kc3-lang/dlfcn-win32/testdll2.c

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• Hash : 2bb5f487
  Author :
  Date : 2019-07-25T20:34:46
  

  Fix gcc warning: ISO C forbids return between function pointer and void * Instead of using compiler specific pragma to disable particular warning, rewrite code which cast from function pointer to data pointer according to POSIX dlopen() documentation. This also fix compile warning under MSVC. According to the ISO C standard, casting between function pointers and 'void *', as done above, produces undefined results. POSIX.1-2003 and POSIX.1-2008 accepted this state of affairs and proposed the following workaround: *(void **) (&cosine) = dlsym(handle, "cos"); This (clumsy) cast conforms with the ISO C standard and will avoid any compiler warnings.

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• testdll2.c

• /*
   * dlfcn-win32
   * Copyright (c) 2007 Ramiro Polla
   * Copyright (c) 2019 Pali Rohár <pali.rohar@gmail.com>
   *
   * dlfcn-win32 is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * dlfcn-win32 is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with dlfcn-win32; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
   */
  
  #ifdef _DEBUG
  #define _CRTDBG_MAP_ALLOC
  #include <stdlib.h>
  #include <crtdbg.h>
  #endif
  #include <stdio.h>
  
  #include "dlfcn.h"
  
  #if defined(_WIN32)
  #define EXPORT __declspec(dllexport)
  #else
  #define EXPORT
  #endif
  
  EXPORT int function2( void )
  {
      char *error;
      int (*function2_orig)(void);
      printf( "Hello, world! from wrapper library\n" );
      *(void **) (&function2_orig) = dlsym( RTLD_NEXT, "function2" );
      if (!function2_orig)
      {
          error = dlerror( );
          printf( "ERROR\tCould not get symbol from RTLD_NEXT handle: %s\n",
                  error ? error : "" );
          return 1;
      }
      if (function2_orig() != 0)
      {
          printf( "ERROR\tOriginal function from RTLD_NEXT handle did not return correct value\n" );
          return 1;
      }
      return 2;
  }
  

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