2.9 KiB
This crate contains API bindings for 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:
[dependencies]
wasi = "0.8.0"
Next you can use the APIs in the root of the module like so:
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 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 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.