SCI-3976 different approach to file download

app/services/model_exporters/model_exporter.rb

@@ -1,11 +1,13 @@
 # frozen_string_literal: true
 
 require 'fileutils'
+require 'active_storage/downloading'
 
 module ModelExporters
   class ModelExporter
     attr_accessor :assets_to_copy
     attr_accessor :tiny_mce_assets_to_copy
+    include ActiveStorage::Downloading
 
     def initialize
       @assets_to_copy = []
@@ -15,22 +17,16 @@ module ModelExporters
     def copy_files(assets, attachment_name, dir_name)
       assets.flatten.each do |a|
         next unless a.public_send(attachment_name).attached?
+        blob = a.public_send(attachment_name).blob
+        dir = FileUtils.mkdir_p(File.join(dir_name, a.id.to_s)).first
+        destination_path = File.join(dir, a.file_name)
+
+        blob.open do |file|
+          system '/path/to/virus/scanner', file.path
+          FileUtils.cp(file.path, destination_path)
+        end
 
         yield if block_given?
-        dir = FileUtils.mkdir_p(File.join(dir_name, a.id.to_s)).first
-
-        tempfile = Tempfile.new
-        tempfile.binmode
-        a.public_send(attachment_name).blob.download { |chunk| tempfile.write(chunk) }
-        tempfile.flush
-        tempfile.rewind
-        FileUtils.cp(
-          tempfile.path,
-          File.join(dir, a.file_name)
-        )
-      ensure
-        tempfile.close
-        tempfile.unlink
       end
     end