3dd5a3cb3f
* Reimplement `wasmtime-wasi` on top of `wasmtime` This commit reimplements the `wasmtime-wasi` crate on top of the `wasmtime` API crate, instead of being placed on top of the `wasmtime-*` family of internal crates. The purpose here is to continue to exercise the API as well as avoid usage of internals wherever possible and instead use the safe API as much as possible. The `wasmtime-wasi` crate's API has been updated as part of this PR as well. The general outline of it is now: * Each module snapshot has a `WasiCtxBuilder`, `WasiCtx`, and `Wasi` type. * The `WasiCtx*` types are reexported from `wasi-common`. * The `Wasi` type is synthesized by the `wig` crate's procedural macro * The `Wasi` type exposes one constructor which takes a `Store` and a `WasiCtx`, and produces a `Wasi` * Each `Wasi` struct fields for all the exported functions in that wasi module. They're all public an they all have type `wasmtime::Func` * The `Wasi` type has a `get_export` method to fetch an struct field by name. The intention here is that we can continue to make progress on #727 by integrating WASI construction into the `Instance::new` experience, but it requires everything to be part of the same system! The main oddity required by the `wasmtime-wasi` crate is that it needs access to the caller's `memory` export, if any. This is currently done with a bit of a hack and is expected to go away once interface types are more fully baked in. * Remove now no-longer-necessary APIs from `wasmtime` * rustfmt * Rename to from_abi
wasmtime-rust - Using WebAssembly from Rust
This crate is intended to be an example of how to load WebAssembly files from a
native Rust application. You can always use wasmtime and its family of crates
directly, but the purpose of this crate is to provide an ergonomic macro:
#[wasmtime_rust::wasmtime]
trait WasmMarkdown {
fn render(&mut self, input: &str) -> String;
}
fn main() -> anyhow::Result<()> {
let mut markdown = WasmMarkdown::load_file("markdown.wasm")?;
println!("{}", markdown.render("# Hello, Rust!"));
Ok(())
}
The wasmtime macro defined in the wasmtime-rust crate is placed on a trait
which includes the set of functionality which a wasm module should export. In
this case we're expecting one render function which takes and returns a
string.
The macro expands to a struct with all of the methods on the trait (they must
all be &mut self) and one function called load_file to actually instantiate
the module.
Note that this macro is still in early stages of development, so error messages aren't great yet and all functionality isn't supported yet.
Missing features
Currently if the wasm module imports any symbols outside of the WASI namespace the module will not load. It's intended that support for this will be added soon though!