Refactor the setuid sandbox client code to its own class.

sandbox/linux/suid/client/setuid_sandbox_client.h

+// Copyright (c) 2012 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_SUID_SUID_CLIENT_H_
+#define SANDBOX_LINUX_SUID_SUID_CLIENT_H_
+
+#include "base/basictypes.h"
+#include "base/environment.h"
+
+namespace sandbox {
+
+// Helper class to use the setuid sandbox. This class is to be used both
+// before launching the setuid helper and after being executed through the
+// setuid helper.
+//
+// A typical use would be:
+// 1. The browser calls SetupLaunchEnvironment()
+// 2. The browser launches a renderer through the setuid sandbox.
+// 3. The renderer requests being chroot-ed through ChrootMe() and
+//    requests other sandboxing status via the status functions.
+class SetuidSandboxClient {
+ public:
+  // All instantation should go through this factory method.
+  static class SetuidSandboxClient* Create();
+  ~SetuidSandboxClient();
+
+  // Ask the setuid helper over the setuid sandbox IPC channel to chroot() us
+  // to an empty directory.
+  // Will only work if we have been launched through the setuid helper.
+  bool ChrootMe();
+  // Did we get launched through an up to date setuid binary ?

[Markus (顧孟勤), 2012/07/23 21:06:30]

Minor nit. I would put blank lines here to make things a little easier to read

[jln (very slow on Chromium), 2012/07/23 21:32:15]

Done. I've put one to separate ChrootMe from the Is* method, I think it's
somewhat readable now.

+  bool IsSuidSandboxUpToDate() const;
+  // Did we get launched through the setuid helper ?
+  bool IsSuidSandboxChild() const;
+  // Did the setuid helper create a new PID namespace ?
+  bool IsInNewPIDNamespace() const;
+  // Did the setuid helper create a new network namespace ?
+  bool IsInNewNETNamespace() const;
+
+  // Set-up the environment. This should be done prior to launching the setuid
+  // helper.
+  void SetupLaunchEnvironment();
+
+ private:
+  // Holds the environment. Will never be NULL.
+  base::Environment* env_;
+  DISALLOW_IMPLICIT_CONSTRUCTORS(SetuidSandboxClient);
+};
+
+}  // namespace sandbox
+
+#endif  // SANDBOX_LINUX_SUID_SUID_CLIENT_H_