Revert of Revert of Make SharedMemoryHandle a class on Mac.

base/memory/shared_memory_handle_mac.cc

+// Copyright 2015 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 "base/memory/shared_memory_handle.h"
+
+#include <unistd.h>
+
+#include "base/posix/eintr_wrapper.h"
+
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+namespace base {
+
+static_assert(sizeof(SharedMemoryHandle::Type) <=
+                  sizeof(SharedMemoryHandle::TypeWireFormat),
+              "Size of enum SharedMemoryHandle::Type exceeds size of type "
+              "transmitted over wire.");
+
+SharedMemoryHandle::SharedMemoryHandle() : type_(POSIX), file_descriptor_() {
+}
+
+SharedMemoryHandle::SharedMemoryHandle(
+    const base::FileDescriptor& file_descriptor)
+    : type_(POSIX), file_descriptor_(file_descriptor) {
+}
+
+SharedMemoryHandle::SharedMemoryHandle(int fd, bool auto_close)
+    : type_(POSIX), file_descriptor_(fd, auto_close) {
+}
+
+SharedMemoryHandle::SharedMemoryHandle(const SharedMemoryHandle& handle)
+    : type_(handle.type_), file_descriptor_(handle.file_descriptor_) {
+}
+
+SharedMemoryHandle& SharedMemoryHandle::operator=(
+    const SharedMemoryHandle& handle) {
+  if (this == &handle)
+    return *this;
+
+  type_ = handle.type_;
+  file_descriptor_ = handle.file_descriptor_;
+  return *this;
+}
+
+bool SharedMemoryHandle::operator==(const SharedMemoryHandle& handle) const {
+  // Invalid handles are always equal, even if they have different types.
+  if (!IsValid() && !handle.IsValid())
+    return true;
+
+  return type_ == handle.type_ && file_descriptor_ == handle.file_descriptor_;
+}
+
+bool SharedMemoryHandle::operator!=(const SharedMemoryHandle& handle) const {
+  return !(*this == handle);
+}
+
+SharedMemoryHandle::Type SharedMemoryHandle::GetType() const {
+  return type_;
+}
+
+bool SharedMemoryHandle::IsValid() const {
+  switch (type_) {
+    case POSIX:
+      return file_descriptor_.fd >= 0;
+    case MACH:
+      return false;
+  }
+}
+
+void SharedMemoryHandle::SetFileHandle(int fd, bool auto_close) {
+  DCHECK_EQ(type_, POSIX);
+  file_descriptor_.fd = fd;
+  file_descriptor_.auto_close = auto_close;
+}
+
+const FileDescriptor SharedMemoryHandle::GetFileDescriptor() const {
+  DCHECK_EQ(type_, POSIX);
+  return file_descriptor_;
+}
+
+SharedMemoryHandle SharedMemoryHandle::Duplicate() const {
+  DCHECK_EQ(type_, POSIX);
+  int duped_handle = HANDLE_EINTR(dup(file_descriptor_.fd));
+  if (duped_handle < 0)
+    return SharedMemoryHandle();
+  return SharedMemoryHandle(duped_handle, true);
+}
+
+}  // namespace base
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)