[ffigen] Support ObjC objects in global variables (#1434)

Author: liamappelbe

pkgs/ffigen/CHANGELOG.md

@@ -6,6 +6,8 @@
 - Add a `external-versions` config option. Setting the minimum target
   version will omit APIs from the generated bindings if they were deprecated
   before this version.
+- Global variables using ObjC types (interfaces or blocks) will now use the
+  correct Dart wrapper types, instead of the raw C-style pointers.
 - Rename `assetId` under *ffi-native* to `asset-id` to follow dash-case.
 
 ## 13.0.0

pkgs/ffigen/lib/src/code_generator/global.dart

@@ -45,19 +45,40 @@ class Global extends LookUpBinding {
     if (dartDoc != null) {
       s.write(makeDartDoc(dartDoc!));
     }
-    final dartType = type.getFfiDartType(w);
+    final dartType = type.getDartType(w);
+    final ffiDartType = type.getFfiDartType(w);
     final cType = type.getCType(w);
 
+    void generateConvertingGetterAndSetter(String pointerValue) {
+      final getValue =
+          type.convertFfiDartTypeToDartType(w, pointerValue, objCRetain: true);
+      s.write('$dartType get $globalVarName => $getValue;\n\n');
+      if (!constant) {
+        final releaseOldValue = type
+            .convertFfiDartTypeToDartType(w, pointerValue, objCRetain: false);
+        final newValue =
+            type.convertDartTypeToFfiDartType(w, 'value', objCRetain: true);
+        s.write('''set $globalVarName($dartType value) {
+  $releaseOldValue.release();
+  $pointerValue = $newValue;
+}''');
+      }
+    }
+
     if (nativeConfig.enabled) {
       if (type case final ConstantArray arr) {
         s.writeln(makeArrayAnnotation(w, arr));
       }
 
+      final pointerName = type.sameDartAndFfiDartType
+          ? globalVarName
+          : w.wrapperLevelUniqueNamer.makeUnique('_$globalVarName');
+
       s
         ..writeln(makeNativeAnnotation(
           w,
           nativeType: cType,
-          dartName: globalVarName,
+          dartName: pointerName,
           nativeSymbolName: originalName,
           isLeaf: false,
         ))
@@ -66,7 +87,11 @@ class Global extends LookUpBinding {
         s.write('final ');
       }
 
-      s.writeln('$dartType $globalVarName;\n');
+      s.writeln('$ffiDartType $pointerName;\n');
+
+      if (!type.sameDartAndFfiDartType) {
+        generateConvertingGetterAndSetter(pointerName);
+      }
 
       if (exposeSymbolAddress) {
         w.symbolAddressWriter.addNativeSymbol(
@@ -84,14 +109,16 @@ class Global extends LookUpBinding {
           s.write('${w.ffiLibraryPrefix}.Pointer<$cType> get $globalVarName =>'
               ' $pointerName;\n\n');
         } else {
-          s.write('$dartType get $globalVarName => $pointerName.ref;\n\n');
+          s.write('$ffiDartType get $globalVarName => $pointerName.ref;\n\n');
         }
-      } else {
+      } else if (type.sameDartAndFfiDartType) {
         s.write('$dartType get $globalVarName => $pointerName.value;\n\n');
         if (!constant) {
           s.write('set $globalVarName($dartType value) =>'
               '$pointerName.value = value;\n\n');
         }
+      } else {
+        generateConvertingGetterAndSetter('$pointerName.value');
       }
 
       if (exposeSymbolAddress) {

pkgs/ffigen/test/native_objc_test/global_config.yaml

@@ -0,0 +1,15 @@
+name: GlobalTestObjCLibrary
+description: 'Tests global variables'
+language: objc
+output: 'global_bindings.dart'
+exclude-all-by-default: true
+globals:
+  include:
+    - globalString
+    - globalObject
+    - globalBlock
+headers:
+  entry-points:
+    - 'global_test.h'
+preamble: |
+  // ignore_for_file: camel_case_types, non_constant_identifier_names, unnecessary_non_null_assertion, unused_element, unused_field

pkgs/ffigen/test/native_objc_test/global_native_config.yaml

@@ -0,0 +1,16 @@
+name: GlobalTestObjCLibrary
+description: 'Tests global variables'
+language: objc
+output: 'global_native_bindings.dart'
+exclude-all-by-default: true
+ffi-native:
+globals:
+  include:
+    - globalString
+    - globalObject
+    - globalBlock
+headers:
+  entry-points:
+    - 'global_test.h'
+preamble: |
+  // ignore_for_file: camel_case_types, non_constant_identifier_names, unnecessary_non_null_assertion, unused_element, unused_field

pkgs/ffigen/test/native_objc_test/global_native_test.dart

@@ -0,0 +1,96 @@
+// Copyright (c) 2024, 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.
+
+// Objective C support is only available on mac.
+@TestOn('mac-os')
+
+import 'dart:ffi';
+import 'dart:io';
+
+import 'package:objective_c/objective_c.dart';
+import 'package:test/test.dart';
+
+import '../test_utils.dart';
+import 'global_native_bindings.dart';
+import 'util.dart';
+
+void main() {
+  group('global using @Native', () {
+    setUpAll(() {
+      // TODO(https://github.com/dart-lang/native/issues/1068): Remove this.
+      DynamicLibrary.open('../objective_c/test/objective_c.dylib');
+      final dylib = File('test/native_objc_test/global_native_test.dylib');
+      verifySetupFile(dylib);
+      DynamicLibrary.open(dylib.absolute.path);
+      generateBindingsForCoverage('global_native');
+    });
+
+    test('Global string', () {
+      expect(globalString.toString(), 'Hello World');
+      globalString = 'Something else'.toNSString();
+      expect(globalString.toString(), 'Something else');
+    });
+
+    (Pointer<ObjCObject>, Pointer<ObjCObject>) globalObjectRefCountingInner() {
+      final obj1 = NSObject.new1();
+      globalObject = obj1;
+      final obj1raw = obj1.pointer;
+      expect(objectRetainCount(obj1raw), 2); // obj1, and the global variable.
+
+      final obj2 = NSObject.new1();
+      globalObject = obj2;
+      final obj2raw = obj2.pointer;
+      expect(objectRetainCount(obj2raw), 2); // obj2, and the global variable.
+      expect(objectRetainCount(obj1raw), 1); // Just obj1.
+
+      return (obj1raw, obj2raw);
+    }
+
+    test('Global object ref counting', () {
+      final (obj1raw, obj2raw) = globalObjectRefCountingInner();
+      doGC();
+
+      expect(objectRetainCount(obj2raw), 1); // Just the global variable.
+      expect(objectRetainCount(obj1raw), 0);
+
+      globalObject = null;
+      expect(objectRetainCount(obj2raw), 0);
+      expect(objectRetainCount(obj1raw), 0);
+    });
+
+    test('Global block', () {
+      globalBlock = ObjCBlock_Int32_Int32.fromFunction((int x) => x * 10);
+      expect(globalBlock!(123), 1230);
+      globalBlock = ObjCBlock_Int32_Int32.fromFunction((int x) => x + 1000);
+      expect(globalBlock!(456), 1456);
+    });
+
+    (Pointer<ObjCBlock>, Pointer<ObjCBlock>) globalBlockRefCountingInner() {
+      final blk1 = ObjCBlock_Int32_Int32.fromFunction((int x) => x * 10);
+      globalBlock = blk1;
+      final blk1raw = blk1.pointer;
+      expect(blockRetainCount(blk1raw), 2); // blk1, and the global variable.
+
+      final blk2 = ObjCBlock_Int32_Int32.fromFunction((int x) => x + 1000);
+      globalBlock = blk2;
+      final blk2raw = blk2.pointer;
+      expect(blockRetainCount(blk2raw), 2); // blk2, and the global variable.
+      expect(blockRetainCount(blk1raw), 1); // Just blk1.
+
+      return (blk1raw, blk2raw);
+    }
+
+    test('Global block ref counting', () {
+      final (blk1raw, blk2raw) = globalBlockRefCountingInner();
+      doGC();
+
+      expect(blockRetainCount(blk2raw), 1); // Just the global variable.
+      expect(blockRetainCount(blk1raw), 0);
+
+      globalBlock = null;
+      expect(blockRetainCount(blk2raw), 0);
+      expect(blockRetainCount(blk1raw), 0);
+    });
+  });
+}

pkgs/ffigen/test/native_objc_test/global_native_test.m

@@ -0,0 +1,5 @@
+// Copyright (c) 2024, 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.
+
+#include "global_test.m"

pkgs/ffigen/test/native_objc_test/global_test.dart

@@ -0,0 +1,98 @@
+// Copyright (c) 2024, 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.
+
+// Objective C support is only available on mac.
+@TestOn('mac-os')
+
+import 'dart:ffi';
+import 'dart:io';
+
+import 'package:objective_c/objective_c.dart';
+import 'package:test/test.dart';
+
+import '../test_utils.dart';
+import 'global_bindings.dart';
+import 'util.dart';
+
+void main() {
+  group('global', () {
+    late GlobalTestObjCLibrary lib;
+
+    setUpAll(() {
+      // TODO(https://github.com/dart-lang/native/issues/1068): Remove this.
+      DynamicLibrary.open('../objective_c/test/objective_c.dylib');
+      final dylib = File('test/native_objc_test/global_test.dylib');
+      verifySetupFile(dylib);
+      lib = GlobalTestObjCLibrary(DynamicLibrary.open(dylib.absolute.path));
+      generateBindingsForCoverage('global');
+    });
+
+    test('Global string', () {
+      expect(lib.globalString.toString(), 'Hello World');
+      lib.globalString = 'Something else'.toNSString();
+      expect(lib.globalString.toString(), 'Something else');
+    });
+
+    (Pointer<ObjCObject>, Pointer<ObjCObject>) globalObjectRefCountingInner() {
+      final obj1 = NSObject.new1();
+      lib.globalObject = obj1;
+      final obj1raw = obj1.pointer;
+      expect(objectRetainCount(obj1raw), 2); // obj1, and the global variable.
+
+      final obj2 = NSObject.new1();
+      lib.globalObject = obj2;
+      final obj2raw = obj2.pointer;
+      expect(objectRetainCount(obj2raw), 2); // obj2, and the global variable.
+      expect(objectRetainCount(obj1raw), 1); // Just obj1.
+
+      return (obj1raw, obj2raw);
+    }
+
+    test('Global object ref counting', () {
+      final (obj1raw, obj2raw) = globalObjectRefCountingInner();
+      doGC();
+
+      expect(objectRetainCount(obj2raw), 1); // Just the global variable.
+      expect(objectRetainCount(obj1raw), 0);
+
+      lib.globalObject = null;
+      expect(objectRetainCount(obj2raw), 0);
+      expect(objectRetainCount(obj1raw), 0);
+    });
+
+    test('Global block', () {
+      lib.globalBlock = ObjCBlock_Int32_Int32.fromFunction((int x) => x * 10);
+      expect(lib.globalBlock!(123), 1230);
+      lib.globalBlock = ObjCBlock_Int32_Int32.fromFunction((int x) => x + 1000);
+      expect(lib.globalBlock!(456), 1456);
+    });
+
+    (Pointer<ObjCBlock>, Pointer<ObjCBlock>) globalBlockRefCountingInner() {
+      final blk1 = ObjCBlock_Int32_Int32.fromFunction((int x) => x * 10);
+      lib.globalBlock = blk1;
+      final blk1raw = blk1.pointer;
+      expect(blockRetainCount(blk1raw), 2); // blk1, and the global variable.
+
+      final blk2 = ObjCBlock_Int32_Int32.fromFunction((int x) => x + 1000);
+      lib.globalBlock = blk2;
+      final blk2raw = blk2.pointer;
+      expect(blockRetainCount(blk2raw), 2); // blk2, and the global variable.
+      expect(blockRetainCount(blk1raw), 1); // Just blk1.
+
+      return (blk1raw, blk2raw);
+    }
+
+    test('Global block ref counting', () {
+      final (blk1raw, blk2raw) = globalBlockRefCountingInner();
+      doGC();
+
+      expect(blockRetainCount(blk2raw), 1); // Just the global variable.
+      expect(blockRetainCount(blk1raw), 0);
+
+      lib.globalBlock = null;
+      expect(blockRetainCount(blk2raw), 0);
+      expect(blockRetainCount(blk1raw), 0);
+    });
+  });
+}

pkgs/ffigen/test/native_objc_test/global_test.h

@@ -0,0 +1,10 @@
+// Copyright (c) 2024, 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.
+
+#import <Foundation/NSObject.h>
+#import <Foundation/NSString.h>
+
+NSString* globalString;
+NSObject* _Nullable globalObject;
+int32_t (^_Nullable globalBlock)(int32_t);

pkgs/ffigen/test/native_objc_test/global_test.m

@@ -0,0 +1,12 @@
+// Copyright (c) 2024, 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.
+
+#import <Foundation/NSObject.h>
+
+#include "global_test.h"
+#include "util.h"
+
+NSString* globalString = @"Hello World";
+NSObject* _Nullable globalObject = nil;
+int32_t (^_Nullable globalBlock)(int32_t) = nil;