update_engine: Add PayloadState Exclusion Logic

|PayloadState| will exclude payloads based on specific update failures.
This is to prevent critical platform updates from being blocked by less
critical updates (e.g. DLCs). A layer of robustness is added in
protecting CrOS devices from falling off the update train.

Some important changes to mention:
 - Only during updates will update_engine exclude non-critical payloads
 - |OmahaRequestAction|, the current precursor |Action| to
 |OmahaResponseHandlerAction|, during a update will exclude
 faulty/excluded payloads prior to setting the |OmahaResponse| as an
 output object for suqsequent bonded |Action| to consume
 - When all payloads are excluded for an update, the |ErrorCode| will
 be indicated as |OmahaResponseInvalid| as this case is not a valid
 Omaha response update_engine should ever run into because non-critical
 updates must tag alongside a critical update

BUG=chromium:928805
TEST=FEATURES=test emerge-$B update_engine update_engine-client

Change-Id: I0551a228d0b84defb4d59966e8ed46a5d9278d60
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/2190237
Tested-by: Jae Hoon Kim <kimjae@chromium.org>
Auto-Submit: Jae Hoon Kim <kimjae@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Commit-Queue: Jae Hoon Kim <kimjae@chromium.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/payload_state.cc b/payload_state.cc
index 2e07ad97..cf3aab91 100644
--- a/payload_state.cc
+++ b/payload_state.cc
@@ -312,6 +312,7 @@ void PayloadState::UpdateFailed(ErrorCode error) {
     case ErrorCode::kUnsupportedMinorPayloadVersion:
     case ErrorCode::kPayloadTimestampError:
     case ErrorCode::kVerityCalculationError:
+      ExcludeCurrentPayload();
       IncrementUrlIndex();
       break;
 
@@ -502,10 +503,29 @@ void PayloadState::IncrementFailureCount() {
   } else {
     LOG(INFO) << "Reached max number of failures for Url" << GetUrlIndex()
               << ". Trying next available URL";
+    ExcludeCurrentPayload();
     IncrementUrlIndex();
   }
 }
 
+void PayloadState::ExcludeCurrentPayload() {
+  const auto& package = response_.packages[payload_index_];
+  if (!package.can_exclude) {
+    LOG(INFO) << "Not excluding as marked non-excludable for package hash="
+              << package.hash;
+    return;
+  }
+  auto exclusion_name = utils::GetExclusionName(GetCurrentUrl());
+  if (!excluder_->Exclude(exclusion_name))
+    LOG(WARNING) << "Failed to exclude "
+                 << " Package Hash=" << package.hash
+                 << " CurrentUrl=" << GetCurrentUrl();
+  else
+    LOG(INFO) << "Excluded "
+              << " Package Hash=" << package.hash
+              << " CurrentUrl=" << GetCurrentUrl();
+}
+
 void PayloadState::UpdateBackoffExpiryTime() {
   if (response_.disable_payload_backoff) {
     LOG(INFO) << "Resetting backoff expiry time as payload backoff is disabled";