UpdateAttempterAndroid::Init initiates merge

On update_engine starts, schedule CleanupPreviousUpdateAction that calls
CleanupSuccessfulUpdate to do necessary cleanup as soon as possible.

In the good case, update_engine initiates merge when
sys.boot_completed, and clean up snapshots.

If the update is
rolled back or partitions are flashed, the following happens (on
a Virtual A/B device):

- UpdateAttempterAndroid::CleanupSuccessfulUpdate is called
  - DynamicPartitionControlAndroid::CleanupSuccessfulUpdate is called
  - SnapshotManager::InitiateMergeAndWait is called
  - SnapshotManager::RemoveAllUpdateState(before_cancel) is called
  - before_cancel is called,
    DeltaPerformer::ResetUpdateProgress is called
    - All update states in update_engine is reset.
  - SnapshotManager proceeds to delete snapshots
    - All update states in SnapshotManager is reset.

Hence, on an VAB device, when an update is rolled back or partitions
are flashed, the whole update needs to be re-applied
(while in A/B, it skips writing and directly start verifying hashes of
the target partitions because the update markers are still there).

Bug: 147696014
Test: apply OTA then reboot, inspect logs and do `snapshotctl dump`

Change-Id: I0fc5e7768dfb53e4fd474f2d8d85d2a1b615a88b

1 files changed, 5 insertions, 0 deletions

diff --git a/update_status_utils.cc b/update_status_utils.cc
index cbc4f14b..11fd2995 100644
--- a/update_status_utils.cc
+++ b/update_status_utils.cc
@@ -46,6 +46,8 @@ const char* UpdateStatusToString(const UpdateStatus& status) {
       return update_engine::kUpdateStatusAttemptingRollback;
     case UpdateStatus::DISABLED:
       return update_engine::kUpdateStatusDisabled;
+    case UpdateStatus::CLEANUP_PREVIOUS_UPDATE:
+      return update_engine::kUpdateStatusCleanupPreviousUpdate;
   }
 
   NOTREACHED();
@@ -86,6 +88,9 @@ bool StringToUpdateStatus(const std::string& s, UpdateStatus* status) {
   } else if (s == update_engine::kUpdateStatusDisabled) {
     *status = UpdateStatus::DISABLED;
     return true;
+  } else if (s == update_engine::kUpdateStatusCleanupPreviousUpdate) {
+    *status = UpdateStatus::CLEANUP_PREVIOUS_UPDATE;
+    return true;
   }
   return false;
 }