src/ipc/ipc_path_manager.h

// Copyright 2010-2015, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef MOZC_IPC_IPC_PATH_MANAGER_H_
#define MOZC_IPC_IPC_PATH_MANAGER_H_

#ifdef OS_WIN
#include <time.h>  // for time_t
#else
#include <sys/time.h>  // for time_t
#endif  // OS_WIN
#ifdef OS_WIN
#include <map>
#endif  // OS_WIN
#include <string>
#include "base/mutex.h"
#include "base/port.h"
#include "base/scoped_ptr.h"
// For FRIEND_TEST
#include "testing/base/public/gunit_prod.h"

namespace mozc {

namespace ipc {
class IPCPathInfo;
}

class ProcessMutex;

class IPCPathManager {
 public:
  // Brief summary of CreateNew / Save / Load / Get PathName().
  // CreateNewPathName: Generates a pathname and save it into the heap.
  // SavePathName:      Saves a pathname into a file from the heap.
  // LoadPathName:      Loads a pathname from a file and save it into the heap.
  // GetPathName:       Sets a pathname on an argument using the heap.

  // Create new pathname and save it into the heap. If pathname is not empty,
  // do nothing.
  bool CreateNewPathName();

  // Save ipc path to ~/.mozc/.<name>.ipc
  // if server_ipc_key_ is empty, CreateNewPathName() is called automatically.
  // If the file is already locked, return false
  bool SavePathName();

  // Load a pathname from a disk and updates |ipc_path_info_| if pathname is
  // empty or ipc key file is updated. Returns false if it cannot load.
  bool LoadPathName();

  // Get a pathanem from the heap. If pathanme is empty, returns false.
  bool GetPathName(string *path_name) const;

  // return protocol version.
  // return 0 if protocol version is not defined.
  uint32 GetServerProtocolVersion() const;

  // return product version.
  // return "0.0.0.0" if product version is not defined
  const string &GetServerProductVersion() const;

  // return process id of the server
  uint32 GetServerProcessId() const;

  // Checks the server pid is the valid server specified with server_path.
  // server pid can be obtained by OS dependent method.
  // This API is only available on Windows Vista or Linux.
  // Due to the restriction of OpenProcess API, always returns true under
  // AppContainer sandbox on Windows 8 (No verification will be done).
  // Always returns true on other operating systems.
  // See also: GetNamedPipeServerProcessId
  // http://msdn.microsoft.com/en-us/library/aa365446.aspx
  // when pid of 0 is passed, IsValidServer() returns true.
  // when pid of static_cast<size_t>(-1) is passed, IsValidServer()
  // returns false.
  // To keep backward compatibility and other operationg system
  // having no support of getting peer's pid, you can set 0 pid.
  bool IsValidServer(uint32 pid, const string &server_path);

  // clear ipc_key;
  void Clear();

  // return singleton instance corresponding to "name"
  static IPCPathManager *GetIPCPathManager(const string &name);

  // do not call constructor directly.
  explicit IPCPathManager(const string &name);
  virtual ~IPCPathManager();

 private:
  FRIEND_TEST(IPCPathManagerTest, ReloadTest);
  FRIEND_TEST(IPCPathManagerTest, PathNameTest);

  bool LoadPathNameInternal();

  // Returns true if the ipc file is updated after it load.
  bool ShouldReload() const;

  // Returns the last modified timestamp of the IPC file.
  time_t GetIPCFileTimeStamp() const;

  scoped_ptr<ProcessMutex> path_mutex_;   // lock ipc path file
  scoped_ptr<Mutex> mutex_;   // mutex for methods
  scoped_ptr<ipc::IPCPathInfo> ipc_path_info_;
  string name_;
  string server_path_;   // cache for server_path
  uint32 server_pid_;    // cache for pid of server_path
  time_t last_modified_;
#ifdef OS_WIN
  map<string, wstring> expected_server_ntpath_cache_;
#endif  // OS_WIN
};
}  // namespace mozc

#endif  // MOZC_IPC_IPC_PATH_MANAGER_H_