1 files changed, 144 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
new file mode 100644
index 0000000000..71c1e1b9a9
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
@@ -0,0 +1,144 @@
+module ActionDispatch
+  class ShowExceptions
+    include StatusCodes
+
+    LOCALHOST = '127.0.0.1'.freeze
+
+    DEFAULT_RESCUE_RESPONSE = :internal_server_error
+    DEFAULT_RESCUE_RESPONSES = {
+      'ActionController::RoutingError'             => :not_found,
+      'ActionController::UnknownAction'            => :not_found,
+      'ActiveRecord::RecordNotFound'               => :not_found,
+      'ActiveRecord::StaleObjectError'             => :conflict,
+      'ActiveRecord::RecordInvalid'                => :unprocessable_entity,
+      'ActiveRecord::RecordNotSaved'               => :unprocessable_entity,
+      'ActionController::MethodNotAllowed'         => :method_not_allowed,
+      'ActionController::NotImplemented'           => :not_implemented,
+      'ActionController::InvalidAuthenticityToken' => :unprocessable_entity
+    }
+
+    DEFAULT_RESCUE_TEMPLATE = 'diagnostics'
+    DEFAULT_RESCUE_TEMPLATES = {
+      'ActionView::MissingTemplate'       => 'missing_template',
+      'ActionController::RoutingError'    => 'routing_error',
+      'ActionController::UnknownAction'   => 'unknown_action',
+      'ActionView::TemplateError'         => 'template_error'
+    }
+
+    RESCUES_TEMPLATE_PATH = File.join(File.dirname(__FILE__), 'templates')
+
+    cattr_accessor :rescue_responses
+    @@rescue_responses = Hash.new(DEFAULT_RESCUE_RESPONSE)
+    @@rescue_responses.update DEFAULT_RESCUE_RESPONSES
+
+    cattr_accessor :rescue_templates
+    @@rescue_templates = Hash.new(DEFAULT_RESCUE_TEMPLATE)
+    @@rescue_templates.update DEFAULT_RESCUE_TEMPLATES
+
+    def initialize(app, consider_all_requests_local = false)
+      @app = app
+      @consider_all_requests_local = consider_all_requests_local
+    end
+
+    def call(env)
+      @app.call(env)
+    rescue Exception => exception
+      raise exception if env['rack.test']
+
+      log_error(exception) if logger
+
+      request = Request.new(env)
+      if @consider_all_requests_local || local_request?(request)
+        rescue_action_locally(request, exception)
+      else
+        rescue_action_in_public(exception)
+      end
+    end
+
+    private
+      # Render detailed diagnostics for unhandled exceptions rescued from
+      # a controller action.
+      def rescue_action_locally(request, exception)
+        template = ActionView::Base.new([RESCUES_TEMPLATE_PATH],
+          :template => template,
+          :request => request,
+          :exception => exception
+        )
+        file = "rescues/#{@@rescue_templates[exception.class.name]}.erb"
+        body = template.render(:file => file, :layout => 'rescues/layout.erb')
+
+        headers = {'Content-Type' => 'text/html', 'Content-Length' => body.length.to_s}
+        status = status_code(exception)
+
+        [status, headers, body]
+      end
+
+      # Attempts to render a static error page based on the
+      # <tt>status_code</tt> thrown, or just return headers if no such file
+      # exists. At first, it will try to render a localized static page.
+      # For example, if a 500 error is being handled Rails and locale is :da,
+      # it will first attempt to render the file at <tt>public/500.da.html</tt>
+      # then attempt to render <tt>public/500.html</tt>. If none of them exist,
+      # the body of the response will be left empty.
+      def rescue_action_in_public(exception)
+        status = status_code(exception)
+        locale_path = "#{public_path}/#{status}.#{I18n.locale}.html" if I18n.locale
+        path = "#{public_path}/#{status}.html"
+
+        if locale_path && File.exist?(locale_path)
+          render_public_file(status, locale_path)
+        elsif File.exist?(path)
+          render_public_file(status, path)
+        else
+          [status, {'Content-Type' => 'text/html', 'Content-Length' => '0'}, []]
+        end
+      end
+
+      # True if the request came from localhost, 127.0.0.1.
+      def local_request?(request)
+        request.remote_addr == LOCALHOST && request.remote_ip == LOCALHOST
+      end
+
+      def render_public_file(status, path)
+        body = File.read(path)
+        [status, {'Content-Type' => 'text/html', 'Content-Length' => body.length.to_s}, body]
+      end
+
+      def status_code(exception)
+        interpret_status(@@rescue_responses[exception.class.name]).to_i
+      end
+
+      def public_path
+        if defined?(Rails)
+          Rails.public_path
+        else
+          "public"
+        end
+      end
+
+      def log_error(exception) #:doc:
+        ActiveSupport::Deprecation.silence do
+          if ActionView::TemplateError === exception
+            logger.fatal(exception.to_s)
+          else
+            logger.fatal(
+              "\n#{exception.class} (#{exception.message}):\n  " +
+              clean_backtrace(exception).join("\n  ") + "\n\n"
+            )
+          end
+        end
+      end
+
+      def clean_backtrace(exception)
+        defined?(Rails) && Rails.respond_to?(:backtrace_cleaner) ?
+          Rails.backtrace_cleaner.clean(exception.backtrace) :
+          exception.backtrace
+      end
+
+      def logger
+        if defined?(Rails.logger)
+          Rails.logger
+        end
+      end
+  end
+end