chrome/browser/importer/firefox_profile_lock_posix.cc

   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/files/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
  59 void FirefoxProfileLock::Init() {
  60   lock_fd_ = -1;
  61 }
  62
  63 void 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
  76 void FirefoxProfileLock::Unlock() {
  77   if (!HasAcquired())
  78     return;
  79   close(lock_fd_);
  80   lock_fd_ = -1;
  81   base::DeleteFile(old_lock_file_, false);
  82 }
  83
  84 bool 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).
  95 bool 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 }