wasmtime/
runtime.rs

1// Wasmtime's runtime has lots of fiddly bits where we're doing operations like
2// casting between wasm i32/i64 and host `usize` values. There's also in general
3// just lots of pieces of low-level manipulation of memory and internals of VM
4// runtime state. To help keep all the integer casts correct be a bit more
5// strict than the default settings to help weed out bugs ahead of time.
6//
7// This inevitably leads to wordier code than might otherwise be used because,
8// for example, `u64 as usize` is warned against and will be an error on CI.
9// This happens pretty frequently and needs to be replaced with `val.try_into()`
10// or `usize::try_from(val)` where the error is handled. In some cases the
11// correct thing to do is to `.unwrap()` the error to indicate a fatal mistake,
12// but in some cases the correct thing is to propagate the error.
13//
14// Some niche cases that explicitly want truncation are recommended to have a
15// function along the lines of
16//
17//     #[allow(clippy::cast_possible_truncation)]
18//     fn truncate_i32_to_i8(a: i32) -> i8 { a as i8 }
19//
20// as this explicitly indicates the intent of truncation is desired. Other
21// locations should use fallible conversions.
22//
23// If performance is absolutely critical then it's recommended to use `#[allow]`
24// with a comment indicating why performance is critical as well as a short
25// explanation of why truncation shouldn't be happening at runtime. This
26// situation should be pretty rare though.
27#![warn(clippy::cast_possible_truncation)]
28
29use crate::prelude::*;
30use core::marker;
31use core::pin::Pin;
32use core::task::{Context, Poll};
33
34mod bug;
35
36#[macro_use]
37pub(crate) mod func;
38
39pub(crate) mod code;
40pub(crate) mod code_memory;
41#[cfg(feature = "debug")]
42pub(crate) mod debug;
43pub(crate) mod exception;
44pub(crate) mod externals;
45#[cfg(feature = "async")]
46pub(crate) mod fiber;
47pub(crate) mod gc;
48pub(crate) mod instance;
49pub(crate) mod instantiate;
50pub(crate) mod limits;
51pub(crate) mod linker;
52pub(crate) mod memory;
53pub(crate) mod module;
54#[cfg(feature = "debug-builtins")]
55pub(crate) mod native_debug;
56pub(crate) mod resources;
57pub(crate) mod store;
58pub(crate) mod trampoline;
59pub(crate) mod trap;
60#[cfg(feature = "component-model-async")]
61pub(crate) mod try_mutex;
62pub(crate) mod type_registry;
63pub(crate) mod types;
64pub(crate) mod v128;
65pub(crate) mod values;
66pub(crate) mod vm;
67
68#[cfg(feature = "component-model")]
69pub mod component;
70
71cfg_if::cfg_if! {
72    if #[cfg(miri)] {
73        // no extensions on miri
74    } else if #[cfg(not(feature = "std"))] {
75        // no extensions on no-std
76    } else if #[cfg(unix)] {
77        pub mod unix;
78    } else if #[cfg(windows)] {
79        pub mod windows;
80    } else {
81        // ... unknown os!
82    }
83}
84
85pub use bug::WasmtimeBug;
86pub(crate) use bug::{bail_bug, bug};
87pub use code_memory::CodeMemory;
88#[cfg(feature = "debug")]
89pub use debug::*;
90pub use exception::*;
91pub use externals::*;
92pub use func::*;
93pub use gc::*;
94pub use instance::{Instance, InstancePre};
95pub use instantiate::CompiledModule;
96pub use limits::*;
97pub use linker::*;
98pub use memory::*;
99pub use module::{Module, ModuleExport, ModuleFunction};
100pub use resources::*;
101#[cfg(all(feature = "async", feature = "call-hook"))]
102pub use store::CallHookHandler;
103pub use store::{
104    AsContext, AsContextMut, CallHook, Store, StoreContext, StoreContextMut, UpdateDeadline,
105};
106pub use trap::*;
107pub use types::*;
108pub use v128::V128;
109pub use values::*;
110
111#[cfg(feature = "pooling-allocator")]
112pub use vm::{PoolConcurrencyLimitError, PoolingAllocatorMetrics};
113
114#[cfg(feature = "profiling")]
115mod profiling;
116#[cfg(feature = "profiling")]
117pub use profiling::GuestProfiler;
118
119#[cfg(feature = "async")]
120pub(crate) mod stack;
121#[cfg(feature = "async")]
122pub use stack::*;
123
124#[cfg(feature = "coredump")]
125mod coredump;
126#[cfg(feature = "coredump")]
127pub use coredump::*;
128
129#[cfg(feature = "wave")]
130mod wave;
131
132/// Helper method to create a future trait object from the future `F` provided.
133///
134/// This requires that the output of `F` is a result where the error can be
135/// created from `OutOfMemory`. This will handle OOM when allocation of `F` on
136/// the heap fails.
137fn box_future<'a, F, T, E>(future: F) -> Pin<Box<dyn Future<Output = Result<T, E>> + Send + 'a>>
138where
139    F: Future<Output = Result<T, E>> + Send + 'a,
140    T: 'a,
141    E: From<OutOfMemory> + 'a,
142{
143    if let Ok(future) = try_new::<Box<F>>(future) {
144        return Pin::from(future);
145    }
146
147    // Use a custom guaranteed-zero-size struct to implement a future that
148    // returns an OOM error which satisfies the type signature of this function.
149    struct OomFuture<F, T, E>(marker::PhantomData<fn() -> (T, F, E)>);
150
151    impl<F, T, E> Future for OomFuture<F, T, E>
152    where
153        E: From<OutOfMemory>,
154    {
155        type Output = Result<T, E>;
156
157        fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Self::Output> {
158            Poll::Ready(Err(OutOfMemory::new(size_of::<F>()).into()))
159        }
160    }
161
162    // Zero-size allocations don't actually allocate memory with a `Box`, so
163    // it's ok to use the standard `Box::pin` here and not worry about OOM.
164    let future = OomFuture::<F, T, E>(marker::PhantomData);
165    assert_eq!(size_of_val(&future), 0);
166    Box::pin(future)
167}
168
169fn _assertions_runtime() {
170    use crate::_assert_send_and_sync;
171
172    #[cfg(feature = "async")]
173    fn _assert_send<T: Send>(_t: T) {}
174
175    _assert_send_and_sync::<Caller<'_, ()>>();
176    _assert_send_and_sync::<ExternRef>();
177    _assert_send_and_sync::<(Func, TypedFunc<(), ()>, Global, Table, Memory)>();
178    _assert_send_and_sync::<Instance>();
179    _assert_send_and_sync::<InstancePre<()>>();
180    _assert_send_and_sync::<InstancePre<*mut u8>>();
181    _assert_send_and_sync::<Linker<()>>();
182    _assert_send_and_sync::<Linker<*mut u8>>();
183    _assert_send_and_sync::<Module>();
184    _assert_send_and_sync::<Store<()>>();
185    _assert_send_and_sync::<StoreContext<'_, ()>>();
186    _assert_send_and_sync::<StoreContextMut<'_, ()>>();
187
188    #[cfg(feature = "async")]
189    fn _call_async(s: &mut Store<()>, f: Func) {
190        _assert_send(f.call_async(&mut *s, &[], &mut []))
191    }
192    #[cfg(feature = "async")]
193    fn _typed_call_async(s: &mut Store<()>, f: TypedFunc<(), ()>) {
194        _assert_send(f.call_async(&mut *s, ()))
195    }
196    #[cfg(feature = "async")]
197    fn _instantiate_async(s: &mut Store<()>, m: &Module) {
198        _assert_send(Instance::new_async(s, m, &[]))
199    }
200}
wasmtime/runtime.rs

wasmtime/
runtime.rs
