loader.c

#define SCM_PAGE_SIZE 4096

static char*
map_file_contents (int fd, size_t len, int *is_read_only)
#define FUNC_NAME "load-thunk-from-file"
{
  char *data;

#ifdef HAVE_SYS_MMAN_H
  data = mmap (NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
  if (data == MAP_FAILED)
    SCM_SYSERROR;
  *is_read_only = 1;
#else
  if (lseek (fd, 0, SEEK_START) < 0)
    {
      int errno_save = errno;
      (void) close (fd);
      errno = errno_save;
      SCM_SYSERROR;
    }

  /* Given that we are using the read fallback, optimistically assume
     that the .go files were made with 8-byte alignment.
     alignment.  */
  data = malloc (end);
  if (!data)
    {
      (void) close (fd);
      scm_misc_error (FUNC_NAME, "failed to allocate ~A bytes",
                      scm_list_1 (scm_from_size_t (end)));
    }

  if (full_read (fd, data, end) != end)
    {
      int errno_save = errno;
      (void) close (fd);
      errno = errno_save;
      if (errno)
        SCM_SYSERROR;
      scm_misc_error (FUNC_NAME, "short read while loading objcode",
                      SCM_EOL);
    }

  /* If our optimism failed, fall back.  */
  {
    unsigned alignment = sniff_elf_alignment (data, end);

    if (alignment != 8)
      {
        char *copy = copy_and_align_elf_data (data, end, alignment);
        free (data);
        data = copy;
      }
  }

  *is_read_only = 0;
#endif

  return data;
}
#undef FUNC_NAME