+ return(fb);
+}
+
+
+/*
+ * Check to see if two events overlap.
+ * (This function is used in both Citadel and WebCit. If you change it in
+ * one place, change it in the other. We should seriously consider moving
+ * this function upstream into libical.)
+ *
+ * Returns nonzero if they do overlap.
+ */
+int ical_ctdl_is_overlap(
+ struct icaltimetype t1start,
+ struct icaltimetype t1end,
+ struct icaltimetype t2start,
+ struct icaltimetype t2end
+) {
+
+ if (icaltime_is_null_time(t1start)) return(0);
+ if (icaltime_is_null_time(t2start)) return(0);
+
+ /* if either event lacks end time, assume end = start */
+ if (icaltime_is_null_time(t1end))
+ memcpy(&t1end, &t1start, sizeof(struct icaltimetype));
+ else {
+ if (t1end.is_date && icaltime_compare(t1start, t1end)) {
+ /*
+ * the end date is non-inclusive so adjust it by one
+ * day because our test is inclusive, note that a day is
+ * not too much because we are talking about all day
+ * events
+ * if start = end we assume that nevertheless the whole
+ * day is meant
+ */
+ icaltime_adjust(&t1end, -1, 0, 0, 0);
+ }
+ }
+
+ if (icaltime_is_null_time(t2end))
+ memcpy(&t2end, &t2start, sizeof(struct icaltimetype));
+ else {
+ if (t2end.is_date && icaltime_compare(t2start, t2end)) {
+ icaltime_adjust(&t2end, -1, 0, 0, 0);
+ }
+ }
+
+ /* First, check for all-day events */
+ if (t1start.is_date || t2start.is_date) {
+ /* If event 1 ends before event 2 starts, we're in the clear. */
+ if (icaltime_compare_date_only(t1end, t2start) < 0) return(0);
+
+ /* If event 2 ends before event 1 starts, we're also ok. */
+ if (icaltime_compare_date_only(t2end, t1start) < 0) return(0);
+
+ return(1);
+ }
+
+ /* syslog(LOG_DEBUG, "Comparing t1start %d:%d t1end %d:%d t2start %d:%d t2end %d:%d \n",
+ t1start.hour, t1start.minute, t1end.hour, t1end.minute,
+ t2start.hour, t2start.minute, t2end.hour, t2end.minute);
+ */
+
+ /* Now check for overlaps using date *and* time. */
+
+ /* If event 1 ends before event 2 starts, we're in the clear. */
+ if (icaltime_compare(t1end, t2start) <= 0) return(0);
+ /* syslog(LOG_DEBUG, "first passed\n"); */
+
+ /* If event 2 ends before event 1 starts, we're also ok. */
+ if (icaltime_compare(t2end, t1start) <= 0) return(0);
+ /* syslog(LOG_DEBUG, "second passed\n"); */
+
+ /* Otherwise, they overlap. */
+ return(1);