Make SharedMemoryHandle a class on Mac.

ipc/ipc_message_utils.cc

Index: ipc/ipc_message_utils.cc
diff --git a/ipc/ipc_message_utils.cc b/ipc/ipc_message_utils.cc
index f86022c691a09cded39dc2cd21928bcaca8b9646..171934c4e55f6dedbea29922dde262852fe92c49 100644
--- a/ipc/ipc_message_utils.cc
+++ b/ipc/ipc_message_utils.cc
@@ -20,6 +20,10 @@
 #include "ipc/ipc_platform_file_attachment_posix.h"
 #endif
 
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+#include "base/memory/shared_memory_handle.h"
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
+
 #if defined(OS_WIN)
 #include <tchar.h>
 #endif
@@ -516,6 +520,57 @@ void ParamTraits<base::FileDescriptor>::Log(const param_type& p,
 }
 #endif  // defined(OS_POSIX)
 
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+void ParamTraits<base::SharedMemoryHandle>::Write(Message* m,
+                                                  const param_type& p) {
+  static_assert(sizeof(base::SharedMemoryHandle::Type) <= sizeof(int),

[Tom Sepez, 2015/06/17 18:51:55]

nit: this assert can go into the class body itself.

[erikchen, 2015/06/18 17:58:33]

Sure, done. I made a new type base::SharedMemoryHandle::TypeWireFormat to use
instead of int on line 535. This ensures that the assert actually matches the
code being used in this file.

+                "Size of enum SharedMemoryHandle::Type exceeds size of type "
+                "transmitted over wire.");
+  m->WriteInt(p.GetType());
+
+  if (p.GetType() == base::SharedMemoryHandle::POSIX)
+    ParamTraits<base::FileDescriptor>::Write(m, *p.GetFileDescriptor());
+}
+
+bool ParamTraits<base::SharedMemoryHandle>::Read(const Message* m,
+                                                 base::PickleIterator* iter,
+                                                 param_type* r) {
+  static_assert(sizeof(base::SharedMemoryHandle::Type) <= sizeof(int),

[Tom Sepez, 2015/06/17 18:51:55]

same here.

[erikchen, 2015/06/18 17:58:33]

Done.

+                "Size of enum SharedMemoryHandle::Type exceeds size of type "
+                "transmitted over wire.");
+  int type;
+  if (!iter->ReadInt(&type))
+    return false;
+
+  switch (type) {
+    case base::SharedMemoryHandle::POSIX:
+    case base::SharedMemoryHandle::MACH: {
+      base::SharedMemoryHandle::Type shm_type =
+          static_cast<base::SharedMemoryHandle::Type>(type);
+      r->SetType(shm_type);
+      break;
+    }
+    default:
+      return false;
+  }
+
+  if (r->GetType() == base::SharedMemoryHandle::POSIX) {
+    return ParamTraits<base::FileDescriptor>::Read(m, iter,
+                                                   r->GetFileDescriptor());
+  }
+

[Tom Sepez, 2015/06/17 18:51:55]

The pattern for these kinds of classes is to not assign them member by member,
but instead use ctor + assignment as in:

  base::FileDescriptor fd;
  if (!read(m, iter, &fd))
      return false;
 *r = base::SharedMemoryHandle(fd);

Then you can avoid having to leak the FD address to the outside world.

[erikchen, 2015/06/18 17:58:33]

Ah, good suggestion. Done.

+  return true;
+}
+
+void ParamTraits<base::SharedMemoryHandle>::Log(const param_type& p,
+                                                std::string* l) {
+  if (p.GetType() == base::SharedMemoryHandle::POSIX) {
+    l->append(base::StringPrintf("Mechanism POSIX Fd"));
+    ParamTraits<base::FileDescriptor>::Log(*p.GetFileDescriptor(), l);
+  }
+}
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
+
 void ParamTraits<base::FilePath>::Write(Message* m, const param_type& p) {
   p.WriteToPickle(m);
 }