wasmtime_c_api/
store.rs

1use crate::{ForeignData, wasm_engine_t, wasmtime_error_t, wasmtime_val_t};
2use std::cell::UnsafeCell;
3use std::ffi::c_void;
4use std::sync::Arc;
5use wasmtime::{
6    AsContext, AsContextMut, Caller, Store, StoreContext, StoreContextMut, StoreLimits,
7    StoreLimitsBuilder, UpdateDeadline, Val,
8};
9
10// Store-related type aliases for `wasm.h` APIs. Not for use with `wasmtime.h`
11// APIs!
12pub type WasmStoreData = ();
13pub type WasmStore = Store<WasmStoreData>;
14pub type WasmStoreContext<'a> = StoreContext<'a, WasmStoreData>;
15pub type WasmStoreContextMut<'a> = StoreContextMut<'a, WasmStoreData>;
16
17/// This representation of a `Store` is used to implement the `wasm.h` API (and
18/// *not* the `wasmtime.h` API!)
19///
20/// This is stored alongside `Func` and such for `wasm.h` so each object is
21/// independently owned. The usage of `Arc` here is mostly to just get it to be
22/// safe to drop across multiple threads, but otherwise acquiring the `context`
23/// values from this struct is considered unsafe due to it being unknown how the
24/// aliasing is working on the C side of things.
25///
26/// The aliasing requirements are documented in the C API `wasm.h` itself (at
27/// least Wasmtime's implementation).
28#[derive(Clone)]
29pub struct WasmStoreRef {
30    store: Arc<UnsafeCell<WasmStore>>,
31}
32
33impl WasmStoreRef {
34    pub unsafe fn context(&self) -> WasmStoreContext<'_> {
35        (*self.store.get()).as_context()
36    }
37
38    pub unsafe fn context_mut(&mut self) -> WasmStoreContextMut<'_> {
39        (*self.store.get()).as_context_mut()
40    }
41}
42
43#[repr(C)]
44#[derive(Clone)]
45pub struct wasm_store_t {
46    pub(crate) store: WasmStoreRef,
47}
48
49wasmtime_c_api_macros::declare_own!(wasm_store_t);
50
51#[unsafe(no_mangle)]
52pub extern "C" fn wasm_store_new(engine: &wasm_engine_t) -> Box<wasm_store_t> {
53    let engine = &engine.engine;
54    let store = Store::new(engine, ());
55    Box::new(wasm_store_t {
56        store: WasmStoreRef {
57            store: Arc::new(UnsafeCell::new(store)),
58        },
59    })
60}
61
62// Store-related type aliases for `wasmtime.h` APIs. Not for use with `wasm.h`
63// APIs!
64pub type WasmtimeStore = Store<WasmtimeStoreData>;
65pub type WasmtimeStoreContext<'a> = StoreContext<'a, WasmtimeStoreData>;
66pub type WasmtimeStoreContextMut<'a> = StoreContextMut<'a, WasmtimeStoreData>;
67pub type WasmtimeCaller<'a> = Caller<'a, WasmtimeStoreData>;
68
69/// Representation of a `Store` for `wasmtime.h` This notably tries to move more
70/// burden of aliasing on the caller rather than internally, allowing for a more
71/// raw representation of contexts and such that requires less `unsafe` in the
72/// implementation.
73///
74/// Note that this notably carries `WasmtimeStoreData` as a payload which allows
75/// storing foreign data and configuring WASI as well.
76#[repr(C)]
77pub struct wasmtime_store_t {
78    pub(crate) store: WasmtimeStore,
79}
80
81wasmtime_c_api_macros::declare_own!(wasmtime_store_t);
82
83pub struct WasmtimeStoreData {
84    foreign: crate::ForeignData,
85    #[cfg(feature = "wasi")]
86    pub(crate) wasi: Option<wasmtime_wasi::p1::WasiP1Ctx>,
87
88    /// Temporary storage for usage during a wasm->host call to store values
89    /// in a slice we pass to the C API.
90    pub hostcall_val_storage: Vec<wasmtime_val_t>,
91
92    /// Temporary storage for usage during host->wasm calls, same as above but
93    /// for a different direction.
94    pub wasm_val_storage: Vec<Val>,
95
96    /// Limits for the store.
97    pub store_limits: StoreLimits,
98
99    #[cfg(feature = "component-model")]
100    pub(crate) resource_table: wasmtime::component::ResourceTable,
101
102    #[cfg(all(feature = "component-model", feature = "wasi"))]
103    pub(crate) wasip2: Option<wasmtime_wasi::WasiCtx>,
104}
105
106#[cfg(all(feature = "component-model", feature = "wasi"))]
107impl wasmtime_wasi::WasiView for WasmtimeStoreData {
108    fn ctx(&mut self) -> wasmtime_wasi::WasiCtxView<'_> {
109        wasmtime_wasi::WasiCtxView {
110            ctx: self.wasip2.as_mut().unwrap(),
111            table: &mut self.resource_table,
112        }
113    }
114}
115
116#[unsafe(no_mangle)]
117pub extern "C" fn wasmtime_store_new(
118    engine: &wasm_engine_t,
119    data: *mut c_void,
120    finalizer: Option<extern "C" fn(*mut c_void)>,
121) -> Box<wasmtime_store_t> {
122    Box::new(wasmtime_store_t {
123        store: Store::new(
124            &engine.engine,
125            WasmtimeStoreData {
126                foreign: ForeignData { data, finalizer },
127                #[cfg(feature = "wasi")]
128                wasi: None,
129                hostcall_val_storage: Vec::new(),
130                wasm_val_storage: Vec::new(),
131                store_limits: StoreLimits::default(),
132                #[cfg(feature = "component-model")]
133                resource_table: wasmtime::component::ResourceTable::default(),
134                #[cfg(all(feature = "component-model", feature = "wasi"))]
135                wasip2: None,
136            },
137        ),
138    })
139}
140
141pub type wasmtime_update_deadline_kind_t = u8;
142pub const WASMTIME_UPDATE_DEADLINE_CONTINUE: wasmtime_update_deadline_kind_t = 0;
143pub const WASMTIME_UPDATE_DEADLINE_YIELD: wasmtime_update_deadline_kind_t = 1;
144
145#[unsafe(no_mangle)]
146pub extern "C" fn wasmtime_store_epoch_deadline_callback(
147    store: &mut wasmtime_store_t,
148    func: extern "C" fn(
149        WasmtimeStoreContextMut<'_>,
150        *mut c_void,
151        *mut u64,
152        *mut wasmtime_update_deadline_kind_t,
153    ) -> Option<Box<wasmtime_error_t>>,
154    data: *mut c_void,
155    finalizer: Option<extern "C" fn(*mut c_void)>,
156) {
157    let foreign = crate::ForeignData { data, finalizer };
158    store.store.epoch_deadline_callback(move |mut store_ctx| {
159        let _ = &foreign; // Move foreign into this closure
160        let mut delta: u64 = 0;
161        let mut kind = WASMTIME_UPDATE_DEADLINE_CONTINUE;
162        let result = (func)(
163            store_ctx.as_context_mut(),
164            foreign.data,
165            &mut delta as *mut u64,
166            &mut kind as *mut wasmtime_update_deadline_kind_t,
167        );
168        match result {
169            Some(err) => Err((*err).into()),
170            None if kind == WASMTIME_UPDATE_DEADLINE_CONTINUE => {
171                Ok(UpdateDeadline::Continue(delta))
172            }
173            #[cfg(feature = "async")]
174            None if kind == WASMTIME_UPDATE_DEADLINE_YIELD => Ok(UpdateDeadline::Yield(delta)),
175            _ => panic!("unknown wasmtime_update_deadline_kind_t: {kind}"),
176        }
177    });
178}
179
180#[unsafe(no_mangle)]
181pub extern "C" fn wasmtime_store_context(
182    store: &mut wasmtime_store_t,
183) -> WasmtimeStoreContextMut<'_> {
184    store.store.as_context_mut()
185}
186
187#[unsafe(no_mangle)]
188pub extern "C" fn wasmtime_store_limiter(
189    store: &mut wasmtime_store_t,
190    memory_size: i64,
191    table_elements: i64,
192    instances: i64,
193    tables: i64,
194    memories: i64,
195) {
196    let mut limiter = StoreLimitsBuilder::new();
197    if memory_size >= 0 {
198        limiter = limiter.memory_size(memory_size as usize);
199    }
200    if table_elements >= 0 {
201        limiter = limiter.table_elements(table_elements as usize);
202    }
203    if instances >= 0 {
204        limiter = limiter.instances(instances as usize);
205    }
206    if tables >= 0 {
207        limiter = limiter.tables(tables as usize);
208    }
209    if memories >= 0 {
210        limiter = limiter.memories(memories as usize);
211    }
212    store.store.data_mut().store_limits = limiter.build();
213    store.store.limiter(|data| &mut data.store_limits);
214}
215
216#[unsafe(no_mangle)]
217pub extern "C" fn wasmtime_context_get_data(store: WasmtimeStoreContext<'_>) -> *mut c_void {
218    store.data().foreign.data
219}
220
221#[unsafe(no_mangle)]
222pub extern "C" fn wasmtime_context_set_data(
223    mut store: WasmtimeStoreContextMut<'_>,
224    data: *mut c_void,
225) {
226    store.data_mut().foreign.data = data;
227}
228
229#[cfg(feature = "wasi")]
230#[unsafe(no_mangle)]
231pub extern "C" fn wasmtime_context_set_wasi(
232    mut context: WasmtimeStoreContextMut<'_>,
233    wasi: Box<crate::wasi_config_t>,
234) -> Option<Box<wasmtime_error_t>> {
235    crate::handle_result(wasi.into_wasi_ctx(), |wasi| {
236        context.data_mut().wasi = Some(wasi);
237    })
238}
239
240#[cfg(all(feature = "component-model", feature = "wasi"))]
241#[unsafe(no_mangle)]
242pub unsafe extern "C" fn wasmtime_context_set_wasip2(
243    mut context: WasmtimeStoreContextMut<'_>,
244    mut config: Box<crate::wasmtime_wasip2_config_t>,
245) {
246    context.data_mut().wasip2 = Some(config.builder.build());
247}
248
249#[unsafe(no_mangle)]
250pub extern "C" fn wasmtime_context_gc(mut context: WasmtimeStoreContextMut<'_>) {
251    context.gc(None);
252}
253
254#[unsafe(no_mangle)]
255pub extern "C" fn wasmtime_context_set_fuel(
256    mut store: WasmtimeStoreContextMut<'_>,
257    fuel: u64,
258) -> Option<Box<wasmtime_error_t>> {
259    crate::handle_result(store.set_fuel(fuel), |()| {})
260}
261
262#[unsafe(no_mangle)]
263pub extern "C" fn wasmtime_context_get_fuel(
264    store: WasmtimeStoreContext<'_>,
265    fuel: &mut u64,
266) -> Option<Box<wasmtime_error_t>> {
267    crate::handle_result(store.get_fuel(), |amt| {
268        *fuel = amt;
269    })
270}
271
272#[unsafe(no_mangle)]
273pub extern "C" fn wasmtime_context_set_epoch_deadline(
274    mut store: WasmtimeStoreContextMut<'_>,
275    ticks_beyond_current: u64,
276) {
277    store.set_epoch_deadline(ticks_beyond_current);
278}
wasmtime_c_api/store.rs

wasmtime_c_api/
store.rs
