这个文件 应该是 OpenJDK 的一部分，

AOSP 里面也有类似关于 Unsafe 的 stub，他们在使用的时候都保留了原 Notice ，例如这个： Unsafe.java

鉴于 GPL 的传染性，也许整个这个项目应该都换成 GPL v2 with Classpath Exception 许可证

my code:

HiddenApiBypass.addHiddenApiExemptions("");
Class<?> c = Class.forName("dalvik.system.VMDebug");
if(android.os.Build.VERSION.SDK_INT>=28) {
                getInstancesOfClassesMethod = c.getDeclaredMethod("getInstancesOfClasses",
                        Class[].class, Boolean.TYPE);
}
//            return (Object[][]) HiddenApiBypass.invoke(
//                    Class.forName("dalvik.system.VMDebug"),
//                    null,"getInstancesOfClasses",
//                    new Object[]{classes, assignable}
//                    );
            return (Object[][]) getInstancesOfClassesMethod.invoke(
                    null,
                    new Object[]{classes, assignable});

This code can run successfully on Android 11, but InvocationTargetException exception on the 12 version 。

hello. I using HokoBlurDrawable and Using method callDrawGLFunction2 in class android.graphics.RecordingCanvas. i try to use this in api 30 to the top.

The code from art/runtime/java_lang_Class.cc

` // Check classes in the java.lang.invoke package. At the time of writing, the // classes of interest are MethodHandles and MethodHandles.Lookup, but this // is subject to change so conservatively cover the entire package. // NB Static initializers within java.lang.invoke are permitted and do not // need further stack inspection. ObjPtrmirror::Class lookup_class = GetClassRootmirror::MethodHandlesLookup(); if ((declaring_class == lookup_class || declaring_class->IsInSamePackage(lookup_class)) && !m->IsClassInitializer()) { return true; }

`

系统api 约束分为：

1. @hide
2. @UnsupportedAppUsage
3. @SystemApi
4. @TestApi

如你示例中，使用ApplicationInfo 中代码进行测试，测试代码如下:

    /**
     * @hide
     */
    public @HiddenApiEnforcementPolicy int getHiddenApiEnforcementPolicy() {}

    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
    private boolean isPackageUnavailable(PackageManager pm) {}

   @SystemApi
    public boolean isEncryptionAware() {}
   /** @hide */
    @TestApi
    public boolean isSystemApp() {}

测试结果如下：

 java.lang.NoSuchMethodException: android.content.pm.ApplicationInfo.isPackageUnavailable [class android.content.pm.PackageManager]

结果： @UnsupportedAppUsage类型兼容需要增强

I noticed that version 3.0 adds a HiddenApiBypass.invoke() function. Is the HiddenApiBypass.invoke() just a helper function, or do we have to change to use this function instead of the traditional Method.invoke() function?

What about the Field.get()? I don't see a HiddenApiBypass.get() function provided.

I found the getStaticFields() will print out some debug messages. Please remove them or only print messages when BuildConfig.DEBUG is true.

public static List<Field> getStaticFields(@NonNull Class<?> clazz) {
    ArrayList<Field> list = new ArrayList<>();
    if (clazz.isPrimitive() || clazz.isArray()) return list;
    MethodHandle mh;
    try {
        mh = MethodHandles.lookup().unreflectGetter(Helper.NeverCall.class.getDeclaredField("s"));
    } catch (IllegalAccessException | NoSuchFieldException e) {
        return list;
    }
    long fields = unsafe.getLong(clazz, sFieldOffset);
    if (fields == 0) return list;
    Log.d(TAG, "sfield: " + fields); <----------------------------------------------------------------- debug message
    int numFields = unsafe.getInt(fields);
    if (BuildConfig.DEBUG) Log.d(TAG, clazz + " has " + numFields + " static fields");
    for (int i = 0; i < numFields; i++) {
        long field = fields + i * artFieldSize + artFieldBias;
        Log.d(TAG, "field " + Long.toString(field, 16)); <--------------------------------------------- debug message
        unsafe.putLong(mh, artOffset, field);
        unsafe.putObject(mh, infoOffset, null);
        try {
            MethodHandles.lookup().revealDirect(mh);
        } catch (Throwable ignored) {
        }
        MethodHandleInfo info = (MethodHandleInfo) unsafe.getObject(mh, infoOffset);
        Field member = (Field) unsafe.getObject(info, memberOffset);
        if (BuildConfig.DEBUG)
            Log.v(TAG, "got " + member.getType() + " " + clazz.getTypeName() + "." + member.getName());
        list.add(member);
    }
    return list;
}

Would you add the following API? Method getDeclaredMethod(String name, Class...<?> parameterTypes)

The reasons are:

1. we can cache the founded Method in our own class so it does not have to look up methods for each invoke() call
2. easier for developers to find the polymorphism function

Public the checkArgsForInvokeMethod() function is also an acceptable workaround.

` struct FirstExternalCallerVisitor : public StackVisitor { explicit FirstExternalCallerVisitor(Thread* thread) : StackVisitor(thread, nullptr, StackVisitor::StackWalkKind::kIncludeInlinedFrames), caller(nullptr) { }

bool VisitFrame() override REQUIRES_SHARED(Locks::mutator_lock_) {
  ArtMethod *m = GetMethod();
  if (m == nullptr) {
    // Attached native thread. Assume this is *not* boot class path.
    caller = nullptr;
    return false;
  } else if (m->IsRuntimeMethod()) {
    // Internal runtime method, continue walking the stack.
    return true;
  }

  ObjPtr<mirror::Class> declaring_class = m->GetDeclaringClass();
  if (declaring_class->IsBootStrapClassLoaded()) {
    if (declaring_class->IsClassClass()) {
      return true;
    }
    **// Check classes in the java.lang.invoke package. At the time of writing, the
    // classes of interest are MethodHandles and MethodHandles.Lookup, but this
    // is subject to change so conservatively cover the entire package.
    // NB Static initializers within java.lang.invoke are permitted and do not
    // need further stack inspection.
    ObjPtr<mirror::Class> lookup_class = GetClassRoot<mirror::MethodHandlesLookup>();
    if ((declaring_class == lookup_class || declaring_class->IsInSamePackage(lookup_class))
        && !m->IsClassInitializer()) {
      return true;
    }**
    // Check for classes in the java.lang.reflect package, except for java.lang.reflect.Proxy.
    // java.lang.reflect.Proxy does its own hidden api checks (https://r.android.com/915496),
    // and walking over this frame would cause a null pointer dereference
    // (e.g. in 691-hiddenapi-proxy).
    ObjPtr<mirror::Class> proxy_class = GetClassRoot<mirror::Proxy>();
    if (declaring_class->IsInSamePackage(proxy_class) && declaring_class != proxy_class) {
      if (Runtime::Current()->isChangeEnabled(kPreventMetaReflectionBlacklistAccess)) {
        return true;
      }
    }
  }

  caller = m;
  return false;
}

`