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//! Running pre-compiled Wasm programs.
use wasmtime::{Config, Engine, Instance, Module, Result, Store};
fn main() -> Result<()> {
// Create the default configuration for this host platform. Note that this
// configuration must match the configuration used to pre-compile the Wasm
// program. We cannot run Wasm programs pre-compiled for configurations that
// do not match our own, therefore if you enabled or disabled any particular
// Wasm proposals or tweaked memory knobs when pre-compiling, you should
// make identical adjustments to this config.
let config = Config::default();
// Create an `Engine` with that configuration.
let engine = Engine::new(&config)?;
// Create a runtime `Module` from a Wasm program that was pre-compiled and
// written to the `add.cwasm` file by `wasmtime/examples/pre_compile.rs`.
//
// **Warning:** Wasmtime does not (and in general cannot) fully validate
// pre-compiled modules for safety -- only create `Module`s and `Component`s
// from pre-compiled bytes you control and trust! Passing unknown or
// untrusted bytes will lead to arbitrary code execution vulnerabilities in
// your system!
let module = match unsafe { Module::deserialize_file(&engine, "add.cwasm") } {
Ok(module) => module,
Err(error) => {
println!("failed to deserialize pre-compiled module: {error:?}");
return Ok(());
}
};
// Instantiate the module and invoke its `add` function!
let mut store = Store::new(&engine, ());
let instance = Instance::new(&mut store, &module, &[])?;
let add = instance.get_typed_func::<(i32, i32), i32>(&mut store, "add")?;
let sum = add.call(&mut store, (3, 8))?;
println!("the sum of 3 and 8 is {sum}");
Ok(())
}