base/win/scoped_process_information.h

   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_