C++ (Cpp) _M_file_size示例

示例#1

文件： fstream_stdio.cpp 项目： 0-T-0/linux-sgx

// Wrapper for lseek or the like.
streamoff _Filebuf_base::_M_seek(streamoff offset, ios_base::seekdir dir)
{
  int whence;

  switch ( dir ) {
    case ios_base::beg:
      if (offset < 0 /* || offset > _M_file_size() */ )
        return streamoff(-1);
      whence = SEEK_SET;
      break;
    case ios_base::cur:
      whence = SEEK_CUR;
      break;
    case ios_base::end:
      if (/* offset > 0 || */  -offset > _M_file_size() )
        return streamoff(-1);
      whence = SEEK_END;
      break;
    default:
      return streamoff(-1);
  }

  if ( FSEEK(_M_file, offset, whence) == 0 ) {
    return FTELL(_M_file);
  }

  return streamoff(-1);
}

示例#2

文件： fstream.cpp 项目： OS2World/DEV-CPLUSPLUS-STLport

// Wrapper for lseek or the like.
streamoff _Filebuf_base::_M_seek(streamoff offset, ios_base::seekdir dir)
{
  streamoff result = -1;

  int whence;

  switch(dir) {
  case ios_base::beg:
    if (offset < 0 /* || offset > _M_file_size() */ )
      return streamoff(-1);
    whence = STL_SEEK_SET;
    break;
  case ios_base::cur:
    whence = STL_SEEK_CUR;
    break;
  case ios_base::end:
    if (/* offset > 0 || */  -offset > _M_file_size() )
      return streamoff(-1);
    whence = STL_SEEK_END;
    break;
  default:
    return streamoff(-1);
  }

#if defined (_STLP_USE_UNIX_IO) || defined (_STLP_USE_UNIX_EMULATION_IO)

  result = LSEEK(_M_file_id, offset, whence);

#elif defined (_STLP_USE_STDIO_IO)

  result = fseek(_M_file, offset, whence);

#elif defined (_STLP_USE_WIN32_IO)

  LARGE_INTEGER li;
  li.QuadPart = offset;
  li.LowPart = SetFilePointer(_M_file_id, li.LowPart, &li.HighPart, whence);
  if (li.LowPart == 0xFFFFFFFF && GetLastError() != NO_ERROR)
    result = -1; // Error
  else
    result = li.QuadPart;

#else
#   error "Port!"
#endif

  return result;
}