wasi-virt-layer

WASI Virtual Layer is a virtual file system layer for WebAssembly System Interface (WASI) modules. It allows you to run WASI modules with a virtual file system that can be customized and extended.

example usage

0. Install the CLI tool with

cargo binstall wasi_virt_layer-cli

1. Prepare a WebAssembly module built for wasip1 (e.g. wasm32-wasip1 or wasm32-wasip1-threads).
2. Create a new virtual filesystem (VFS) project with

wasi_virt_layer new my_vfs_project

This will automatically set up Cargo.toml with crate-type = ["cdylib"] and the necessary dependencies (wasi_virt_layer, wit-bindgen), as well as a basic wit directory and template source code. 3. Edit your VFS implementation. Use the import_wasm! macro to prepare for using the target wasm module. 4. Use the plug! macro series (plug_process!, plug_env!, plug_fs!, etc.) to connect to the wasip1 ABI, and link virtual filesystems or virtual environment variables. 5. Run the build command

wasi_virt_layer build <wasm_path>

to execute the virtualization process. Note: use -p <package_name> if your VFS project is part of a workspace. 6. The built files (including the transpiled JavaScript if applicable) will be generated in the dist directory. 7. Run it with Deno or Node.js:

deno run dist/test_run.ts

or start a static server and open test_run.html in your browser.

As a component

By using plug! to block all WASIp1 ABIs and creating the ABI solely with wit-bindgen, it is entirely possible to treat it as a component. However, wasip1-threads is not supported as per the specification. For further details, please refer to the example.

TODO!

• Support non-binary Wasm modules
• Enable specifying multiple Wasm modules
• Support self is not passed in plug_thread!
• Support self binary
• support flush sync to file system
• Fake global allocator and center allocator and merge with vfs
• Access Time Trait
• Multiple lfs file system (VFS)
• Static file system
• Feature Access time etc traits
• Separate mode (connect function by javascript)
• threading vfs with non threading wasm
• validator with error on threads
• Unicode support
• Async wit support

run example

cargo r -r -- -p example_vfs examples/test_wasm/example/test_wasm_opt.wasm
cargo r -r -- -p threads_vfs test_threads -t single --threads true

cannot

• support wasm-bindgen because it cannot use wasi

non goal

goal

development

install cargo binstall cargo-nextest -y install deno

• cargo nextest run -r --fail-fast

メモ

cargo r -- -p threads_vfs test_threads -t multi --threads true _resetなしだとsingleもmultiも成功

    test_threads::_reset();
    test_threads::_start();
    test_threads::_main();

だとmultiで成功。singleでunreacable

ここら辺もテストに追加 build target dirのキャッシュ(--no-cache) 同時実行対策 超絶長い引数で失敗するかも 自分自身を呼び出す（フォールバック）

色んなスレッド作成の順番での失敗か

single_memory failed multi_memory OK VFS -> Body

success Body -> Body

success VFS -> VFS