go: add LoadAndConfigure method

CHANGELOG.md

@@ -7,13 +7,17 @@ and this project adheres to [Semantic Versioning].
 
 ## [6.3.1] - unreleased
 
+### Added
+
+- Added `LoadAndConfigure` method to the Go API.
+  [[#404](https://github.com/ethereum/evmc/pull/404)]
+
 ### Fixed
 
 - In C++ API the `get_balance()` method now returns expected `evmc::uint256be` 
   instead of `evmc_uint256be`.
   [[#403](https://github.com/ethereum/evmc/pull/403)]
 
-
 ## [6.3.0] - 2019-08-12
 
 ### Added

bindings/go/evmc/evmc.go

@@ -168,6 +168,26 @@ func Load(filename string) (instance *Instance, err error) {
 	return instance, err
 }
 
+func LoadAndConfigure(config string) (instance *Instance, err error) {
+	cconfig := C.CString(config)
+	var loaderErr C.enum_evmc_loader_error_code
+	handle := C.evmc_load_and_configure(cconfig, &loaderErr)
+	C.free(unsafe.Pointer(cconfig))
+
+	if loaderErr == C.EVMC_LOADER_SUCCESS {
+		instance = &Instance{handle}
+	} else {
+		errMsg := C.evmc_last_error_msg()
+		if errMsg != nil {
+			err = fmt.Errorf("EVMC loading error: %s", C.GoString(errMsg))
+		} else {
+			err = fmt.Errorf("EVMC loading error %d", int(loaderErr))
+		}
+	}
+
+	return instance, err
+}
+
 func (instance *Instance) Destroy() {
 	C.evmc_destroy(instance.handle)
 }

bindings/go/evmc/evmc_test.go

@@ -29,6 +29,20 @@ func TestLoad(t *testing.T) {
 	}
 }
 
+func TestLoadConfigure(t *testing.T) {
+	i, err := LoadAndConfigure(modulePath)
+	if err != nil {
+		t.Fatal(err.Error())
+	}
+	defer i.Destroy()
+	if i.Name() != "example_vm" {
+		t.Fatalf("name is %s", i.Name())
+	}
+	if i.Version()[0] < '0' || i.Version()[0] > '9' {
+		t.Fatalf("version number is weird: %s", i.Version())
+	}
+}
+
 func TestExecute(t *testing.T) {
 	vm, _ := Load(modulePath)
 	defer vm.Destroy()