1 files changed, 119 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
new file mode 100644
index 0000000000..b98b553c38
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
@@ -0,0 +1,119 @@
+require 'action_controller/metal/exceptions'
+require 'active_support/core_ext/module/attribute_accessors'
+
+module ActionDispatch
+  class ExceptionWrapper
+    cattr_accessor :rescue_responses
+    @@rescue_responses = Hash.new(:internal_server_error)
+    @@rescue_responses.merge!(
+      'ActionController::RoutingError'             => :not_found,
+      'AbstractController::ActionNotFound'         => :not_found,
+      'ActionController::MethodNotAllowed'         => :method_not_allowed,
+      'ActionController::UnknownHttpMethod'        => :method_not_allowed,
+      'ActionController::NotImplemented'           => :not_implemented,
+      'ActionController::UnknownFormat'            => :not_acceptable,
+      'ActionController::InvalidAuthenticityToken' => :unprocessable_entity,
+      'ActionDispatch::ParamsParser::ParseError'   => :bad_request,
+      'ActionController::BadRequest'               => :bad_request,
+      'ActionController::ParameterMissing'         => :bad_request
+    )
+
+    cattr_accessor :rescue_templates
+    @@rescue_templates = Hash.new('diagnostics')
+    @@rescue_templates.merge!(
+      'ActionView::MissingTemplate'         => 'missing_template',
+      'ActionController::RoutingError'      => 'routing_error',
+      'AbstractController::ActionNotFound'  => 'unknown_action',
+      'ActionView::Template::Error'         => 'template_error'
+    )
+
+    attr_reader :env, :exception, :line_number, :file
+
+    def initialize(env, exception)
+      @env = env
+      @exception = original_exception(exception)
+
+      expand_backtrace if exception.is_a?(SyntaxError) || exception.try(:original_exception).try(:is_a?, SyntaxError)
+    end
+
+    def rescue_template
+      @@rescue_templates[@exception.class.name]
+    end
+
+    def status_code
+      self.class.status_code_for_exception(@exception.class.name)
+    end
+
+    def application_trace
+      clean_backtrace(:silent)
+    end
+
+    def framework_trace
+      clean_backtrace(:noise)
+    end
+
+    def full_trace
+      clean_backtrace(:all)
+    end
+
+    def self.status_code_for_exception(class_name)
+      Rack::Utils.status_code(@@rescue_responses[class_name])
+    end
+
+    def source_extract
+      exception.backtrace.map do |trace|
+        file, line = trace.split(":")
+        line_number = line.to_i
+        {
+          code: source_fragment(file, line_number),
+          file: file,
+          line_number: line_number
+        }
+      end if exception.backtrace
+    end
+
+    private
+
+    def original_exception(exception)
+      if registered_original_exception?(exception)
+        exception.original_exception
+      else
+        exception
+      end
+    end
+
+    def registered_original_exception?(exception)
+      exception.respond_to?(:original_exception) && @@rescue_responses.has_key?(exception.original_exception.class.name)
+    end
+
+    def clean_backtrace(*args)
+      if backtrace_cleaner
+        backtrace_cleaner.clean(@exception.backtrace, *args)
+      else
+        @exception.backtrace
+      end
+    end
+
+    def backtrace_cleaner
+      @backtrace_cleaner ||= @env['action_dispatch.backtrace_cleaner']
+    end
+
+    def source_fragment(path, line)
+      return unless Rails.respond_to?(:root) && Rails.root
+      full_path = Rails.root.join(path)
+      if File.exist?(full_path)
+        File.open(full_path, "r") do |file|
+          start = [line - 3, 0].max
+          lines = file.each_line.drop(start).take(6)
+          Hash[*(start+1..(lines.count+start)).zip(lines).flatten]
+        end
+      end
+    end
+
+    def expand_backtrace
+      @exception.backtrace.unshift(
+        @exception.to_s.split("\n")
+      ).flatten!
+    end
+  end
+end