mirror of
https://github.com/mii443/wasmer.git
synced 2025-12-09 22:28:21 +00:00
a419ccdf52
Co-authored-by: ptitSeb <sebastien.chev@gmail.com> Co-authored-by: Manos Pitsidianakis <manos@wasmer.io>
105 lines
4.0 KiB
Markdown
105 lines
4.0 KiB
Markdown
# `wasmer-wasi` [](https://github.com/wasmerio/wasmer/actions?query=workflow%3Abuild) [](https://slack.wasmer.io) [](https://github.com/wasmerio/wasmer/blob/master/LICENSE) [](https://crates.io/crates/wasmer-wasi)
|
|
|
|
This crate provides the necessary imports to use WASI easily from Wasmer.
|
|
[WebAssembly System Interface](https://github.com/WebAssembly/WASI)
|
|
(WASI for short) is a modular system interface for WebAssembly. WASI
|
|
is being standardized in the WebAssembly subgroup.
|
|
|
|
Very succinctly, from the user perspective, WASI is a set of
|
|
WebAssembly module _imports_ under a specific _namespace_ (which
|
|
varies based on the WASI version). A program compiled for the
|
|
`wasm32-wasi` target will be able to support standard I/O, file I/O,
|
|
filesystem manipulation, memory management, time, string, environment
|
|
variables, program startup etc.
|
|
|
|
This crate provides the necessary API to create the imports to use
|
|
WASI easily from the Wasmer runtime, through our `ImportObject` API.
|
|
|
|
## Supported WASI versions
|
|
|
|
| WASI version | Support |
|
|
|-|-|
|
|
| `wasi_unstable` | ✅ |
|
|
| `wasi_snapshot_preview1` | ✅ |
|
|
|
|
The special `Latest` version points to `wasi_snapshot_preview1`.
|
|
|
|
Learn more about [the WASI version
|
|
process](https://github.com/WebAssembly/WASI/tree/main/phases)
|
|
(ephemeral, snapshot, old).
|
|
|
|
## Usage
|
|
|
|
Let's consider the following `hello.rs` Rust program:
|
|
|
|
```rust
|
|
fn main() {
|
|
println!("Hello, {:?}", std::env::args().nth(1));
|
|
}
|
|
```
|
|
|
|
Then, let's compile it to a WebAssembly module with WASI support:
|
|
|
|
```sh
|
|
$ rustc --target wasm32-wasi hello.rs
|
|
```
|
|
|
|
Finally, let's execute it with the `wasmer` CLI:
|
|
|
|
```sh
|
|
$ wasmer run hello.wasm Gordon
|
|
Hello, Some("Gordon")
|
|
```
|
|
|
|
… and programatically with the `wasmer` and the `wasmer-wasi` libraries:
|
|
|
|
```rust
|
|
use wasmer::{Store, Module, Instance};
|
|
use wasmer_wasi::WasiState;
|
|
|
|
let mut store = Store::default();
|
|
let module = Module::from_file(&store, "hello.wasm")?;
|
|
|
|
// Create the `WasiEnv`.
|
|
let wasi_env = WasiState::new("command-name")
|
|
.args(&["Gordon"])
|
|
.finalize()?;
|
|
|
|
// Generate an `ImportObject`.
|
|
let mut wasi_thread = wasi_env.new_thread();
|
|
let import_object = wasi_thread.import_object(&module)?;
|
|
|
|
// Let's instantiate the module with the imports.
|
|
let instance = Instance::new(&module, &import_object)?;
|
|
|
|
// Let's call the `_start` function, which is our `main` function in Rust.
|
|
let start = instance.exports.get_function("_start")?;
|
|
start.call(&[])?;
|
|
```
|
|
|
|
Check the [fully working example using
|
|
WASI](https://github.com/wasmerio/wasmer/blob/master/examples/wasi.rs).
|
|
|
|
## More resources
|
|
|
|
This library is about the WASI implementation inside the Wasmer
|
|
runtime. It contains documentation about the implementation
|
|
itself. However, if you wish to learn more about WASI, here is a list
|
|
of links that may help you:
|
|
|
|
* [`wasi-libc`](https://github.com/WebAssembly/wasi-libc/), WASI libc
|
|
implementation for WebAssembly programs built on top of WASI system
|
|
calls. It provides a wide array of POSIX-compatible C APIs,
|
|
including support for standard I/O, file I/O, filesystem
|
|
manipulation, memory management, time, string, environment
|
|
variables, program startup, and many other APIs,
|
|
* [`wasi-sdk`](https://github.com/WebAssembly/wasi-sdk/), WASI-enabled
|
|
WebAssembly C/C++ toolchain, based on `wasi-libc`,
|
|
* [WASI API
|
|
documentation](https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/docs.md),
|
|
* [WASI C API header
|
|
file](https://github.com/WebAssembly/wasi-libc/blob/main/libc-bottom-half/headers/public/wasi/api.h),
|
|
* [WASI Application Binary Interface
|
|
(ABI)](https://github.com/WebAssembly/WASI/blob/main/legacy/application-abi.md),
|
|
where we learn about `_start` and `_initialize` (for _reactors_) for example.
|