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_ZYGOTE_ZYGOTE_H_
6#define CONTENT_ZYGOTE_ZYGOTE_H_
7
8#include <stddef.h>
9
10#include <string>
11
12#include "base/containers/small_map.h"
13#include "base/files/scoped_file.h"
14#include "base/memory/scoped_vector.h"
15#include "base/posix/global_descriptors.h"
16#include "base/process/kill.h"
17#include "base/process/process.h"
18
19class Pickle;
20class PickleIterator;
21
22namespace content {
23
24class ZygoteForkDelegate;
25
26// This is the object which implements the zygote. The ZygoteMain function,
27// which is called from ChromeMain, simply constructs one of these objects and
28// runs it.
29class Zygote {
30 public:
31  Zygote(int sandbox_flags, ScopedVector<ZygoteForkDelegate> helpers,
32         const std::vector<base::ProcessHandle>& extra_children,
33         const std::vector<int>& extra_fds);
34  ~Zygote();
35
36  bool ProcessRequests();
37
38 private:
39  struct ZygoteProcessInfo {
40    // Pid from inside the Zygote's PID namespace.
41    base::ProcessHandle internal_pid;
42    // Keeps track of which fork delegate helper the process was started from.
43    ZygoteForkDelegate* started_from_helper;
44  };
45  typedef base::SmallMap< std::map<base::ProcessHandle, ZygoteProcessInfo> >
46      ZygoteProcessMap;
47
48  // Retrieve a ZygoteProcessInfo from the process_info_map_.
49  // Returns true and write to process_info if |pid| can be found, return
50  // false otherwise.
51  bool GetProcessInfo(base::ProcessHandle pid,
52                      ZygoteProcessInfo* process_info);
53
54  // Returns true if the SUID sandbox is active.
55  bool UsingSUIDSandbox() const;
56
57  // ---------------------------------------------------------------------------
58  // Requests from the browser...
59
60  // Read and process a request from the browser. Returns true if we are in a
61  // new process and thus need to unwind back into ChromeMain.
62  bool HandleRequestFromBrowser(int fd);
63
64  void HandleReapRequest(int fd, const Pickle& pickle, PickleIterator iter);
65
66  // Get the termination status of |real_pid|. |real_pid| is the PID as it
67  // appears outside of the sandbox.
68  // Return true if it managed to get the termination status and return the
69  // status in |status| and the exit code in |exit_code|.
70  bool GetTerminationStatus(base::ProcessHandle real_pid, bool known_dead,
71                            base::TerminationStatus* status,
72                            int* exit_code);
73
74  void HandleGetTerminationStatus(int fd,
75                                  const Pickle& pickle,
76                                  PickleIterator iter);
77
78  // This is equivalent to fork(), except that, when using the SUID sandbox, it
79  // returns the real PID of the child process as it appears outside the
80  // sandbox, rather than returning the PID inside the sandbox.  The child's
81  // real PID is determined by having it call content::SendZygoteChildPing(int)
82  // using the |pid_oracle| descriptor.
83  // Finally, when using a ZygoteForkDelegate helper, |uma_name|, |uma_sample|,
84  // and |uma_boundary_value| may be set if the helper wants to make a UMA
85  // report via UMA_HISTOGRAM_ENUMERATION.
86  int ForkWithRealPid(const std::string& process_type,
87                      const base::GlobalDescriptors::Mapping& fd_mapping,
88                      const std::string& channel_id,
89                      base::ScopedFD pid_oracle,
90                      std::string* uma_name,
91                      int* uma_sample,
92                      int* uma_boundary_value);
93
94  // Unpacks process type and arguments from |pickle| and forks a new process.
95  // Returns -1 on error, otherwise returns twice, returning 0 to the child
96  // process and the child process ID to the parent process, like fork().
97  base::ProcessId ReadArgsAndFork(const Pickle& pickle,
98                                  PickleIterator iter,
99                                  ScopedVector<base::ScopedFD> fds,
100                                  std::string* uma_name,
101                                  int* uma_sample,
102                                  int* uma_boundary_value);
103
104  // Handle a 'fork' request from the browser: this means that the browser
105  // wishes to start a new renderer. Returns true if we are in a new process,
106  // otherwise writes the child_pid back to the browser via |fd|. Writes a
107  // child_pid of -1 on error.
108  bool HandleForkRequest(int fd,
109                         const Pickle& pickle,
110                         PickleIterator iter,
111                         ScopedVector<base::ScopedFD> fds);
112
113  bool HandleGetSandboxStatus(int fd,
114                              const Pickle& pickle,
115                              PickleIterator iter);
116
117  // The Zygote needs to keep some information about each process. Most
118  // notably what the PID of the process is inside the PID namespace of
119  // the Zygote and whether or not a process was started by the
120  // ZygoteForkDelegate helper.
121  ZygoteProcessMap process_info_map_;
122
123  const int sandbox_flags_;
124  ScopedVector<ZygoteForkDelegate> helpers_;
125
126  // Count of how many fork delegates for which we've invoked InitialUMA().
127  size_t initial_uma_index_;
128
129  // This vector contains the PIDs of any child processes which have been
130  // created prior to the construction of the Zygote object, and must be reaped
131  // before the Zygote exits. The Zygote will perform a blocking wait on these
132  // children, so they must be guaranteed to be exiting by the time the Zygote
133  // exits.
134  std::vector<base::ProcessHandle> extra_children_;
135
136  // This vector contains the FDs that must be closed before reaping the extra
137  // children.
138  std::vector<int> extra_fds_;
139};
140
141}  // namespace content
142
143#endif  // CONTENT_ZYGOTE_ZYGOTE_H_
144