Correctly offset app op history on reboot

The offset was computed based off the offset represented by
the most recent historical file while we have to use the time
this file was written.

Also now we persist the history on reboot and shutdown,
significantly minimizing the possibility of data loss.

Added test API to emulate reboot of the history to allow for
precise and tightly controlled test to prevent flakes due to
boot time deviations.

Test: atest android.app.appops.cts.HistoricalAppopsTest#testRebootHistory

Fixes:156853195

Change-Id: I4142371f8bc2b1d710cc8c300e7e79cb03764c04

5 files changed, 72 insertions, 11 deletions

diff --git a/api/test-current.txt b/api/test-current.txt
index 66b5015902f0..1142fb631891 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -193,6 +193,7 @@ package android.app {
     method public static int opToDefaultMode(@NonNull String);
     method public static String opToPermission(int);
     method public static int permissionToOpCode(String);
+    method @RequiresPermission("android.permission.MANAGE_APPOPS") public void rebootHistory(long);
     method @RequiresPermission("android.permission.MANAGE_APPOPS") public void reloadNonHistoricalState();
     method @RequiresPermission("android.permission.MANAGE_APPOPS") public void resetHistoryParameters();
     method @RequiresPermission("android.permission.MANAGE_APPOPS") public void setHistoryParameters(int, long, int);
diff --git a/core/java/android/app/AppOpsManager.java b/core/java/android/app/AppOpsManager.java
index b058dcd714dd..50bb9a38f8e8 100644
--- a/core/java/android/app/AppOpsManager.java
+++ b/core/java/android/app/AppOpsManager.java
@@ -8577,6 +8577,25 @@ public class AppOpsManager {
     }
 
     /**
+     * Reboots the ops history.
+     *
+     * @param offlineDurationMillis The duration to wait between
+     * tearing down and initializing the history. Must be greater
+     * than or equal to zero.
+     *
+     * @hide
+     */
+    @TestApi
+    @RequiresPermission(Manifest.permission.MANAGE_APPOPS)
+    public void rebootHistory(long offlineDurationMillis) {
+        try {
+            mService.rebootHistory(offlineDurationMillis);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
      * Pulls current AppOps access report and picks package and op to watch for next access report
      * Returns null if no reports were collected since last call. There is no guarantee of report
      * collection, hence this method should be called periodically even if no report was collected
diff --git a/core/java/com/android/internal/app/IAppOpsService.aidl b/core/java/com/android/internal/app/IAppOpsService.aidl
index 06c21ab8832d..e614a0eb996b 100644
--- a/core/java/com/android/internal/app/IAppOpsService.aidl
+++ b/core/java/com/android/internal/app/IAppOpsService.aidl
@@ -76,6 +76,7 @@ interface IAppOpsService {
     void addHistoricalOps(in AppOpsManager.HistoricalOps ops);
     void resetHistoryParameters();
     void clearHistory();
+    void rebootHistory(long offlineDurationMillis);
     List<AppOpsManager.PackageOps> getUidOps(int uid, in int[] ops);
     void setUidMode(int code, int uid, int mode);
     @UnsupportedAppUsage
diff --git a/services/core/java/com/android/server/appop/AppOpsService.java b/services/core/java/com/android/server/appop/AppOpsService.java
index a33ad7dc0ea1..a2b2ed3ce6d3 100644
--- a/services/core/java/com/android/server/appop/AppOpsService.java
+++ b/services/core/java/com/android/server/appop/AppOpsService.java
@@ -322,7 +322,7 @@ public class AppOpsService extends IAppOpsService.Stub {
     @VisibleForTesting
     final SparseArray<UidState> mUidStates = new SparseArray<>();
 
-    final HistoricalRegistry mHistoricalRegistry = new HistoricalRegistry(this);
+    volatile @NonNull HistoricalRegistry mHistoricalRegistry = new HistoricalRegistry(this);
 
     long mLastRealtime;
 
@@ -1978,6 +1978,8 @@ public class AppOpsService extends IAppOpsService.Stub {
         if (AppOpsManager.NOTE_OP_COLLECTION_ENABLED && mWriteNoteOpsScheduled) {
             writeNoteOps();
         }
+
+        mHistoricalRegistry.shutdown();
     }
 
     private ArrayList<AppOpsManager.OpEntry> collectOps(Ops pkgOps, int[] ops) {
@@ -5881,6 +5883,25 @@ public class AppOpsService extends IAppOpsService.Stub {
         mHistoricalRegistry.clearHistory();
     }
 
+    @Override
+    public void rebootHistory(long offlineDurationMillis) {
+        mContext.enforceCallingOrSelfPermission(android.Manifest.permission.MANAGE_APPOPS,
+                "rebootHistory");
+
+        Preconditions.checkArgument(offlineDurationMillis >= 0);
+
+        // Must not hold the appops lock
+        mHistoricalRegistry.shutdown();
+
+        if (offlineDurationMillis > 0) {
+            SystemClock.sleep(offlineDurationMillis);
+        }
+
+        mHistoricalRegistry = new HistoricalRegistry(mHistoricalRegistry);
+        mHistoricalRegistry.systemReady(mContext.getContentResolver());
+        mHistoricalRegistry.persistPendingHistory();
+    }
+
     /**
      * Report runtime access to AppOp together with message (including stack trace)
      *
diff --git a/services/core/java/com/android/server/appop/HistoricalRegistry.java b/services/core/java/com/android/server/appop/HistoricalRegistry.java
index ed4506902f0a..3d22a156b91c 100644
--- a/services/core/java/com/android/server/appop/HistoricalRegistry.java
+++ b/services/core/java/com/android/server/appop/HistoricalRegistry.java
@@ -199,6 +199,13 @@ final class HistoricalRegistry {
         mInMemoryLock = lock;
     }
 
+    HistoricalRegistry(@NonNull HistoricalRegistry other) {
+        this(other.mInMemoryLock);
+        mMode = other.mMode;
+        mBaseSnapshotInterval = other.mBaseSnapshotInterval;
+        mIntervalCompressionMultiplier = other.mIntervalCompressionMultiplier;
+    }
+
     void systemReady(@NonNull ContentResolver resolver) {
         final Uri uri = Settings.Global.getUriFor(Settings.Global.APPOP_HISTORY_PARAMETERS);
         resolver.registerContentObserver(uri, false, new ContentObserver(
@@ -223,9 +230,16 @@ final class HistoricalRegistry {
                     // When starting always adjust history to now.
                     final long lastPersistTimeMills =
                             mPersistence.getLastPersistTimeMillisDLocked();
+
                     if (lastPersistTimeMills > 0) {
-                        mPendingHistoryOffsetMillis =
-                                System.currentTimeMillis() - lastPersistTimeMills;
+                        mPendingHistoryOffsetMillis = System.currentTimeMillis()
+                                - lastPersistTimeMills;
+
+                        if (DEBUG) {
+                            Slog.i(LOG_TAG, "Time since last write: "
+                                    + TimeUtils.formatDuration(mPendingHistoryOffsetMillis)
+                                    + " by which to push history on next write");
+                        }
                     }
                 }
             }
@@ -597,6 +611,9 @@ final class HistoricalRegistry {
                     return;
                 }
                 clearHistoryOnDiskDLocked();
+                mNextPersistDueTimeMillis = 0;
+                mPendingHistoryOffsetMillis = 0;
+                mCurrentHistoricalOps = null;
             }
         }
     }
@@ -650,7 +667,15 @@ final class HistoricalRegistry {
         return mCurrentHistoricalOps;
     }
 
-    private void persistPendingHistory() {
+    void shutdown() {
+        synchronized (mInMemoryLock) {
+            if (mMode != AppOpsManager.HISTORICAL_MODE_DISABLED) {
+                persistPendingHistory();
+            }
+        }
+    }
+
+    void persistPendingHistory() {
         final List<HistoricalOps> pendingWrites;
         synchronized (mOnDiskLock) {
             synchronized (mInMemoryLock) {
@@ -844,13 +869,7 @@ final class HistoricalRegistry {
                     if (shortestFile == null) {
                         return 0;
                     }
-                    final String shortestNameNoExtension = shortestFile.getName()
-                            .replace(HISTORY_FILE_SUFFIX, "");
-                    try {
-                        return Long.parseLong(shortestNameNoExtension);
-                    } catch (NumberFormatException e) {
-                        return 0;
-                    }
+                    return shortestFile.lastModified();
                 }
                 sHistoricalAppOpsDir.finishRead();
             } catch (Throwable e) {