1 files changed, 180 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..b55c937e0c
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
@@ -0,0 +1,180 @@
+require 'action_dispatch/http/request'
+require 'action_dispatch/middleware/exception_wrapper'
+require 'action_dispatch/routing/inspector'
+require 'action_view'
+require 'action_view/base'
+
+require 'pp'
+
+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__)
+
+    class DebugView < ActionView::Base
+      def debug_params(params)
+        clean_params = params.clone
+        clean_params.delete("action")
+        clean_params.delete("controller")
+
+        if clean_params.empty?
+          'None'
+        else
+          PP.pp(clean_params, "", 200)
+        end
+      end
+
+      def debug_headers(headers)
+        if headers.present?
+          headers.inspect.gsub(',', ",\n")
+        else
+          'None'
+        end
+      end
+
+      def debug_hash(object)
+        object.to_hash.sort_by { |k, _| k.to_s }.map { |k, v| "#{k}: #{v.inspect rescue $!.message}" }.join("\n")
+      end
+    end
+
+    def initialize(app, routes_app = nil, response_format = :default)
+      @app             = app
+      @routes_app      = routes_app
+      @response_format = response_format
+    end
+
+    def call(env)
+      request = ActionDispatch::Request.new 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 unless request.show_exceptions?
+      render_exception(request, exception)
+    end
+
+    private
+
+    def render_exception(request, exception)
+      backtrace_cleaner = request.get_header('action_dispatch.backtrace_cleaner')
+      wrapper = ExceptionWrapper.new(backtrace_cleaner, exception)
+      log_error(request, wrapper)
+
+      if request.get_header('action_dispatch.show_detailed_exceptions')
+        case @response_format
+        when :api
+          render_for_api_application(request, wrapper)
+        when :default
+          render_for_default_application(request, wrapper)
+        end
+      else
+        raise exception
+      end
+    end
+
+    def render_for_default_application(request, wrapper)
+      template = create_template(request, wrapper)
+      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)
+    end
+
+    def render_for_api_application(request, wrapper)
+      body = {
+        status: wrapper.status_code,
+        error:  Rack::Utils::HTTP_STATUS_CODES.fetch(
+          wrapper.status_code,
+          Rack::Utils::HTTP_STATUS_CODES[500]
+        ),
+        exception: wrapper.exception.inspect,
+        traces: wrapper.traces
+      }
+
+      content_type = request.formats.first
+      to_format = "to_#{content_type.to_sym}"
+
+      if content_type && body.respond_to?(to_format)
+        formatted_body = body.public_send(to_format)
+        format = content_type
+      else
+        formatted_body = body.to_json
+        format = Mime[:json]
+      end
+
+      render(wrapper.status_code, formatted_body, format)
+    end
+
+    def create_template(request, wrapper)
+      traces = wrapper.traces
+
+      trace_to_show = 'Application Trace'
+      if traces[trace_to_show].empty? && wrapper.rescue_template != 'routing_error'
+        trace_to_show = 'Full Trace'
+      end
+
+      if source_to_show = traces[trace_to_show].first
+        source_to_show_id = source_to_show[:id]
+      end
+
+      DebugView.new([RESCUES_TEMPLATE_PATH],
+        request: request,
+        exception: wrapper.exception,
+        traces: traces,
+        show_source_idx: source_to_show_id,
+        trace_to_show: trace_to_show,
+        routes_inspector: routes_inspector(wrapper.exception),
+        source_extracts: wrapper.source_extracts,
+        line_number: wrapper.line_number,
+        file: wrapper.file
+      )
+    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(request, wrapper)
+      logger = logger(request)
+      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(request)
+      request.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
+  end
+end