1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CONTENT_PUBLIC_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_
6#define CONTENT_PUBLIC_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_
7
8#include <unistd.h>
9
10#include <string>
11#include <vector>
12
13// TODO(jln) base::TerminationStatus should be forward declared when switching
14// to C++11.
15#include "base/process/kill.h"
16
17namespace content {
18
19// The ZygoteForkDelegate allows the Chrome Linux zygote to delegate
20// fork operations to another class that knows how to do some
21// specialized version of fork.
22class ZygoteForkDelegate {
23 public:
24  // A ZygoteForkDelegate is created during Chrome linux zygote
25  // initialization, and provides "fork()" functionality as an
26  // alternative to forking the zygote.  A new delegate is passed in
27  // as an argument to ZygoteMain().
28  virtual ~ZygoteForkDelegate() {}
29
30  // Initialization happens in the zygote after it has been
31  // started by ZygoteMain.
32  // If |enable_layer1_sandbox| is true, the delegate must enable a
33  // layer-1 sandbox such as the setuid sandbox.
34  virtual void Init(int sandboxdesc, bool enable_layer1_sandbox) = 0;
35
36  // After Init, supply a UMA_HISTOGRAM_ENUMERATION the delegate would like
37  // reported to the browser process.  (Note: Because these reports are
38  // piggy-backed onto fork responses that don't otherwise contain UMA reports,
39  // this method may not be called until much later.)
40  virtual void InitialUMA(std::string* uma_name,
41                          int* uma_sample,
42                          int* uma_boundary_value) = 0;
43
44  // Returns 'true' if the delegate would like to handle a given fork
45  // request.  Otherwise returns false.  Optionally, fills in uma_name et al
46  // with a report the helper wants to make via UMA_HISTOGRAM_ENUMERATION.
47  virtual bool CanHelp(const std::string& process_type, std::string* uma_name,
48                       int* uma_sample, int* uma_boundary_value) = 0;
49
50  // Indexes of FDs in the vector passed to Fork().
51  enum {
52    // Used to pass in the descriptor for talking to the Browser
53    kBrowserFDIndex,
54    // The PID oracle is used in the protocol for discovering the
55    // child process's real PID from within the SUID sandbox.
56    // The child process is required to write to the socket after
57    // successfully forking.
58    kPIDOracleFDIndex,
59    kNumPassedFDs  // Number of FDs in the vector passed to Fork().
60  };
61
62  // Delegate forks, returning a -1 on failure. Outside the
63  // suid sandbox, Fork() returns the Linux process ID.
64  // This method is not aware of any potential pid namespaces, so it'll
65  // return a raw pid just like fork() would.
66  // Delegate is responsible for communicating the channel ID to the
67  // newly created child process.
68  virtual pid_t Fork(const std::string& process_type,
69                     const std::vector<int>& fds,
70                     const std::string& channel_id) = 0;
71
72  // The fork delegate must also assume the role of waiting for its children
73  // since the caller will not be their parents and cannot do it. |pid| here
74  // should be a pid that has been returned by the Fork() method. i.e. This
75  // method is completely unaware of eventual PID namespaces due to sandboxing.
76  // |known_dead| indicates that the process is already dead and that a
77  // blocking wait() should be performed. In this case, GetTerminationStatus()
78  // will send a SIGKILL to the target process first.
79  virtual bool GetTerminationStatus(pid_t pid, bool known_dead,
80                                    base::TerminationStatus* status,
81                                    int* exit_code) = 0;
82};
83
84}  // namespace content
85
86#endif  // CONTENT_PUBLIC_COMMON_ZYGOTE_FORK_DELEGATE_LINUX_H_
87