export_dir (int           source_parent_fd,
            const char   *source_name,
            const char   *source_symlink_prefix,
            const char   *source_relpath,
            int           destination_parent_fd,
            const char   *destination_name,
            GCancellable *cancellable,
            GError      **error)
{
  gboolean ret = FALSE;
  int res;

  g_auto(GLnxDirFdIterator) source_iter = {0};
  glnx_autofd int destination_dfd = -1;
  struct dirent *dent;

  if (!glnx_dirfd_iterator_init_at (source_parent_fd, source_name, FALSE, &source_iter, error))
    goto out;

  do
    res = mkdirat (destination_parent_fd, destination_name, 0755);
  while (G_UNLIKELY (res == -1 && errno == EINTR));
  if (res == -1)
    {
      if (errno != EEXIST)
        {
          glnx_set_error_from_errno (error);
          goto out;
        }
    }

  if (!glnx_opendirat (destination_parent_fd, destination_name, TRUE,
                       &destination_dfd, error))
    goto out;

  while (TRUE)
    {
      struct stat stbuf;

      if (!glnx_dirfd_iterator_next_dent (&source_iter, &dent, cancellable, error))
        goto out;

      if (dent == NULL)
        break;

      if (fstatat (source_iter.fd, dent->d_name, &stbuf, AT_SYMLINK_NOFOLLOW) == -1)
        {
          if (errno == ENOENT)
            {
              continue;
            }
          else
            {
              glnx_set_error_from_errno (error);
              goto out;
            }
        }

      if (S_ISDIR (stbuf.st_mode))
        {
          g_autofree gchar *child_symlink_prefix = g_build_filename ("..", source_symlink_prefix, dent->d_name, NULL);
          g_autofree gchar *child_relpath = g_strconcat (source_relpath, dent->d_name, "/", NULL);

          if (!export_dir (source_iter.fd, dent->d_name, child_symlink_prefix, child_relpath, destination_dfd, dent->d_name,
                           cancellable, error))
            goto out;
        }
      else if (S_ISREG (stbuf.st_mode))
        {
          g_autofree gchar *target = NULL;

          target = g_build_filename (source_symlink_prefix, dent->d_name, NULL);

          if (unlinkat (destination_dfd, dent->d_name, 0) != 0 && errno != ENOENT)
            {
              glnx_set_error_from_errno (error);
              goto out;
            }

          if (symlinkat (target, destination_dfd, dent->d_name) != 0)
            {
              glnx_set_error_from_errno (error);
              goto out;
            }
        }
    }

  ret = TRUE;
out:

  return ret;
}
export_dir (int           source_parent_fd,
            const char   *source_name,
            const char   *source_symlink_prefix,
            const char   *source_relpath,
            int           destination_parent_fd,
            const char   *destination_name,
            GCancellable *cancellable,
            GError      **error)
{
  gboolean ret = FALSE;
  int res;

  g_auto(GLnxDirFdIterator) source_iter = {0};
  glnx_autofd int destination_dfd = -1;
  struct dirent *dent;

  if (!glnx_dirfd_iterator_init_at (source_parent_fd, source_name, FALSE, &source_iter, error))
    goto out;

  do
    res = mkdirat (destination_parent_fd, destination_name, 0755);
  while (G_UNLIKELY (res == -1 && errno == EINTR));
  if (res == -1)
    {
      if (errno != EEXIST)
        {
          glnx_set_error_from_errno (error);
          goto out;
        }
    }

  if (!glnx_opendirat (destination_parent_fd, destination_name, TRUE,
                       &destination_dfd, error))
    goto out;

  while (TRUE)
    {
      struct stat stbuf;

      if (!glnx_dirfd_iterator_next_dent (&source_iter, &dent, cancellable, error))
        goto out;

      if (dent == NULL)
        break;

      if (fstatat (source_iter.fd, dent->d_name, &stbuf, AT_SYMLINK_NOFOLLOW) == -1)
        {
          if (errno == ENOENT)
            {
              continue;
            }
          else
            {
              glnx_set_error_from_errno (error);
              goto out;
            }
        }

      if (S_ISDIR (stbuf.st_mode))
        {
          g_autofree gchar *child_symlink_prefix = g_build_filename ("..", source_symlink_prefix, dent->d_name, NULL);
          g_autofree gchar *child_relpath = g_strconcat (source_relpath, dent->d_name, "/", NULL);

          if (!export_dir (source_iter.fd, dent->d_name, child_symlink_prefix, child_relpath, destination_dfd, dent->d_name,
                           cancellable, error))
            goto out;
        }
      else if (S_ISREG (stbuf.st_mode))
        {
          g_autofree gchar *target = NULL;

          target = g_build_filename (source_symlink_prefix, dent->d_name, NULL);

          if (unlinkat (destination_dfd, dent->d_name, 0) != 0 && errno != ENOENT)
            {
              glnx_set_error_from_errno (error);
              goto out;
            }

          if (symlinkat (target, destination_dfd, dent->d_name) != 0)
            {
              glnx_set_error_from_errno (error);
              goto out;
            }
        }
    }

  ret = TRUE;
out:

  return ret;
}