mojo/embedder/platform_channel_pair.h

   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
  15 namespace base {
  16 class CommandLine;
  17 }
  18
  19 namespace mojo {
  20 namespace 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)
  25 typedef base::HandlesToInheritVector HandlePassingInformation;
  26 #elif defined(OS_POSIX)
  27 typedef 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 class MOJO_SYSTEM_IMPL_EXPORT PlatformChannelPair {
  49  public:
  50   PlatformChannelPair();
  51   ~PlatformChannelPair();
  52
  53   ScopedPlatformHandle PassServerHandle();
  54
  55   // For in-process use (e.g., in tests or to pass over another channel).
  56   ScopedPlatformHandle PassClientHandle();
  57
  58   // To be called in the child process, after the parent process called
  59   // |PrepareToPassClientHandleToChildProcess()| and launched the child (using
  60   // the provided data), to create a client handle connected to the server
  61   // handle (in the parent process).
  62   static ScopedPlatformHandle PassClientHandleFromParentProcess(
  63       const base::CommandLine& command_line);
  64
  65   // Prepares to pass the client channel to a new child process, to be launched
  66   // using |LaunchProcess()| (from base/launch.h). Modifies |*command_line| and
  67   // |*handle_passing_info| as needed.
  68   // Note: For Windows, this method only works on Vista and later.
  69   void PrepareToPassClientHandleToChildProcess(
  70       base::CommandLine* command_line,
  71       HandlePassingInformation* handle_passing_info) const;
  72
  73   // To be called once the child process has been successfully launched, to do
  74   // any cleanup necessary.
  75   void ChildProcessLaunched();
  76
  77  private:
  78   static const char kMojoPlatformChannelHandleSwitch[];
  79
  80   ScopedPlatformHandle server_handle_;
  81   ScopedPlatformHandle client_handle_;
  82
  83   DISALLOW_COPY_AND_ASSIGN(PlatformChannelPair);
  84 };
  85
  86 }  // namespace embedder
  87 }  // namespace mojo
  88
  89 #endif  // MOJO_EMBEDDER_PLATFORM_CHANNEL_PAIR_H_