src/Utils/FormatMessageWrapper.h

   1 // TortoiseGit - a Windows shell extension for easy version control
   2
   3 // Copyright (C) 2009-2010, 2014 - TortoiseSVN
   4
   5 // This program is free software; you can redistribute it and/or
   6 // modify it under the terms of the GNU General Public License
   7 // as published by the Free Software Foundation; either version 2
   8 // of the License, or (at your option) any later version.
   9
  10 // This program is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14
  15 // You should have received a copy of the GNU General Public License
  16 // along with this program; if not, write to the Free Software Foundation,
  17 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 //
  19 #pragma once
  20
  21 /**
  22  * A wrapper class for calling the FormatMessage() Win32 function and controlling
  23  * the lifetime of the allocated error message buffer.
  24  */
  25
  26 class CFormatMessageWrapper
  27 {
  28 private:
  29         LPTSTR buffer;
  30         DWORD result;
  31         void release();
  32         void obtainMessage() { obtainMessage(::GetLastError()); }
  33         void obtainMessage(DWORD errorCode);
  34
  35 public:
  36         CFormatMessageWrapper() : buffer(0), result(0) {obtainMessage();}
  37         CFormatMessageWrapper(DWORD lastError) : buffer(0), result(0) {obtainMessage(lastError);}
  38         ~CFormatMessageWrapper() { release(); }
  39         operator LPCTSTR() const { return buffer; }
  40         operator bool() const { return result != 0; }
  41         bool operator!() const { return result == 0; }
  42 };
  43
  44 inline void CFormatMessageWrapper::obtainMessage(DWORD errorCode)
  45 {
  46         // First of all release the buffer to make it possible to call this
  47         // method more than once on the same object.
  48         release();
  49         result = FormatMessage (FORMAT_MESSAGE_ALLOCATE_BUFFER |
  50                                                         FORMAT_MESSAGE_FROM_SYSTEM |
  51                                                         FORMAT_MESSAGE_IGNORE_INSERTS,
  52                                                         nullptr,
  53                                                         errorCode,
  54                                                         MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
  55                                                         (LPTSTR) &buffer,
  56                                                         0,
  57                                                         nullptr
  58                                                         );
  59 }
  60
  61 inline void CFormatMessageWrapper::release()
  62 {
  63         if (buffer)
  64         {
  65                 LocalFree(buffer);
  66                 buffer = nullptr;
  67         }
  68
  69         result = 0;
  70 }