Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/wasi-common/README.md

@@ -0,0 +1,63 @@
+# wasi-common
+
+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][lucet-wasi-tracker] git revision.
+
+Please note that the library requires Rust compiler version at least 1.37.0.
+
+[Wasmtime]: https://github.com/CraneStation/wasmtime
+[Lucet]: https://github.com/fastly/lucet
+[lucet-wasi]: https://github.com/fastly/lucet/tree/master/lucet-wasi
+[lucet-wasi-tracker]: https://github.com/fastly/lucet/commit/40ae1df64536250a2b6ab67e7f167d22f4aa7f94
+
+## Supported syscalls
+
+### *nix
+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.
+
+[WASI API]: https://github.com/CraneStation/wasmtime/blob/master/docs/WASI-api.md
+
+### Windows
+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
+```
+
+[rustup]: https://rustup.rs
+
+Next initiate submodules containing the integration testsuite
+
+```
+git submodule update --init
+```
+
+Now, you should be able to run the integration testsuite by enabling the `wasm_tests` feature
+
+```
+cargo test --features wasm_tests
+```
+
+## Third-Party Code
+Significant parts of our hostcall implementations are derived from the C implementations in
+`cloudabi-utils`. See [LICENSE.cloudabi-utils](LICENSE.cloudabi-utils) for license information.
+