1 files changed, 72 insertions, 34 deletions

diff --git a/sparse-index.c b/sparse-index.c
index 56eb65dc34..a1d505d50e 100644
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -33,19 +33,14 @@ static int convert_to_sparse_rec(struct index_state *istate,
 {
 	int i, can_convert = 1;
 	int start_converted = num_converted;
-	enum pattern_match_result match;
-	int dtype = DT_UNKNOWN;
 	struct strbuf child_path = STRBUF_INIT;
-	struct pattern_list *pl = istate->sparse_checkout_patterns;
 
 	/*
 	 * Is the current path outside of the sparse cone?
 	 * Then check if the region can be replaced by a sparse
 	 * directory entry (everything is sparse and merged).
 	 */
-	match = path_matches_pattern_list(ct_path, ct_pathlen,
-					  NULL, &dtype, pl, istate);
-	if (match != NOT_MATCHED)
+	if (path_in_sparse_checkout(ct_path, istate))
 		can_convert = 0;
 
 	for (i = start; can_convert && i < end; i++) {
@@ -127,41 +122,64 @@ static int index_has_unmerged_entries(struct index_state *istate)
 	return 0;
 }
 
-int convert_to_sparse(struct index_state *istate)
+static int is_sparse_index_allowed(struct index_state *istate, int flags)
 {
-	int test_env;
-	if (istate->split_index || istate->sparse_index ||
-	    !core_apply_sparse_checkout || !core_sparse_checkout_cone)
+	if (!core_apply_sparse_checkout || !core_sparse_checkout_cone)
 		return 0;
 
 	if (!istate->repo)
 		istate->repo = the_repository;
 
-	/*
-	 * The GIT_TEST_SPARSE_INDEX environment variable triggers the
-	 * index.sparse config variable to be on.
-	 */
-	test_env = git_env_bool("GIT_TEST_SPARSE_INDEX", -1);
-	if (test_env >= 0)
-		set_sparse_index_config(istate->repo, test_env);
+	if (!(flags & SPARSE_INDEX_MEMORY_ONLY)) {
+		int test_env;
+
+		/*
+		 * The sparse index is not (yet) integrated with a split index.
+		 */
+		if (istate->split_index)
+			return 0;
+		/*
+		 * The GIT_TEST_SPARSE_INDEX environment variable triggers the
+		 * index.sparse config variable to be on.
+		 */
+		test_env = git_env_bool("GIT_TEST_SPARSE_INDEX", -1);
+		if (test_env >= 0)
+			set_sparse_index_config(istate->repo, test_env);
+
+		/*
+		 * Only convert to sparse if index.sparse is set.
+		 */
+		prepare_repo_settings(istate->repo);
+		if (!istate->repo->settings.sparse_index)
+			return 0;
+	}
+
+	if (init_sparse_checkout_patterns(istate))
+		return 0;
 
 	/*
-	 * Only convert to sparse if index.sparse is set.
+	 * We need cone-mode patterns to use sparse-index. If a user edits
+	 * their sparse-checkout file manually, then we can detect during
+	 * parsing that they are not actually using cone-mode patterns and
+	 * hence we need to abort this conversion _without error_. Warnings
+	 * already exist in the pattern parsing to inform the user of their
+	 * bad patterns.
 	 */
-	prepare_repo_settings(istate->repo);
-	if (!istate->repo->settings.sparse_index)
+	if (!istate->sparse_checkout_patterns->use_cone_patterns)
 		return 0;
 
-	if (!istate->sparse_checkout_patterns) {
-		istate->sparse_checkout_patterns = xcalloc(1, sizeof(struct pattern_list));
-		if (get_sparse_checkout_patterns(istate->sparse_checkout_patterns) < 0)
-			return 0;
-	}
+	return 1;
+}
 
-	if (!istate->sparse_checkout_patterns->use_cone_patterns) {
-		warning(_("attempting to use sparse-index without cone mode"));
-		return -1;
-	}
+int convert_to_sparse(struct index_state *istate, int flags)
+{
+	/*
+	 * If the index is already sparse, empty, or otherwise
+	 * cannot be converted to sparse, do not convert.
+	 */
+	if (istate->sparse_index || !istate->cache_nr ||
+	    !is_sparse_index_allowed(istate, flags))
+		return 0;
 
 	/*
 	 * NEEDSWORK: If we have unmerged entries, then stay full.
@@ -170,11 +188,19 @@ int convert_to_sparse(struct index_state *istate)
 	if (index_has_unmerged_entries(istate))
 		return 0;
 
-	/* Clear and recompute the cache-tree */
-	cache_tree_free(&istate->cache_tree);
-	if (cache_tree_update(istate, 0)) {
-		warning(_("unable to update cache-tree, staying full"));
-		return -1;
+	if (!cache_tree_fully_valid(istate->cache_tree)) {
+		/* Clear and recompute the cache-tree */
+		cache_tree_free(&istate->cache_tree);
+
+		/*
+		 * Silently return if there is a problem with the cache tree update,
+		 * which might just be due to a conflict state in some entry.
+		 *
+		 * This might create new tree objects, so be sure to use
+		 * WRITE_TREE_MISSING_OK.
+		 */
+		if (cache_tree_update(istate, WRITE_TREE_MISSING_OK))
+			return 0;
 	}
 
 	remove_fsmonitor(istate);
@@ -303,6 +329,18 @@ void ensure_full_index(struct index_state *istate)
 	trace2_region_leave("index", "ensure_full_index", istate->repo);
 }
 
+void ensure_correct_sparsity(struct index_state *istate)
+{
+	/*
+	 * If the index can be sparse, make it sparse. Otherwise,
+	 * ensure the index is full.
+	 */
+	if (is_sparse_index_allowed(istate, 0))
+		convert_to_sparse(istate, 0);
+	else
+		ensure_full_index(istate);
+}
+
 /*
  * This static global helps avoid infinite recursion between
  * expand_to_path() and index_file_exists().