1 files changed, 38 insertions, 0 deletions
diff --git a/lib/gitlab/checks/file_size_check/allow_existing_oversized_blobs.rb b/lib/gitlab/checks/file_size_check/allow_existing_oversized_blobs.rb
new file mode 100644
index 00000000000..78f1716274e
--- /dev/null
+++ b/lib/gitlab/checks/file_size_check/allow_existing_oversized_blobs.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Checks
+    module FileSizeCheck
+      class AllowExistingOversizedBlobs
+        def initialize(project:, changes:, file_size_limit_megabytes:)
+          @project = project
+          @changes = changes
+          @oldrevs = changes.pluck(:oldrev).compact # rubocop:disable CodeReuse/ActiveRecord just plucking from an array
+          @file_size_limit_megabytes = file_size_limit_megabytes
+        end
+
+        def find(timeout: nil)
+          oversize_blobs = any_oversize_blobs.find(timeout: timeout)
+
+          return oversize_blobs unless oldrevs.present?
+
+          revs_paths = oldrevs.product(oversize_blobs.map(&:path))
+          existing_blobs = project.repository.blobs_at(revs_paths, blob_size_limit: 1)
+          map_existing_path_to_size = existing_blobs.group_by(&:path).transform_values { |blobs| blobs.map(&:size).max }
+
+          # return blobs that are going to be over the limit that were previously within the limit
+          oversize_blobs.select { |blob| map_existing_path_to_size.fetch(blob.path, 0) <= file_size_limit_megabytes }
+        end
+
+        private
+
+        attr_reader :project, :changes, :newrevs, :oldrevs, :file_size_limit_megabytes
+
+        def any_oversize_blobs
+          AnyOversizedBlobs.new(project: project, changes: changes,
+            file_size_limit_megabytes: file_size_limit_megabytes)
+        end
+      end
+    end
+  end
+end