Commit 7f8f9ef1 introduced the ability to store a list of
integers as a sorted list of ranges, but when merging ranges,
it leaks one or more ranges. It was also using range_get_last()
incorrectly within range_compare() (a range is a start/end pair,
but range_get_last() is for start/len pairs), and will also
mishandle a range ending in UINT64_MAX (remember, we document
that no range covers 2**64 bytes, but that ranges that end on
UINT64_MAX have end < begin).
The whole merge algorithm was rather complex, especially since
we are hard-coding things to a list of ranges; so just rewrite
the thing to open-code the traversal and comparisons, making
the range_compare() helper function give us a nicer answer,
avoiding the need to pass any callbacks to g_list_*(). And
reusing range_extend() ensures we cover the corner cases
correctly.
Drop the now-unused range_merge() and ranges_can_merge().
Doing this lets test-string-{input,output}-visitor pass under
valgrind without leaks.
CC: qemu-sta...@nongnu.org
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
include/qemu/range.h | 78 +++++++++++++++++++++-------------------------------
1 file changed, 31 insertions(+), 47 deletions(-)
diff --git a/include/qemu/range.h b/include/qemu/range.h
index 4a4801b..9955cca 100644
--- a/include/qemu/range.h
+++ b/include/qemu/range.h
@@ -59,67 +59,51 @@ static inline int ranges_overlap(uint64_t first1, uint64_t
len1,
return !(last2 < first1 || last1 < first2);
}
-/* 0,1 can merge with 1,2 but don't overlap */
-static inline bool ranges_can_merge(Range *range1, Range *range2)
+/* Return -1 if @a < b, 1 if greater, and 0 if they overlap. */
+static inline int range_compare(Range *a, Range *b)
{
- return !(range1->end < range2->begin || range2->end < range1->begin);
-}
-
-static inline void range_merge(Range *range1, Range *range2)
-{
- if (range1->end < range2->end) {
- range1->end = range2->end;
- }
- if (range1->begin > range2->begin) {
- range1->begin = range2->begin;
- }
-}
-
-static inline gint range_compare(gconstpointer a, gconstpointer b)
-{
- Range *ra = (Range *)a, *rb = (Range *)b;
- if (ra->begin == rb->begin && ra->end == rb->end) {
- return 0;
- } else if (range_get_last(ra->begin, ra->end) <
- range_get_last(rb->begin, rb->end)) {
+ if (a->end && a->end < b->begin) {
return -1;
- } else {
+ }
+ if (b->end && a->begin > b->end) {
return 1;
}
+ return 0;
}
+/* Insert @data into @list of ranges; caller no longer owns @data */
static inline GList *range_list_insert(GList *list, Range *data)
{
- GList *l, *next = NULL;
- Range *r, *nextr;
+ GList *l = list;
- if (!list) {
- list = g_list_insert_sorted(list, data, range_compare);
- return list;
+ /* Range lists require no empty ranges */
+ assert(data->begin || data->end);
+
+ /* Skip all list elements strictly less than data */
+ while (l && range_compare(l->data, data) < 0) {
+ l = l->next;
+ }
+
+ /* If no list, or rest of list exceeds data, insert data and done */
+ if (!l || range_compare(l->data, data) > 0) {
+ return g_list_insert_before(list, l, data);
}
- nextr = data;
- l = list;
- while (l && l != next && nextr) {
- r = l->data;
- if (ranges_can_merge(r, nextr)) {
- range_merge(r, nextr);
- l = g_list_remove_link(l, next);
- next = g_list_next(l);
- if (next) {
- nextr = next->data;
- } else {
- nextr = NULL;
- }
- } else {
- l = g_list_next(l);
+ /* Merge data into current list element */
+ range_extend(l->data, data);
+ g_free(data);
+
+ /* Merge any subsequent list elements that now also overlap */
+ while (l->next && range_compare(l->data, l->next->data) == 0) {
+ range_extend(l->data, l->next->data);
+ g_free(l->next->data);
+ /* We know we aren't deleting the list head, so shave time
+ * by passing l instead of list */
+ if (g_list_delete_link(l, l->next) != l) {
+ abort();
}
}
- if (!l) {
- list = g_list_insert_sorted(list, data, range_compare);
- }
-
return list;
}
--
2.5.5
