+bool null_or_empty(struct stat *st);
+
+DIR *xopendirat(int dirfd, const char *name);
+
+void dual_timestamp_serialize(FILE *f, const char *name, dual_timestamp *t);
+void dual_timestamp_deserialize(const char *value, dual_timestamp *t);
+
+char *fstab_node_to_udev_node(const char *p);
+
+void filter_environ(const char *prefix);
+
+#define NULSTR_FOREACH(i, l) \