Enforce handle ownership in base::Process

base/process/process_posix.cc

 // Copyright (c) 2011 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/process/process.h"
 
 #include <sys/resource.h>
 #include <sys/time.h>
 #include <sys/types.h>
 
 #include "base/logging.h"
 #include "base/process/kill.h"
 
 namespace base {
 
+Process::Process(ProcessHandle handle) : process_(handle) {
+  CHECK_NE(handle, GetCurrentProcessHandle());
+}
+
+Process::Process(RValue other)
+    : process_(other.object->process_) {
+  other.object->Close();
+}
+
+Process& Process::operator=(RValue other) {
+  if (this != other.object) {
+    process_ = other.object->process_;
+    other.object->Close();
+  }
+  return *this;
+}
+
 // static
 Process Process::Current() {
-  return Process(GetCurrentProcessHandle());
+  Process process;
+  process.process_ = GetCurrentProcessHandle();
+  return process.Pass();
+}
+
+#if !defined(OS_LINUX)
+// static
+bool Process::CanBackgroundProcesses() {
+  return false;
+}
+#endif  // !defined(OS_LINUX)
+
+bool Process::IsValid() const {
+  return process_ != kNullProcessHandle;
+}
+
+ProcessHandle Process::Handle() const {
+  return process_;
+}
+
+Process Process::Duplicate() const {
+  if (is_current())
+    return Current();
+
+  return Process(process_);
 }
 
 ProcessId Process::pid() const {
-  if (process_ == 0)
-    return 0;
-
+  DCHECK(IsValid());
   return GetProcId(process_);
 }
 
 bool Process::is_current() const {
   return process_ == GetCurrentProcessHandle();
 }
 
 void Process::Close() {
-  process_ = 0;
+  process_ = kNullProcessHandle;
   // if the process wasn't terminated (so we waited) or the state
   // wasn't already collected w/ a wait from process_utils, we're gonna
   // end up w/ a zombie when it does finally exit.
 }
 
 void Process::Terminate(int result_code) {
   // result_code isn't supportable.
-  if (!process_)
-    return;
+  DCHECK(IsValid());
   // We don't wait here. It's the responsibility of other code to reap the
   // child.
   KillProcess(process_, result_code, false);
 }
 
 #if !defined(OS_LINUX)
 bool Process::IsProcessBackgrounded() const {
   // See SetProcessBackgrounded().
+  DCHECK(IsValid());
   return false;
 }
 
 bool Process::SetProcessBackgrounded(bool value) {
   // POSIX only allows lowering the priority of a process, so if we
   // were to lower it we wouldn't be able to raise it back to its initial
   // priority.
+  DCHECK(IsValid());
   return false;
 }
-
-// static
-bool Process::CanBackgroundProcesses() {
-  return false;
-}
-
-#endif
+#endif  // !defined(OS_LINUX)
 
 int Process::GetPriority() const {
-  DCHECK(process_);
+  DCHECK(IsValid());
   return getpriority(PRIO_PROCESS, process_);
 }
 
 }  // namspace base