ScopedProcessInformation protects against process/thread handle leaks from CreateProcess calls.

base/win/scoped_process_information.h

+// 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.
+
+#ifndef BASE_WIN_SCOPED_PROCESS_INFORMATION_H_
+#define BASE_WIN_SCOPED_PROCESS_INFORMATION_H_
+#pragma once
+
+#include <windows.h>
+
+#include "base/basictypes.h"
+#include "base/base_export.h"
+
+namespace base {
+namespace win {
+
+// Manages the closing of process and thread handles from PROCESS_INFORMATION
+// structures. Allows clients to take ownership of either handle independently.
+class BASE_EXPORT ScopedProcessInformation {
+ public:
+  // Creates an instance holding a null PROCESS_INFORMATION.
+  ScopedProcessInformation();
+
+  // Closes the held thread and process handles, if any.
+  ~ScopedProcessInformation();
+
+  // Returns a pointer that may be passed to API calls such as CreateProcess.
+  // DCHECKs that the object is not currently holding any handles.
+  // HANDLEs stored in the returned PROCESS_INFORMATION will be owned by this
+  // instance.
+  PROCESS_INFORMATION* Receive();
+
+  // Returns true iff this instance is holding a thread and/or process handle.
+  bool IsValid() const;
+
+  // Closes the held thread and process handles, if any, and resets the held
+  // PROCESS_INFORMATION to null.
+  void Close();
+
+  // Swaps contents with the other ScopedProcessInformation.
+  void Swap(ScopedProcessInformation* other);
+
+  // Populates this instance with duplicate handles and the thread/process IDs
+  // from |other|. Returns false in case of failure, in which case this instance
+  // will be completely unpopulated.
+  bool DuplicateFrom(const ScopedProcessInformation& other);
+
+  // Transfers ownership of the held PROCESS_INFORMATION, if any, away from this
+  // instance. Resets the held PROCESS_INFORMATION to null.
+  PROCESS_INFORMATION Take();
+
+  // Transfers ownership of the held process handle, if any, away from this
+  // instance. The hProcess and dwProcessId members of the held
+  // PROCESS_INFORMATION will be reset.
+  HANDLE TakeProcessHandle();
+
+  // Transfers ownership of the held thread handle, if any, away from this
+  // instance. The hThread and dwThreadId members of the held
+  // PROCESS_INFORMATION will be reset.
+  HANDLE TakeThreadHandle();
+
+  // Returns the held process handle, if any, while retaining ownership.
+  HANDLE process_handle() const {
+    return process_information_.hProcess;
+  }
+
+  // Returns the held thread handle, if any, while retaining ownership.
+  HANDLE thread_handle() const {
+    return process_information_.hThread;
+  }
+
+  // Returns the held process id, if any.
+  DWORD process_id() const {
+    return process_information_.dwProcessId;
+  }
+
+  // Returns the held thread id, if any.
+  DWORD thread_id() const {
+    return process_information_.dwThreadId;
+  }
+
+ private:
+  // Resets the held PROCESS_INFORMATION to null.
+  void Reset();
+
+  PROCESS_INFORMATION process_information_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedProcessInformation);
+};
+
+}  // namespace win
+}  // namespace base
+
+#endif  // BASE_WIN_SCOPED_PROCESS_INFORMATION_H_