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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#include "base/process_util.h"
#include "nsIObserver.h"
#include "nsString.h"
#include "mozilla/ipc/MiniTransceiver.h"
#include "mozilla/ipc/LaunchError.h"
#include "mozilla/Result.h"
#include <sys/types.h>
#include <poll.h>
namespace mozilla {
namespace ipc {
class GeckoChildProcessHost;
* This is the interface to the fork server.
* When the chrome process calls |ForkServiceChild| to create a new
* process, this class send a message to the fork server through a
* pipe and get the PID of the new process from the reply.
class ForkServiceChild {
ForkServiceChild(int aFd, GeckoChildProcessHost* aProcess);
virtual ~ForkServiceChild();
struct Args {
#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
int mForkFlags = 0;
bool mChroot = false;
nsTArray<nsCString> mArgv;
nsTArray<EnvVar> mEnv;
nsTArray<FdMapping> mFdsRemap;
* Ask the fork server to create a new process with given parameters.
* The fork server uses |base::LaunchApp()| to create a new
* content process with the following parameters.
* \param aArgv assigns |argv| of the content process.
* \param aEnvMap sets |LaunchOptions::env_map|.
* \param aFdsRemap sets |LaunchOptions::fd_to_remap|.
* \param aPid returns the PID of the content process created.
* \return true if success.
Result<Ok, LaunchError> SendForkNewSubprocess(const Args& aArgs, pid_t* aPid);
* Create a fork server process and the singleton of this class.
* This function uses |GeckoChildProcessHost| to launch the fork
* server, getting the fd of a pipe/socket to the fork server from
* it's |IPC::Channel|.
static void StartForkServer();
static void StopForkServer();
* Return the singleton.
static ForkServiceChild* Get() {
auto child = sForkServiceChild.get();
return child == nullptr || child->mFailed ? nullptr : child;
* Returns whether the fork server was ever active. Thread-safe.
static bool WasUsed() { return sForkServiceUsed; }
// Called when a message is received.
void OnMessageReceived(UniquePtr<IPC::Message> message);
void OnError();
UniquePtr<MiniTransceiver> mTcver;
static UniquePtr<ForkServiceChild> sForkServiceChild;
static Atomic<bool> sForkServiceUsed;
pid_t mRecvPid;
bool mFailed; // The forkserver has crashed or disconnected.
GeckoChildProcessHost* mProcess;
* Start a fork server at |xpcom-startup| from the chrome process.
class ForkServerLauncher : public nsIObserver {
static already_AddRefed<ForkServerLauncher> Create();
friend class ForkServiceChild;
virtual ~ForkServerLauncher();
static void RestartForkServer();
static bool mHaveStartedClient;
static StaticRefPtr<ForkServerLauncher> mSingleton;
} // namespace ipc
} // namespace mozilla
#endif /* __FORKSERVICE_CHILD_H_ */