1    :  // Copyright 2014 Google Inc. All Rights Reserved.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  //
  15    :  // Utilities for COM objects, error codes etc.
  16    :  
  17    :  #ifndef SYZYGY_COMMON_COM_UTILS_H_
  18    :  #define SYZYGY_COMMON_COM_UTILS_H_
  19    :  
  20    :  #include <windows.h>
  21    :  #include <wtypes.h>
  22    :  #include <ostream>
  23    :  
  24    :  namespace common {
  25    :  
  26    :  // Returns the provided hr if it is an error, otherwise default_error.
  27  E :  inline HRESULT AlwaysError(HRESULT hr, HRESULT default_error) {
  28  E :    if (FAILED(hr)) {
  29  E :      return hr;
  30  i :    } else {
  31  E :      return default_error;
  32    :    }
  33  E :  }
  34    :  
  35    :  // Returns the provided hr if it is an error, otherwise E_FAIL.
  36  E :  inline HRESULT AlwaysError(HRESULT hr) {
  37  E :    return AlwaysError(hr, E_FAIL);
  38  E :  }
  39    :  
  40    :  // Converts a Win32 result code to a HRESULT. If the 'win32_code'
  41    :  // does not indicate an error, it returns 'default_error'.
  42    :  inline HRESULT AlwaysErrorFromWin32(DWORD win32_code,
  43  E :                                      HRESULT default_error) {
  44  E :    HRESULT hr = HRESULT_FROM_WIN32(win32_code);
  45  E :    return AlwaysError(hr, default_error);
  46  E :  }
  47    :  
  48    :  // Converts a Win32 result code to a HRESULT. If the 'win32_code'
  49    :  // does not indicate an error, it returns E_FAIL
  50  E :  inline HRESULT AlwaysErrorFromWin32(DWORD win32_code) {
  51  E :    return AlwaysErrorFromWin32(win32_code, E_FAIL);
  52  E :  }
  53    :  
  54    :  // Returns the HRESULT equivalent of GetLastError(), unless it does not
  55    :  // represent an error in which case it returns 'default_error'.
  56  E :  inline HRESULT AlwaysErrorFromLastError(HRESULT default_error) {
  57  E :    return AlwaysErrorFromWin32(::GetLastError(), default_error);
  58  E :  }
  59    :  
  60    :  // Returns the HRESULT equivalent of GetLastError(), unless it does not
  61    :  // represent an error in which case it returns E_FAIL.
  62  E :  inline HRESULT AlwaysErrorFromLastError() {
  63  E :    return AlwaysErrorFromLastError(E_FAIL);
  64  E :  }
  65    :  
  66    :  // Return the specified string, or the empty string if it is NULL.
  67  E :  inline const wchar_t* ToString(BSTR str) {
  68  E :    return str ? str : L"";
  69  E :  }
  70    :  
  71    :  // Logs HRESULTs verbosely, with the error code and human-readable error
  72    :  // text if available.
  73    :  class LogHr {
  74    :   public:
  75  E :    explicit LogHr(HRESULT hr) : hr_(hr) {}
  76    :   private:
  77    :    HRESULT hr_;
  78    :    friend std::ostream& operator<<(std::ostream&, const LogHr&);
  79    :  };
  80    :  
  81    :  std::ostream& operator<<(std::ostream& os, const LogHr& hr);
  82    :  
  83    :  // Logs Windows errors verbosely, with the error code and human-readable error
  84    :  // text if available.
  85    :  class LogWe {
  86    :   public:
  87  i :    LogWe() : we_(::GetLastError()) {}
  88  E :    explicit LogWe(DWORD we) : we_(we) {}
  89    :   private:
  90    :    DWORD we_;
  91    :    friend std::ostream& operator<<(std::ostream&, const LogWe&);
  92    :  };
  93    :  
  94    :  std::ostream& operator<<(std::ostream& os, const LogWe& we);
  95    :  
  96    :  }  // namespace common
  97    :  
  98    :  #endif  // SYZYGY_COMMON_COM_UTILS_H_