include/comphelper/windowserrorstring.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  */
   9
  10 #ifndef INCLUDED_COMPHELPER_WINDOWSERRORSTRING_HXX
  11 #define INCLUDED_COMPHELPER_WINDOWSERRORSTRING_HXX
  12
  13 #include <prewin.h>
  14 #include <postwin.h>
  15 #include <rtl/ustring.hxx>
  16 #include <o3tl/char16_t2wchar_t.hxx>
  17
  18 namespace {
  19
  20 inline OUString WindowsErrorString(DWORD nErrorCode)
  21 {
  22     LPWSTR pMsgBuf;
  23
  24     if (FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
  25                        nullptr,
  26                        nErrorCode,
  27                        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
  28                        reinterpret_cast<LPWSTR>(&pMsgBuf),
  29                        0,
  30                        nullptr) == 0)
  31         return OUString::number(nErrorCode, 16);
  32
  33     OUString result(o3tl::toU(pMsgBuf));
  34     result.endsWith("\r\n", &result);
  35
  36     HeapFree(GetProcessHeap(), 0, pMsgBuf);
  37
  38     return result;
  39 }
  40
  41 inline OUString WindowsErrorStringFromHRESULT(HRESULT hr)
  42 {
  43     // See https://devblogs.microsoft.com/oldnewthing/20061103-07/?p=29133
  44     // Also https://social.msdn.microsoft.com/Forums/vstudio/en-US/c33d9a4a-1077-4efd-99e8-0c222743d2f8
  45     // (which refers to https://msdn.microsoft.com/en-us/library/aa382475)
  46     // explains why can't we just reinterpret_cast HRESULT to DWORD Win32 error:
  47     // we might actually have a Win32 error code converted using HRESULT_FROM_WIN32 macro
  48
  49     DWORD nErrorCode = DWORD(hr);
  50     if (HRESULT(hr & 0xFFFF0000) == MAKE_HRESULT(SEVERITY_ERROR, FACILITY_WIN32, 0) || hr == S_OK)
  51     {
  52         nErrorCode = HRESULT_CODE(hr);
  53         // https://msdn.microsoft.com/en-us/library/ms679360 mentions that the codes might have
  54         // high word bits set (e.g., bit 29 could be set if error comes from a 3rd-party library).
  55         // So try to restore the original error code to avoid wrong error messages
  56         DWORD nLastError = GetLastError();
  57         if ((nLastError & 0xFFFF) == nErrorCode)
  58             nErrorCode = nLastError;
  59     }
  60
  61     return WindowsErrorString(nErrorCode);
  62 }
  63
  64 } // anonymous namespace
  65
  66 #endif
  67
  68 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */