Compress the preferred-app backup payloads

They can be Very Very Large, so take advantage of the new BlobBackupHelper
infrastructure to keep them tiny!

Also fix an issue in which the restore path wasn't properly passing
notification payloads along for processing, and an issue in which the
blob helper wasn't handling empty states properly.

Change-Id: I11a7ca3cd2e26f634a8971e874ac97385b0b500c

3 files changed, 34 insertions, 134 deletions

diff --git a/core/java/android/app/backup/BlobBackupHelper.java b/core/java/android/app/backup/BlobBackupHelper.java
index 8e4002d..cdc62dc 100644
--- a/core/java/android/app/backup/BlobBackupHelper.java
+++ b/core/java/android/app/backup/BlobBackupHelper.java
@@ -133,7 +133,7 @@ public abstract class BlobBackupHelper implements BackupHelper {
 
             out.writeInt(mCurrentBlobVersion);
 
-            final int N = state.size();
+            final int N = (state != null) ? state.size() : 0;
             out.writeInt(N);
             for (int i = 0; i < N; i++) {
                 out.writeUTF(state.keyAt(i));
diff --git a/core/java/com/android/server/backup/PreferredActivityBackupHelper.java b/core/java/com/android/server/backup/PreferredActivityBackupHelper.java
index 6ac0d89..26f5bf4 100644
--- a/core/java/com/android/server/backup/PreferredActivityBackupHelper.java
+++ b/core/java/com/android/server/backup/PreferredActivityBackupHelper.java
@@ -17,159 +17,58 @@
 package com.android.server.backup;
 
 import android.app.AppGlobals;
-import android.app.backup.BackupDataInputStream;
-import android.app.backup.BackupDataOutput;
-import android.app.backup.BackupHelper;
-import android.content.Context;
+import android.app.backup.BlobBackupHelper;
 import android.content.pm.IPackageManager;
-import android.os.IBinder;
-import android.os.ParcelFileDescriptor;
-import android.os.ServiceManager;
 import android.os.UserHandle;
 import android.util.Slog;
-import android.util.Xml;
 
-import com.android.internal.util.FastXmlSerializer;
-import com.android.org.bouncycastle.util.Arrays;
-
-import org.xmlpull.v1.XmlPullParser;
-import org.xmlpull.v1.XmlSerializer;
-
-import java.io.BufferedInputStream;
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.EOFException;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-
-public class PreferredActivityBackupHelper implements BackupHelper {
+public class PreferredActivityBackupHelper extends BlobBackupHelper {
     private static final String TAG = "PreferredBackup";
-    private static final boolean DEBUG = true;
+    private static final boolean DEBUG = false;
 
     // current schema of the backup state blob
-    private static final int STATE_VERSION = 1;
+    private static final int STATE_VERSION = 2;
 
     // key under which the preferred-activity state blob is committed to backup
     private static final String KEY_PREFERRED = "preferred-activity";
 
-    final Context mContext;
-
-    public PreferredActivityBackupHelper(Context context) {
-        mContext = context;
-    }
-
-    // The fds passed here are shared among all helpers, so we mustn't close them
-    private void writeState(ParcelFileDescriptor stateFile, byte[] payload) {
-        try {
-            FileOutputStream fos = new FileOutputStream(stateFile.getFileDescriptor());
-
-            // We explicitly don't close 'out' because we must not close the backing fd.
-            // The FileOutputStream will not close it implicitly.
-            @SuppressWarnings("resource")
-            DataOutputStream out = new DataOutputStream(fos);
-
-            out.writeInt(STATE_VERSION);
-            if (payload == null) {
-                out.writeInt(0);
-            } else {
-                out.writeInt(payload.length);
-                out.write(payload);
-            }
-        } catch (IOException e) {
-            Slog.e(TAG, "Unable to write updated state", e);
-        }
-    }
-
-    private byte[] readState(ParcelFileDescriptor oldStateFd) {
-        FileInputStream fis = new FileInputStream(oldStateFd.getFileDescriptor());
-        BufferedInputStream bis = new BufferedInputStream(fis);
-
-        @SuppressWarnings("resource")
-        DataInputStream in = new DataInputStream(bis);
-
-        byte[] oldState = null;
-        try {
-            int version = in.readInt();
-            if (version == STATE_VERSION) {
-                int size = in.readInt();
-                if (size > 0) {
-                    if (size > 200*1024) {
-                        Slog.w(TAG, "Suspiciously large state blog; ignoring.  N=" + size);
-                    } else {
-                        // size looks okay; make the return buffer and fill it
-                        oldState = new byte[size];
-                        in.read(oldState);
-                    }
-                }
-            } else {
-                Slog.w(TAG, "Prior state from unrecognized version " + version);
-            }
-        } catch (EOFException e) {
-            // Empty file is expected on first backup,  so carry on. If the state
-            // is truncated we just treat it the same way.
-            oldState = null;
-        } catch (Exception e) {
-            Slog.w(TAG, "Error examing prior backup state " + e.getMessage());
-            oldState = null;
-        }
-
-        return oldState;
+    public PreferredActivityBackupHelper() {
+        super(STATE_VERSION, KEY_PREFERRED);
     }
 
     @Override
-    public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
-            ParcelFileDescriptor newState) {
-        byte[] payload = null;
-        try {
-            byte[] oldPayload = readState(oldState);
-
+    protected byte[] getBackupPayload(String key) {
+        if (KEY_PREFERRED.equals(key)) {
+            if (DEBUG) {
+                Slog.v(TAG, "Checking whether to back up");
+            }
             IPackageManager pm = AppGlobals.getPackageManager();
-            byte[] newPayload = pm.getPreferredActivityBackup(UserHandle.USER_OWNER);
-            if (!Arrays.areEqual(oldPayload, newPayload)) {
-                if (DEBUG) {
-                    Slog.i(TAG, "State has changed => writing new preferred app payload");
-                }
-                data.writeEntityHeader(KEY_PREFERRED, newPayload.length);
-                data.writeEntityData(newPayload, newPayload.length);
-            } else {
-                if (DEBUG) {
-                    Slog.i(TAG, "No change to state => not writing to wire");
-                }
+            try {
+                return pm.getPreferredActivityBackup(UserHandle.USER_OWNER);
+            } catch (Exception e) {
+                Slog.e(TAG, "Unable to store backup payload", e);
+                // fall through to report null state
             }
-
-            // Always need to re-record the state, even if nothing changed
-            payload = newPayload;
-        } catch (Exception e) {
-            // On failures we'll wind up committing a zero-size state payload.  This is
-            // a forward-safe situation because we know we commit the entire new payload
-            // on prior-state mismatch.
-            Slog.w(TAG, "Unable to record preferred activities", e);
-        } finally {
-            writeState(newState, payload);
+        } else {
+            Slog.w(TAG, "Unexpected backup key " + key);
         }
+        return null;
     }
 
     @Override
-    public void restoreEntity(BackupDataInputStream data) {
-        IPackageManager pm = AppGlobals.getPackageManager();
-        try {
-            byte[] payload = new byte[data.size()];
-            data.read(payload);
+    protected void applyRestoredPayload(String key, byte[] payload) {
+        if (KEY_PREFERRED.equals(key)) {
             if (DEBUG) {
-                Slog.i(TAG, "Restoring preferred activities; size=" + payload.length);
+                Slog.v(TAG, "Restoring");
             }
-            pm.restorePreferredActivities(payload, UserHandle.USER_OWNER);
-        } catch (Exception e) {
-            Slog.e(TAG, "Exception reading restore data", e);
+            IPackageManager pm = AppGlobals.getPackageManager();
+            try {
+                pm.restorePreferredActivities(payload, UserHandle.USER_OWNER);
+            } catch (Exception e) {
+                Slog.e(TAG, "Unable to restore", e);
+            }
+        } else {
+            Slog.w(TAG, "Unexpected restore key " + key);
         }
     }
-
-    @Override
-    public void writeNewStateDescription(ParcelFileDescriptor newState) {
-        writeState(newState, null);
-    }
-
 }
diff --git a/core/java/com/android/server/backup/SystemBackupAgent.java b/core/java/com/android/server/backup/SystemBackupAgent.java
index 8e97aa9..a80abce 100644
--- a/core/java/com/android/server/backup/SystemBackupAgent.java
+++ b/core/java/com/android/server/backup/SystemBackupAgent.java
@@ -94,7 +94,7 @@ public class SystemBackupAgent extends BackupAgentHelper {
         addHelper(WALLPAPER_HELPER, new WallpaperBackupHelper(this, files, keys));
         addHelper(RECENTS_HELPER, new RecentsBackupHelper(this));
         addHelper(SYNC_SETTINGS_HELPER, new AccountSyncSettingsBackupHelper(this));
-        addHelper(PREFERRED_HELPER, new PreferredActivityBackupHelper(this));
+        addHelper(PREFERRED_HELPER, new PreferredActivityBackupHelper());
         addHelper(NOTIFICATION_HELPER, new NotificationBackupHelper(this));
 
         super.onBackup(oldState, data, newState);
@@ -129,7 +129,8 @@ public class SystemBackupAgent extends BackupAgentHelper {
                 new String[] { WALLPAPER_IMAGE_KEY} ));
         addHelper(RECENTS_HELPER, new RecentsBackupHelper(this));
         addHelper(SYNC_SETTINGS_HELPER, new AccountSyncSettingsBackupHelper(this));
-        addHelper(PREFERRED_HELPER, new PreferredActivityBackupHelper(this));
+        addHelper(PREFERRED_HELPER, new PreferredActivityBackupHelper());
+        addHelper(NOTIFICATION_HELPER, new NotificationBackupHelper(this));
 
         try {
             super.onRestore(data, appVersionCode, newState);