Extend C API with interfaces needed to use threads (#7940)

crates/c-api/include/wasmtime.h

@@ -193,6 +193,7 @@
 #include <wasmtime/memory.h>
 #include <wasmtime/module.h>
 #include <wasmtime/profiling.h>
+#include <wasmtime/sharedmemory.h>
 #include <wasmtime/store.h>
 #include <wasmtime/table.h>
 #include <wasmtime/trap.h>

crates/c-api/include/wasmtime/extern.h

@@ -85,6 +85,11 @@ typedef uint8_t wasmtime_extern_kind_t;
 /// \brief Value of #wasmtime_extern_kind_t meaning that #wasmtime_extern_t is a
 /// memory
 #define WASMTIME_EXTERN_MEMORY 3
+/// \brief Value of #wasmtime_extern_kind_t meaning that #wasmtime_extern_t is a
+/// shared memory
+#define WASMTIME_EXTERN_SHAREDMEMORY 4
+
+struct wasmtime_sharedmemory;
 
 /**
  * \typedef wasmtime_extern_union_t
@@ -105,6 +110,8 @@ typedef union wasmtime_extern_union {
   wasmtime_table_t table;
   /// Field used if #wasmtime_extern_t::kind is #WASMTIME_EXTERN_MEMORY
   wasmtime_memory_t memory;
+  /// Field used if #wasmtime_extern_t::kind is #WASMTIME_EXTERN_SHAREDMEMORY
+  struct wasmtime_sharedmemory *sharedmemory;
 } wasmtime_extern_union_t;
 
 /**

crates/c-api/include/wasmtime/linker.h

@@ -42,6 +42,15 @@ typedef struct wasmtime_linker wasmtime_linker_t;
  */
 WASM_API_EXTERN wasmtime_linker_t *wasmtime_linker_new(wasm_engine_t *engine);
 
+/**
+ * \brief Clones existing linker.
+ *
+ * This function does not take ownership of the linker argument, and the caller
+ * is expected to delete the returned linker.
+ */
+WASM_API_EXTERN wasmtime_linker_t *
+wasmtime_linker_clone(wasmtime_linker_t *linker);
+
 /**
  * \brief Deletes a linker
  */

crates/c-api/include/wasmtime/memory.h

@@ -54,6 +54,11 @@ WASM_API_EXTERN bool wasmtime_memorytype_maximum(const wasm_memorytype_t *ty,
  */
 WASM_API_EXTERN bool wasmtime_memorytype_is64(const wasm_memorytype_t *ty);
 
+/**
+ * \brief Returns whether this type of memory represents a shared memory.
+ */
+WASM_API_EXTERN bool wasmtime_memorytype_isshared(const wasm_memorytype_t *ty);
+
 /**
  * \brief Creates a new WebAssembly linear memory
  *

crates/c-api/include/wasmtime/sharedmemory.h

@@ -0,0 +1,115 @@
+/**
+ * \file wasmtime/sharedmemory.h
+ *
+ * Wasmtime API for interacting with wasm shared memories.
+ */
+
+#ifndef WASMTIME_SHAREDMEMORY_H
+#define WASMTIME_SHAREDMEMORY_H
+
+#include <wasm.h>
+#include <wasmtime/error.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief Interface for shared memories.
+ *
+ * For more information see the Rust documentation at:
+ * https://docs.wasmtime.dev/api/wasmtime/struct.SharedMemory.html
+ */
+typedef struct wasmtime_sharedmemory wasmtime_sharedmemory_t;
+
+/**
+ * \brief Creates a new WebAssembly shared linear memory
+ *
+ * \param engine engine that created shared memory is associated with
+ * \param ty the type of the memory to create
+ * \param ret where to store the returned memory
+ *
+ * If an error happens when creating the memory it's returned and owned by the
+ * caller. If an error happens then `ret` is not filled in.
+ */
+WASM_API_EXTERN wasmtime_error_t *
+wasmtime_sharedmemory_new(const wasm_engine_t *engine,
+                          const wasm_memorytype_t *ty,
+                          wasmtime_sharedmemory_t **ret);
+
+/**
+ * \brief Deletes shared linear memory
+ *
+ * \param memory memory to be deleted
+ */
+WASM_API_EXTERN void
+wasmtime_sharedmemory_delete(wasmtime_sharedmemory_t *memory);
+
+/**
+ * \brief Clones shared linear memory
+ *
+ * \param memory memory to be cloned
+ *
+ * This function makes shallow clone, ie. copy of reference counted
+ * memory handle.
+ */
+WASM_API_EXTERN wasmtime_sharedmemory_t *
+wasmtime_sharedmemory_clone(const wasmtime_sharedmemory_t *memory);
+
+/**
+ * \brief Moves shared linear memory into wasmtime_extern_t object
+ *
+ * \param memory memory to be moved
+ * \param out where to store resulting `wasmtime_extern_t`
+ *
+ * This function moves ownership of `memory` into resulting `wasmtime_extern_t`.
+ */
+WASM_API_EXTERN void
+wasmtime_sharedmemory_into_extern(wasmtime_sharedmemory_t *memory,
+                                  wasmtime_extern_t *out);
+
+/**
+ * \brief Returns the type of the shared memory specified
+ */
+WASM_API_EXTERN wasm_memorytype_t *
+wasmtime_sharedmemory_type(const wasmtime_sharedmemory_t *memory);
+
+/**
+ * \brief Returns the base pointer in memory where
+          the shared linear memory starts.
+ */
+WASM_API_EXTERN uint8_t *
+wasmtime_sharedmemory_data(const wasmtime_sharedmemory_t *memory);
+
+/**
+ * \brief Returns the byte length of this shared linear memory.
+ */
+WASM_API_EXTERN size_t
+wasmtime_sharedmemory_data_size(const wasmtime_sharedmemory_t *memory);
+
+/**
+ * \brief Returns the length, in WebAssembly pages, of this shared linear memory
+ */
+WASM_API_EXTERN uint64_t
+wasmtime_sharedmemory_size(const wasmtime_sharedmemory_t *memory);
+
+/**
+ * \brief Attempts to grow the specified shared memory by `delta` pages.
+ *
+ * \param memory the memory to grow
+ * \param delta the number of pages to grow by
+ * \param prev_size where to store the previous size of memory
+ *
+ * If memory cannot be grown then `prev_size` is left unchanged and an error is
+ * returned. Otherwise `prev_size` is set to the previous size of the memory, in
+ * WebAssembly pages, and `NULL` is returned.
+ */
+WASM_API_EXTERN wasmtime_error_t *
+wasmtime_sharedmemory_grow(const wasmtime_sharedmemory_t *memory,
+                           uint64_t delta, uint64_t *prev_size);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif // WASMTIME_SHAREDMEMORY_H

crates/c-api/src/extern.rs

@@ -3,7 +3,7 @@ use crate::{
     CStoreContext, StoreRef,
 };
 use std::mem::ManuallyDrop;
-use wasmtime::{Extern, Func, Global, Memory, Table};
+use wasmtime::{Extern, Func, Global, Memory, SharedMemory, Table};
 
 #[derive(Clone)]
 pub struct wasm_extern_t {
@@ -82,13 +82,25 @@ pub const WASMTIME_EXTERN_FUNC: wasmtime_extern_kind_t = 0;
 pub const WASMTIME_EXTERN_GLOBAL: wasmtime_extern_kind_t = 1;
 pub const WASMTIME_EXTERN_TABLE: wasmtime_extern_kind_t = 2;
 pub const WASMTIME_EXTERN_MEMORY: wasmtime_extern_kind_t = 3;
+pub const WASMTIME_EXTERN_SHAREDMEMORY: wasmtime_extern_kind_t = 4;
 
 #[repr(C)]
 pub union wasmtime_extern_union {
     pub func: Func,
     pub table: Table,
     pub global: Global,
     pub memory: Memory,
+    pub sharedmemory: ManuallyDrop<Box<SharedMemory>>,
+}
+
+impl Drop for wasmtime_extern_t {
+    fn drop(&mut self) {
+        if self.kind == WASMTIME_EXTERN_SHAREDMEMORY {
+            unsafe {
+                ManuallyDrop::drop(&mut self.of.sharedmemory);
+            }
+        }
+    }
 }
 
 impl wasmtime_extern_t {
@@ -98,7 +110,8 @@ impl wasmtime_extern_t {
             WASMTIME_EXTERN_GLOBAL => Extern::Global(self.of.global),
             WASMTIME_EXTERN_TABLE => Extern::Table(self.of.table),
             WASMTIME_EXTERN_MEMORY => Extern::Memory(self.of.memory),
-            other => panic!("unknown wasm_extern_kind_t: {}", other),
+            WASMTIME_EXTERN_SHAREDMEMORY => Extern::SharedMemory((**self.of.sharedmemory).clone()),
+            other => panic!("unknown wasmtime_extern_kind_t: {}", other),
         }
     }
 }
@@ -122,7 +135,12 @@ impl From<Extern> for wasmtime_extern_t {
                 kind: WASMTIME_EXTERN_MEMORY,
                 of: wasmtime_extern_union { memory },
             },
-            Extern::SharedMemory(_memory) => todo!(),
+            Extern::SharedMemory(sharedmemory) => wasmtime_extern_t {
+                kind: WASMTIME_EXTERN_SHAREDMEMORY,
+                of: wasmtime_extern_union {
+                    sharedmemory: ManuallyDrop::new(Box::new(sharedmemory)),
+                },
+            },
         }
     }
 }

crates/c-api/src/lib.rs

@@ -29,6 +29,7 @@ mod module;
 #[cfg(feature = "profiling")]
 mod profiling;
 mod r#ref;
+mod sharedmemory;
 mod store;
 mod table;
 mod trap;

crates/c-api/src/linker.rs

@@ -21,6 +21,13 @@ pub extern "C" fn wasmtime_linker_new(engine: &wasm_engine_t) -> Box<wasmtime_li
     })
 }
 
+#[no_mangle]
+pub extern "C" fn wasmtime_linker_clone(linker: &wasmtime_linker_t) -> Box<wasmtime_linker_t> {
+    Box::new(wasmtime_linker_t {
+        linker: linker.linker.clone(),
+    })
+}
+
 #[no_mangle]
 pub extern "C" fn wasmtime_linker_allow_shadowing(
     linker: &mut wasmtime_linker_t,

crates/c-api/src/sharedmemory.rs

@@ -0,0 +1,68 @@
+use crate::{handle_result, wasm_engine_t, wasm_memorytype_t, wasmtime_error_t, wasmtime_extern_t};
+use std::cell::UnsafeCell;
+use std::mem::MaybeUninit;
+use wasmtime::{Extern, SharedMemory};
+
+type wasmtime_sharedmemory_t = SharedMemory;
+
+wasmtime_c_api_macros::declare_own!(wasmtime_sharedmemory_t);
+
+#[no_mangle]
+pub extern "C" fn wasmtime_sharedmemory_new(
+    engine: &wasm_engine_t,
+    ty: &wasm_memorytype_t,
+    ret: &mut *mut wasmtime_sharedmemory_t,
+) -> Option<Box<wasmtime_error_t>> {
+    handle_result(
+        SharedMemory::new(&engine.engine, ty.ty().ty.clone()),
+        |mem| *ret = Box::<wasmtime_sharedmemory_t>::into_raw(Box::new(mem)),
+    )
+}
+
+#[no_mangle]
+pub extern "C" fn wasmtime_sharedmemory_clone(
+    mem: &wasmtime_sharedmemory_t,
+) -> Box<wasmtime_sharedmemory_t> {
+    Box::new(mem.clone())
+}
+
+#[no_mangle]
+pub extern "C" fn wasmtime_sharedmemory_into_extern(
+    mem: Box<wasmtime_sharedmemory_t>,
+    ext: &mut MaybeUninit<wasmtime_extern_t>,
+) {
+    crate::initialize(ext, Extern::from(*mem).into());
+}
+
+#[no_mangle]
+pub extern "C" fn wasmtime_sharedmemory_type(
+    mem: &wasmtime_sharedmemory_t,
+) -> Box<wasm_memorytype_t> {
+    Box::new(wasm_memorytype_t::new(mem.ty()))
+}
+
+#[no_mangle]
+pub extern "C" fn wasmtime_sharedmemory_data(
+    mem: &wasmtime_sharedmemory_t,
+) -> *const UnsafeCell<u8> {
+    mem.data().as_ptr()
+}
+
+#[no_mangle]
+pub extern "C" fn wasmtime_sharedmemory_data_size(mem: &wasmtime_sharedmemory_t) -> usize {
+    mem.data().len()
+}
+
+#[no_mangle]
+pub extern "C" fn wasmtime_sharedmemory_size(mem: &wasmtime_sharedmemory_t) -> u64 {
+    mem.size()
+}
+
+#[no_mangle]
+pub extern "C" fn wasmtime_sharedmemory_grow(
+    mem: &wasmtime_sharedmemory_t,
+    delta: u64,
+    prev_size: &mut u64,
+) -> Option<Box<wasmtime_error_t>> {
+    handle_result(mem.grow(delta), |prev| *prev_size = prev)
+}

crates/c-api/src/types/memory.rs

@@ -108,6 +108,11 @@ pub extern "C" fn wasmtime_memorytype_is64(mt: &wasm_memorytype_t) -> bool {
     mt.ty().ty.is_64()
 }
 
+#[no_mangle]
+pub extern "C" fn wasmtime_memorytype_isshared(mt: &wasm_memorytype_t) -> bool {
+    mt.ty().ty.is_shared()
+}
+
 #[no_mangle]
 pub extern "C" fn wasm_memorytype_as_externtype(ty: &wasm_memorytype_t) -> &wasm_externtype_t {
     &ty.ext