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   struct Args {
  37 #if defined(XP_LINUX) && defined(MOZ_SANDBOX)
  38     int mForkFlags = 0;
  39     bool mChroot = false;
  40 #endif
  41     nsTArray<nsCString> mArgv;
  42     nsTArray<EnvVar> mEnv;
  43     nsTArray<FdMapping> mFdsRemap;
  44   };
  45
  46   /**
  47    * Ask the fork server to create a new process with given parameters.
  48    *
  49    * The fork server uses |base::LaunchApp()| to create a new
  50    * content process with the following parameters.
  51    *
  52    * \param aArgv assigns |argv| of the content process.
  53    * \param aEnvMap sets |LaunchOptions::env_map|.
  54    * \param aFdsRemap sets |LaunchOptions::fd_to_remap|.
  55    * \param aPid returns the PID of the content process created.
  56    * \return true if success.
  57    */
  58   Result<Ok, LaunchError> SendForkNewSubprocess(const Args& aArgs, pid_t* aPid);
  59
  60   /**
  61    * Create a fork server process and the singleton of this class.
  62    *
  63    * This function uses |GeckoChildProcessHost| to launch the fork
  64    * server, getting the fd of a pipe/socket to the fork server from
  65    * it's |IPC::Channel|.
  66    */
  67   static void StartForkServer();
  68   static void StopForkServer();
  69   /**
  70    * Return the singleton.
  71    */
  72   static ForkServiceChild* Get() {
  73     auto child = sForkServiceChild.get();
  74     return child == nullptr || child->mFailed ? nullptr : child;
  75   }
  76
  77   /**
  78    * Returns whether the fork server was ever active.  Thread-safe.
  79    */
  80   static bool WasUsed() { return sForkServiceUsed; }
  81
  82  private:
  83   // Called when a message is received.
  84   void OnMessageReceived(UniquePtr<IPC::Message> message);
  85   void OnError();
  86
  87   UniquePtr<MiniTransceiver> mTcver;
  88   static UniquePtr<ForkServiceChild> sForkServiceChild;
  89   static Atomic<bool> sForkServiceUsed;
  90   pid_t mRecvPid;
  91   bool mFailed;  // The forkserver has crashed or disconnected.
  92   GeckoChildProcessHost* mProcess;
  93 };
  94
  95 /**
  96  * Start a fork server at |xpcom-startup| from the chrome process.
  97  */
  98 class ForkServerLauncher : public nsIObserver {
  99  public:
 100   NS_DECL_ISUPPORTS
 101   NS_DECL_NSIOBSERVER
 102
 103   ForkServerLauncher();
 104   static already_AddRefed<ForkServerLauncher> Create();
 105
 106  private:
 107   friend class ForkServiceChild;
 108   virtual ~ForkServerLauncher();
 109
 110   static void RestartForkServer();
 111
 112   static bool mHaveStartedClient;
 113   static StaticRefPtr<ForkServerLauncher> mSingleton;
 114 };
 115
 116 }  // namespace ipc
 117 }  // namespace mozilla
 118
 119 #endif /* __FORKSERVICE_CHILD_H_ */