firefox_profile_lock_posix.cc revision eb525c5499e34cc9c4b825d6d9e75bb07cc06ace 
1// Copyright (c) 2009 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "chrome/browser/importer/firefox_profile_lock.h"
6
7#include <errno.h>
8#include <fcntl.h>
9#include <sys/stat.h>
10#include <sys/types.h>
11
12#include "base/file_util.h"
13
14// This class is based on Firefox code in:
15//   profile/dirserviceprovider/src/nsProfileLock.cpp
16// The license block is:
17
18/* ***** BEGIN LICENSE BLOCK *****
19* Version: MPL 1.1/GPL 2.0/LGPL 2.1
20*
21* The contents of this file are subject to the Mozilla Public License Version
22* 1.1 (the "License"); you may not use this file except in compliance with
23* the License. You may obtain a copy of the License at
24* http://www.mozilla.org/MPL/
25*
26* Software distributed under the License is distributed on an "AS IS" basis,
27* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
28* for the specific language governing rights and limitations under the
29* License.
30*
31* The Original Code is mozilla.org code.
32*
33* The Initial Developer of the Original Code is
34* Netscape Communications Corporation.
35* Portions created by the Initial Developer are Copyright (C) 2002
36* the Initial Developer. All Rights Reserved.
37*
38* Contributor(s):
39*   Conrad Carlen <ccarlen@netscape.com>
40*   Brendan Eich <brendan@mozilla.org>
41*   Colin Blake <colin@theblakes.com>
42*   Javier Pedemonte <pedemont@us.ibm.com>
43*   Mats Palmgren <mats.palmgren@bredband.net>
44*
45* Alternatively, the contents of this file may be used under the terms of
46* either the GNU General Public License Version 2 or later (the "GPL"), or
47* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
48* in which case the provisions of the GPL or the LGPL are applicable instead
49* of those above. If you wish to allow use of your version of this file only
50* under the terms of either the GPL or the LGPL, and not to allow others to
51* use your version of this file under the terms of the MPL, indicate your
52* decision by deleting the provisions above and replace them with the notice
53* and other provisions required by the GPL or the LGPL. If you do not delete
54* the provisions above, a recipient may use your version of this file under
55* the terms of any one of the MPL, the GPL or the LGPL.
56*
57* ***** END LICENSE BLOCK ***** */
58
59void FirefoxProfileLock::Init() {
60  lock_fd_ = -1;
61}
62
63void FirefoxProfileLock::Lock() {
64  if (HasAcquired())
65    return;
66
67  bool fcntl_lock = LockWithFcntl();
68  if (!fcntl_lock) {
69    return;
70  } else if (!HasAcquired()) {
71    old_lock_file_ = lock_file_.DirName().Append(kOldLockFileName);
72    lock_fd_ = open(old_lock_file_.value().c_str(), O_CREAT | O_EXCL, 0644);
73  }
74}
75
76void FirefoxProfileLock::Unlock() {
77  if (!HasAcquired())
78    return;
79  close(lock_fd_);
80  lock_fd_ = -1;
81  base::Delete(old_lock_file_, false);
82}
83
84bool FirefoxProfileLock::HasAcquired() {
85  return (lock_fd_ >= 0);
86}
87
88// This function tries to lock Firefox profile using fcntl(). The return
89// value of this function together with HasAcquired() tells the current status
90// of lock.
91// if return == false: Another process has lock to the profile.
92// if return == true && HasAcquired() == true: successfully acquired the lock.
93// if return == false && HasAcquired() == false: Failed to acquire lock due
94// to some error (so that we can try alternate method of profile lock).
95bool FirefoxProfileLock::LockWithFcntl() {
96  lock_fd_ = open(lock_file_.value().c_str(), O_WRONLY | O_CREAT | O_TRUNC,
97                  0666);
98  if (lock_fd_ == -1)
99    return true;
100
101  struct flock lock;
102  lock.l_start = 0;
103  lock.l_len = 0;
104  lock.l_type = F_WRLCK;
105  lock.l_whence = SEEK_SET;
106  lock.l_pid = 0;
107
108  struct flock testlock = lock;
109  if (fcntl(lock_fd_, F_GETLK, &testlock) == -1) {
110    close(lock_fd_);
111    lock_fd_ = -1;
112    return true;
113  } else if (fcntl(lock_fd_, F_SETLK, &lock) == -1) {
114    close(lock_fd_);
115    lock_fd_ = -1;
116    if (errno == EAGAIN || errno == EACCES)
117      return false;
118    else
119      return true;
120  } else {
121    // We have the lock.
122    return true;
123  }
124}
125