Make PlatformCompat a Binder class

This allows PlatformCompat to be called from anywhere in the platform.
In follow-up CLs, we'll define permissions for each method and/or
filtering rules to prevent abuse from apps.

Test: m
Bug: 137769727
Change-Id: I19e5fbfefcf59e0b53b197ea8e9e3cb78439b4c4
Merged-In: I19e5fbfefcf59e0b53b197ea8e9e3cb78439b4c4

services/core/Android.bp

@@ -12,6 +12,7 @@ java_library_static {
     },
     srcs: [
         "java/**/*.java",
+        ":platformcompat_aidl",
         ":dumpstate_aidl",
         ":installd_aidl",
         ":storaged_aidl",
@@ -78,3 +79,11 @@ prebuilt_etc {
     name: "gps_debug.conf",
     src: "java/com/android/server/location/gps_debug.conf",
 }
+
+filegroup {
+    name: "platformcompat_aidl",
+    srcs: [
+        "java/com/android/server/compat/IPlatformCompat.aidl",
+    ],
+    path: "java",
+}

services/core/java/com/android/server/compat/IPlatformCompat.aidl

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.compat;
+
+import android.content.pm.ApplicationInfo;
+
+/**
+ * System private API for talking with the PlatformCompat service.
+ * {@hide}
+ */
+interface IPlatformCompat
+{
+
+    /**
+     * Reports that a compatibility change is affecting an app process now.
+     *
+     * <p>Note: for changes that are gated using {@link #isChangeEnabled(long, ApplicationInfo)},
+     * you do not need to call this API directly. The change will be reported for you in the case
+     * that {@link #isChangeEnabled(long, ApplicationInfo)} returns {@code true}.
+     *
+     * @param changeId The ID of the compatibility change taking effect.
+     * @param appInfo Representing the affected app.
+     */
+    void reportChange(long changeId, in ApplicationInfo appInfo);
+
+    /**
+     * Query if a given compatibility change is enabled for an app process. This method should
+     * be called when implementing functionality on behalf of the affected app.
+     *
+     * <p>If this method returns {@code true}, the calling code should implement the compatibility
+     * change, resulting in differing behaviour compared to earlier releases. If this method returns
+     * {@code false}, the calling code should behave as it did in earlier releases.
+     *
+     * <p>When this method returns {@code true}, it will also report the change as
+     * {@link #reportChange(long, ApplicationInfo)} would, so there is no need to call that method
+     * directly.
+     *
+     * @param changeId The ID of the compatibility change in question.
+     * @param appInfo Representing the app in question.
+     * @return {@code true} if the change is enabled for the current app.
+     */
+    boolean isChangeEnabled(long changeId, in ApplicationInfo appInfo);
+}

services/core/java/com/android/server/compat/PlatformCompat.java

@@ -16,52 +16,46 @@
 
 package com.android.server.compat;
 
+import android.content.Context;
 import android.content.pm.ApplicationInfo;
 import android.util.Slog;
 
+import com.android.internal.util.DumpUtils;
+
+import java.io.FileDescriptor;
+import java.io.PrintWriter;
+
 /**
  * System server internal API for gating and reporting compatibility changes.
  */
-public class PlatformCompat {
+public class PlatformCompat extends IPlatformCompat.Stub {
 
     private static final String TAG = "Compatibility";
 
-    /**
-     * Reports that a compatibility change is affecting an app process now.
-     *
-     * <p>Note: for changes that are gated using {@link #isChangeEnabled(long, ApplicationInfo)},
-     * you do not need to call this API directly. The change will be reported for you in the case
-     * that {@link #isChangeEnabled(long, ApplicationInfo)} returns {@code true}.
-     *
-     * @param changeId The ID of the compatibility change taking effect.
-     * @param appInfo Representing the affected app.
-     */
-    public static void reportChange(long changeId, ApplicationInfo appInfo) {
+    private final Context mContext;
+
+    public PlatformCompat(Context context) {
+        mContext = context;
+    }
+
+    @Override
+    public void reportChange(long changeId, ApplicationInfo appInfo) {
         Slog.d(TAG, "Compat change reported: " + changeId + "; UID " + appInfo.uid);
         // TODO log via StatsLog
     }
 
-    /**
-     * Query if a given compatibility change is enabled for an app process. This method should
-     * be called when implementing functionality on behalf of the affected app.
-     *
-     * <p>If this method returns {@code true}, the calling code should implement the compatibility
-     * change, resulting in differing behaviour compared to earlier releases. If this method returns
-     * {@code false}, the calling code should behave as it did in earlier releases.
-     *
-     * <p>When this method returns {@code true}, it will also report the change as
-     * {@link #reportChange(long, ApplicationInfo)} would, so there is no need to call that method
-     * directly.
-     *
-     * @param changeId The ID of the compatibility change in question.
-     * @param appInfo Representing the app in question.
-     * @return {@code true} if the change is enabled for the current app.
-     */
-    public static boolean isChangeEnabled(long changeId, ApplicationInfo appInfo) {
+    @Override
+    public boolean isChangeEnabled(long changeId, ApplicationInfo appInfo) {
         if (CompatConfig.get().isChangeEnabled(changeId, appInfo)) {
             reportChange(changeId, appInfo);
             return true;
         }
         return false;
     }
+
+    @Override
+    protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
+        if (!DumpUtils.checkDumpAndUsageStatsPermission(mContext, "platform_compat", pw)) return;
+        // TODO: Dump info about compatibility changes.
+    }
 }

services/java/com/android/server/SystemServer.java

@@ -79,6 +79,7 @@ import com.android.server.audio.AudioService;
 import com.android.server.broadcastradio.BroadcastRadioService;
 import com.android.server.camera.CameraServiceProxy;
 import com.android.server.clipboard.ClipboardService;
+import com.android.server.compat.PlatformCompat;
 import com.android.server.connectivity.IpConnectivityMetrics;
 import com.android.server.coverage.CoverageService;
 import com.android.server.devicepolicy.DevicePolicyManagerService;
@@ -975,6 +976,11 @@ public final class SystemServer {
             traceBeginAndSlog("PinnerService");
             mSystemServiceManager.startService(PinnerService.class);
             traceEnd();
+
+            traceBeginAndSlog("PlatformCompat");
+            ServiceManager.addService("platform_compat", new PlatformCompat(context));
+            traceEnd();
+
         } catch (RuntimeException e) {
             Slog.e("System", "******************************************");
             Slog.e("System", "************ Failure starting core service", e);