Resurrect POSIX shared memory support 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 be83e5a236bb2322e66b36d13aa0640759cdc691..6362b343cd730bfee349a9edbc36073765e58f37 100644
--- a/ipc/ipc_message_utils.cc
+++ b/ipc/ipc_message_utils.cc
@@ -690,40 +690,88 @@ void ParamTraits<base::SharedMemoryHandle>::GetSize(base::PickleSizer* sizer,
 
 void ParamTraits<base::SharedMemoryHandle>::Write(base::Pickle* m,
                                                   const param_type& p) {
-  MachPortMac mach_port_mac(p.GetMemoryObject());
-  ParamTraits<MachPortMac>::Write(m, mach_port_mac);
-  size_t size = 0;
-  bool result = p.GetSize(&size);
-  DCHECK(result);
-  ParamTraits<uint32_t>::Write(m, static_cast<uint32_t>(size));
+  m->WriteInt(p.GetType());
+  switch (p.GetType()) {
+    case base::SharedMemoryHandle::POSIX:
+      ParamTraits<base::FileDescriptor>::Write(m, p.GetFileDescriptor());
+      break;
+    case base::SharedMemoryHandle::MACH:
+      MachPortMac mach_port_mac(p.GetMemoryObject());
+      ParamTraits<MachPortMac>::Write(m, mach_port_mac);
+      size_t size = 0;
+      bool result = p.GetSize(&size);
+      DCHECK(result);
+      ParamTraits<uint32_t>::Write(m, static_cast<uint32_t>(size));
 
-  // If the caller intended to pass ownership to the IPC stack, release a
-  // reference.
-  if (p.OwnershipPassesToIPC())
-    p.Close();
+      // If the caller intended to pass ownership to the IPC stack, release a
+      // reference.
+      if (p.OwnershipPassesToIPC())
+        p.Close();
+      break;
+  }
 }
 
 bool ParamTraits<base::SharedMemoryHandle>::Read(const base::Pickle* m,
                                                  base::PickleIterator* iter,
                                                  param_type* r) {
-  MachPortMac mach_port_mac;
-  if (!ParamTraits<MachPortMac>::Read(m, iter, &mach_port_mac))
+  base::SharedMemoryHandle::TypeWireFormat type;
+  if (!iter->ReadInt(&type))
     return false;
 
-  uint32_t size;
-  if (!ParamTraits<uint32_t>::Read(m, iter, &size))
-    return false;
+  base::SharedMemoryHandle::Type shm_type = base::SharedMemoryHandle::POSIX;
+  switch (type) {
+    case base::SharedMemoryHandle::POSIX:
+    case base::SharedMemoryHandle::MACH: {
+      shm_type = static_cast<base::SharedMemoryHandle::Type>(type);
+      break;
+    }
+    default: {
+      return false;
+    }
+  }
 
-  *r = base::SharedMemoryHandle(mach_port_mac.get_mach_port(),
-                                static_cast<size_t>(size),
-                                base::GetCurrentProcId());
-  return true;
+  switch(shm_type) {
+    case base::SharedMemoryHandle::POSIX: {
+      base::FileDescriptor file_descriptor;
+
+      bool success =
+          ParamTraits<base::FileDescriptor>::Read(m, iter, &file_descriptor);
+      if (!success)
+        return false;
+
+      *r = base::SharedMemoryHandle(file_descriptor.fd,
+                                    file_descriptor.auto_close);
+      return true;
+    }
+    case base::SharedMemoryHandle::MACH: {
+      MachPortMac mach_port_mac;
+      if (!ParamTraits<MachPortMac>::Read(m, iter, &mach_port_mac))
+        return false;
+
+      uint32_t size;
+      if (!ParamTraits<uint32_t>::Read(m, iter, &size))
+        return false;
+
+      *r = base::SharedMemoryHandle(mach_port_mac.get_mach_port(),
+                                    static_cast<size_t>(size),
+                                    base::GetCurrentProcId());
+      return true;
+    }
+  }
 }
 
 void ParamTraits<base::SharedMemoryHandle>::Log(const param_type& p,
                                                 std::string* l) {
-  l->append("Mach port: ");
-  LogParam(p.GetMemoryObject(), l);
+  switch (p.GetType()) {
+    case base::SharedMemoryHandle::POSIX:
+      l->append("POSIX Fd: ");
+      ParamTraits<base::FileDescriptor>::Log(p.GetFileDescriptor(), l);
+      break;
+    case base::SharedMemoryHandle::MACH:
+      l->append("Mach port: ");
+      LogParam(p.GetMemoryObject(), l);
+      break;
+  }
 }
 
 #elif defined(OS_WIN)