57  * Do a `read wait': poll for reading from stdin, with timeout *limit.
58  * On return, subtract the time spent waiting from *limit.
62  * If limit is NULL, wait forever, but return if poll is interrupted.
67 rwait(struct timespec *limit)  in rwait()  argument
75 	if (limit != NULL)  in rwait()
78 	switch (ppoll(pfd, 1, limit, NULL)) {  in rwait()
80 		if (limit == NULL)  in rwait()
86 		timespecclear(limit);  in rwait()
89 	if (limit != NULL) {  in rwait()
90 		/* we have input, so subtract the elapsed time from *limit */  in rwait()
93 		timespecsub(limit, &elapsed, limit);  in rwait()