add validator for usage of storage plugins

lib/fluent/plugin_helper/storage.rb

@@ -33,6 +33,9 @@ def storage_create(usage: '', type: nil, conf: nil, default_type: nil)
         if conf && !conf.arg.empty?
           usage = conf.arg
         end
+        if !usage.empty? && usage !~ /^[a-zA-Z][-_.a-zA-Z0-9]*$/
+          raise Fluent::ConfigError, "Argument in <storage ARG> uses invalid characters: '#{usage}'"
+        end
 
         s = @_storages[usage]
         if s && s.running
@@ -98,6 +101,9 @@ def configure(conf)
         super
 
         @storage_configs.each do |section|
+          if !section.usage.empty? && section.usage !~ /^[a-zA-Z][-_.a-zA-Z0-9]*$/
+            raise Fluent::ConfigError, "Argument in <storage ARG> uses invalid characters: '#{section.usage}'"
+          end
           if @_storages[section.usage]
             raise Fluent::ConfigError, "duplicated storages configured: #{section.usage}"
           end

test/plugin_helper/test_storage.rb

@@ -135,6 +135,17 @@ class Dummy2 < Fluent::Plugin::TestBase
     end
   end
 
+  test 'raises config error if config argument has invalid characters' do
+    d = Dummy.new
+    assert_raise Fluent::ConfigError.new("Argument in <storage ARG> uses invalid characters: 'yaa y'") do
+      d.configure(config_element('root', '', {}, [config_element('storage', 'yaa y', {'@type' => 'local'})]))
+    end
+    d.configure(config_element())
+    assert_raise Fluent::ConfigError.new("Argument in <storage ARG> uses invalid characters: 'a,b'") do
+      d.storage_create(usage: 'a,b', type: 'local')
+    end
+  end
+
   test 'can be configured without storage sections' do
     d = Dummy.new
     assert_nothing_raised do