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// Copyright (c) 2010 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.
#ifndef CHROME_COMMON_CHILD_PROCESS_HOST_H_
#define CHROME_COMMON_CHILD_PROCESS_HOST_H_
#pragma once
#include <list>
#include <string>
// Must be included early (e.g. before chrome/common/plugin_messages.h)
#include "ipc/ipc_logging.h"
// Putting this before ipc_logging.h does not work (OS_WIN isn't defined)
#if defined(OS_WIN)
#include <windows.h>
#endif // defined(OS_WIN)
#include "base/basictypes.h"
#include "base/file_path.h"
#include "base/scoped_ptr.h"
#include "chrome/common/notification_type.h"
#include "ipc/ipc_channel.h"
class CommandLine;
// Provides common functionality for hosting a child process and processing IPC
// messages between the host and the child process. Subclasses are responsible
// for the actual launching and terminating of the child processes.
//
class ChildProcessHost : public IPC::Channel::Listener {
public:
virtual ~ChildProcessHost();
// Returns the pathname to be used for a child process. If a subprocess
// pathname was specified on the command line, that will be used. Otherwise,
// the default child process pathname will be returned. On most platforms,
// this will be the same as the currently-executing process.
//
// The argument allow_self is used on Linux to indicate that we allow us to
// fork from /proc/self/exe rather than using the "real" app path. This
// prevents autoupdate from confusing us if it changes the file out from
// under us. You will generally want to set this to true, except when there
// is an override to the command line (for example, we're forking a renderer
// in gdb). In this case, you'd use GetChildPath to get the real executable
// file name, and then prepend the GDB command to the command line.
//
// On failure, returns an empty FilePath.
static FilePath GetChildPath(bool allow_self);
#if defined(OS_WIN)
// See comments in the cc file. This is a common hack needed for a process
// hosting a sandboxed child process. Hence it lives in this file.
static void PreCacheFont(LOGFONT font);
#endif // defined(OS_WIN)
protected:
ChildProcessHost();
// A helper method to send an IPC message to the child on the channel.
// It behavies just like IPC::Message::Sender::Send. The implementor takes
// ownership of the given Message regardless of whether or not this method
// succeeds. This class does not implement IPC::Message::Sender to prevent
// conflicts with subclasses which indirectly could inherit from
// IPC::Message::Sender.
bool SendOnChannel(IPC::Message* msg);
// Derived classes return true if it's ok to shut down the child process.
virtual bool CanShutdown() = 0;
// Send the shutdown message to the child process.
// Does not check if CanShutdown is true.
virtual void ForceShutdown();
// Creates the IPC channel. Returns true iff it succeeded.
virtual bool CreateChannel();
// Notifies us that an instance has been created on this child process.
virtual void InstanceCreated();
// IPC::Channel::Listener implementation:
virtual void OnMessageReceived(const IPC::Message& msg) { }
virtual void OnChannelConnected(int32 peer_pid) { }
virtual void OnChannelError() { }
bool opening_channel() { return opening_channel_; }
const std::string& channel_id() { return channel_id_; }
IPC::Channel* channel() { return channel_.get(); }
// Called when the child process goes away.
virtual void OnChildDied();
// Allows the derived implementation to intercept a message before it is
// handed to the IPC::Channel::Listener::OnMessageReceived implementation.
virtual bool InterceptMessageFromChild(const IPC::Message& msg) {
return false;
}
// Subclasses can implement specific notification methods.
virtual void Notify(NotificationType type) { }
private:
// By using an internal class as the IPC::Channel::Listener, we can intercept
// OnMessageReceived/OnChannelConnected and do our own processing before
// calling the subclass' implementation.
class ListenerHook : public IPC::Channel::Listener {
public:
explicit ListenerHook(ChildProcessHost* host);
virtual void OnMessageReceived(const IPC::Message& msg);
virtual void OnChannelConnected(int32 peer_pid);
virtual void OnChannelError();
private:
ChildProcessHost* host_;
};
ListenerHook listener_;
bool opening_channel_; // True while we're waiting the channel to be opened.
scoped_ptr<IPC::Channel> channel_;
std::string channel_id_;
};
#endif // CHROME_COMMON_CHILD_PROCESS_HOST_H_
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