server: handle "permission denied" error

packages/ruby/server/lib/server/dir.rb

@@ -10,8 +10,12 @@ class Server::Dir
     headers = Rack::Headers.new(env)
     h, body = read(local_path(req.path))
     [200, headers.merge!(h), body]
+  rescue Errno::EPERM, Errno::EACCES
+    body = "Permission denied"
+    [403, {"content-length" => body.bytesize, "content-type" => "text/plain"}, [body]]
   rescue Errno::ENOENT
-    not_found
+    body = "The requested URL was not found"
+    [404, {"content-length" => body.bytesize, "content-type" => "text/plain"}, [body]]
   end
 
   private
@@ -31,8 +35,4 @@ class Server::Dir
     lpath = File.join root, File.expand_path(req_path)
     File.directory?(lpath) ? File.join(lpath, "index.html") : lpath
   end
-
-  def not_found
-    [404, {"content-type" => "text/plain"}, ["The requested URL was not found"]]
-  end
 end

packages/ruby/server/test/server_dir_test.rb

@@ -11,6 +11,17 @@ class ServerDirTest < Test::Unit::TestCase
     assert_equal bytesize("./test/fakeweb/index.html"), last_response.content_length
   end
 
+  def test_permission_denied
+    File.chmod 0, "./test/fakeweb/permission_denied.html"
+    get "/permission_denied.html"
+    assert_equal 403, last_response.status
+    assert_equal "text/plain", last_response.content_type
+    assert_equal "Permission denied".bytesize, last_response.content_length
+    assert_equal "Permission denied", last_response.body
+  ensure
+    File.chmod 0440, "./test/fakeweb/permission_denied.html"
+  end
+
   private
 
   def app