1 files changed, 128 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
new file mode 100644
index 0000000000..274f6f2f22
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
@@ -0,0 +1,128 @@
+require 'action_dispatch/http/request'
+require 'action_dispatch/middleware/exception_wrapper'
+require 'action_dispatch/routing/inspector'
+
+module ActionDispatch
+  # This middleware is responsible for logging exceptions and
+  # showing a debugging page in case the request is local.
+  class DebugExceptions
+    RESCUES_TEMPLATE_PATH = File.expand_path('../templates', __FILE__)
+
+    def initialize(app, routes_app = nil)
+      @app        = app
+      @routes_app = routes_app
+    end
+
+    def call(env)
+      _, headers, body = response = @app.call(env)
+
+      if headers['X-Cascade'] == 'pass'
+        body.close if body.respond_to?(:close)
+        raise ActionController::RoutingError, "No route matches [#{env['REQUEST_METHOD']}] #{env['PATH_INFO'].inspect}"
+      end
+
+      response
+    rescue Exception => exception
+      raise exception if env['action_dispatch.show_exceptions'] == false
+      render_exception(env, exception)
+    end
+
+    private
+
+    def render_exception(env, exception)
+      wrapper = ExceptionWrapper.new(env, exception)
+      log_error(env, wrapper)
+
+      if env['action_dispatch.show_detailed_exceptions']
+        request = Request.new(env)
+        template = ActionView::Base.new([RESCUES_TEMPLATE_PATH],
+          request: request,
+          exception: wrapper.exception,
+          traces: traces_from_wrapper(wrapper),
+          routes_inspector: routes_inspector(exception),
+          source_extract: wrapper.source_extract,
+          line_number: wrapper.line_number,
+          file: wrapper.file
+        )
+        file = "rescues/#{wrapper.rescue_template}"
+
+        if request.xhr?
+          body = template.render(template: file, layout: false, formats: [:text])
+          format = "text/plain"
+        else
+          body = template.render(template: file, layout: 'rescues/layout')
+          format = "text/html"
+        end
+        render(wrapper.status_code, body, format)
+      else
+        raise exception
+      end
+    end
+
+    def render(status, body, format)
+      [status, {'Content-Type' => "#{format}; charset=#{Response.default_charset}", 'Content-Length' => body.bytesize.to_s}, [body]]
+    end
+
+    def log_error(env, wrapper)
+      logger = logger(env)
+      return unless logger
+
+      exception = wrapper.exception
+
+      trace = wrapper.application_trace
+      trace = wrapper.framework_trace if trace.empty?
+
+      ActiveSupport::Deprecation.silence do
+        message = "\n#{exception.class} (#{exception.message}):\n"
+        message << exception.annoted_source_code.to_s if exception.respond_to?(:annoted_source_code)
+        message << "  " << trace.join("\n  ")
+        logger.fatal("#{message}\n\n")
+      end
+    end
+
+    def logger(env)
+      env['action_dispatch.logger'] || stderr_logger
+    end
+
+    def stderr_logger
+      @stderr_logger ||= ActiveSupport::Logger.new($stderr)
+    end
+
+    def routes_inspector(exception)
+      if @routes_app.respond_to?(:routes) && (exception.is_a?(ActionController::RoutingError) || exception.is_a?(ActionView::Template::Error))
+        ActionDispatch::Routing::RoutesInspector.new(@routes_app.routes.routes)
+      end
+    end
+
+    # Augment the exception traces by providing ids for all unique stack frame
+    def traces_from_wrapper(wrapper)
+      application_trace = wrapper.application_trace
+      framework_trace = wrapper.framework_trace
+      full_trace = wrapper.full_trace
+
+      if application_trace && framework_trace
+        id_counter = 0
+
+        application_trace = application_trace.map do |trace|
+          prev = id_counter
+          id_counter += 1
+          { id: prev, trace: trace }
+        end
+
+        framework_trace = framework_trace.map do |trace|
+          prev = id_counter
+          id_counter += 1
+          { id: prev, trace: trace }
+        end
+
+        full_trace = application_trace + framework_trace
+      end
+
+      {
+        "Application Trace" => application_trace,
+        "Framework Trace" => framework_trace,
+        "Full Trace" => full_trace
+      }
+    end
+  end
+end