Add ORIGINAL_FULLPATH to env

This behaves similarly to REQUEST_URI, but
we need to implement it on our own because
REQUEST_URI is not reliable.

Note that since PATH_INFO does not contain
information about trailing question mark,
this is not 100% accurate, for example
`/foo?` will result in `/foo` in ORIGINAL_FULLPATH

railties/lib/rails/application.rb

@@ -215,6 +215,11 @@ module Rails
       config.helpers_paths
     end
 
+    def call(env)
+      env["ORIGINAL_FULLPATH"] = build_original_fullpath(env)
+      super(env)
+    end
+
   protected
 
     alias :build_middleware_stack :app
@@ -291,5 +296,17 @@ module Rails
       require "rails/console/app"
       require "rails/console/helpers"
     end
+
+    def build_original_fullpath(env)
+      path_info    = env["PATH_INFO"]
+      query_string = env["QUERY_STRING"]
+      script_name  = env["SCRIPT_NAME"]
+
+      if query_string.present?
+        "#{script_name}#{path_info}?#{query_string}"
+      else
+        "#{script_name}#{path_info}"
+      end
+    end
   end
 end

railties/test/application/build_original_fullpath_test.rb

@@ -0,0 +1,27 @@
+require "abstract_unit"
+
+module ApplicationTests
+  class BuildOriginalPathTest < Test::Unit::TestCase
+    def test_include_original_PATH_info_in_ORIGINAL_FULLPATH
+      env = { 'PATH_INFO' => '/foo/' }
+      assert_equal "/foo/", Rails.application.send(:build_original_fullpath, env)
+    end
+
+    def test_include_SCRIPT_NAME
+      env = {
+        'SCRIPT_NAME' => '/foo',
+        'PATH_INFO' => '/bar'
+      }
+
+      assert_equal "/foo/bar", Rails.application.send(:build_original_fullpath, env)
+    end
+
+    def test_include_QUERY_STRING
+      env = {
+        'PATH_INFO' => '/foo',
+        'QUERY_STRING' => 'bar',
+      }
+      assert_equal "/foo?bar", Rails.application.send(:build_original_fullpath, env)
+    end
+  end
+end

railties/test/application/middleware_test.rb

@@ -1,5 +1,6 @@
 require 'isolation/abstract_unit'
 require 'stringio'
+require 'rack/test'
 
 module ApplicationTests
   class MiddlewareTest < Test::Unit::TestCase
@@ -75,7 +76,7 @@ module ApplicationTests
       add_to_config "config.force_ssl = true"
       add_to_config "config.ssl_options = { :host => 'example.com' }"
       boot!
-      
+
       assert_equal AppTemplate::Application.middleware.first.args, [{:host => 'example.com'}]
     end
 
@@ -193,6 +194,14 @@ module ApplicationTests
       assert_equal nil, last_response.headers["Etag"]
     end
 
+    test "ORIGINAL_FULLPATH is passed to env" do
+      boot!
+      env = ::Rack::MockRequest.env_for("/foo/?something")
+      Rails.application.call(env)
+
+      assert_equal "/foo/?something", env["ORIGINAL_FULLPATH"]
+    end
+
     private
 
       def boot!