https://github.com/ImageMagick/ImageMagick6/issues/43
MagickExport MagickBooleanType UnmapBlob(void *map,const size_t length)
{
#if defined(MAGICKCORE_HAVE_MMAP)
  int
    status;

  status=munmap(map,length);
  return(status == -1 ? MagickFalse : MagickTrue);
#else
  (void) map;
  (void) length;
  return(MagickFalse);
#endif
}

MagickExport MagickBooleanType UnmapBlob(void *map,const size_t length)
{
#if defined(MAGICKCORE_HAVE_MMAP)
  int
    status;

  status=munmap(map,length);
  return(status == -1 ? MagickFalse : MagickTrue);
#else
  (void) map;
  (void) length;
  return(MagickFalse);
#endif
}
