// 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.
#ifndef CONTENT_PUBLIC_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_
#define CONTENT_PUBLIC_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_
#include <unistd.h>
#include <string>
#include <vector>
// TODO(jln) base::TerminationStatus should be forward declared when switching
// to C++11.
#include "base/process/kill.h"
namespace content {
// The ZygoteForkDelegate allows the Chrome Linux zygote to delegate
// fork operations to another class that knows how to do some
// specialized version of fork.
class ZygoteForkDelegate {
public:
// A ZygoteForkDelegate is created during Chrome linux zygote
// initialization, and provides "fork()" functionality as an
// alternative to forking the zygote. A new delegate is passed in
// as an argument to ZygoteMain().
virtual ~ZygoteForkDelegate() {}
// Initialization happens in the zygote after it has been
// started by ZygoteMain.
virtual void Init(int sandboxdesc) = 0;
// After Init, supply a UMA_HISTOGRAM_ENUMERATION the delegate
// would like to supply on the first fork.
virtual void InitialUMA(std::string* uma_name,
int* uma_sample,
int* uma_boundary_value) = 0;
// Returns 'true' if the delegate would like to handle a given fork
// request. Otherwise returns false. Optionally, fills in uma_name et al
// with a report the helper wants to make via UMA_HISTOGRAM_ENUMERATION.
virtual bool CanHelp(const std::string& process_type, std::string* uma_name,
int* uma_sample, int* uma_boundary_value) = 0;
// Indexes of FDs in the vector passed to Fork().
enum {
// Used to pass in the descriptor for talking to the Browser
kBrowserFDIndex,
// The next two are used in the protocol for discovering the
// child processes real PID from within the SUID sandbox. See
// http://code.google.com/p/chromium/wiki/LinuxZygote
kDummyFDIndex,
kParentFDIndex,
kNumPassedFDs // Number of FDs in the vector passed to Fork().
};
// Delegate forks, returning a -1 on failure. Outside the
// suid sandbox, Fork() returns the Linux process ID.
// This method is not aware of any potential pid namespaces, so it'll
// return a raw pid just like fork() would.
virtual pid_t Fork(const std::string& process_type,
const std::vector<int>& fds) = 0;
// After a successful fork, signal the child to indicate that
// the child's PID has been received. Also communicate the
// channel switch as a part of acknowledgement message.
virtual bool AckChild(int fd, const std::string& channel_switch) = 0;
// The fork delegate must also assume the role of waiting for its children
// since the caller will not be their parents and cannot do it. |pid| here
// should be a pid that has been returned by the Fork() method. i.e. This
// method is completely unaware of eventual PID namespaces due to sandboxing.
// |known_dead| indicates that the process is already dead and that a
// blocking wait() should be performed. In this case, GetTerminationStatus()
// will send a SIGKILL to the target process first.
virtual bool GetTerminationStatus(pid_t pid, bool known_dead,
base::TerminationStatus* status,
int* exit_code) = 0;
};
} // namespace content
#endif // CONTENT_PUBLIC_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_