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/win/scoped_handle.h"
+
+namespace base {
+namespace win {
+
+class ProcessInfoTraits {
+ public:
+  typedef PROCESS_INFORMATION Handle;
+
+  static bool CloseHandle(const PROCESS_INFORMATION& handle) {
+    bool ret = true;
+    if (handle.hThread && !::CloseHandle(handle.hThread))
+      ret = false;
+    if (handle.hProcess && !::CloseHandle(handle.hProcess))
+      ret = false;
+    return ret;
+  }
+
+  static bool IsHandleValid(const PROCESS_INFORMATION& handle) {
+    return handle.hThread || handle.hProcess ||
+      handle.dwProcessId || handle.dwThreadId;
+  }
+
+  static bool IsSame(const PROCESS_INFORMATION& lhs,
+                     const PROCESS_INFORMATION& rhs) {
+    return lhs.hProcess == rhs.hProcess &&
+      lhs.hThread == rhs.hThread &&
+      lhs.dwProcessId == rhs.dwProcessId &&
+      lhs.dwThreadId == rhs.dwThreadId;
+  }
+
+  static const PROCESS_INFORMATION& NullHandle() {
+    return kNullHandle;
+  }
+
+ private:
+  static const PROCESS_INFORMATION kNullHandle;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(ProcessInfoTraits);
+};
+
+const PROCESS_INFORMATION ProcessInfoTraits::kNullHandle = {0};
+
+// Manages the closing of process and thread handles from PROCESS_INFORMATION
+// structures. Allows clients to take ownership of either handle independently.
+class ScopedProcessInformation : public GenericScopedHandle<ProcessInfoTraits> {
+ public:
+  ScopedProcessInformation()
+      : GenericScopedHandle(ProcessInfoTraits::NullHandle()) {}
+
+  explicit ScopedProcessInformation(Handle handle)
+      : GenericScopedHandle(handle) {}
+
+  // Transfers ownership of the process handle away from this object. The
+  // hProcess and dwProcessId members will be reset.
+  HANDLE TakeProcessHandle() {
+    PROCESS_INFORMATION process_info = Take();
+    HANDLE process = process_info.hProcess;
+    process_info.hProcess = NULL;
+    process_info.dwProcessId = 0;

[sanjeevr, 2012/03/15 17:42:55]

Drive-by: Zeroing out the process id here (and the  thread id below) seems like
overkill. There is no reason why a consumer should not be able to access the
process id after taking ownership of the handle.

[erikwright (departed), 2012/03/15 18:02:44]

It's primarily to simplify the usage pattern. If someone calls
"TakeProcessHandle" and "TakeThreadHandle", they have taken everything and
therefore it's easier if the object is considered reset at that point.

The alternative introduces some weird states that I would rather not have to
deal with (or document).

+    Set(process_info);
+    return process;
+  }
+
+  // Transfers ownership of the thread handle away from this object. The hThread
+  // and dwThreadId members will be reset.
+  HANDLE TakeThreadHandle() {
+    PROCESS_INFORMATION process_info = Take();
+    HANDLE thread = process_info.hThread;
+    process_info.hThread = NULL;
+    process_info.dwThreadId = 0;
+    Set(process_info);
+    return thread;
+  }
+};
+
+}  // namespace win
+}  // namespace base
+
+#endif  // BASE_SCOPED_HANDLE_WIN_H_