Move a couple of utility functions to a new namespace_utils class.

sandbox/linux/services/namespace_utils.h

+// Copyright (c) 2014 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.
+
+#ifndef SANDBOX_LINUX_SERVICES_NAMESPACE_UTILS_H_
+#define SANDBOX_LINUX_SERVICES_NAMESPACE_UTILS_H_
+
+#include <sys/types.h>
+
+#include "base/macros.h"
+#include "base/template_util.h"
+#include "sandbox/sandbox_export.h"
+
+namespace sandbox {
+
+class SANDBOX_EXPORT NamespaceUtils {
+ public:
+  COMPILE_ASSERT((base::is_same<uid_t, gid_t>::value), UidAndGidAreSameType);
+  // generic_id_t can be used for either uid_t or gid_t.
+  typedef uid_t generic_id_t;
+
+  // Write a uid or gid mapping from |id| to |id| in |map_file|.
+  static bool WriteToIdMapFile(const char* map_file, generic_id_t id);
+
+  // Returns true if the namespace type |type| is supported. |type| must be one
+  // of CLONE_NEWIPC, CLONE_NEWNET, CLONE_NEWNS, CLONE_NEWPID, CLONE_NEWUSER, or
+  // CLONE_NEWUTS. This relies on access to /proc, so it will not work from
+  // within a chroot.
+  static bool SupportsLinuxNamespace(int type);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(NamespaceUtils);
+};
+
+}  // namespace sandbox
+
+#endif  // SANDBOX_LINUX_SERVICES_NAMESPACE_UTILS_H_