Introduce base::ScopedPlatformHandle

base/files/scoped_platform_handle.h

+// Copyright 2017 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.
+
+#ifndef BASE_FILES_SCOPED_PLATFORM_HANDLE_H_
+#define BASE_FILES_SCOPED_PLATFORM_HANDLE_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "base/base_export.h"
+#include "build/build_config.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+
+#include "base/win/scoped_handle.h"
+#elif defined(OS_POSIX)
+#include "base/files/scoped_file.h"
+#endif
+
+namespace base {
+
+// A ScopedPlatformHandle encapsulates ownership of either a Windows handle or
+// a POSIX file descriptor, while presenting a common interface for the sake
+// of simple, consistent, and safe ownership semantics. Platform-specific usage
+// details are thus relegated to code which either acquires or uses the
+// underlying platform resource.
+class BASE_EXPORT ScopedPlatformHandle {
+ public:
+#if defined(OS_WIN)
+  using HandleType = HANDLE;
+  using ScopedHandleType = win::ScopedHandle;
+#elif defined(OS_POSIX)
+  using HandleType = int;
+  using ScopedHandleType = ScopedFD;
+#endif
+
+  // Constructors for an invalid ScopedPlatformHandle.
+  ScopedPlatformHandle();
+  ScopedPlatformHandle(std::nullptr_t);
+
+  ScopedPlatformHandle(ScopedPlatformHandle&& other);
+
+  // These constructors always take ownership of the given handle.
+  explicit ScopedPlatformHandle(HandleType handle);
+  explicit ScopedPlatformHandle(ScopedHandleType handle);
+
+  ~ScopedPlatformHandle();
+
+  ScopedPlatformHandle& operator=(ScopedPlatformHandle&& other);
+
+  // Indicates whether this ScopedPlatformHandle is holding a valid handle.
+  bool is_valid() const;
+
+  // Closes the handle.
+  void reset();
+
+  // Returns the platform-specific handle value.
+  HandleType get() const;
+
+  // Returns the platform-specific handle value, releasing ownership of the
+  // handle.
+  HandleType release();
+
+  // Transfers ownership of the handle to a platform-specific scoper.
+  ScopedHandleType Take();
+
+ private:
+  ScopedHandleType handle_;
+};
+
+}  // namespace base
+
+#endif  // BASE_FILES_SCOPED_PLATFORM_HANDLE_H_