Eable post-MVP feature wasm-c-api (#315)

samples/wasm-c-api/CMakeLists.txt

@@ -0,0 +1,89 @@
+# Copyright (C) 2019 Intel Corporation. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+cmake_minimum_required (VERSION 2.8)
+project(c-api)
+
+if(NOT CMAKE_BUILD_TYPE)
+  set(CMAKE_BUILD_TYPE Release)
+endif()
+################  runtime settings  ################
+set(WAMR_BUILD_PLATFORM "linux")
+
+# Resetdefault linker flags
+set(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "")
+set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "")
+
+# WAMR features switch
+set(WAMR_BUILD_TARGET "X86_64")
+
+if(NOT DEFINED WAMR_BUILD_INTERP)
+  set(WAMR_BUILD_INTERP 1)
+endif()
+
+if(NOT DEFINED WAMR_BUILD_AOT)
+  set(WAMR_BUILD_AOT 0)
+endif()
+
+if(NOT DEFINED WAMR_BUILD_JOT)
+  set(WAMR_BUILD_JIT 0)
+endif()
+
+set(WAMR_BUILD_LIBC_BUILTIN 1)
+set(WAMR_BUILD_LIBC_WASI 0)
+
+if(NOT DEFINED WAMR_BUILD_FAST_INTERP)
+  set(WAMR_BUILD_FAST_INTERP 0)
+endif()
+
+# compiling and linking flags
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--gc-sections -pie -fPIE")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wformat -Wformat-security -mindirect-branch-register")
+
+# build out vmlib
+set(WAMR_ROOT_DIR ${CMAKE_CURRENT_LIST_DIR}/../..)
+set(WAMRC ${WAMR_ROOT_DIR}/wamr-compiler/build/wamrc)
+include (${WAMR_ROOT_DIR}/build-scripts/runtime_lib.cmake)
+
+add_library(vmlib STATIC ${WAMR_RUNTIME_LIB_SOURCE})
+################################################
+
+################  application related  ################
+file(GLOB SOURCES src/*.c)
+add_library(c-api ${SOURCES})
+target_include_directories(c-api
+  PRIVATE ${C_API_PATH}/include
+)
+target_link_libraries(c-api PRIVATE vmlib -lpthread -lm)
+
+foreach(SRC ${SOURCES})
+  get_filename_component(APPNAME ${SRC} NAME_WE)
+
+  # build executable for each .c
+  add_executable(${APPNAME} ${SRC})
+  message("create executable about ${APPNAME}")
+  target_link_libraries(${APPNAME} c-api)
+
+  # copy .wasm
+  add_custom_command(TARGET ${APPNAME} POST_BUILD
+      COMMAND ${CMAKE_COMMAND} -E copy
+                  ${CMAKE_CURRENT_SOURCE_DIR}/src/${APPNAME}.wasm
+                  ${PROJECT_BINARY_DIR}/
+      BYPRODUCTS ${APPNAME}.wasm
+      COMMENT "Copy ${SRC} to the output directory"
+  )
+
+  # generate .aot file
+  if(${WAMR_BUILD_AOT} EQUAL 1)
+    if(EXISTS ${WAMRC})
+      add_custom_command(TARGET ${APPNAME} POST_BUILD
+          COMMAND ${WAMRC} -o ${APPNAME}.aot
+              ${CMAKE_CURRENT_SOURCE_DIR}/src/${APPNAME}.wasm
+          BYPRODUCTS ${APPNAME}.aot
+          COMMENT "generate a aot file ${APPNAME}.aot"
+      )
+    endif()
+  endif()
+
+endforeach(SRC ${SOURCES})
+################################################

samples/wasm-c-api/README.md

@@ -0,0 +1,39 @@
+WAMR supports *wasm-c-api* in both *interpreter* mode and *aot* mode. By default,
+all samples are compiled and run in "interpreter" mode.
+
+``` shell
+$ mkdir build
+$ cd build
+$ cmake ..
+$ make
+$ # it will build a library with c-api supporting.
+$ # Also copy *.wasm from ../src/
+$ # and generate executable files
+$ # now, it is ok to run samples
+$ ./hello
+$ ...
+$ ./global
+$ ...
+$ ./callback
+$ ...
+```
+
+They can be compiled and run in *aot* mode when some compiling flags are given.
+
+``` shell
+$ mkdir build
+$ cd build
+$ cmake -DWAMR_BUILD_INTERP=0 -DWAMR_BUILD_AOT=1 ..
+$ make
+$ # it will build a library with c-api supporting.
+$ # Also copy *.wasm from ../src/
+$ # and transform *.wasm to *.aot
+$ # and generate executable files
+$ # now, it is ok to run samples
+$ ./hello
+$ ...
+$ ./global
+$ ...
+$ ./callback
+$ ...
+```

samples/wasm-c-api/src/callback.c

@@ -0,0 +1,168 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include "wasm_c_api.h"
+
+#define own
+
+// Print a Wasm value
+void wasm_val_print(wasm_val_t val) {
+  switch (val.kind) {
+    case WASM_I32: {
+      printf("%" PRIu32, val.of.i32);
+    } break;
+    case WASM_I64: {
+      printf("%" PRIu64, val.of.i64);
+    } break;
+    case WASM_F32: {
+      printf("%f", val.of.f32);
+    } break;
+    case WASM_F64: {
+      printf("%g", val.of.f64);
+    } break;
+    case WASM_ANYREF:
+    case WASM_FUNCREF: {
+      if (val.of.ref == NULL) {
+        printf("null");
+      } else {
+        printf("ref(%p)", val.of.ref);
+      }
+    } break;
+  }
+}
+
+// A function to be called from Wasm code.
+own wasm_trap_t* print_callback(
+  const wasm_val_t args[], wasm_val_t results[]
+) {
+  printf("Calling back...\n> ");
+  wasm_val_print(args[0]);
+  printf("\n");
+
+  wasm_val_copy(&results[0], &args[0]);
+  return NULL;
+}
+
+
+// A function closure.
+own wasm_trap_t* closure_callback(
+  void* env, const wasm_val_t args[], wasm_val_t results[]
+) {
+  int i = *(int*)env;
+  printf("Calling back closure...\n");
+  printf("> %d\n", i);
+
+  results[0].kind = WASM_I32;
+  results[0].of.i32 = (int32_t)i;
+  return NULL;
+}
+
+
+int main(int argc, const char* argv[]) {
+  // Initialize.
+  printf("Initializing...\n");
+  wasm_engine_t* engine = wasm_engine_new();
+  wasm_store_t* store = wasm_store_new(engine);
+
+  // Load binary.
+  printf("Loading binary...\n");
+  FILE* file = fopen("callback.wasm", "rb");
+  if (!file) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fseek(file, 0L, SEEK_END);
+  size_t file_size = ftell(file);
+  fseek(file, 0L, SEEK_SET);
+  wasm_byte_vec_t binary;
+  wasm_byte_vec_new_uninitialized(&binary, file_size);
+  if (fread(binary.data, file_size, 1, file) != 1) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fclose(file);
+
+  // Compile.
+  printf("Compiling module...\n");
+  own wasm_module_t* module = wasm_module_new(store, &binary);
+  if (!module) {
+    printf("> Error compiling module!\n");
+    return 1;
+  }
+
+  wasm_byte_vec_delete(&binary);
+
+  // Create external print functions.
+  printf("Creating callback...\n");
+  own wasm_functype_t* print_type = wasm_functype_new_1_1(wasm_valtype_new_i32(), wasm_valtype_new_i32());
+  own wasm_func_t* print_func = wasm_func_new(store, print_type, print_callback);
+
+  int i = 42;
+  own wasm_functype_t* closure_type = wasm_functype_new_0_1(wasm_valtype_new_i32());
+  own wasm_func_t* closure_func = wasm_func_new_with_env(store, closure_type, closure_callback, &i, NULL);
+
+  wasm_functype_delete(print_type);
+  wasm_functype_delete(closure_type);
+
+  // Instantiate.
+  printf("Instantiating module...\n");
+  const wasm_extern_t* imports[] = {
+    wasm_func_as_extern(print_func), wasm_func_as_extern(closure_func)
+  };
+  own wasm_instance_t* instance =
+    wasm_instance_new(store, module, imports, NULL);
+  if (!instance) {
+    printf("> Error instantiating module!\n");
+    return 1;
+  }
+
+  wasm_func_delete(print_func);
+  wasm_func_delete(closure_func);
+
+  // Extract export.
+  printf("Extracting export...\n");
+  own wasm_extern_vec_t exports;
+  wasm_instance_exports(instance, &exports);
+  if (exports.size == 0) {
+    printf("> Error accessing exports!\n");
+    return 1;
+  }
+  const wasm_func_t* run_func = wasm_extern_as_func(exports.data[0]);
+  if (run_func == NULL) {
+    printf("> Error accessing export!\n");
+    return 1;
+  }
+
+  wasm_module_delete(module);
+  wasm_instance_delete(instance);
+
+  // Call.
+  printf("Calling export...\n");
+  wasm_val_t args[2];
+  args[0].kind = WASM_I32;
+  args[0].of.i32 = 3;
+  args[1].kind = WASM_I32;
+  args[1].of.i32 = 4;
+  wasm_val_t results[1];
+  if (wasm_func_call(run_func, args, results)) {
+    printf("> Error calling function!\n");
+    return 1;
+  }
+
+  wasm_extern_vec_delete(&exports);
+
+  // Print result.
+  printf("Printing result...\n");
+  printf("> %u\n", results[0].of.i32);
+
+  // Shut down.
+  printf("Shutting down...\n");
+  wasm_store_delete(store);
+  wasm_engine_delete(engine);
+
+  // All done.
+  printf("Done.\n");
+  return 0;
+}

samples/wasm-c-api/src/callback.wat

@@ -0,0 +1,10 @@
+(module
+  (func $print (import "" "print") (param i32) (result i32))
+  (func $closure (import "" "closure") (result i32))
+  (func (export "run") (param $x i32) (param $y i32) (result i32)
+    (i32.add
+      (call $print (i32.add (local.get $x) (local.get $y)))
+      (call $closure)
+    )
+  )
+)

samples/wasm-c-api/src/global.c

@@ -0,0 +1,236 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include "wasm_c_api.h"
+
+#define own
+
+wasm_global_t* get_export_global(const wasm_extern_vec_t* exports, size_t i) {
+  if (exports->size <= i || !wasm_extern_as_global(exports->data[i])) {
+    printf("> Error accessing global export %zu!\n", i);
+    exit(1);
+  }
+  return wasm_extern_as_global(exports->data[i]);
+}
+
+wasm_func_t* get_export_func(const wasm_extern_vec_t* exports, size_t i) {
+  if (exports->size <= i || !wasm_extern_as_func(exports->data[i])) {
+    printf("> Error accessing function export %zu!\n", i);
+    exit(1);
+  }
+  return wasm_extern_as_func(exports->data[i]);
+}
+
+
+#define check(val, type, expected) \
+  if (val.of.type != expected) { \
+    printf("> Error reading value\n"); \
+    exit(1); \
+  }
+
+#define check_global(global, type, expected) \
+  { \
+    wasm_val_t val; \
+    wasm_global_get(global, &val); \
+    check(val, type, expected); \
+  }
+
+#define check_call(func, type, expected) \
+  { \
+    wasm_val_t results[1]; \
+    wasm_func_call(func, NULL, results); \
+    check(results[0], type, expected); \
+  }
+
+
+int main(int argc, const char* argv[]) {
+  // Initialize.
+  printf("Initializing...\n");
+  wasm_engine_t* engine = wasm_engine_new();
+  wasm_store_t* store = wasm_store_new(engine);
+
+  // Load binary.
+  printf("Loading binary...\n");
+#if WASM_ENABLE_AOT != 0 && WASM_ENABLE_INTERP == 0
+  FILE* file = fopen("global.aot", "rb");
+#else
+  FILE* file = fopen("global.wasm", "rb");
+#endif
+  if (!file) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fseek(file, 0L, SEEK_END);
+  size_t file_size = ftell(file);
+  fseek(file, 0L, SEEK_SET);
+  wasm_byte_vec_t binary;
+  wasm_byte_vec_new_uninitialized(&binary, file_size);
+  if (fread(binary.data, file_size, 1, file) != 1) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fclose(file);
+
+  // Compile.
+  printf("Compiling module...\n");
+  own wasm_module_t* module = wasm_module_new(store, &binary);
+  if (!module) {
+    printf("> Error compiling module!\n");
+    return 1;
+  }
+
+  wasm_byte_vec_delete(&binary);
+
+  // Create external globals.
+  printf("Creating globals...\n");
+  own wasm_globaltype_t* const_f32_type = wasm_globaltype_new(
+    wasm_valtype_new(WASM_F32), WASM_CONST);
+  own wasm_globaltype_t* const_i64_type = wasm_globaltype_new(
+    wasm_valtype_new(WASM_I64), WASM_CONST);
+  own wasm_globaltype_t* var_f32_type = wasm_globaltype_new(
+    wasm_valtype_new(WASM_F32), WASM_VAR);
+  own wasm_globaltype_t* var_i64_type = wasm_globaltype_new(
+    wasm_valtype_new(WASM_I64), WASM_VAR);
+
+  wasm_val_t val_f32_1 = {.kind = WASM_F32, .of = {.f32 = 1}};
+  own wasm_global_t* const_f32_import =
+    wasm_global_new(store, const_f32_type, &val_f32_1);
+  wasm_val_t val_i64_2 = {.kind = WASM_I64, .of = {.i64 = 2}};
+  own wasm_global_t* const_i64_import =
+    wasm_global_new(store, const_i64_type, &val_i64_2);
+  wasm_val_t val_f32_3 = {.kind = WASM_F32, .of = {.f32 = 3}};
+  own wasm_global_t* var_f32_import =
+    wasm_global_new(store, var_f32_type, &val_f32_3);
+  wasm_val_t val_i64_4 = {.kind = WASM_I64, .of = {.i64 = 4}};
+  own wasm_global_t* var_i64_import =
+    wasm_global_new(store, var_i64_type, &val_i64_4);
+
+  wasm_globaltype_delete(const_f32_type);
+  wasm_globaltype_delete(const_i64_type);
+  wasm_globaltype_delete(var_f32_type);
+  wasm_globaltype_delete(var_i64_type);
+
+  // Instantiate.
+  printf("Instantiating module...\n");
+  const wasm_extern_t* imports[] = {
+    wasm_global_as_extern(const_f32_import),
+    wasm_global_as_extern(const_i64_import),
+    wasm_global_as_extern(var_f32_import),
+    wasm_global_as_extern(var_i64_import)
+  };
+  own wasm_instance_t* instance =
+    wasm_instance_new(store, module, imports, NULL);
+  if (!instance) {
+    printf("> Error instantiating module!\n");
+    return 1;
+  }
+
+  wasm_module_delete(module);
+
+  // Extract export.
+  printf("Extracting exports...\n");
+  own wasm_extern_vec_t exports;
+  wasm_instance_exports(instance, &exports);
+  size_t i = 0;
+  wasm_global_t* const_f32_export = get_export_global(&exports, i++);
+  wasm_global_t* const_i64_export = get_export_global(&exports, i++);
+  wasm_global_t* var_f32_export = get_export_global(&exports, i++);
+  wasm_global_t* var_i64_export = get_export_global(&exports, i++);
+  wasm_func_t* get_const_f32_import = get_export_func(&exports, i++);
+  wasm_func_t* get_const_i64_import = get_export_func(&exports, i++);
+  wasm_func_t* get_var_f32_import = get_export_func(&exports, i++);
+  wasm_func_t* get_var_i64_import = get_export_func(&exports, i++);
+  wasm_func_t* get_const_f32_export = get_export_func(&exports, i++);
+  wasm_func_t* get_const_i64_export = get_export_func(&exports, i++);
+  wasm_func_t* get_var_f32_export = get_export_func(&exports, i++);
+  wasm_func_t* get_var_i64_export = get_export_func(&exports, i++);
+  wasm_func_t* set_var_f32_import = get_export_func(&exports, i++);
+  wasm_func_t* set_var_i64_import = get_export_func(&exports, i++);
+  wasm_func_t* set_var_f32_export = get_export_func(&exports, i++);
+  wasm_func_t* set_var_i64_export = get_export_func(&exports, i++);
+
+  // Try cloning.
+  own wasm_global_t* copy = wasm_global_copy(var_f32_import);
+  assert(wasm_global_same(var_f32_import, copy));
+  wasm_global_delete(copy);
+
+  // Interact.
+  printf("Accessing globals...\n");
+
+  // Check initial values.
+  check_global(const_f32_import, f32, 1);
+  check_global(const_i64_import, i64, 2);
+  check_global(var_f32_import, f32, 3);
+  check_global(var_i64_import, i64, 4);
+  check_global(const_f32_export, f32, 5);
+  check_global(const_i64_export, i64, 6);
+  check_global(var_f32_export, f32, 7);
+  check_global(var_i64_export, i64, 8);
+
+  check_call(get_const_f32_import, f32, 1);
+  check_call(get_const_i64_import, i64, 2);
+  check_call(get_var_f32_import, f32, 3);
+  check_call(get_var_i64_import, i64, 4);
+  check_call(get_const_f32_export, f32, 5);
+  check_call(get_const_i64_export, i64, 6);
+  check_call(get_var_f32_export, f32, 7);
+  check_call(get_var_i64_export, i64, 8);
+
+  // Modify variables through API and check again.
+  wasm_val_t val33 = {.kind = WASM_F32, .of = {.f32 = 33}};
+  wasm_global_set(var_f32_import, &val33);
+  wasm_val_t val34 = {.kind = WASM_I64, .of = {.i64 = 34}};
+  wasm_global_set(var_i64_import, &val34);
+  wasm_val_t val37 = {.kind = WASM_F32, .of = {.f32 = 37}};
+  wasm_global_set(var_f32_export, &val37);
+  wasm_val_t val38 = {.kind = WASM_I64, .of = {.i64 = 38}};
+  wasm_global_set(var_i64_export, &val38);
+
+  check_global(var_f32_import, f32, 33);
+  check_global(var_i64_import, i64, 34);
+  check_global(var_f32_export, f32, 37);
+  check_global(var_i64_export, i64, 38);
+
+  check_call(get_var_f32_import, f32, 33);
+  check_call(get_var_i64_import, i64, 34);
+  check_call(get_var_f32_export, f32, 37);
+  check_call(get_var_i64_export, i64, 38);
+
+  // Modify variables through calls and check again.
+  wasm_val_t args73[] = { {.kind = WASM_F32, .of = {.f32 = 73}} };
+  wasm_func_call(set_var_f32_import, args73, NULL);
+  wasm_val_t args74[] = { {.kind = WASM_I64, .of = {.i64 = 74}} };
+  wasm_func_call(set_var_i64_import, args74, NULL);
+  wasm_val_t args77[] = { {.kind = WASM_F32, .of = {.f32 = 77}} };
+  wasm_func_call(set_var_f32_export, args77, NULL);
+  wasm_val_t args78[] = { {.kind = WASM_I64, .of = {.i64 = 78}} };
+  wasm_func_call(set_var_i64_export, args78, NULL);
+
+  check_global(var_f32_import, f32, 73);
+  check_global(var_i64_import, i64, 74);
+  check_global(var_f32_export, f32, 77);
+  check_global(var_i64_export, i64, 78);
+
+  check_call(get_var_f32_import, f32, 73);
+  check_call(get_var_i64_import, i64, 74);
+  check_call(get_var_f32_export, f32, 77);
+  check_call(get_var_i64_export, i64, 78);
+
+  wasm_global_delete(const_f32_import);
+  wasm_global_delete(const_i64_import);
+  wasm_global_delete(var_f32_import);
+  wasm_global_delete(var_i64_import);
+  wasm_extern_vec_delete(&exports);
+  wasm_instance_delete(instance);
+
+  // Shut down.
+  printf("Shutting down...\n");
+  wasm_store_delete(store);
+  wasm_engine_delete(engine);
+
+  // All done.
+  printf("Done.\n");
+  return 0;
+}

samples/wasm-c-api/src/global.wat

@@ -0,0 +1,27 @@
+(module
+  (global $f32_import (import "" "const f32") f32)
+  (global $i64_import (import "" "const i64") i64)
+  (global $mut_f32_import (import "" "var f32") (mut f32))
+  (global $mut_i64_import (import "" "var i64") (mut i64))
+
+  (global $f32_export (export "const f32") f32 (f32.const 5))
+  (global $i64_export (export "const i64") i64 (i64.const 6))
+  (global $mut_f32_export (export "var f32") (mut f32) (f32.const 7))
+  (global $mut_i64_export (export "var i64") (mut i64) (i64.const 8))
+
+  (func (export "get const f32 import") (result f32) (global.get $f32_import))
+  (func (export "get const i64 import") (result i64) (global.get $i64_import))
+  (func (export "get var f32 import") (result f32) (global.get $mut_f32_import))
+  (func (export "get var i64 import") (result i64) (global.get $mut_i64_import))
+
+  (func (export "get const f32 export") (result f32) (global.get $f32_export))
+  (func (export "get const i64 export") (result i64) (global.get $i64_export))
+  (func (export "get var f32 export") (result f32) (global.get $mut_f32_export))
+  (func (export "get var i64 export") (result i64) (global.get $mut_i64_export))
+
+  (func (export "set var f32 import") (param f32) (global.set $mut_f32_import (local.get 0)))
+  (func (export "set var i64 import") (param i64) (global.set $mut_i64_import (local.get 0)))
+
+  (func (export "set var f32 export") (param f32) (global.set $mut_f32_export (local.get 0)))
+  (func (export "set var f64 export") (param i64) (global.set $mut_i64_export (local.get 0)))
+)

samples/wasm-c-api/src/hello.c

@@ -0,0 +1,112 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include "wasm_c_api.h"
+
+#define own
+
+// A function to be called from Wasm code.
+own wasm_trap_t* hello_callback(
+  const wasm_val_t args[], wasm_val_t results[]
+) {
+  printf("Calling back...\n");
+  printf("> Hello World!\n");
+  return NULL;
+}
+
+
+int main(int argc, const char* argv[]) {
+  // Initialize.
+  printf("Initializing...\n");
+  wasm_engine_t* engine = wasm_engine_new();
+  wasm_store_t* store = wasm_store_new(engine);
+
+  // Load binary.
+  printf("Loading binary...\n");
+#if WASM_ENABLE_AOT != 0 && WASM_ENABLE_INTERP == 0
+  FILE* file = fopen("hello.aot", "rb");
+#else
+  FILE* file = fopen("hello.wasm", "rb");
+#endif
+  if (!file) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fseek(file, 0L, SEEK_END);
+  size_t file_size = ftell(file);
+  fseek(file, 0L, SEEK_SET);
+  wasm_byte_vec_t binary;
+  wasm_byte_vec_new_uninitialized(&binary, file_size);
+  if (fread(binary.data, file_size, 1, file) != 1) {
+    printf("> Error loading module!\n");
+    return 1;
+  }
+  fclose(file);
+
+  // Compile.
+  printf("Compiling module...\n");
+  own wasm_module_t* module = wasm_module_new(store, &binary);
+  if (!module) {
+    printf("> Error compiling module!\n");
+    return 1;
+  }
+
+  wasm_byte_vec_delete(&binary);
+
+  // Create external print functions.
+  printf("Creating callback...\n");
+  own wasm_functype_t* hello_type = wasm_functype_new_0_0();
+  own wasm_func_t* hello_func =
+    wasm_func_new(store, hello_type, hello_callback);
+
+  wasm_functype_delete(hello_type);
+
+  // Instantiate.
+  printf("Instantiating module...\n");
+  const wasm_extern_t* imports[] = { wasm_func_as_extern(hello_func) };
+  own wasm_instance_t* instance =
+    wasm_instance_new(store, module, imports, NULL);
+  if (!instance) {
+    printf("> Error instantiating module!\n");
+    return 1;
+  }
+
+  wasm_func_delete(hello_func);
+
+  // Extract export.
+  printf("Extracting export...\n");
+  own wasm_extern_vec_t exports;
+  wasm_instance_exports(instance, &exports);
+  if (exports.size == 0) {
+    printf("> Error accessing exports!\n");
+    return 1;
+  }
+  const wasm_func_t* run_func = wasm_extern_as_func(exports.data[0]);
+  if (run_func == NULL) {
+    printf("> Error accessing export!\n");
+    return 1;
+  }
+
+  wasm_module_delete(module);
+  wasm_instance_delete(instance);
+
+  // Call.
+  printf("Calling export...\n");
+  if (wasm_func_call(run_func, NULL, NULL)) {
+    printf("> Error calling function!\n");
+    return 1;
+  }
+
+  wasm_extern_vec_delete(&exports);
+
+  // Shut down.
+  printf("Shutting down...\n");
+  wasm_store_delete(store);
+  wasm_engine_delete(engine);
+
+  // All done.
+  printf("Done.\n");
+  return 0;
+}

samples/wasm-c-api/src/hello.wat

@@ -0,0 +1,4 @@
+(module
+  (func $hello (import "" "hello"))
+  (func (export "run") (call $hello))
+)