cc4be18119
This commit uses the `*.witx` files describing the current wasi API to reduce the boilerplate used to define implementations in the `wasmtime-wasi` crate. Eventually I'd like to remove lots of boilerplate in the `wasi-common` crate too, but this should at least be a good start! The boilerplate removed here is: * No need to list each function to add it to the `wasmtime_runtime::Module` being created * No need to list the signature of the function in a separate `syscalls.rs` file. Instead the `*.witx` file is processed in a single-use macro inside the `wasmtime-wasi` crate. This macro uses the signatures known from `*.witx` to automatically register with the right type in the wasm module as well as define a wrapper that the wasm module will call into. Functionally this is all the same as before, it's just defined in a different way now! The shim generated by this macro which wasmtime calls into only uses `i32`/`i64`/etc wasm types, and it internally uses `as` casts to convert to the right wasi types when delegating into the `wasi-common` crate. One change was necessary to get this implemented, however. The functions in `wasi-common` sometimes took `WasiCtx` and sometimes took a slice of memory. After this PR they uniformly all require both `WasiCtx` and memory so the wrappers can be auto-generated. The arguments are ignored if they weren't previously required.
This is the wasmtime-wasi crate, which implements the
WebAssembly System Interface (WASI) API in Rust.
WASI is greatly inspired by and directly derived from CloudABI. It differs in that it has aspirations to expand to a greater scope, and to better support the needs of WebAssembly engines.