wasmtime/runtime/vm/
store_box.rs

1use crate::error::OutOfMemory;
2use crate::prelude::*;
3use crate::runtime::vm::SendSyncPtr;
4use core::ptr::NonNull;
5
6/// A `Box<T>` lookalike for memory that's stored in a `Store<T>`
7///
8/// This is intended to be quite similar to a `Box<T>` except without the
9/// `Deref` implementations. The main motivation for this type's existence is to
10/// appease the aliasing rules in miri to ensure that `StoreBox` can be moved
11/// around without invalidating pointers to the contents within the box. The
12/// standard `Box<T>` type does not implement this for example and moving that
13/// will invalidate derived pointers.
14pub struct StoreBox<T: ?Sized>(SendSyncPtr<T>);
15
16impl<T> StoreBox<T> {
17    /// Allocates space on the heap to store `val` and returns a pointer to it
18    /// living on the heap.
19    pub fn new(val: T) -> Result<StoreBox<T>, OutOfMemory> {
20        let ptr = Box::into_raw(try_new(val)?);
21        Ok(StoreBox(SendSyncPtr::from(NonNull::new(ptr).unwrap())))
22    }
23}
24
25impl<T: ?Sized> StoreBox<T> {
26    /// Returns the underlying pointer to `T` which is owned by the store.
27    pub fn get(&self) -> NonNull<T> {
28        self.0.as_non_null()
29    }
30}
31
32impl<T: ?Sized> Drop for StoreBox<T> {
33    fn drop(&mut self) {
34        unsafe {
35            drop(Box::from_raw(self.0.as_ptr()));
36        }
37    }
38}
wasmtime/runtime/vm/store_box.rs

wasmtime/runtime/vm/
store_box.rs
