aa78d491b0
This allows getN to return a detailed explanation of any type signature mismatch, and makes it easy to just use `?` on the result of getN rather than constructing a (necessarily vaguer) error message in the caller.
76 lines
2.3 KiB
Rust
76 lines
2.3 KiB
Rust
pub mod old;
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use wasi_common::hostcalls;
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pub use wasi_common::{WasiCtx, WasiCtxBuilder};
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// Defines a `struct Wasi` with member fields and appropriate APIs for dealing
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// with all the various WASI exports.
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wig::define_wasi_struct!(
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"snapshot" "wasi_snapshot_preview1"
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);
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pub fn is_wasi_module(name: &str) -> bool {
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// FIXME: this should be more conservative, but while WASI is in flux and
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// we're figuring out how to support multiple revisions, this should do the
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// trick.
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name.starts_with("wasi")
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}
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/// This is an internal structure used to acquire a handle on the caller's
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/// wasm memory buffer.
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///
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/// This exploits how we can implement `WasmTy` for ourselves locally even
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/// though crates in general should not be doing that. This is a crate in
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/// the wasmtime project, however, so we should be able to keep up with our own
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/// changes.
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///
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/// In general this type is wildly unsafe. We need to update the wasi crates to
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/// probably work with more `wasmtime`-like APIs to grip with the unsafety
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/// around dealing with caller memory.
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struct WasiCallerMemory {
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base: *mut u8,
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len: usize,
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}
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impl wasmtime::WasmTy for WasiCallerMemory {
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type Abi = ();
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fn push(_dst: &mut Vec<wasmtime::ValType>) {}
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fn matches(_tys: impl Iterator<Item = wasmtime::ValType>) -> anyhow::Result<()> {
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Ok(())
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}
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fn from_abi(vmctx: *mut wasmtime_runtime::VMContext, _abi: ()) -> Self {
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unsafe {
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match wasmtime_runtime::InstanceHandle::from_vmctx(vmctx).lookup("memory") {
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Some(wasmtime_runtime::Export::Memory {
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definition,
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vmctx: _,
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memory: _,
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}) => WasiCallerMemory {
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base: (*definition).base,
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len: (*definition).current_length,
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},
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_ => WasiCallerMemory {
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base: std::ptr::null_mut(),
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len: 0,
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},
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}
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}
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}
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fn into_abi(self) {}
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}
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impl WasiCallerMemory {
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unsafe fn get(&self) -> Result<&mut [u8], wasi_common::wasi::__wasi_errno_t> {
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if self.base.is_null() {
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Err(wasi_common::wasi::__WASI_ERRNO_INVAL)
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} else {
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Ok(std::slice::from_raw_parts_mut(self.base, self.len))
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}
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}
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}
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