How to pass Vec<u8> to WASM and back?

[matthiasbeyer]

Hi,

I am trying to implement a tool that needs to "map" bytes to bytes. That mapping should be written in Rust or any other WASM-compatible language (for now only Rust is fine) and essentially be a fn(Vec<u8>) -> Vec<u8> or fn(Vec<u8>) -> Result<Vec<u8>, ()>.

Following the tutorial for having a function add(i32) -> i32 was pretty easy, but the step up to the above is not.

Can someone point me to the right documentation for that? All examples for wasmer only come with WAT, which does not help me at all. I don't even know what the right way for doing this is? Should I allocate host memory for that? VM memory? Is there some other way?