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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef BASE_WIN_SCOPED_PROCESS_INFORMATION_H_
      6 #define BASE_WIN_SCOPED_PROCESS_INFORMATION_H_
      7 
      8 #include <windows.h>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/base_export.h"
     12 #include "base/win/scoped_handle.h"
     13 
     14 namespace base {
     15 namespace win {
     16 
     17 // Manages the closing of process and thread handles from PROCESS_INFORMATION
     18 // structures. Allows clients to take ownership of either handle independently.
     19 class BASE_EXPORT ScopedProcessInformation {
     20  public:
     21   // Helper object to contain the effect of Receive() to the funtion that needs
     22   // a pointer.
     23   class Receiver {
     24    public:
     25     explicit Receiver(ScopedProcessInformation* owner)
     26         : info_(),
     27           owner_(owner) {}
     28     ~Receiver() { owner_->Set(info_); }
     29 
     30     operator PROCESS_INFORMATION*() { return &info_; }
     31 
     32    private:
     33     PROCESS_INFORMATION info_;
     34     ScopedProcessInformation* owner_;
     35   };
     36 
     37   ScopedProcessInformation();
     38   ~ScopedProcessInformation();
     39 
     40   // Returns an object that may be passed to API calls such as CreateProcess.
     41   // DCHECKs that the object is not currently holding any handles.
     42   // HANDLEs stored in the returned PROCESS_INFORMATION will be owned by this
     43   // instance.
     44   // The intended use case is something like this:
     45   //   if (::CreateProcess(..., startup_info, scoped_proces_info.Receive()))
     46   Receiver Receive();
     47 
     48   // Returns true iff this instance is holding a thread and/or process handle.
     49   bool IsValid() const;
     50 
     51   // Closes the held thread and process handles, if any.
     52   void Close();
     53 
     54   // Populates this instance with the provided |process_info|.
     55   void Set(const PROCESS_INFORMATION& process_info);
     56 
     57   // Populates this instance with duplicate handles and the thread/process IDs
     58   // from |other|. Returns false in case of failure, in which case this instance
     59   // will be completely unpopulated.
     60   bool DuplicateFrom(const ScopedProcessInformation& other);
     61 
     62   // Transfers ownership of the held PROCESS_INFORMATION, if any, away from this
     63   // instance.
     64   PROCESS_INFORMATION Take();
     65 
     66   // Transfers ownership of the held process handle, if any, away from this
     67   // instance. Note that the related process_id will also be cleared.
     68   HANDLE TakeProcessHandle();
     69 
     70   // Transfers ownership of the held thread handle, if any, away from this
     71   // instance. Note that the related thread_id will also be cleared.
     72   HANDLE TakeThreadHandle();
     73 
     74   // Returns the held process handle, if any, while retaining ownership.
     75   HANDLE process_handle() const {
     76     return process_handle_.Get();
     77   }
     78 
     79   // Returns the held thread handle, if any, while retaining ownership.
     80   HANDLE thread_handle() const {
     81     return thread_handle_.Get();
     82   }
     83 
     84   // Returns the held process id, if any.
     85   DWORD process_id() const {
     86     return process_id_;
     87   }
     88 
     89   // Returns the held thread id, if any.
     90   DWORD thread_id() const {
     91     return thread_id_;
     92   }
     93 
     94  private:
     95   ScopedHandle process_handle_;
     96   ScopedHandle thread_handle_;
     97   DWORD process_id_;
     98   DWORD thread_id_;
     99 
    100   DISALLOW_COPY_AND_ASSIGN(ScopedProcessInformation);
    101 };
    102 
    103 }  // namespace win
    104 }  // namespace base
    105 
    106 #endif  // BASE_WIN_SCOPED_PROCESS_INFORMATION_H_
    107