ipc/glue/ForkServiceChild.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6 #ifndef __FORKSERVICE_CHILD_H_
   7 #define __FORKSERVICE_CHILD_H_
   8
   9 #include "base/process_util.h"
  10 #include "nsIObserver.h"
  11 #include "nsString.h"
  12 #include "mozilla/ipc/MiniTransceiver.h"
  13 #include "mozilla/ipc/LaunchError.h"
  14 #include "mozilla/Result.h"
  15
  16 #include <sys/types.h>
  17 #include <poll.h>
  18
  19 namespace mozilla {
  20 namespace ipc {
  21
  22 class GeckoChildProcessHost;
  23
  24 /**
  25  * This is the interface to the fork server.
  26  *
  27  * When the chrome process calls |ForkServiceChild| to create a new
  28  * process, this class send a message to the fork server through a
  29  * pipe and get the PID of the new process from the reply.
  30  */
  31 class ForkServiceChild {
  32  public:
  33   ForkServiceChild(int aFd, GeckoChildProcessHost* aProcess);
  34   virtual ~ForkServiceChild();
  35
  36   /**
  37    * Ask the fork server to create a new process with given parameters.
  38    *
  39    * The fork server uses |base::LaunchApp()| to create a new
  40    * content process with the following parameters.
  41    *
  42    * \param aArgv assigns |argv| of the content process.
  43    * \param aEnvMap sets |LaunchOptions::env_map|.
  44    * \param aFdsRemap sets |LaunchOptions::fd_to_remap|.
  45    * \param aPid returns the PID of the content process created.
  46    * \return true if success.
  47    */
  48   Result<Ok, LaunchError> SendForkNewSubprocess(
  49       const nsTArray<nsCString>& aArgv, const nsTArray<EnvVar>& aEnvMap,
  50       const nsTArray<FdMapping>& aFdsRemap, pid_t* aPid);
  51
  52   /**
  53    * Create a fork server process and the singleton of this class.
  54    *
  55    * This function uses |GeckoChildProcessHost| to launch the fork
  56    * server, getting the fd of a pipe/socket to the fork server from
  57    * it's |IPC::Channel|.
  58    */
  59   static void StartForkServer();
  60   static void StopForkServer();
  61   /**
  62    * Return the singleton.
  63    */
  64   static ForkServiceChild* Get() {
  65     auto child = sForkServiceChild.get();
  66     return child == nullptr || child->mFailed ? nullptr : child;
  67   }
  68
  69  private:
  70   // Called when a message is received.
  71   void OnMessageReceived(UniquePtr<IPC::Message> message);
  72   void OnError();
  73
  74   UniquePtr<MiniTransceiver> mTcver;
  75   static UniquePtr<ForkServiceChild> sForkServiceChild;
  76   pid_t mRecvPid;
  77   bool mFailed;  // The forkserver has crashed or disconnected.
  78   GeckoChildProcessHost* mProcess;
  79 };
  80
  81 /**
  82  * Start a fork server at |xpcom-startup| from the chrome process.
  83  */
  84 class ForkServerLauncher : public nsIObserver {
  85  public:
  86   NS_DECL_ISUPPORTS
  87   NS_DECL_NSIOBSERVER
  88
  89   ForkServerLauncher();
  90   static already_AddRefed<ForkServerLauncher> Create();
  91
  92  private:
  93   friend class ForkServiceChild;
  94   virtual ~ForkServerLauncher();
  95
  96   static void RestartForkServer();
  97
  98   static bool mHaveStartedClient;
  99   static StaticRefPtr<ForkServerLauncher> mSingleton;
 100 };
 101
 102 }  // namespace ipc
 103 }  // namespace mozilla
 104
 105 #endif /* __FORKSERVICE_CHILD_H_ */