This commit deletes the old `snapshot_0` implementation of wasi-common, along with the `wig` crate that was used to generate bindings for it. This then reimplements `snapshot_0` in terms of `wasi_snapshot_preview1`. There were very few changes between the two snapshots: * The `nlink` field of `FileStat` was increased from 32 to 64 bits. * The `set` field of `whence` was reordered. * Clock subscriptions in polling dropped their redundant userdata field. This makes all of the syscalls relatively straightforward to simply delegate to the next snapshot's implementation. Some trickery happens to avoid extra cost when dealing with iovecs, but since the memory layout of iovecs remained the same this should still work. Now that `snapshot_0` is using wiggle we simply have a trait to implement, and that's implemented for the same `WasiCtx` that has the `wasi_snapshot_preview1` trait implemented for it as well. While this theoretically means that you could share the file descriptor table between the two snapshots that's not supported in the generated bindings just yet. A separate `WasiCtx` will be created for each WASI module.
wasi-common
A Bytecode Alliance project
A library providing a common implementation of WASI hostcalls for re-use in any WASI-enabled runtime.
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
*nix
In our *nix implementation, we currently support the entire WASI API with the exception of socket hostcalls:
sock_recvsock_sendsock_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.
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
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
Third-Party Code
Significant parts of our hostcall implementations are derived from the C implementations in
cloudabi-utils. See LICENSE.cloudabi-utils for license information.