chrome/browser/mac/relauncher.h

   1 // Copyright (c) 2011 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 #ifndef CHROME_BROWSER_MAC_RELAUNCHER_H_
   6 #define CHROME_BROWSER_MAC_RELAUNCHER_H_
   7
   8 // mac_relauncher implements main browser application relaunches on the Mac.
   9 // When a browser wants to relaunch itself, it can't simply fork off a new
  10 // process and exec a new browser from within. That leaves open a window
  11 // during which two browser applications might be running concurrently. If
  12 // that happens, each will wind up with a distinct Dock icon, which is
  13 // especially bad if the user expected the Dock icon to be persistent by
  14 // choosing Keep in Dock from the icon's contextual menu.
  15 //
  16 // mac_relauncher approaches this problem by introducing an intermediate
  17 // process (the "relauncher") in between the original browser ("parent") and
  18 // replacement browser ("relaunched"). The helper executable is used for the
  19 // relauncher process; because it's an LSUIElement, it doesn't get a Dock
  20 // icon and isn't visible as a running application at all. The parent will
  21 // start a relauncher process, giving it the "writer" side of a pipe that it
  22 // retains the "reader" end of. When the relauncher starts up, it will
  23 // establish a kqueue to wait for the parent to exit, and will then write to
  24 // the pipe. The parent, upon reading from the pipe, is free to exit. When the
  25 // relauncher is notified via its kqueue that the parent has exited, it
  26 // proceeds, launching the relaunched process. The handshake to synchronize
  27 // the parent with the relauncher is necessary to avoid races: the relauncher
  28 // needs to be sure that it's monitoring the parent and not some other process
  29 // in light of PID reuse, so the parent must remain alive long enough for the
  30 // relauncher to set up its kqueue.
  31
  32 #include <string>
  33 #include <vector>
  34
  35 namespace content {
  36 struct MainFunctionParams;
  37 }
  38
  39 namespace mac_relauncher {
  40
  41 // The relauncher process can unmount and eject a mounted disk image and move
  42 // its disk image file to the trash. This argument may be supplied to
  43 // RelaunchAppWithHelper to achieve this. The argument's value must be a BSD
  44 // device name of the form "diskN" or "diskNsM".
  45 extern const char* const kRelauncherDMGDeviceArg;
  46
  47 // Relaunches the application using the helper application associated with the
  48 // currently running instance of Chrome in the parent browser process as the
  49 // executable for the relauncher process. |args| is an argv-style vector of
  50 // command line arguments of the form normally passed to execv. args[0] is
  51 // also the path to the relaunched process. Because the relauncher process
  52 // will ultimately launch the relaunched process via Launch Services, args[0]
  53 // may be either a pathname to an executable file or a pathname to an .app
  54 // bundle directory. The caller should exit soon after RelaunchApp returns
  55 // successfully. Returns true on success, although some failures can occur
  56 // after this function returns true if, for example, they occur within the
  57 // relauncher process. Returns false when the relaunch definitely failed.
  58 bool RelaunchApp(const std::vector<std::string>& args);
  59
  60 // Identical to RelaunchApp, but uses |helper| as the path to the relauncher
  61 // process, and allows additional arguments to be supplied to the relauncher
  62 // process in relauncher_args. Unlike args[0], |helper| must be a pathname to
  63 // an executable file. The helper path given must be from the same version of
  64 // Chrome as the running parent browser process, as there are no guarantees
  65 // that the parent and relauncher processes from different versions will be
  66 // able to communicate with one another. This variant can be useful to
  67 // relaunch the same version of Chrome from another location, using that
  68 // location's helper.
  69 bool RelaunchAppWithHelper(const std::string& helper,
  70                            const std::vector<std::string>& relauncher_args,
  71                            const std::vector<std::string>& args);
  72
  73 namespace internal {
  74
  75 // The entry point from ChromeMain into the relauncher process. This is not a
  76 // user API. Don't call it if your name isn't ChromeMain.
  77 int RelauncherMain(const content::MainFunctionParams& main_parameters);
  78
  79 }  // namespace internal
  80
  81 }  // namespace mac_relauncher
  82
  83 #endif  // CHROME_BROWSER_MAC_RELAUNCHER_H_