// UNNEEDED clockid_t clock_boottime_or_monotonic(void);
-#define xstrftime(buf, fmt, tm) assert_se(strftime(buf, ELEMENTSOF(buf), fmt, tm) > 0)
+#define xstrftime(buf, fmt, tm) \
+ assert_message_se(strftime(buf, ELEMENTSOF(buf), fmt, tm) > 0, \
+ "xstrftime: " #buf "[] must be big enough")
// UNNEEDED int get_timezone(char **timezone);