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  • /***************************************************************************
     *                                  _   _ ____  _
     *  Project                     ___| | | |  _ \| |
     *                             / __| | | | |_) | |
     *                            | (__| |_| |  _ <| |___
     *                             \___|\___/|_| \_\_____|
     *
     * Copyright (C) 2016, Steve Holme, <steve_holme@hotmail.com>.
     *
     * This software is licensed as described in the file COPYING, which
     * you should have received as part of this distribution. The terms
     * are also available at https://curl.haxx.se/docs/copyright.html.
     *
     * You may opt to use, copy, modify, merge, publish, distribute and/or sell
     * copies of the Software, and permit persons to whom the Software is
     * furnished to do so, under the terms of the COPYING file.
     *
     * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
     * KIND, either express or implied.
     *
     ***************************************************************************/
    
    #include "curl_setup.h"
    
    #if defined(WIN32)
    
    #if defined(USE_WINDOWS_SSPI) || (!defined(CURL_DISABLE_TELNET) && \
                                      defined(USE_WINSOCK))
    
    #include <curl/curl.h>
    #include "system_win32.h"
    
    /* The last #include files should be: */
    #include "curl_memory.h"
    #include "memdebug.h"
    
    #if !defined(LOAD_WITH_ALTERED_SEARCH_PATH)
    #define LOAD_WITH_ALTERED_SEARCH_PATH  0x00000008
    #endif
    
    #if !defined(LOAD_LIBRARY_SEARCH_SYSTEM32)
    #define LOAD_LIBRARY_SEARCH_SYSTEM32   0x00000800
    #endif
    
    /* We use our own typedef here since some headers might lack these */
    typedef HMODULE (APIENTRY *LOADLIBRARYEX_FN)(LPCTSTR, HANDLE, DWORD);
    
    /* See function definitions in winbase.h */
    #ifdef UNICODE
    #  ifdef _WIN32_WCE
    #    define LOADLIBARYEX  L"LoadLibraryExW"
    #  else
    #    define LOADLIBARYEX  "LoadLibraryExW"
    #  endif
    #else
    #  define LOADLIBARYEX    "LoadLibraryExA"
    #endif
    
    /*
     * Curl_load_library()
     *
     * This is used to dynamically load DLLs using the most secure method available
     * for the version of Windows that we are running on.
     *
     * Parameters:
     *
     * filename  [in] - The filename or full path of the DLL to load. If only the
     *                  filename is passed then the DLL will be loaded from the
     *                  Windows system directory.
     *
     * Returns the handle of the module on success; otherwise NULL.
     */
    HMODULE Curl_load_library(LPCTSTR filename)
    {
      HMODULE hModule = NULL;
      LOADLIBRARYEX_FN pLoadLibraryEx = NULL;
    
      /* Get a handle to kernel32 so we can access it's functions at runtime */
      HMODULE hKernel32 = GetModuleHandle(TEXT("kernel32"));
      if(!hKernel32)
        return NULL;
    
      /* Attempt to find LoadLibraryEx() which is only available on Windows 2000
         and above */
      pLoadLibraryEx = (LOADLIBRARYEX_FN) GetProcAddress(hKernel32, LOADLIBARYEX);
    
      /* Detect if there's already a path in the filename and load the library if
         there is. Note: Both back slashes and forward slashes have been supported
         since the earlier days of DOS at an API level although they are not
         supported by command prompt */
      if(_tcspbrk(filename, TEXT("\\/")))
        hModule = pLoadLibraryEx ?
          pLoadLibraryEx(filename, NULL, LOAD_WITH_ALTERED_SEARCH_PATH) :
          LoadLibrary(filename);
      /* Detect if KB2533623 is installed, as LOAD_LIBARY_SEARCH_SYSTEM32 is only
         supported on Windows Vista, Windows Server 2008, Windows 7 and Windows
         Server 2008 R2 with this patch or natively on Windows 8 and above */
      else if(pLoadLibraryEx && GetProcAddress(hKernel32, "AddDllDirectory")) {
        /* Load the DLL from the Windows system directory */
        hModule = pLoadLibraryEx(filename, NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
      }
      else {
        /* Attempt to get the Windows system path */
        UINT systemdirlen = GetSystemDirectory(NULL, 0);
        if(systemdirlen) {
          /* Allocate space for the full DLL path (Room for the null terminator
             is included in systemdirlen) */
          size_t filenamelen = _tcslen(filename);
          TCHAR *path = malloc(sizeof(TCHAR) * (systemdirlen + 1 + filenamelen));
          if(path && GetSystemDirectory(path, systemdirlen)) {
            /* Calculate the full DLL path */
            _tcscpy(path + _tcslen(path), TEXT("\\"));
            _tcscpy(path + _tcslen(path), filename);
    
            /* Load the DLL from the Windows system directory */
            hModule = pLoadLibraryEx ?
              pLoadLibraryEx(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH) :
              LoadLibrary(path);
    
            free(path);
          }
        }
      }
    
      return hModule;
    }
    
    #endif /* USE_WINDOWS_SSPI || (!CURL_DISABLE_TELNET && USE_WINSOCK) */
    
    #endif /* WIN32 */