+_noreturn_ void freeze(void);
+
+bool null_or_empty(struct stat *st);
+
+DIR *xopendirat(int dirfd, const char *name, int flags);
+
+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);
+
+bool tty_is_vc(const char *tty);
+const char *default_term_for_tty(const char *tty);
+
+int detect_vm(const char **id);
+int detect_virtualization(const char **id);
+
+void execute_directory(const char *directory, DIR *_d, char *argv[]);
+
+#define NULSTR_FOREACH(i, l) \