from another language -- is a bit less developed, and tends to rely on code generation that doesn't necessarily produce a natural C API. cbindgen, uniffi, cxx, and Diplomat all take this course.

There's also cbindgen for automating the generation of C headers once you've got your code in the right shape and you'll also want to read the Rustonomicon.

You can backport Rust standard library to C using https://github.com/eqrion/cbindgen .

Later we'll see what cbindgen essentially does is receive a configuration and a Rust library and then spit out a C header (.h) file. One might think that what cbindgen is doing might not be that special and can be done by hand. In which some cases that might be true if the project is simple enough. Though additionally as the cbindgen documentation states:

Fuck it, I'll take the bait. Rust allows for amazing C interop by allowing for exporting of C types as a dynamic library, like C. Unlike C, this still allows for Rust's advanced checking at compile time. librsvg is one such library that is being used in the GTK ecosystem that is also almost completely Rust. You can use tools like cbindgen to generate C bindings.

Or alternatively cbindgen to create the header file from the Rust source.

The easiest way to obtain the headers for the rust code is to use the cbingen library.

I do have education and real experience in the field. See, for example, my recent work on the rather arcane subject of Rust↔Java FFI. You don't get to pull rank with me, son. I know quite well what CreateFile does. (Fun fact: it creates a file handle, i.e. opens a file, and may or may not create the file itself.)

I've been playing around with jni-rs, I'm eventually planning on developing an app with Java gui and Rust backend. However I'm having some trouble advancing past HelloWorld lol. For example, here's some simple code that doesn't work and I really can't figure out why:

- JNI - how well does https://github.com/jni-rs/jni-rs work? Assuming that Firefox runs on Android and uses Rust this should be reasonable to work with?

Even so, staying relatively close to the Java focus of the class might be a good idea, since it will help prepare you for the AP exam. One idea would be using jni-rs to build Java bindings for a useful Rust library. Interesting candidates might be io-uring, lockfree, or even pyo3, if you wanted to try your hand at integrating Java and Python.