Use process_singleton_linux on Mac.

chrome/browser/process_singleton_posix.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.
 
 // On Linux, when the user tries to launch a second copy of chrome, we check
 // for a socket in the user's profile directory.  If the socket file is open we
 // send a message to the first chrome browser process with the current
 // directory and second process command line flags.  The second process then
 // exits.
 //
@@ skipping 56 matching lines @@
 #include "base/sequenced_task_runner_helpers.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
-#include "chrome/browser/ui/process_singleton_dialog_linux.h"
 #include "chrome/common/chrome_constants.h"
 #include "content/public/browser/browser_thread.h"
 #include "grit/chromium_strings.h"
 #include "grit/generated_resources.h"
 #include "net/base/net_util.h"
 #include "ui/base/l10n/l10n_util.h"
 
+#if defined(OS_LINUX)
+#include "chrome/browser/ui/process_singleton_dialog_linux.h"
+#endif
+
 #if defined(TOOLKIT_VIEWS) && !defined(OS_CHROMEOS)
 #include "ui/views/linux_ui/linux_ui.h"
 #endif
 
 using content::BrowserThread;
 
 const int ProcessSingleton::kTimeoutInSeconds;
 
 namespace {
 
@@ skipping 196 matching lines @@
     *pid = -1;
 
   return true;
 }
 
 // Returns true if the user opted to unlock the profile.
 bool DisplayProfileInUseError(const base::FilePath& lock_path,
                               const std::string& hostname,
                               int pid) {
   base::string16 error = l10n_util::GetStringFUTF16(
-      IDS_PROFILE_IN_USE_LINUX,
+      IDS_PROFILE_IN_USE_POSIX,
       base::IntToString16(pid),
       base::ASCIIToUTF16(hostname));
+  LOG(ERROR) << error;
+
+  if (g_disable_prompt)
+    return false;
+
+#if defined(OS_LINUX)
   base::string16 relaunch_button_text = l10n_util::GetStringUTF16(
       IDS_PROFILE_IN_USE_LINUX_RELAUNCH);
-  LOG(ERROR) << base::SysWideToNativeMB(base::UTF16ToWide(error)).c_str();
-  if (!g_disable_prompt)
-    return ShowProcessSingletonDialog(error, relaunch_button_text);
+  return ShowProcessSingletonDialog(error, relaunch_button_text);
+#elif defined(OS_MACOSX)
+  // On Mac, always usurp the lock.
+  return true;
+#endif
+
+  NOTREACHED();
   return false;
 }
 
 bool IsChromeProcess(pid_t pid) {
   base::FilePath other_chrome_path(base::GetProcessExecutablePath(pid));
   return (!other_chrome_path.empty() &&
           other_chrome_path.BaseName() ==
           base::FilePath(chrome::kBrowserProcessExecutableName));
 }
 
@@ skipping 67 matching lines @@
                                    sizeof(addr)));
     return (ret == 0);
   } else {
     // File is missing, or other error.
     if (errno != ENOENT)
       PLOG(ERROR) << "readlink failed";
     return false;
   }
 }
 
+#if defined(OS_MACOSX)
+bool ReplaceOldSingletonLock(const base::FilePath& symlink_content,
+                             const base::FilePath& lock_path) {
+  // Try taking an flock(2) on the file. Failure means the lock is taken so we
+  // should quit.
+  base::ScopedFD lock_fd(HANDLE_EINTR(
+      open(lock_path.value().c_str(), O_RDWR | O_CREAT | O_SYMLINK, 0644)));
+  if (!lock_fd.is_valid()) {
+    PLOG(ERROR) << "Could not open singleton lock";
+    return false;
+  }
+
+  int rc = HANDLE_EINTR(flock(lock_fd.get(), LOCK_EX | LOCK_NB));
+  if (rc == -1) {
+    if (errno == EWOULDBLOCK) {
+      LOG(ERROR) << "Singleton lock held by old process.";
+    } else {
+      PLOG(ERROR) << "Error locking singleton lock";
+    }
+    return false;
+  }
+
+  // Successfully taking the lock means we can replace it with the a new symlink
+  // lock. We never flock() the lock file from now on. I.e. we assume that an
+  // old version of Chrome will not run with the same user data dir after this
+  // version has run.
+  if (!base::DeleteFile(lock_path, false)) {
+    PLOG(ERROR) << "Could not delete old singleton lock.";
+    return false;
+  }
+
+  return SymlinkPath(symlink_content, lock_path);
+}
+#endif  // defined(OS_MACOSX)
+
 }  // namespace
 
 ///////////////////////////////////////////////////////////////////////////////
 // ProcessSingleton::LinuxWatcher
 // A helper class for a Linux specific implementation of the process singleton.
 // This class sets up a listener on the singleton socket and handles parsing
 // messages that come in on the singleton socket.
 class ProcessSingleton::LinuxWatcher
     : public base::MessageLoopForIO::Watcher,
       public base::MessageLoop::DestructionObserver,
@@ skipping 470 matching lines @@
   // processes can find it out.
   base::FilePath symlink_content(base::StringPrintf(
       "%s%c%u",
       net::GetHostName().c_str(),
       kLockDelimiter,
       current_pid_));
 
   // Create symbol link before binding the socket, to ensure only one instance
   // can have the socket open.
   if (!SymlinkPath(symlink_content, lock_path_)) {
-      // If we failed to create the lock, most likely another instance won the
-      // startup race.
+    // TODO(jackhou): Remove this case once this code is stable on Mac.
+    // http://crbug.com/367612
+#if defined(OS_MACOSX)
+    // On Mac, an existing non-symlink lock file means the lock could be held by
+    // the old process singleton code. If we can successfully replace the lock,
+    // continue as normal.
+    if (base::IsLink(lock_path_) ||
+        !ReplaceOldSingletonLock(symlink_content, lock_path_)) {
       return false;
+    }
+#else
+    // If we failed to create the lock, most likely another instance won the
+    // startup race.
+    return false;
+#endif
   }
 
   // Create the socket file somewhere in /tmp which is usually mounted as a
   // normal filesystem. Some network filesystems (notably AFS) are screwy and
   // do not support Unix domain sockets.
   if (!socket_dir_.CreateUniqueTempDir()) {
     LOG(ERROR) << "Failed to create socket directory.";
     return false;
   }
+
+  // Check that the directory was created with the correct permissions.
+  int dir_mode = 0;
+  CHECK(base::GetPosixFilePermissions(socket_dir_.path(), &dir_mode) &&
+        dir_mode == base::FILE_PERMISSION_USER_MASK)
+      << "Temp directory mode is not 700: " << std::oct << dir_mode;
+
   // Setup the socket symlink and the two cookies.
   base::FilePath socket_target_path =
       socket_dir_.path().Append(chrome::kSingletonSocketFilename);
   base::FilePath cookie(GenerateCookie());
   base::FilePath remote_cookie_path =
       socket_dir_.path().Append(chrome::kSingletonCookieFilename);
   UnlinkPath(socket_path_);
   UnlinkPath(cookie_path_);
   if (!SymlinkPath(socket_target_path, socket_path_) ||
       !SymlinkPath(cookie, cookie_path_) ||
@@ skipping 69 matching lines @@
 }
 
 void ProcessSingleton::KillProcess(int pid) {
   // TODO(james.su@gmail.com): Is SIGKILL ok?
   int rv = kill(static_cast<base::ProcessHandle>(pid), SIGKILL);
   // ESRCH = No Such Process (can happen if the other process is already in
   // progress of shutting down and finishes before we try to kill it).
   DCHECK(rv == 0 || errno == ESRCH) << "Error killing process: "
                                     << safe_strerror(errno);
 }