1// Copyright 2014 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 MOJO_EMBEDDER_PLATFORM_CHANNEL_PAIR_H_
6#define MOJO_EMBEDDER_PLATFORM_CHANNEL_PAIR_H_
7
8#include "base/macros.h"
9#include "base/memory/scoped_ptr.h"
10#include "base/process/launch.h"
11#include "build/build_config.h"
12#include "mojo/embedder/scoped_platform_handle.h"
13#include "mojo/system/system_impl_export.h"
14
15namespace base {
16class CommandLine;
17}
18
19namespace mojo {
20namespace embedder {
21
22// It would be nice to refactor base/process/launch.h to have a more platform-
23// independent way of representing handles that are passed to child processes.
24#if defined(OS_WIN)
25typedef base::HandlesToInheritVector HandlePassingInformation;
26#elif defined(OS_POSIX)
27typedef base::FileHandleMappingVector HandlePassingInformation;
28#else
29#error "Unsupported."
30#endif
31
32// This is used to create a pair of |PlatformHandle|s that are connected by a
33// suitable (platform-specific) bidirectional "pipe" (e.g., socket on POSIX,
34// named pipe on Windows). The resulting handles can then be used in the same
35// process (e.g., in tests) or between processes. (The "server" handle is the
36// one that will be used in the process that created the pair, whereas the
37// "client" handle is the one that will be used in a different process.)
38//
39// This class provides facilities for passing the client handle to a child
40// process. The parent should call |PrepareToPassClientHandlelToChildProcess()|
41// to get the data needed to do this, spawn the child using that data, and then
42// call |ChildProcessLaunched()|. Note that on Windows this facility (will) only
43// work on Vista and later (TODO(vtl)).
44//
45// Note: |PlatformChannelPair()|, |PassClientHandleFromParentProcess()| and
46// |PrepareToPassClientHandleToChildProcess()| have platform-specific
47// implementations.
48//
49// Note: On POSIX platforms, to write to the "pipe", use
50// |PlatformChannel{Write,Writev}()| (from platform_channel_utils_posix.h)
51// instead of |write()|, |writev()|, etc. Otherwise, you have to worry about
52// platform differences in suppressing |SIGPIPE|.
53class MOJO_SYSTEM_IMPL_EXPORT PlatformChannelPair {
54 public:
55  PlatformChannelPair();
56  ~PlatformChannelPair();
57
58  ScopedPlatformHandle PassServerHandle();
59
60  // For in-process use (e.g., in tests or to pass over another channel).
61  ScopedPlatformHandle PassClientHandle();
62
63  // To be called in the child process, after the parent process called
64  // |PrepareToPassClientHandleToChildProcess()| and launched the child (using
65  // the provided data), to create a client handle connected to the server
66  // handle (in the parent process).
67  static ScopedPlatformHandle PassClientHandleFromParentProcess(
68      const base::CommandLine& command_line);
69
70  // Prepares to pass the client channel to a new child process, to be launched
71  // using |LaunchProcess()| (from base/launch.h). Modifies |*command_line| and
72  // |*handle_passing_info| as needed.
73  // Note: For Windows, this method only works on Vista and later.
74  void PrepareToPassClientHandleToChildProcess(
75      base::CommandLine* command_line,
76      HandlePassingInformation* handle_passing_info) const;
77
78  // To be called once the child process has been successfully launched, to do
79  // any cleanup necessary.
80  void ChildProcessLaunched();
81
82 private:
83  static const char kMojoPlatformChannelHandleSwitch[];
84
85  ScopedPlatformHandle server_handle_;
86  ScopedPlatformHandle client_handle_;
87
88  DISALLOW_COPY_AND_ASSIGN(PlatformChannelPair);
89};
90
91}  // namespace embedder
92}  // namespace mojo
93
94#endif  // MOJO_EMBEDDER_PLATFORM_CHANNEL_PAIR_H_
95