From 7b1d974d71a1c7033a56f443a39f76872789ce7b Mon Sep 17 00:00:00 2001
From: Oscar Key <okey@google.com>
Date: Sat, 13 Jan 2018 17:21:49 +0000
Subject: [PATCH] Add FLAG_INCREMENTAL and FLAG_NON_INCREMENTAL to
 performBackup().

These indicate if backup manager passed any previous state to the backup
agent when building a backup. The transport will use these to decide
whether to clear any existing encryption related state for the app.

I left the new flags as @hide for now.

Bug: b/71792427
Test: Tested manually with a buid of GmsCore updated to process the new
flag. I am attempting to write a robolectric test.

Change-Id: Ica0f6f578cd7d1ad29af532a45a2ee6685c84747
---
 .../android/app/backup/BackupTransport.java   | 24 ++++++++++++++++++-
 .../backup/internal/PerformBackupTask.java    | 10 +++++++-
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/core/java/android/app/backup/BackupTransport.java b/core/java/android/app/backup/BackupTransport.java
index da81d19ca3cb2..3558e34304707 100644
--- a/core/java/android/app/backup/BackupTransport.java
+++ b/core/java/android/app/backup/BackupTransport.java
@@ -55,6 +55,22 @@ public class BackupTransport {
     // Transport should ignore its own moratoriums for call with this flag set.
     public static final int FLAG_USER_INITIATED = 1;
 
+    /**
+     * For key value backup, indicates that the backup data is a diff from a previous backup. The
+     * transport must apply this diff to an existing backup to build the new backup set.
+     *
+     * @hide
+     */
+    public static final int FLAG_INCREMENTAL = 1 << 1;
+
+    /**
+     * For key value backup, indicates that the backup data is a complete set, not a diff from a
+     * previous backup. The transport should clear any previous backup when storing this backup.
+     *
+     * @hide
+     */
+    public static final int FLAG_NON_INCREMENTAL = 1 << 2;
+
     IBackupTransport mBinderImpl = new TransportImpl();
 
     public IBinder getBinder() {
@@ -231,12 +247,18 @@ public class BackupTransport {
      * {@link #TRANSPORT_OK}, {@link #finishBackup} will then be called to ensure the data
      * is sent and recorded successfully.
      *
+     * If the backup data is a diff against the previous backup then the flag {@link
+     * BackupTransport#FLAG_INCREMENTAL} will be set. Otherwise, if the data is a complete backup
+     * set then {@link BackupTransport#FLAG_NON_INCREMENTAL} will be set. Before P neither flag will
+     * be set regardless of whether the backup is incremental or not.
+     *
      * @param packageInfo The identity of the application whose data is being backed up.
      *   This specifically includes the signature list for the package.
      * @param inFd Descriptor of file with data that resulted from invoking the application's
      *   BackupService.doBackup() method.  This may be a pipe rather than a file on
      *   persistent media, so it may not be seekable.
-     * @param flags {@link BackupTransport#FLAG_USER_INITIATED} or 0.
+     * @param flags a combination of {@link BackupTransport#FLAG_USER_INITIATED}, {@link
+     *   BackupTransport#FLAG_NON_INCREMENTAL}, {@link BackupTransport#FLAG_INCREMENTAL}, or 0.
      * @return one of {@link BackupTransport#TRANSPORT_OK} (OK so far),
      *  {@link BackupTransport#TRANSPORT_PACKAGE_REJECTED} (to suppress backup of this
      *  specific package, but allow others to proceed),
diff --git a/services/backup/java/com/android/server/backup/internal/PerformBackupTask.java b/services/backup/java/com/android/server/backup/internal/PerformBackupTask.java
index a002334dac3bd..cd28b748aad4f 100644
--- a/services/backup/java/com/android/server/backup/internal/PerformBackupTask.java
+++ b/services/backup/java/com/android/server/backup/internal/PerformBackupTask.java
@@ -914,7 +914,15 @@ public class PerformBackupTask implements BackupRestoreTask {
                         backupData = ParcelFileDescriptor.open(mBackupDataName,
                                 ParcelFileDescriptor.MODE_READ_ONLY);
                         backupManagerService.addBackupTrace("sending data to transport");
-                        int flags = mUserInitiated ? BackupTransport.FLAG_USER_INITIATED : 0;
+
+                        int userInitiatedFlag =
+                                mUserInitiated ? BackupTransport.FLAG_USER_INITIATED : 0;
+                        int incrementalFlag =
+                                mSavedStateName.length() == 0
+                                    ? BackupTransport.FLAG_NON_INCREMENTAL
+                                    : BackupTransport.FLAG_INCREMENTAL;
+                        int flags = userInitiatedFlag | incrementalFlag;
+
                         mStatus = transport.performBackup(mCurrentPackage, backupData, flags);
                     }