Make rawdatastore API safer for writing filters.

impl/memory/globalinfo.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package memory
 
 import (
-        "golang.org/x/net/context"
+        "fmt"
+        "regexp"
 
         "github.com/luci/gae/impl/dummy"
         "github.com/luci/gae/service/info"
+        "golang.org/x/net/context"
 )
 
 type giContextKeyType int
 
 var giContextKey giContextKeyType
 
+// validNamespace matches valid namespace names.
+var validNamespace = regexp.MustCompile(`^[0-9A-Za-z._-]{0,100}$`)
+
 func curGID(c context.Context) *globalInfoData {
         return c.Value(giContextKey).(*globalInfoData)
 }
 
 // useGI adds a gae.GlobalInfo context, accessible
 // by gae.GetGI(c)
 func useGI(c context.Context) context.Context {
         return info.SetFactory(c, func(ic context.Context) info.Interface {
                 return &giImpl{dummy.Info(), curGID(ic), ic}
         })
@@ skipping 10 matching lines @@
 }
 
 type giImpl struct {
         info.Interface
         *globalInfoData
         c context.Context
 }
 
 var _ = info.Interface((*giImpl)(nil))
 
+func (gi *giImpl) GetNamespace() string {
+        return gi.namespace
+}
+
 func (gi *giImpl) Namespace(ns string) (ret context.Context, err error) {
+        if !validNamespace.MatchString(ns) {
+                return nil, fmt.Errorf("appengine: namespace %q does not match /%s/", ns, validNamespace)
+        }
         return context.WithValue(gi.c, giContextKey, &globalInfoData{ns}), nil
 }
 
 func (gi *giImpl) AppID() string {
         return globalAppID
 }