c-api: component-model: Values and function calling

crates/c-api/CMakeLists.txt

@@ -166,6 +166,7 @@ target_include_directories(
 
 if (BUILD_TESTS)
   message(STATUS "Building tests")
+  set(CMAKE_CXX_STANDARD 20)
 
   enable_language(CXX)
   set(INSTALL_GTEST OFF CACHE BOOL "" FORCE)

crates/c-api/doxygen.conf.in

@@ -949,7 +949,8 @@ EXCLUDE_SYMBOLS        = assertions \
                          wasmtime::detail \
                          CASE_KIND_PRINT_NAME \
                          CASE_KIND_TO_C \
-                         CASE_C_TO_KIND
+                         CASE_C_TO_KIND \
+                         DECLARE_VEC
 
 # The EXAMPLE_PATH tag can be used to specify one or more files or directories
 # that contain example code fragments that are included (see the \include

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

@@ -5,5 +5,6 @@
 #include <wasmtime/component/func.h>
 #include <wasmtime/component/instance.h>
 #include <wasmtime/component/linker.h>
+#include <wasmtime/component/val.h>
 
 #endif // WASMTIME_COMPONENT_H

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

@@ -1,3 +1,5 @@
+/// \file wasmtime/component/component.h
+
 #ifndef WASMTIME_COMPONENT_COMPONENT_H
 #define WASMTIME_COMPONENT_COMPONENT_H
 
@@ -101,13 +103,13 @@ WASM_API_EXTERN wasmtime_component_t *
 wasmtime_component_clone(const wasmtime_component_t *component);
 
 /**
- * \brief Deletes a #wasmtime_component_t created by
- * #wasmtime_component_from_binary
+ * \brief Deletes a #wasmtime_component_t created by #wasmtime_component_new
  *
  * \param component the component to delete
  */
 WASM_API_EXTERN void wasmtime_component_delete(wasmtime_component_t *component);
 
+/// A value which represents a known export of a component.
 typedef struct wasmtime_component_export_index_t
     wasmtime_component_export_index_t;
 

crates/c-api/include/wasmtime/component/func.h

@@ -1,7 +1,12 @@
+/// \file wasmtime/component/func.h
+
 #ifndef WASMTIME_COMPONENT_FUNC_H
 #define WASMTIME_COMPONENT_FUNC_H
 
+#include <wasmtime/component/val.h>
 #include <wasmtime/conf.h>
+#include <wasmtime/error.h>
+#include <wasmtime/store.h>
 
 #ifdef WASMTIME_FEATURE_COMPONENT_MODEL
 
@@ -23,6 +28,19 @@ typedef struct wasmtime_component_func {
   size_t index;
 } wasmtime_component_func_t;
 
+/// \brief Invokes \p func with the \p args given and returns the result.
+///
+/// The \p args provided must match the parameters that this function takes in
+/// terms of their types and the number of parameters. Results will be written
+/// to the \p results provided if the call completes successfully. The initial
+/// types of the values in \p results are ignored and values are overwritten to
+/// write the result. It's required that the \p results_size exactly matches the
+/// number of results that this function produces.
+WASM_API_EXTERN wasmtime_error_t *wasmtime_component_func_call(
+    const wasmtime_component_func_t *func, wasmtime_context_t *context,
+    const wasmtime_component_val_t *args, size_t args_size,
+    wasmtime_component_val_t *results, size_t results_size);
+
 #ifdef __cplusplus
 } // extern "C"
 #endif

crates/c-api/include/wasmtime/component/instance.h

@@ -1,3 +1,5 @@
+/// \file wasmtime/component/instance.h
+
 #ifndef WASMTIME_COMPONENT_INSTANCE_H
 #define WASMTIME_COMPONENT_INSTANCE_H
 
@@ -27,8 +29,8 @@ typedef struct wasmtime_component_instance {
 } wasmtime_component_instance_t;
 
 /**
- * \brief A methods similar to \fn wasmtime_component_get_export_index() except
- * for this instance.
+ * \brief A methods similar to #wasmtime_component_get_export_index except for
+ * this instance.
  *
  * \param instance the instance to look up \p name in
  * \param context the context where \p instance lives in

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

@@ -1,3 +1,5 @@
+/// \file wasmtime/component/linker.h
+
 #ifndef WASMTIME_COMPONENT_LINKER_H
 #define WASMTIME_COMPONENT_LINKER_H
 
@@ -14,7 +16,10 @@
 extern "C" {
 #endif
 
+/// A type used to instantiate a #wasmtime_component_t.
 typedef struct wasmtime_component_linker_t wasmtime_component_linker_t;
+
+/// Structure representing an "instance" being defined within a linker.
 typedef struct wasmtime_component_linker_instance_t
     wasmtime_component_linker_instance_t;
 
@@ -82,7 +87,8 @@ wasmtime_component_linker_delete(wasmtime_component_linker_t *linker);
  * \param linker_instance the linker instance from which the new one is created
  * \param name new instance name
  * \param name_len length of \p name in bytes
- * \param linker_instance_out on success, the new #component_linker_instance_t
+ * \param linker_instance_out on success, the new
+ * #wasmtime_component_linker_instance_t
  * \return on success `NULL`, otherwise an error
  */
 WASM_API_EXTERN wasmtime_error_t *
@@ -108,6 +114,28 @@ WASM_API_EXTERN wasmtime_error_t *wasmtime_component_linker_instance_add_module(
     wasmtime_component_linker_instance_t *linker_instance, const char *name,
     size_t name_len, const wasmtime_module_t *module);
 
+/// Type of the callback used in #wasmtime_component_linker_instance_add_func
+typedef wasmtime_error_t *(*wasmtime_component_func_callback_t)(
+    void *, wasmtime_context_t *, const wasmtime_component_val_t *, size_t,
+    wasmtime_component_val_t *, size_t);
+
+/**
+ * \brief Define a function within this instance.
+ *
+ * \param linker_instance the instance to define the function in
+ * \param name the module name
+ * \param name_len length of \p name in bytes
+ * \param callback the callback when this function gets called
+ * \param data host-specific data passed to the callback invocation, can be
+ * `NULL`
+ * \param finalizer optional finalizer for \p data, can be `NULL`
+ * \return on success `NULL`, otherwise an error
+ */
+WASM_API_EXTERN wasmtime_error_t *wasmtime_component_linker_instance_add_func(
+    wasmtime_component_linker_instance_t *linker_instance, const char *name,
+    size_t name_len, wasmtime_component_func_callback_t callback, void *data,
+    void (*finalizer)());
+
 /**
  * \brief Deletes a #wasmtime_component_linker_instance_t
  *

crates/c-api/include/wasmtime/component/val.h

@@ -0,0 +1,157 @@
+/// \file wasmtime/component/val.h
+
+#ifndef WASMTIME_COMPONENT_VAL_H
+#define WASMTIME_COMPONENT_VAL_H
+
+#include <wasmtime/conf.h>
+
+#ifdef WASMTIME_FEATURE_COMPONENT_MODEL
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/// \brief Discriminant used in #wasmtime_component_val_t::kind
+typedef uint8_t wasmtime_component_valkind_t;
+
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a bool
+#define WASMTIME_COMPONENT_BOOL 0
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a s8
+#define WASMTIME_COMPONENT_S8 1
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a u8
+#define WASMTIME_COMPONENT_U8 2
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a s16
+#define WASMTIME_COMPONENT_S16 3
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a u16
+#define WASMTIME_COMPONENT_U16 4
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a s32
+#define WASMTIME_COMPONENT_S32 5
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a u32
+#define WASMTIME_COMPONENT_U32 6
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a s64
+#define WASMTIME_COMPONENT_S64 7
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a u64
+#define WASMTIME_COMPONENT_U64 8
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a f32
+#define WASMTIME_COMPONENT_F32 9
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a f64
+#define WASMTIME_COMPONENT_F64 10
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a char
+#define WASMTIME_COMPONENT_CHAR 11
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a string
+#define WASMTIME_COMPONENT_STRING 12
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a list
+#define WASMTIME_COMPONENT_LIST 13
+/// \brief Value of #wasmtime_component_valkind_t meaning that
+/// #wasmtime_component_val_t is a record
+#define WASMTIME_COMPONENT_RECORD 14
+
+struct wasmtime_component_val;
+struct wasmtime_component_valrecord_entry;
+
+#define DECLARE_VEC(name, type)                                                \
+  /** \brief A vec of a type */                                                \
+  typedef struct name {                                                        \
+    /** Length of the vec */                                                   \
+    size_t size;                                                               \
+    /** Pointer to the elements */                                             \
+    type *data;                                                                \
+  } name##_t;                                                                  \
+                                                                               \
+  /** \brief Create vec from \p ptr and \p size */                             \
+  WASM_API_EXTERN void name##_new(name##_t *out, size_t size, type *ptr);      \
+  /** \brief Create an empty vec */                                            \
+  WASM_API_EXTERN void name##_new_empty(name##_t *out);                        \
+  /** \brief Create a vec with length \p size */                               \
+  WASM_API_EXTERN void name##_new_uninit(name##_t *out, size_t size);          \
+  /** \brief Copy \p src to \p dst */                                          \
+  WASM_API_EXTERN void name##_copy(name##_t *dst, const name##_t *src);        \
+  /** \brief Delete \p value */                                                \
+  WASM_API_EXTERN void name##_delete(name##_t *value);
+
+DECLARE_VEC(wasmtime_component_vallist, struct wasmtime_component_val)
+DECLARE_VEC(wasmtime_component_valrecord,
+            struct wasmtime_component_valrecord_entry)
+
+#undef DECLARE_VEC
+
+/// \brief Represents possible runtime values which a component function can
+/// either consume or produce
+typedef union {
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_BOOL
+  bool boolean;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_S8
+  int8_t s8;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_U8
+  uint8_t u8;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_S16
+  int16_t s16;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_U16
+  uint16_t u16;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_S32
+  int32_t s32;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_U32
+  uint32_t u32;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_S64
+  int64_t s64;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_U64
+  uint64_t u64;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_F32
+  float32_t f32;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_F64
+  float64_t f64;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_CHAR
+  uint32_t character;
+  /// Field used if #wasmtime_component_val_t::kind is
+  /// #WASMTIME_COMPONENT_STRING
+  wasm_name_t string;
+  /// Field used if #wasmtime_component_val_t::kind is #WASMTIME_COMPONENT_LIST
+  wasmtime_component_vallist_t list;
+  /// Field used if #wasmtime_component_val_t::kind is
+  /// #WASMTIME_COMPONENT_RECORD
+  wasmtime_component_valrecord_t record;
+} wasmtime_component_valunion_t;
+
+/// \brief Represents possible runtime values which a component function can
+/// either consume or produce
+typedef struct wasmtime_component_val {
+  /// The type discriminant
+  wasmtime_component_valkind_t kind;
+  /// Value of type \ref kind
+  wasmtime_component_valunion_t of;
+} wasmtime_component_val_t;
+
+/// \brief A pair of a name and a value that represents one entry in a value
+/// with kind #WASMTIME_COMPONENT_RECORD
+typedef struct wasmtime_component_valrecord_entry {
+  /// The name of this entry
+  wasm_name_t name;
+  /// The value of this entry
+  wasmtime_component_val_t val;
+} wasmtime_component_valrecord_entry_t;
+
+/// \brief Calls the destructor on \p value deallocating any owned memory
+WASM_API_EXTERN void
+wasmtime_component_val_delete(wasmtime_component_val_t *value);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif // WASMTIME_FEATURE_COMPONENT_MODEL
+
+#endif // WASMTIME_COMPONENT_VAL_H

crates/c-api/src/component/func.rs

@@ -0,0 +1,31 @@
+use wasmtime::component::{Func, Val};
+
+use crate::{WasmtimeStoreContextMut, wasmtime_error_t};
+
+use super::wasmtime_component_val_t;
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn wasmtime_component_func_call(
+    func: &Func,
+    mut context: WasmtimeStoreContextMut<'_>,
+    args: *const wasmtime_component_val_t,
+    args_len: usize,
+    results: *mut wasmtime_component_val_t,
+    results_len: usize,
+) -> Option<Box<wasmtime_error_t>> {
+    let c_args = unsafe { std::slice::from_raw_parts(args, args_len) };
+    let c_results = unsafe { std::slice::from_raw_parts_mut(results, results_len) };
+
+    let args = c_args.iter().map(Val::from).collect::<Vec<_>>();
+    let mut results = vec![Val::Bool(false); results_len];
+
+    let result = func
+        .call(&mut context, &args, &mut results)
+        .and_then(|_| func.post_return(&mut context));
+
+    crate::handle_result(result, |_| {
+        for (c_val, rust_val) in std::iter::zip(c_results, results) {
+            *c_val = wasmtime_component_val_t::from(&rust_val);
+        }
+    })
+}