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_EDK_EMBEDDER_PLATFORM_CHANNEL_PAIR_H_ 6 #define MOJO_EDK_EMBEDDER_PLATFORM_CHANNEL_PAIR_H_ 7 8 #include <memory> 9 10 #include "base/macros.h" 11 #include "base/process/launch.h" 12 #include "build/build_config.h" 13 #include "mojo/edk/embedder/scoped_platform_handle.h" 14 #include "mojo/edk/system/system_impl_export.h" 15 16 namespace base { 17 class CommandLine; 18 } 19 20 namespace mojo { 21 namespace edk { 22 23 // It would be nice to refactor base/process/launch.h to have a more platform- 24 // independent way of representing handles that are passed to child processes. 25 #if defined(OS_WIN) 26 using HandlePassingInformation = base::HandlesToInheritVector; 27 #elif defined(OS_POSIX) 28 using HandlePassingInformation = base::FileHandleMappingVector; 29 #else 30 #error "Unsupported." 31 #endif 32 33 // This is used to create a pair of |PlatformHandle|s that are connected by a 34 // suitable (platform-specific) bidirectional "pipe" (e.g., socket on POSIX, 35 // named pipe on Windows). The resulting handles can then be used in the same 36 // process (e.g., in tests) or between processes. (The "server" handle is the 37 // one that will be used in the process that created the pair, whereas the 38 // "client" handle is the one that will be used in a different process.) 39 // 40 // This class provides facilities for passing the client handle to a child 41 // process. The parent should call |PrepareToPassClientHandlelToChildProcess()| 42 // to get the data needed to do this, spawn the child using that data, and then 43 // call |ChildProcessLaunched()|. Note that on Windows this facility (will) only 44 // work on Vista and later (TODO(vtl)). 45 // 46 // Note: |PlatformChannelPair()|, |PassClientHandleFromParentProcess()| and 47 // |PrepareToPassClientHandleToChildProcess()| have platform-specific 48 // implementations. 49 // 50 // Note: On POSIX platforms, to write to the "pipe", use 51 // |PlatformChannel{Write,Writev}()| (from platform_channel_utils_posix.h) 52 // instead of |write()|, |writev()|, etc. Otherwise, you have to worry about 53 // platform differences in suppressing |SIGPIPE|. 54 class MOJO_SYSTEM_IMPL_EXPORT PlatformChannelPair { 55 public: 56 static const char kMojoPlatformChannelHandleSwitch[]; 57 58 // If |client_is_blocking| is true, then the client handle only supports 59 // blocking reads and writes. The default is nonblocking. 60 PlatformChannelPair(bool client_is_blocking = false); 61 ~PlatformChannelPair(); 62 63 ScopedPlatformHandle PassServerHandle(); 64 65 // For in-process use (e.g., in tests or to pass over another channel). 66 ScopedPlatformHandle PassClientHandle(); 67 68 // To be called in the child process, after the parent process called 69 // |PrepareToPassClientHandleToChildProcess()| and launched the child (using 70 // the provided data), to create a client handle connected to the server 71 // handle (in the parent process). 72 // TODO(jcivelli): remove the command_line param. http://crbug.com/670106 73 static ScopedPlatformHandle PassClientHandleFromParentProcess( 74 const base::CommandLine& command_line); 75 76 // Like above, but gets the handle from the passed in string. 77 static ScopedPlatformHandle PassClientHandleFromParentProcessFromString( 78 const std::string& value); 79 80 // Prepares to pass the client channel to a new child process, to be launched 81 // using |LaunchProcess()| (from base/launch.h). Modifies |*command_line| and 82 // |*handle_passing_info| as needed. 83 // Note: For Windows, this method only works on Vista and later. 84 void PrepareToPassClientHandleToChildProcess( 85 base::CommandLine* command_line, 86 HandlePassingInformation* handle_passing_info) const; 87 88 // Like above, but returns a string instead of changing the command line. 89 std::string PrepareToPassClientHandleToChildProcessAsString( 90 HandlePassingInformation* handle_passing_info) const; 91 92 // To be called once the child process has been successfully launched, to do 93 // any cleanup necessary. 94 void ChildProcessLaunched(); 95 96 private: 97 ScopedPlatformHandle server_handle_; 98 ScopedPlatformHandle client_handle_; 99 100 DISALLOW_COPY_AND_ASSIGN(PlatformChannelPair); 101 }; 102 103 } // namespace edk 104 } // namespace mojo 105 106 #endif // MOJO_EDK_EMBEDDER_PLATFORM_CHANNEL_PAIR_H_ 107