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// Copyright (c) 2012 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.
#include "build/build_config.h"
#include "content/common/content_export.h"
#include "ipc/ipc_channel_proxy.h"
namespace base {
class FilePath;
namespace IPC {
class MessageFilter;
namespace content {
class ChildProcessHostDelegate;
// This represents a non-browser process. This can include traditional child
// processes like plugins, or an embedder could even use this for long lived
// processes that run independent of the browser process.
class CONTENT_EXPORT ChildProcessHost : public IPC::Sender {
virtual ~ChildProcessHost() {}
// This is a value never returned as the unique id of any child processes of
// any kind, including the values returned by RenderProcessHost::GetID().
static int kInvalidUniqueID;
// Used to create a child process host. The delegate must outlive this object.
static ChildProcessHost* Create(ChildProcessHostDelegate* delegate);
// These flags may be passed to GetChildPath in order to alter its behavior,
// causing it to return a child path more suited to a specific task.
enum {
// No special behavior requested.
#if defined(OS_LINUX)
// Indicates that the child execed after forking may be execced 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 on Linux, 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.
#elif defined(OS_MACOSX)
// Requests that the child run in a process that does not have the
// PIE (position-independent executable) bit set, effectively disabling
// ASLR. For process types that need to allocate a large contiguous
// region, ASLR may not leave a large enough "hole" for the purpose. This
// option should be used sparingly, and only when absolutely necessary.
// This option is currently incompatible with CHILD_ALLOW_HEAP_EXECUTION.
CHILD_NO_PIE = 1 << 1,
// Requests that the child run in a process that does not protect the
// heap against execution. Normally, heap pages may be made executable
// with mprotect, so this mode should be used sparingly. It is intended
// for processes that may host plug-ins that expect an executable heap
// without having to call mprotect. This option is currently incompatible
// with CHILD_NO_PIE.
// 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 |flags| argument accepts one or more flags such as CHILD_ALLOW_SELF
// and CHILD_ALLOW_HEAP_EXECUTION as defined above. Pass only CHILD_NORMAL
// if none of these special behaviors are required.
// On failure, returns an empty FilePath.
static base::FilePath GetChildPath(int flags);
// Send the shutdown message to the child process.
// Does not check with the delegate's CanShutdown.
virtual void ForceShutdown() = 0;
// Creates the IPC channel. Returns the channel id if it succeeded, an
// empty string otherwise
virtual std::string CreateChannel() = 0;
// Returns true iff the IPC channel is currently being opened;
virtual bool IsChannelOpening() = 0;
// Adds an IPC message filter. A reference will be kept to the filter.
virtual void AddFilter(IPC::MessageFilter* filter) = 0;
#if defined(OS_POSIX)
// See IPC::Channel::TakeClientFileDescriptor.
virtual int TakeClientFileDescriptor() = 0;
}; // namespace content