Implement wasm_config_new and wasm_engine_new_with_config (#901)

* Implement wasm_config_new and wasm_engine_new_with_config

crates/c-api/examples/Makefile

@@ -153,3 +153,19 @@ CARGO_RUN:
 clean:
 	rm -rf ${OUT_DIR}
 
+###############################################################################
+# Other examples
+
+WASM_EXT_INCLUDE = ${WASMTIME_API_DIR}/include
+
+run-config-debug-c: ${EXAMPLE_OUT}/config-debug-c ${EXAMPLE_OUT}/fib-wasm.wasm
+	@echo ==== C config ====; \
+	cd ${EXAMPLE_OUT}; ./config-debug-c
+	@echo ==== Done ====
+
+${EXAMPLE_OUT}/fib-wasm.wasm: fib-wasm.wasm
+	cp $< $@
+
+${EXAMPLE_OUT}/config-debug-c.o: config-debug.c ${WASM_INCLUDE}/wasm.h ${WASM_EXT_INCLUDE}/wasmtime.h
+	mkdir -p ${EXAMPLE_OUT}
+	${C_COMP} -c ${C_FLAGS} -I. -I${WASM_INCLUDE} -I${WASM_EXT_INCLUDE} $< -o $@

crates/c-api/examples/config-debug.c

@@ -0,0 +1,99 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include <wasm.h>
+#include "wasmtime.h"
+
+#define own
+
+int main(int argc, const char* argv[]) {
+  // Configuring engine to support generating of DWARF info.
+  // lldb can be used to attach to the program and observe
+  // original fib-wasm.c source code and variables.
+  wasm_config_t* config = wasm_config_new();
+  wasmtime_config_debug_info_set(config, true);
+
+  // Initialize.
+  printf("Initializing...\n");
+  wasm_engine_t* engine = wasm_engine_new_with_config(config);
+  wasm_store_t* store = wasm_store_new(engine);
+
+  // Load binary.
+  printf("Loading binary...\n");
+  FILE* file = fopen("fib-wasm.wasm", "r");
+  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);
+
+  // Instantiate.
+  printf("Instantiating module...\n");
+  own wasm_instance_t* instance =
+    wasm_instance_new(store, module, NULL, NULL);
+  if (!instance) {
+    printf("> Error instantiating module!\n");
+    return 1;
+  }
+
+  // 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;
+  }
+  // Getting second export (first is memory).
+  const wasm_func_t* run_func = wasm_extern_as_func(exports.data[1]);
+  if (run_func == NULL) {
+    printf("> Error accessing export!\n");
+    return 1;
+  }
+
+  wasm_module_delete(module);
+  wasm_instance_delete(instance);
+
+  // Call.
+  printf("Calling fib...\n");
+  wasm_val_t params[1] = { {.kind = WASM_I32, .of = {.i32 = 6}} };
+  wasm_val_t results[1];
+  if (wasm_func_call(run_func, params, results)) {
+    printf("> Error calling function!\n");
+    return 1;
+  }
+
+  wasm_extern_vec_delete(&exports);
+
+  printf("> fib(6) = %d\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;
+}

crates/c-api/examples/fib-wasm.c

@@ -0,0 +1,13 @@
+// Compile with:
+//   clang --target=wasm32 fib-wasm.c -o fib-wasm.wasm -g \
+//     -Wl,--no-entry,--export=fib -nostdlib -fdebug-prefix-map=$PWD=.
+
+int fib(int n) {
+  int i, t, a = 0, b = 1;
+  for (i = 0; i < n; i++) {
+    t = a;
+    a = b;
+    b += t;
+  }
+  return b;
+}