Support using a Mojo message pipe in a ChannelHandle.

ipc/ipc_message_utils.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ipc/ipc_message_utils.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/files/file_path.h"
 #include "base/json/json_writer.h"
 #include "base/strings/nullable_string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_message_attachment.h"
 #include "ipc/ipc_message_attachment_set.h"
+#include "ipc/ipc_mojo_param_traits.h"
 
 #if defined(OS_POSIX)
 #include "ipc/ipc_platform_file_attachment_posix.h"
 #endif
 
 #if (defined(OS_MACOSX) && !defined(OS_IOS)) || defined(OS_WIN)
 #include "base/memory/shared_memory_handle.h"
 #endif  // (defined(OS_MACOSX) && !defined(OS_IOS)) || defined(OS_WIN)
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
@@ skipping 600 matching lines @@
                                              std::string* l) {
   std::string json;
   base::JSONWriter::Write(p, &json);
   l->append(json);
 }
 
 #if defined(OS_POSIX)
 void ParamTraits<base::FileDescriptor>::GetSize(base::PickleSizer* sizer,
                                                 const param_type& p) {
   GetParamSize(sizer, p.fd >= 0);
-  sizer->AddAttachment();
+  if (p.fd >= 0)
+    sizer->AddAttachment();
 }
 
 void ParamTraits<base::FileDescriptor>::Write(base::Pickle* m,
                                               const param_type& p) {
   const bool valid = p.fd >= 0;
   WriteParam(m, valid);
 
   if (!valid)
     return;
 
@@ skipping 343 matching lines @@
 void ParamTraits<base::TimeTicks>::Log(const param_type& p, std::string* l) {
   ParamTraits<int64_t>::Log(p.ToInternalValue(), l);
 }
 
 void ParamTraits<IPC::ChannelHandle>::GetSize(base::PickleSizer* sizer,
                                               const param_type& p) {
   GetParamSize(sizer, p.name);
 #if defined(OS_POSIX)
   GetParamSize(sizer, p.socket);
 #endif
+  GetParamSize(sizer, p.mojo_handle);
 }
 
 void ParamTraits<IPC::ChannelHandle>::Write(base::Pickle* m,
                                             const param_type& p) {
 #if defined(OS_WIN)
   // On Windows marshalling pipe handle is not supported.
   DCHECK(p.pipe.handle == NULL);
 #endif  // defined (OS_WIN)
   WriteParam(m, p.name);
 #if defined(OS_POSIX)
   WriteParam(m, p.socket);
 #endif
+  ParamTraits<mojo::MessagePipeHandle>::Write(
+      static_cast<IPC::Message*>(m), p.mojo_handle);

[dcheng, 2016/06/24 07:50:48]

Why does this need the explicit static_cast? Normally, WriteParam / ReadParam /
LogParam are the canonical way to delegate.

[Anand Mistry (off Chromium), 2016/06/27 00:46:23]

Because ParamTraits<> functions operate on base::Pickle whereas the MessagePipe
one use IPC::Message. The cast is needed because C++ templates use exact type
matching and don't recognise subclasses.

I've decided to switch the MessagePipe param trait to use base::Pickle instead,
which gets rid of this cast and makes the param trait look like all the others.

 }
 
 bool ParamTraits<IPC::ChannelHandle>::Read(const base::Pickle* m,
                                            base::PickleIterator* iter,
                                            param_type* r) {
   return ReadParam(m, iter, &r->name)
 #if defined(OS_POSIX)
       && ReadParam(m, iter, &r->socket)
 #endif
-      ;
+      && ParamTraits<mojo::MessagePipeHandle>::Read(
+          static_cast<const IPC::Message*>(m), iter, &r->mojo_handle);
 }
 
 void ParamTraits<IPC::ChannelHandle>::Log(const param_type& p,
                                           std::string* l) {
   l->append(base::StringPrintf("ChannelHandle(%s", p.name.c_str()));
 #if defined(OS_POSIX)
   l->append(", ");
   ParamTraits<base::FileDescriptor>::Log(p.socket, l);
 #endif
+  l->append(", ");
+  ParamTraits<mojo::MessagePipeHandle>::Log(p.mojo_handle, l);
   l->append(")");
 }
 
 void ParamTraits<LogData>::GetSize(base::PickleSizer* sizer,
                                    const param_type& p) {
   GetParamSize(sizer, p.channel);
   GetParamSize(sizer, p.routing_id);
   GetParamSize(sizer, p.type);
   GetParamSize(sizer, p.flags);
   GetParamSize(sizer, p.sent);
@@ skipping 159 matching lines @@
   return result;
 }
 
 void ParamTraits<MSG>::Log(const param_type& p, std::string* l) {
   l->append("<MSG>");
 }
 
 #endif  // OS_WIN
 
 }  // namespace IPC