+
+struct span {
+ struct span *next;
+ unsigned long ofs;
+ unsigned long end;
+};
+
+static void touch_range(struct span **span,
+ unsigned long ofs, unsigned long end)
+{
+ struct span *e = *span;
+ struct span *p = NULL;
+
+ while (e && e->ofs <= ofs) {
+ again:
+ if (ofs < e->end) {
+ while (e->end < end) {
+ if (e->next && e->next->ofs <= end) {
+ e->end = e->next->ofs;
+ e = e->next;
+ }
+ else {
+ e->end = end;
+ return;
+ }
+ }
+ return;
+ }
+ p = e;
+ e = e->next;
+ }
+ if (e && e->ofs <= end) {
+ e->ofs = ofs;
+ goto again;
+ }
+ else {
+ e = xmalloc(sizeof(*e));
+ e->ofs = ofs;
+ e->end = end;
+ if (p) {
+ e->next = p->next;
+ p->next = e;
+ }
+ else {
+ e->next = *span;
+ *span = e;
+ }
+ }
+}
+
+static unsigned long count_range(struct span *s)
+{
+ struct span *t;
+ unsigned long sz = 0;
+ while (s) {
+ t = s;
+ sz += s->end - s->ofs;
+ s = s->next;
+ free(t);
+ }
+ return sz;
+}