Editor: Allow file retrieval after code run

app/models/code_ocean/file.rb

@@ -18,6 +18,8 @@ module CodeOcean
     before_validation :set_ancestor_values, if: :incomplete_descendent?
 
     attr_writer :size
+    # These attributes are mainly used when retrieving files from a runner
+    attr_accessor :download_path
 
     belongs_to :context, polymorphic: true
     belongs_to :file, class_name: 'CodeOcean::File', optional: true # This is only required for submissions and is validated below
@@ -100,6 +102,14 @@ module CodeOcean
       end
     end
 
+    def filepath_without_extension
+      if path.present?
+        ::File.join(path, name)
+      else
+        name
+      end
+    end
+
     def hash_content
       self.hashed_content = Digest::MD5.new.hexdigest(read || '')
     end
@@ -114,6 +124,10 @@ module CodeOcean
       name.to_s + (file_type&.file_extension || '')
     end
 
+    def name_with_extension_and_size
+      "#{name_with_extension} (#{ActionController::Base.helpers.number_to_human_size(size)})"
+    end
+
     def set_ancestor_values
       %i[feedback_message file_type_id hidden name path read_only role weight].each do |attribute|
         send(:"#{attribute}=", ancestor.send(attribute))

app/models/runner.rb

@@ -52,6 +52,34 @@ class Runner < ApplicationRecord
     @strategy.copy_files(files)
   end
 
+  def download_file(path, **options, &block)
+    @strategy.download_file(path, **options, &block)
+  end
+
+  def retrieve_files(raise_exception: true, **options)
+    try = 0
+    begin
+      if try.nonzero?
+        request_new_id
+        save
+      end
+      @strategy.retrieve_files(**options)
+    rescue Runner::Error::RunnerNotFound => e
+      Rails.logger.debug { "Retrieving files failed for the first time: #{e.message}" }
+      try += 1
+
+      if try == 1
+        # This is only used if no files were copied to the runner. Thus requesting a second runner is performed here
+        # Reset the variable. This is required to prevent raising an outdated exception after a successful second try
+        e = nil
+        retry
+      end
+    ensure
+      # We forward the exception if requested
+      raise e if raise_exception && defined?(e) && e.present?
+    end
+  end
+
   def attach_to_execution(command, privileged_execution: false, &block)
     Rails.logger.debug { "#{Time.zone.now.getutc.inspect}: Starting execution with Runner #{id} for #{user_type} #{user_id}." }
     starting_time = Time.zone.now

app/models/testrun_message.rb

@@ -17,6 +17,7 @@ class TestrunMessage < ApplicationRecord
     exception: 10,
     result: 11,
     canvasevent: 12,
+    files: 13,
   }, _default: :write, _prefix: true
 
   enum stream: {