Add a method to IBackupTransport to get the current backup set token

This will be used to specifically manage restores of last-known-good data
generated from the current device during its normal provisioned lifetime.

2 files changed, 22 insertions, 3 deletions

diff --git a/core/java/com/android/internal/backup/IBackupTransport.aidl b/core/java/com/android/internal/backup/IBackupTransport.aidl
index a830ebd..9da1066 100644
--- a/core/java/com/android/internal/backup/IBackupTransport.aidl
+++ b/core/java/com/android/internal/backup/IBackupTransport.aidl
@@ -102,7 +102,7 @@ interface IBackupTransport {
     int finishBackup();
 
     /**
-     * Get the set of backups currently available over this transport.
+     * Get the set of all backups currently available over this transport.
      *
      * @return Descriptions of the set of restore images available for this device,
      *   or null if an error occurred (the attempt should be rescheduled).
@@ -110,11 +110,22 @@ interface IBackupTransport {
     RestoreSet[] getAvailableRestoreSets();
 
     /**
+     * Get the identifying token of the backup set currently being stored from
+     * this device.  This is used in the case of applications wishing to restore
+     * their last-known-good data.
+     *
+     * @return A token that can be passed to {@link #startRestore}, or 0 if there
+     *   is no backup set available corresponding to the current device state.
+     */
+    long getCurrentRestoreSet();
+
+    /**
      * Start restoring application data from backup.  After calling this function,
      * alternate calls to {@link #nextRestorePackage} and {@link #nextRestoreData}
      * to walk through the actual application data.
      *
-     * @param token A backup token as returned by {@link #getAvailableRestoreSets}.
+     * @param token A backup token as returned by {@link #getAvailableRestoreSets}
+     *   or {@link #getCurrentRestoreSet}.
      * @param packages List of applications to restore (if data is available).
      *   Application data will be restored in the order given.
      * @return One of {@link BackupConstants#TRANSPORT_OK} (OK so far, call
diff --git a/core/java/com/android/internal/backup/LocalTransport.java b/core/java/com/android/internal/backup/LocalTransport.java
index 12bc5a8..23ec647 100644
--- a/core/java/com/android/internal/backup/LocalTransport.java
+++ b/core/java/com/android/internal/backup/LocalTransport.java
@@ -33,6 +33,9 @@ public class LocalTransport extends IBackupTransport.Stub {
     private static final String TRANSPORT_DIR_NAME
             = "com.android.internal.backup.LocalTransport";
 
+    // The single hardcoded restore set always has the same (nonzero!) token
+    private static final long RESTORE_TOKEN = 1;
+
     private Context mContext;
     private PackageManager mPackageManager;
     private File mDataDir = new File(Environment.getDownloadCacheDirectory(), "backup");
@@ -149,11 +152,16 @@ public class LocalTransport extends IBackupTransport.Stub {
     // Restore handling
     public RestoreSet[] getAvailableRestoreSets() throws android.os.RemoteException {
         // one hardcoded restore set
-        RestoreSet set = new RestoreSet("Local disk image", "flash", 0);
+        RestoreSet set = new RestoreSet("Local disk image", "flash", RESTORE_TOKEN);
         RestoreSet[] array = { set };
         return array;
     }
 
+    public long getCurrentRestoreSet() {
+        // The hardcoded restore set always has the same token
+        return RESTORE_TOKEN;
+    }
+
     public int startRestore(long token, PackageInfo[] packages) {
         if (DEBUG) Log.v(TAG, "start restore " + token);
         mRestorePackages = packages;