1 files changed, 49 insertions, 14 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/static.rb b/actionpack/lib/action_dispatch/middleware/static.rb
index 25e32cdef8..0733132277 100644
--- a/actionpack/lib/action_dispatch/middleware/static.rb
+++ b/actionpack/lib/action_dispatch/middleware/static.rb
@@ -16,8 +16,8 @@ module ActionDispatch
     def initialize(root, cache_control)
       @root          = root.chomp('/')
       @compiled_root = /^#{Regexp.escape(root)}/
-      headers = cache_control && { 'Cache-Control' => cache_control }
-      @file_server   = ::Rack::File.new(@root, headers)
+      headers        = cache_control && { 'Cache-Control' => cache_control }
+      @file_server = ::Rack::File.new(@root, headers)
     end
 
     def match?(path)
@@ -36,23 +36,58 @@ module ActionDispatch
     end
 
     def call(env)
-      @file_server.call(env)
-    end
+      path      = env['PATH_INFO']
+      gzip_path = gzip_file_path(path)
 
-    def ext
-      @ext ||= begin
-        ext = ::ActionController::Base.default_static_extension
-        "{,#{ext},/index#{ext}}"
+      if gzip_path && gzip_encoding_accepted?(env)
+        env['PATH_INFO']            = gzip_path
+        status, headers, body       = @file_server.call(env)
+        headers['Content-Encoding'] = 'gzip'
+        headers['Content-Type']     = content_type(path)
+      else
+        status, headers, body = @file_server.call(env)
       end
-    end
 
-    def unescape_path(path)
-      URI.parser.unescape(path)
-    end
+      headers['Vary'] = 'Accept-Encoding' if gzip_path
 
-    def escape_glob_chars(path)
-      path.gsub(/[*?{}\[\]]/, "\\\\\\&")
+      return [status, headers, body]
+    ensure
+      env['PATH_INFO'] = path
     end
+
+    private
+      def ext
+        @ext ||= begin
+          ext = ::ActionController::Base.default_static_extension
+          "{,#{ext},/index#{ext}}"
+        end
+      end
+
+      def unescape_path(path)
+        URI.parser.unescape(path)
+      end
+
+      def escape_glob_chars(path)
+        path.gsub(/[*?{}\[\]]/, "\\\\\\&")
+      end
+
+      def content_type(path)
+        ::Rack::Mime.mime_type(::File.extname(path), 'text/plain')
+      end
+
+      def gzip_encoding_accepted?(env)
+        env['HTTP_ACCEPT_ENCODING'] =~ /\bgzip\b/i
+      end
+
+      def gzip_file_path(path)
+        can_gzip_mime = content_type(path) =~ /\A(?:text\/|application\/javascript)/
+        gzip_path     = "#{path}.gz"
+        if can_gzip_mime && File.exist?(File.join(@root, ::Rack::Utils.unescape(gzip_path)))
+          gzip_path
+        else
+          false
+        end
+      end
   end
 
   # This middleware will attempt to return the contents of a file's body from