sparse-checkout: avoid using internal API of unpack-trees

struct unpack_trees_options has the following field and comment:

	struct pattern_list *pl; /* for internal use */

Despite the internal-use comment, commit e091228 ("sparse-checkout:
update working directory in-process", 2019-11-21) starting setting this
field from an external caller.  At the time, the only way around that
would have been to modify unpack_trees() to take an extra pattern_list
argument, and there's a lot of callers of that function.  However, when
we split update_sparsity() off as a separate function, with
sparse-checkout being the sole caller, the need to update other callers
went away.  Fix this API problem by adding a pattern_list argument to
update_sparsity() and stop setting the internal o.pl field directly.

Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: newren

builtin/sparse-checkout.c

@@ -219,14 +219,13 @@ static int update_working_directory(struct pattern_list *pl)
 	o.dst_index = r->index;
 	index_state_init(&o.result, r);
 	o.skip_sparse_checkout = 0;
-	o.pl = pl;
 
 	setup_work_tree();
 
 	repo_hold_locked_index(r, &lock_file, LOCK_DIE_ON_ERROR);
 
 	setup_unpack_trees_porcelain(&o, "sparse-checkout");
-	result = update_sparsity(&o);
+	result = update_sparsity(&o, pl);
 	clear_unpack_trees_porcelain(&o);
 
 	if (result == UPDATE_SPARSITY_WARNINGS)

unpack-trees.c

@@ -2091,10 +2091,10 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
  *
  * CE_NEW_SKIP_WORKTREE is used internally.
  */
-enum update_sparsity_result update_sparsity(struct unpack_trees_options *o)
+enum update_sparsity_result update_sparsity(struct unpack_trees_options *o,
+					    struct pattern_list *pl)
 {
 	enum update_sparsity_result ret = UPDATE_SPARSITY_SUCCESS;
-	struct pattern_list pl;
 	int i;
 	unsigned old_show_all_errors;
 	int free_pattern_list = 0;
@@ -2111,11 +2111,12 @@ enum update_sparsity_result update_sparsity(struct unpack_trees_options *o)
 	trace_performance_enter();
 
 	/* If we weren't given patterns, use the recorded ones */
-	if (!o->pl) {
-		memset(&pl, 0, sizeof(pl));
+	if (!pl) {
 		free_pattern_list = 1;
-		populate_from_existing_patterns(o, &pl);
+		pl = xcalloc(1, sizeof(*pl));
+		populate_from_existing_patterns(o, pl);
 	}
+	o->pl = pl;
 
 	/* Expand sparse directories as needed */
 	expand_index(o->src_index, o->pl);
@@ -2147,8 +2148,11 @@ enum update_sparsity_result update_sparsity(struct unpack_trees_options *o)
 
 	display_warning_msgs(o);
 	o->show_all_errors = old_show_all_errors;
-	if (free_pattern_list)
-		clear_pattern_list(&pl);
+	if (free_pattern_list) {
+		clear_pattern_list(pl);
+		free(pl);
+		o->pl = NULL;
+	}
 	trace_performance_leave("update_sparsity");
 	return ret;
 }

unpack-trees.h

@@ -112,7 +112,8 @@ enum update_sparsity_result {
 	UPDATE_SPARSITY_WORKTREE_UPDATE_FAILURES = -2
 };
 
-enum update_sparsity_result update_sparsity(struct unpack_trees_options *options);
+enum update_sparsity_result update_sparsity(struct unpack_trees_options *options,
+					    struct pattern_list *pl);
 
 int verify_uptodate(const struct cache_entry *ce,
 		    struct unpack_trees_options *o);