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//! Example of instantiating a wasm module which uses WASI preview1 imports
//! implemented through the async preview2 WASI implementation.
/*
You can execute this example with:
cmake examples/
cargo run --example wasi-async
*/
use anyhow::Result;
use wasmtime::{Config, Engine, Linker, Module, Store};
use wasmtime_wasi::preview1::{self, WasiP1Ctx};
use wasmtime_wasi::WasiCtxBuilder;
#[tokio::main]
async fn main() -> Result<()> {
// Construct the wasm engine with async support enabled.
let mut config = Config::new();
config.async_support(true);
let engine = Engine::new(&config)?;
// Add the WASI preview1 API to the linker (will be implemented in terms of
// the preview2 API)
let mut linker: Linker<WasiP1Ctx> = Linker::new(&engine);
preview1::add_to_linker_async(&mut linker, |t| t)?;
// Add capabilities (e.g. filesystem access) to the WASI preview2 context
// here. Here only stdio is inherited, but see docs of `WasiCtxBuilder` for
// more.
let wasi_ctx = WasiCtxBuilder::new().inherit_stdio().build_p1();
let mut store = Store::new(&engine, wasi_ctx);
// Instantiate our 'Hello World' wasm module.
// Note: This is a module built against the preview1 WASI API.
let module = Module::from_file(&engine, "target/wasm32-wasip1/debug/wasi.wasm")?;
let func = linker
.module_async(&mut store, "", &module)
.await?
.get_default(&mut store, "")?
.typed::<(), ()>(&store)?;
// Invoke the WASI program default function.
func.call_async(&mut store, ()).await?;
Ok(())
}
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