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Uses new Rust 2021

0.39.1 Jul 21, 2022
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0.35.2 Mar 31, 2022
0.32.0 Dec 13, 2021
0.0.0 Jul 18, 2019

#735 in WebAssembly

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Used in 40 crates (14 directly)

Apache-2.0 WITH LLVM-exception

4.5K SLoC


A Bytecode Alliance project

A library providing a common implementation of WASI hostcalls for re-use in any WASI-enabled runtime.

Crates.io version Download docs.rs docs

The wasi-common crate will ultimately serve as a library providing a common implementation of WASI hostcalls for re-use in any WASI (and potentially non-WASI) runtimes such as Wasmtime and Lucet.

The library is an adaption of lucet-wasi crate from the Lucet project, and it is currently based on 40ae1df git revision.

Please note that the library requires Rust compiler version at least 1.37.0.

Supported syscalls


In our *nix implementation, we currently support the entire WASI API with the exception of socket hostcalls:

  • sock_recv
  • sock_send
  • sock_shutdown

We expect these to be implemented when network access is standardised.

We also currently do not support the proc_raise hostcall, as it is expected to be dropped entirely from WASI.


In our Windows implementation, we currently support the minimal subset of WASI API which allows for running the very basic "Hello world!" style WASM apps. More coming shortly, so stay tuned!

Development hints

When testing the crate, you may want to enable and run full wasm32 integration testsuite. This requires wasm32-wasi target installed which can be done as follows using rustup

rustup target add wasm32-wasi

Now, you should be able to run the integration testsuite by running cargo test on the test-programs package with test-programs/test_programs feature enabled:

cargo test --features test-programs/test_programs --package test-programs


~224K SLoC