{
      CameraFilesystemFile **new;
      CameraFilesystemFolder *f;

      CHECK_NULL (fs && folder);
      CC (context);
      CA (folder, context);

      gp_log (GP_LOG_DEBUG, "gphoto2-filesystem", "Append %s/%s to filesystem", folder, filename);
      /* Check folder for existence, if not, create it. */
      f = lookup_folder (fs, fs->rootfolder, folder, context);
      if (!f)
            CR (append_folder (fs, folder, &f, context));

      new = &f->files;
      while (*new) {
            if (!strcmp((*new)->name, filename)) break;
            new = &((*new)->next);
      }
      if (*new) {
            gp_context_error (context,
                  _("Could not append '%s' to folder '%s' because "
                    "this file already exists."), filename, folder);
            return (GP_ERROR_FILE_EXISTS);
      }

      CHECK_MEM ((*new) = calloc (sizeof (CameraFilesystemFile), 1))
      (*new)->name = strdup (filename);
      if (!(*new)->name) {
            free (*new);
            *new = NULL;
            return (GP_ERROR_NO_MEMORY);
      }
      (*new)->info_dirty = 1;
      f->files_dirty = 0;
      return (GP_OK);
}