parser_regexp: Check named capture. ref #2330

Signed-off-by: Masahiro Nakagawa <[email protected]>

lib/fluent/plugin/parser_regexp.rb

@@ -40,6 +40,10 @@ def configure(conf)
           @expression = Regexp.compile(@expression.source, options)
         end
         @regexp = @expression # For backward compatibility
+
+        if @expression.named_captures.empty?
+          raise Fluent::ConfigError, "No named captures in 'expression' parameter. The regexp must have at least one named capture"
+        end
       end
 
       def parse(text)

test/plugin/test_parser_regexp.rb

@@ -153,6 +153,15 @@ def create_driver(conf)
     end
 
     sub_test_case "configure" do
+      def test_bad_expression
+        conf = {
+          'expression' => %q!/.*/!,
+        }
+        assert_raise Fluent::ConfigError do
+          create_driver(conf)
+        end
+      end
+
       def test_default_options
         conf = {
           'expression' => %q!/^(?<host>[^ ]*) [^ ]* (?<user>[^ ]*) \[(?<time>[^\]]*)\] \[(?<date>[^\]]*)\] "(?<flag>\S+)(?: +(?<path>[^ ]*) +\S*)?" (?<code>[^ ]*) (?<size>[^ ]*)$/!,