`wasi`

A Bytecode Alliance project

WASI API Bindings for Rust

This crate contains API bindings for [WASI](https://github.com/WebAssembly/WASI) system calls in Rust, and currently reflects the `wasi_snapshot_preview1` module. This crate is quite low-level and provides conceptually a "system call" interface. In most settings, it's better to use the Rust standard library, which has WASI support. The `wasi` crate is also entirely procedurally generated from the `*.witx` files describing the WASI apis. While some conveniences are provided the bindings here are intentionally low-level! # Usage First you can depend on this crate via `Cargo.toml`: ```toml [dependencies] wasi = "0.8.0" ``` Next you can use the APIs in the root of the module like so: ```rust fn main() { let stdout = 1; let message = "Hello, World!\n"; let data = [wasi::Ciovec { buf: message.as_ptr(), buf_len: message.len(), }]; wasi::fd_write(stdout, &data).unwrap(); } ``` Next you can use a tool like [`cargo wasi`](https://github.com/bytecodealliance/cargo-wasi) to compile and run your project: To compile Rust projects to wasm using WASI, use the `wasm32-wasi` target, like this: ``` $ cargo wasi run Compiling wasi v0.8.0+wasi-snapshot-preview1 Compiling wut v0.1.0 (/code) Finished dev [unoptimized + debuginfo] target(s) in 0.34s Running `/.cargo/bin/cargo-wasi target/wasm32-wasi/debug/wut.wasm` Running `target/wasm32-wasi/debug/wut.wasm` Hello, World! ``` # Development The bulk of the `wasi` crate is generated by the `witx-bindgen` tool, which lives at `crates/witx-bindgen` and is part of the cargo workspace. The `src/lib_generated.rs` file can be re-generated with the following command: ``` cargo run -p witx-bindgen -- crates/witx-bindgen/WASI/phases/snapshot/witx/wasi_snapshot_preview1.witx > src/lib_generated.rs ``` Note that this uses the WASI standard repository as a submodule. If you do not have this submodule present in your source tree, run: ``` git submodule update --init ``` # License This project is licensed under the Apache 2.0 license with the LLVM exception. See [LICENSE](LICENSE) for more details. ### Contribution Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.