Workers WASI

$3

An experimental implementation of the WebAssembly System Interface designed to run on Cloudflare Workers

Usage

``typescript
import { WASI } from '@cloudflare/workers-wasi';
import mywasm from './mywasm.wasm';

const wasi = new WASI();
const instance = new WebAssembly.Instance(mywasm, {
wasi_snapshot_preview1: wasi.wasiImport
});

await wasi.start(instance);
`



Development


Install Rust and nvm then run
`
nvm use --lts
`
Build and test

`
git clone --recursive git@github.com:cloudflare/workers-wasi.git
cd ./workers-wasi
make -j test
`

Build with Docker

`
git clone --recursive git@github.com:cloudflare/workers-wasi.git
cd ./workers-wasi
cat ./Dockerfile | docker build -t workers-wasi-build -
docker run --rm -it -v $(pwd):/workers-wasi workers-wasi-build
`

Testing

We aim to be interchangeable with other WASI implementations. Integration tests are run locally using Miniflare against the following test suites:
- [x] (52/52) https://github.com/caspervonb/wasi-test-suite
- [ ] (28/42) https://github.com/bytecodealliance/wasmtime/tree/main/crates/test-programs/wasi-tests

Notes

An ephemeral filesystem implementation built on littlefs is included.
Both soft and hard links are not yet supported.

The following syscalls are not yet supported and return ENOSYS
- fd_readdir
- path_link
- path_readlink
- path_symlink
- poll_oneoff
- sock_recv
- sock_send
- sock_shutdown

Timestamps are captured using Date.now() which has unique behavior on the Workers platform for security reasons. This affects the implementation of
- clock_res_get
- clock_time_get
- fd_filestat_set_times
- path_filestat_set_times`

TODO (remove)

Misc TODO:
- [ ] path_rename (update old path for existing open fds)
- [ ] fix preopens interface (use object), and update options docs
- [ ] document difference between nodejs options and ours (streams/fs)
- [ ] fd_close (stdio)
- [ ] fd_renumber (stdio)
- [ ] fd_read/fd_write does not work with renumbering stdio
- [ ] update file timestamps appropriately