ref-filter: clear reachable list pointers after freeing

In `reach_filter()`, we pop all commits from the reachable lists,
leaving them empty. But because we're operating on a list pointer that
was passed by value, the original `filter.reachable_from` and
`filter.unreachable_from` pointers are left dangling.

As is the case with the previous commit, nobody touches either of these
fields after calling `reach_filter()`, so leaving them dangling is OK.
But this future proofs against dangerous situations.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/ref-filter.c b/ref-filter.c
index 4991cd4f7a860be1cf508e88668d1fd8af2ff9ae..048d277cbf798ea8765e38f89b57a697a9936e61 100644 (file)
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -2418,13 +2418,13 @@ void ref_array_clear(struct ref_array *array)
 #define EXCLUDE_REACHED 0
 #define INCLUDE_REACHED 1
 static void reach_filter(struct ref_array *array,
-                        struct commit_list *check_reachable,
+                        struct commit_list **check_reachable,
                         int include_reached)
 {
        int i, old_nr;
        struct commit **to_clear;
 
-       if (!check_reachable)
+       if (!*check_reachable)
                return;
 
        CALLOC_ARRAY(to_clear, array->nr);
@@ -2434,7 +2434,7 @@ static void reach_filter(struct ref_array *array,
        }
 
        tips_reachable_from_bases(the_repository,
-                                 check_reachable,
+                                 *check_reachable,
                                  to_clear, array->nr,
                                  UNINTERESTING);
 
@@ -2455,8 +2455,8 @@ static void reach_filter(struct ref_array *array,
 
        clear_commit_marks_many(old_nr, to_clear, ALL_REV_FLAGS);
 
-       while (check_reachable) {
-               struct commit *merge_commit = pop_commit(&check_reachable);
+       while (*check_reachable) {
+               struct commit *merge_commit = pop_commit(check_reachable);
                clear_commit_marks(merge_commit, ALL_REV_FLAGS);
        }
 
@@ -2553,8 +2553,8 @@ int filter_refs(struct ref_array *array, struct ref_filter *filter, unsigned int
        clear_contains_cache(&ref_cbdata.no_contains_cache);
 
        /*  Filters that need revision walking */
-       reach_filter(array, filter->reachable_from, INCLUDE_REACHED);
-       reach_filter(array, filter->unreachable_from, EXCLUDE_REACHED);
+       reach_filter(array, &filter->reachable_from, INCLUDE_REACHED);
+       reach_filter(array, &filter->unreachable_from, EXCLUDE_REACHED);
 
        save_commit_buffer = save_commit_buffer_orig;
        return ret;