+char *format_timestamp(char *buf, size_t l, usec_t t) {
+ struct tm tm;
+ time_t sec;
+
+ assert(buf);
+ assert(l > 0);
+
+ if (t <= 0)
+ return NULL;
+
+ sec = (time_t) t / USEC_PER_SEC;
+
+ if (strftime(buf, l, "%a, %d %b %Y %H:%M:%S %z", localtime_r(&sec, &tm)) <= 0)
+ return NULL;
+
+ return buf;
+}
+