wasmtime_wasi/
error.rs

1use std::error::Error;
2use std::fmt;
3use std::marker;
4
5/// An error returned from the `proc_exit` host syscall.
6///
7/// Embedders can test if an error returned from wasm is this error, in which
8/// case it may signal a non-fatal trap.
9#[derive(Debug)]
10pub struct I32Exit(pub i32);
11
12impl fmt::Display for I32Exit {
13    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
14        write!(f, "Exited with i32 exit status {}", self.0)
15    }
16}
17
18impl std::error::Error for I32Exit {}
19
20/// A helper error type used by many other modules through type aliases.
21///
22/// This type is an `Error` itself and is intended to be a representation of
23/// either:
24///
25/// * A custom error type `T`
26/// * A trap, represented as `anyhow::Error`
27///
28/// This error is created through either the `::trap` constructor representing a
29/// full-fledged trap or the `From<T>` constructor which is intended to be used
30/// with `?`. The goal is to make normal errors `T` "automatic" but enable error
31/// paths to return a `::trap` error optionally still as necessary without extra
32/// boilerplate everywhere else.
33///
34/// Note that this type isn't used directly but instead is intended to be used
35/// as:
36///
37/// ```rust,ignore
38/// type MyError = TrappableError<bindgen::TheError>;
39/// ```
40///
41/// where `MyError` is what you'll use throughout bindings code and
42/// `bindgen::TheError` is the type that this represents as generated by the
43/// `bindgen!` macro.
44#[repr(transparent)]
45pub struct TrappableError<T> {
46    err: anyhow::Error,
47    _marker: marker::PhantomData<T>,
48}
49
50impl<T> TrappableError<T> {
51    pub fn trap(err: impl Into<anyhow::Error>) -> TrappableError<T> {
52        TrappableError {
53            err: err.into(),
54            _marker: marker::PhantomData,
55        }
56    }
57
58    pub fn downcast(self) -> anyhow::Result<T>
59    where
60        T: Error + Send + Sync + 'static,
61    {
62        self.err.downcast()
63    }
64
65    pub fn downcast_ref(&self) -> Option<&T>
66    where
67        T: Error + Send + Sync + 'static,
68    {
69        self.err.downcast_ref()
70    }
71}
72
73impl<T> From<T> for TrappableError<T>
74where
75    T: Error + Send + Sync + 'static,
76{
77    fn from(error: T) -> Self {
78        Self {
79            err: error.into(),
80            _marker: marker::PhantomData,
81        }
82    }
83}
84
85impl<T> fmt::Debug for TrappableError<T> {
86    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
87        self.err.fmt(f)
88    }
89}
90
91impl<T> fmt::Display for TrappableError<T> {
92    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
93        self.err.fmt(f)
94    }
95}
96
97impl<T> Error for TrappableError<T> {}
wasmtime_wasi/error.rs

wasmtime_wasi/
error.rs
