AU: Don't request data ranges beyond the end of the payload.

update_attempter.cc

Index: update_attempter.cc
diff --git a/update_attempter.cc b/update_attempter.cc
index 1e3bf5db730f252134479075dbd843ff44e61c5b..7c324755aa328e3c97f108c637ca086ed65572f8 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -535,12 +535,19 @@ void UpdateAttempter::SetupDownload() {
           download_action_->http_fetcher());
   MultiHttpFetcher<LibcurlHttpFetcher>::RangesVect ranges;
   if (response_handler_action_->install_plan().is_resume) {
+    // Resuming an update so fetch the update manifest metadata first.
     int64_t manifest_metadata_size = 0;
     prefs_->GetInt64(kPrefsManifestMetadataSize, &manifest_metadata_size);
+    ranges.push_back(make_pair(0, manifest_metadata_size));
+    // If there're remaining unprocessed data blobs, fetch them. Be careful not
+    // to request data beyond the end of the payload to avoid 416 HTTP response
+    // error codes.
     int64_t next_data_offset = 0;
     prefs_->GetInt64(kPrefsUpdateStateNextDataOffset, &next_data_offset);
-    ranges.push_back(make_pair(0, manifest_metadata_size));
-    ranges.push_back(make_pair(manifest_metadata_size + next_data_offset, -1));
+    uint64_t resume_offset = manifest_metadata_size + next_data_offset;
+    if (resume_offset < response_handler_action_->install_plan().size) {
+      ranges.push_back(make_pair(resume_offset, -1));
+    }
   } else {
     ranges.push_back(make_pair(0, -1));
   }