Merge branch 'exceptions' with the following features:

* A Railtie API for registering new exceptions and their respective status code (check Active Record railtie for an example)

* Extraction of ShowExceptions middleware logging and debugging features into a middleware called DebugExceptions

Conflicts:
	actionpack/CHANGELOG.md

6 files changed, 213 insertions, 140 deletions

diff --git a/actionpack/lib/action_controller/log_subscriber.rb b/actionpack/lib/action_controller/log_subscriber.rb
index 8666ecc9c8..de250053d3 100644
--- a/actionpack/lib/action_controller/log_subscriber.rb
+++ b/actionpack/lib/action_controller/log_subscriber.rb
@@ -20,7 +20,7 @@ module ActionController
 
       status = payload[:status]
       if status.nil? && payload[:exception].present?
-        status = Rack::Utils.status_code(ActionDispatch::ShowExceptions.rescue_responses[payload[:exception].first]) rescue nil
+        status = Rack::Utils.status_code(ActionDispatch::ExceptionWrapper.new({}, payload[:exception]).status_code)
       end
       message = "Completed #{status} #{Rack::Utils::HTTP_STATUS_CODES[status]} in %.0fms" % event.duration
       message << " (#{additions.join(" | ")})" unless additions.blank?
diff --git a/actionpack/lib/action_dispatch.rb b/actionpack/lib/action_dispatch.rb
index 1e92d14542..89f515ee3d 100644
--- a/actionpack/lib/action_dispatch.rb
+++ b/actionpack/lib/action_dispatch.rb
@@ -51,6 +51,8 @@ module ActionDispatch
     autoload :BestStandardsSupport
     autoload :Callbacks
     autoload :Cookies
+    autoload :DebugExceptions
+    autoload :ExceptionWrapper
     autoload :Flash
     autoload :Head
     autoload :ParamsParser
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..5da21ddd3d
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
@@ -0,0 +1,77 @@
+require 'action_dispatch/http/request'
+require 'action_dispatch/middleware/exception_wrapper'
+
+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.join(File.dirname(__FILE__), 'templates')
+
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      begin
+        response = @app.call(env)
+
+        if response[1]['X-Cascade'] == 'pass'
+          raise ActionController::RoutingError, "No route matches [#{env['REQUEST_METHOD']}] #{env['PATH_INFO'].inspect}"
+        end
+      rescue Exception => exception
+        raise exception if env['action_dispatch.show_exceptions'] == false
+      end
+
+      response ? response : 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']
+        template = ActionView::Base.new([RESCUES_TEMPLATE_PATH],
+          :request => Request.new(env),
+          :exception => wrapper.exception,
+          :application_trace => wrapper.application_trace,
+          :framework_trace => wrapper.framework_trace,
+          :full_trace => wrapper.full_trace
+        )
+
+        file = "rescues/#{wrapper.rescue_template}"
+        body = template.render(:template => file, :layout => 'rescues/layout')
+        render(wrapper.status_code, body)
+      else
+        raise exception
+      end
+    end
+
+    def render(status, body)
+      [status, {'Content-Type' => "text/html; 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
+
+      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 << "  " << wrapper.application_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 ||= Logger.new($stderr)
+    end
+  end
+end
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..c0532c80c4
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
@@ -0,0 +1,78 @@
+require 'action_controller/metal/exceptions'
+require 'active_support/core_ext/exception'
+
+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::NotImplemented'           => :not_implemented,
+      'ActionController::InvalidAuthenticityToken' => :unprocessable_entity
+    )
+
+    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
+
+    def initialize(env, exception)
+      @env = env
+      @exception = original_exception(exception)
+    end
+
+    def rescue_template
+      @@rescue_templates[@exception.class.name]
+    end
+
+    def status_code
+      Rack::Utils.status_code(@@rescue_responses[@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
+
+    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
+  end
+end
\ No newline at end of file
diff --git a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
index c850e25507..c801bcf2ef 100644
--- a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
@@ -1,44 +1,33 @@
-require 'active_support/core_ext/exception'
-require 'action_controller/metal/exceptions'
-require 'active_support/notifications'
 require 'action_dispatch/http/request'
+require 'action_dispatch/middleware/exception_wrapper'
 require 'active_support/deprecation'
 
 module ActionDispatch
-  # This middleware rescues any exception returned by the application and renders
-  # nice exception pages if it's being rescued locally.
+  # This middleware rescues any exception returned by the application
+  # and wraps them in a format for the end user.
   class ShowExceptions
     RESCUES_TEMPLATE_PATH = File.join(File.dirname(__FILE__), 'templates')
 
-    cattr_accessor :rescue_responses
-    @@rescue_responses = Hash.new(:internal_server_error)
-    @@rescue_responses.update({
-      'ActionController::RoutingError'             => :not_found,
-      'AbstractController::ActionNotFound'         => :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
-    })
-
-    cattr_accessor :rescue_templates
-    @@rescue_templates = Hash.new('diagnostics')
-    @@rescue_templates.update({
-      'ActionView::MissingTemplate'         => 'missing_template',
-      'ActionController::RoutingError'      => 'routing_error',
-      'AbstractController::ActionNotFound'  => 'unknown_action',
-      'ActionView::Template::Error'         => 'template_error'
-    })
-
     FAILSAFE_RESPONSE = [500, {'Content-Type' => 'text/html'},
       ["<html><body><h1>500 Internal Server Error</h1>" <<
        "If you are the administrator of this website, then please read this web " <<
        "application's log file and/or the web server's log file to find out what " <<
        "went wrong.</body></html>"]]
 
+    class << self
+      def rescue_responses
+        ActiveSupport::Deprecation.warn "ActionDispatch::ShowExceptions.rescue_responses is deprecated. " \
+          "Please configure your exceptions using a railtie or in your application config instead."
+        ExceptionWrapper.rescue_responses
+      end
+
+      def rescue_templates
+        ActiveSupport::Deprecation.warn "ActionDispatch::ShowExceptions.rescue_templates is deprecated. " \
+          "Please configure your exceptions using a railtie or in your application config instead."
+        ExceptionWrapper.rescue_templates
+      end
+    end
+
     def initialize(app, consider_all_requests_local = nil)
       ActiveSupport::Deprecation.warn "Passing consider_all_requests_local option to ActionDispatch::ShowExceptions middleware no longer works" unless consider_all_requests_local.nil?
       @app = app
@@ -46,131 +35,47 @@ module ActionDispatch
 
     def call(env)
       begin
-        status, headers, body = @app.call(env)
-        exception = nil
-
-        # Only this middleware cares about RoutingError. So, let's just raise
-        # it here.
-        if headers['X-Cascade'] == 'pass'
-           raise ActionController::RoutingError, "No route matches [#{env['REQUEST_METHOD']}] #{env['PATH_INFO'].inspect}"
-        end
+        response  = @app.call(env)
       rescue Exception => exception
         raise exception if env['action_dispatch.show_exceptions'] == false
       end
 
-      exception ? render_exception(env, exception) : [status, headers, body]
+      response ? response : render_exception_with_failsafe(env, exception)
     end
 
     private
-      def render_exception(env, exception)
-        log_error(env, exception)
-        exception = original_exception(exception)
-
-        if env['action_dispatch.show_detailed_exceptions'] == true
-          rescue_action_diagnostics(env, exception)
-        else
-          rescue_action_error_page(exception)
-        end
-      rescue Exception => failsafe_error
-        $stderr.puts "Error during failsafe response: #{failsafe_error}\n  #{failsafe_error.backtrace * "\n  "}"
-        FAILSAFE_RESPONSE
-      end
-
-      # Render detailed diagnostics for unhandled exceptions rescued from
-      # a controller action.
-      def rescue_action_diagnostics(env, exception)
-        template = ActionView::Base.new([RESCUES_TEMPLATE_PATH],
-          :request => Request.new(env),
-          :exception => exception,
-          :application_trace => application_trace(env, exception),
-          :framework_trace => framework_trace(env, exception),
-          :full_trace => full_trace(env, exception)
-        )
-        file = "rescues/#{@@rescue_templates[exception.class.name]}"
-        body = template.render(:template => file, :layout => 'rescues/layout')
-        render(status_code(exception), 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_error_page(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(status, File.read(locale_path))
-        elsif File.exist?(path)
-          render(status, File.read(path))
-        else
-          render(status, '')
-        end
-      end
-
-      def status_code(exception)
-        Rack::Utils.status_code(@@rescue_responses[exception.class.name])
-      end
-
-      def render(status, body)
-        [status, {'Content-Type' => "text/html; charset=#{Response.default_charset}", 'Content-Length' => body.bytesize.to_s}, [body]]
-      end
-
-      def public_path
-        defined?(Rails.public_path) ? Rails.public_path : 'public_path'
-      end
-
-      def log_error(env, exception)
-        return unless logger(env)
-
-        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 << "  " << application_trace(env, exception).join("\n  ")
-          logger(env).fatal("#{message}\n\n")
-        end
-      end
-
-      def application_trace(env, exception)
-        clean_backtrace(env, exception, :silent)
-      end
-
-      def framework_trace(env, exception)
-        clean_backtrace(env, exception, :noise)
-      end
 
-      def full_trace(env, exception)
-        clean_backtrace(env, exception, :all)
-      end
+    def render_exception_with_failsafe(env, exception)
+      render_exception(env, exception)
+    rescue Exception => failsafe_error
+      $stderr.puts "Error during failsafe response: #{failsafe_error}\n  #{failsafe_error.backtrace * "\n  "}"
+      FAILSAFE_RESPONSE
+    end
 
-      def clean_backtrace(env, exception, *args)
-        env['action_dispatch.backtrace_cleaner'] ?
-          env['action_dispatch.backtrace_cleaner'].clean(exception.backtrace, *args) :
-          exception.backtrace
-      end
+    def render_exception(env, exception)
+      wrapper = ExceptionWrapper.new(env, exception)
 
-      def logger(env)
-        env['action_dispatch.logger'] || stderr_logger
-      end
+      status      = wrapper.status_code
+      locale_path = "#{public_path}/#{status}.#{I18n.locale}.html" if I18n.locale
+      path        = "#{public_path}/#{status}.html"
 
-      def stderr_logger
-        Logger.new($stderr)
-      end
-
-    def original_exception(exception)
-      if registered_original_exception?(exception)
-        exception.original_exception
+      if locale_path && File.exist?(locale_path)
+        render(status, File.read(locale_path))
+      elsif File.exist?(path)
+        render(status, File.read(path))
       else
-        exception
+        render(status, '')
       end
     end
 
-    def registered_original_exception?(exception)
-      exception.respond_to?(:original_exception) && @@rescue_responses.has_key?(exception.original_exception.class.name)
+    def render(status, body)
+      [status, {'Content-Type' => "text/html; charset=#{Response.default_charset}", 'Content-Length' => body.bytesize.to_s}, [body]]
+    end
+
+    # TODO: Make this a middleware initialization parameter once
+    # we removed the second option (which is deprecated)
+    def public_path
+      defined?(Rails.public_path) ? Rails.public_path : 'public_path'
     end
   end
 end
diff --git a/actionpack/lib/action_dispatch/railtie.rb b/actionpack/lib/action_dispatch/railtie.rb
index f18ebabf29..2ba3198ebd 100644
--- a/actionpack/lib/action_dispatch/railtie.rb
+++ b/actionpack/lib/action_dispatch/railtie.rb
@@ -9,11 +9,22 @@ module ActionDispatch
     config.action_dispatch.best_standards_support = true
     config.action_dispatch.tld_length = 1
     config.action_dispatch.ignore_accept_header = false
-    config.action_dispatch.rack_cache = {:metastore => "rails:/", :entitystore => "rails:/", :verbose => true}
+    config.action_dispatch.rescue_templates = { }
+    config.action_dispatch.rescue_responses = { }
+
+    config.action_dispatch.rack_cache = {
+      :metastore => "rails:/",
+      :entitystore => "rails:/",
+      :verbose => true
+    }
+
     initializer "action_dispatch.configure" do |app|
       ActionDispatch::Http::URL.tld_length = app.config.action_dispatch.tld_length
       ActionDispatch::Request.ignore_accept_header = app.config.action_dispatch.ignore_accept_header
 
+      ActionDispatch::ExceptionWrapper.rescue_responses.merge!(config.action_dispatch.rescue_responses)
+      ActionDispatch::ExceptionWrapper.rescue_templates.merge!(config.action_dispatch.rescue_templates)
+
       config.action_dispatch.always_write_cookie = Rails.env.development? if config.action_dispatch.always_write_cookie.nil?
       ActionDispatch::Cookies::CookieJar.always_write_cookie = config.action_dispatch.always_write_cookie
     end