Use process_singleton_linux on Mac.

chrome/browser/process_singleton_mac.cc

-// 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.
-
-#include <errno.h>
-#include <fcntl.h>
-#include <sys/file.h>
-
-#include "chrome/browser/process_singleton.h"
-
-#include "base/metrics/histogram.h"
-#include "base/posix/eintr_wrapper.h"
-#include "chrome/common/chrome_constants.h"
-
-namespace {
-
-// From "man 2 intro", the largest errno is |EOPNOTSUPP|, which is
-// |102|.  Since the histogram memory usage is proportional to this
-// number, using the |102| directly rather than the macro.
-const int kMaxErrno = 102;
-
-}  // namespace
-
-// This class is used to funnel messages to a single instance of the browser
-// process. This is needed for several reasons on other platforms.
-//
-// On Windows, when the user re-opens the application from the shell (e.g. an
-// explicit double-click, a shortcut that opens a webpage, etc.) we need to send
-// the message to the currently-existing copy of the browser.
-//
-// On Linux, opening a URL is done by creating an instance of the web browser
-// process and passing it the URL to go to on its commandline.
-//
-// Neither of those cases apply on the Mac. Launch Services ensures that there
-// is only one instance of the process, and we get URLs to open via AppleEvents
-// and, once again, the Launch Services system. We have no need to manage this
-// ourselves.  An exclusive lock is used to flush out anyone making incorrect
-// assumptions.
-
-ProcessSingleton::ProcessSingleton(
-    const base::FilePath& user_data_dir,
-    const NotificationCallback& /* notification_callback */)
-    : lock_path_(user_data_dir.Append(chrome::kSingletonLockFilename)),
-      lock_fd_(-1) {
-}
-
-ProcessSingleton::~ProcessSingleton() {
-  // Make sure the lock is released.  Process death will also release
-  // it, even if this is not called.
-  Cleanup();
-}
-
-ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcess() {
-  // This space intentionally left blank.
-  return PROCESS_NONE;
-}
-
-ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcessOrCreate() {
-  // Windows tries NotifyOtherProcess() first.
-  return Create() ? PROCESS_NONE : PROFILE_IN_USE;
-}
-
-// Attempt to acquire an exclusive lock on an empty file in the
-// profile directory.  Returns |true| if it gets the lock.  Returns
-// |false| if the lock is held, or if there is an error.
-// |notification_callback| is not actually used. See the comments at the top of
-// this file for details.
-// TODO(shess): Rather than logging failures, popup an alert.  Punting
-// that for now because it would require confidence that this code is
-// never called in a situation where an alert wouldn't work.
-// http://crbug.com/59061
-bool ProcessSingleton::Create() {
-  DCHECK_EQ(-1, lock_fd_) << "lock_path_ is already open.";
-
-  lock_fd_ = HANDLE_EINTR(open(lock_path_.value().c_str(),
-                               O_RDONLY | O_CREAT, 0644));
-  if (lock_fd_ == -1) {
-    const int capture_errno = errno;
-    DPCHECK(lock_fd_ != -1) << "Unexpected failure opening profile lockfile";
-    UMA_HISTOGRAM_ENUMERATION("ProcessSingleton.OpenError",
-                              capture_errno, kMaxErrno);
-    return false;
-  }
-
-  // Acquire an exclusive lock in non-blocking fashion.  If the lock
-  // is already held, this will return |EWOULDBLOCK|.
-  int rc = HANDLE_EINTR(flock(lock_fd_, LOCK_EX|LOCK_NB));
-  if (rc == -1) {
-    const int capture_errno = errno;
-    DPCHECK(errno == EWOULDBLOCK)
-        << "Unexpected failure locking profile lockfile";
-
-    Cleanup();
-
-    // Other errors indicate something crazy is happening.
-    if (capture_errno != EWOULDBLOCK) {
-      UMA_HISTOGRAM_ENUMERATION("ProcessSingleton.LockError",
-                                capture_errno, kMaxErrno);
-      return false;
-    }
-
-    // The file is open by another process and locked.
-    LOG(ERROR) << "Unable to obtain profile lock.";
-    return false;
-  }
-
-  return true;
-}
-
-void ProcessSingleton::Cleanup() {
-  // Closing the file also releases the lock.
-  if (lock_fd_ != -1) {
-    int rc = IGNORE_EINTR(close(lock_fd_));
-    DPCHECK(!rc) << "Closing lock_fd_:";
-  }
-  lock_fd_ = -1;
-}