samples/ffi/resource_management/unmanaged_sample.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
//
// Sample illustrating manual resource management, not advised.

import 'dart:ffi';

import 'package:expect/expect.dart';
import 'package:ffi/ffi.dart';

import 'utf8_helpers.dart';
import '../dylib_utils.dart';

main() {
  final ffiTestDynamicLibrary = dlopenPlatformSpecific(
    "ffi_test_dynamic_library",
  );

  final memMove = ffiTestDynamicLibrary
      .lookupFunction<
        Void Function(Pointer<Void>, Pointer<Void>, IntPtr),
        void Function(Pointer<Void>, Pointer<Void>, int)
      >("MemMove");

  // To ensure resources are freed, call free manually.
  //
  // For automatic management use a Arena.
  final p = calloc<Int64>(2);
  p[0] = 24;
  memMove((p + 1).cast<Void>(), p.cast<Void>(), sizeOf<Int64>());
  print(p[1]);
  Expect.equals(24, p[1]);
  calloc.free(p);

  // Using Strings.
  final p2 = "Hello world!".toUtf8(calloc);
  print(p2.contents());
  calloc.free(p2);
}