118 lines
4.0 KiB
Markdown
118 lines
4.0 KiB
Markdown
<div align="center">
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<h1><code>wasip2</code></h1>
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<strong>A <a href="https://bytecodealliance.org/">Bytecode Alliance</a> project</strong>
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<p>
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<strong>WASIp2 API Bindings for Rust</strong>
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</p>
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<p>
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<a href="https://crates.io/crates/wasip2"><img src="https://img.shields.io/crates/v/wasip2.svg?style=flat-square" alt="Crates.io version" /></a>
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<a href="https://crates.io/crates/wasip2"><img src="https://img.shields.io/crates/d/wasip2.svg?style=flat-square" alt="Download" /></a>
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<a href="https://docs.rs/wasip2/"><img src="https://img.shields.io/badge/docs-latest-blue.svg?style=flat-square" alt="docs.rs docs" /></a>
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</p>
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</div>
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This crate contains bindings for [WASIp2](https://github.com/WebAssembly/WASI)
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APIs for the worlds:
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* [`wasi:cli/command`]
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* [`wasi:http/proxy`]
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This crate is procedurally generated from [WIT] files using [`wit-bindgen`].
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[`wasi:cli/command`]: https://github.com/WebAssembly/wasi-cli
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[`wasi:http/proxy`]: https://github.com/WebAssembly/wasi-http
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[WIT]: https://component-model.bytecodealliance.org/design/wit.html
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[`wit-bindgen`]: https://github.com/bytecodealliance/wit-bindgen
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[components]: https://component-model.bytecodealliance.org/
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[`wasm-tools`]: https://github.com/bytecodealliance/wasm-tools
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# Usage
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Depending on this crate can be done by adding it to your dependencies:
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```sh
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$ cargo add wasip2
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```
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Next you can use the APIs in the root of the module like so:
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```rust
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fn main() {
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let stdout = wasip2::cli::stdout::get_stdout();
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stdout.blocking_write_and_flush(b"Hello, world!\n").unwrap();
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}
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```
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This crate can currently be used in three main ways.
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- One is to use it and compile for the [`wasm32-wasip2` target] in Rust 1.82 and later.
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this is the simplest approach, as all the tools needed are included in the
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Rust tooling, however it doesn't yet support some of the features of the
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other approaches.
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- Another is to use it and compile using [`cargo component`]. This is essentially
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the same as the next option, except that `cargo component` handles most of the
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steps for you. `cargo component` also has a number of additional features for
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working with dependencies and custom WIT interfaces.
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- And the third is to compile for the `wasm32-wasip1` target, and then adapt
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the resulting modules into component using `wasm-tools component new`; see
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the next section here for details.
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[`wasm32-wasip2` target]: https://blog.rust-lang.org/2024/11/26/wasip2-tier-2.html
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[`cargo component`]: https://github.com/bytecodealliance/cargo-component
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## Building with wasm32-wasip1 and `cargo component new`.
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The `wasm32-wasip2` target works with a simple `cargo build --target wasm32-wasip2`
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and doesn't need a lot of documentation here, and `cargo component` has its own
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documentation, so here we have some documentation for the `wasm32-wasip1` way.
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```
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$ cargo build --target wasm32-wasip1
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```
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Next you'll want an "adapter" to convert the Rust standard library's usage of
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`wasi_snapshot_preview1` to the component model. An example adapter can be found
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from [Wasmtime's release page](https://github.com/bytecodealliance/wasmtime/releases/download/v17.0.0/wasi_snapshot_preview1.command.wasm).
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```
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$ curl -LO https://github.com/bytecodealliance/wasmtime/releases/download/v17.0.0/wasi_snapshot_preview1.command.wasm
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```
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Next to create a component you'll use the [`wasm-tools`] CLI to create a
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component:
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```
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$ cargo install wasm-tools
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$ wasm-tools component new target/wasm32-wasip1/debug/foo.wasm \
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--adapt ./wasi_snapshot_preview1.command.wasm \
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-o component.wasm
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```
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And finally the component can be run by a runtime that has Component Model
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support, such as [Wasmtime]:
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```
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$ wasmtime run component.wasm
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Hello, world!
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```
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[Wasmtime]: https://github.com/bytecodealliance/wasmtime
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# Development
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The bulk of the `wasip2` crate is generated by the [`wit-bindgen`] tool. The
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`src/bindings.rs` file can be regenerated with:
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```
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$ ./ci/regenerate.sh
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```
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WASI definitions are located in the `wit` directory of this repository.
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Currently they're copied from upstream repositories but are hoped to be better
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managed in the future.
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