98848 Use FileUtils.mv over File.rename to account for external d…

…evice error - IVC CHAMPVA forms (#19885)

* updated file move operation to account for possible file system issues

* missing end

modules/ivc_champva/app/services/ivc_champva/attachments.rb

@@ -4,7 +4,7 @@ module IvcChampva
   module Attachments
     attr_accessor :form_id, :uuid, :data
 
-    def handle_attachments(file_path)
+    def handle_attachments(file_path) # rubocop:disable Metrics/MethodLength
       file_paths = [file_path]
       attachments = get_attachments
 
@@ -22,7 +22,14 @@ def handle_attachments(file_path)
                           File.join(File.dirname(attachment), new_file_name)
                         end
 
-        File.rename(attachment, new_file_path)
+        if Flipper.enabled?(:champva_pdf_decrypt, @current_user)
+          # Use FileUtils.mv to handle `Errno::EXDEV` error since encrypted PDFs
+          # get stashed in the clamav_tmp dir which is a different device on staging, apparently
+          FileUtils.mv(attachment, new_file_path) # Performs a copy automatically if mv fails
+        else
+          File.rename(attachment, new_file_path)
+        end
+
         file_paths << new_file_path
       end