Add callback to git_objects_table

This adds create and free callback to the git_objects_table so
that more of the creation and destruction of objects can be table
driven instead of using switch statements.  This also makes the
semantics of certain object creation functions consistent so that
we can make better use of function pointers.  This also fixes a
theoretical error case where an object allocation fails and we
end up storing NULL into the cache.

1 files changed, 52 insertions, 93 deletions

diff --git a/src/object.c b/src/object.c
index 80b765ef9..3698808c3 100644
--- a/src/object.c
+++ b/src/object.c
@@ -18,63 +18,39 @@
 
 static const int OBJECT_BASE_SIZE = 4096;
 
-static struct {
+typedef struct {
 	const char	*str;	/* type name string */
-	int			loose; /* valid loose object type flag */
 	size_t		size;	/* size in bytes of the object structure */
-} git_objects_table[] = {
+
+	int  (*from_odb)(void *self, git_odb_object *obj);
+	int  (*parse)(void *self, const char *buf, const char *buf_end);
+	void (*free)(void *self);
+} git_object_def;
+
+static git_object_def git_objects_table[] = {
 	/* 0 = GIT_OBJ__EXT1 */
-	{ "", 0, 0},
+	{ "", 0, NULL, NULL, NULL },
 
 	/* 1 = GIT_OBJ_COMMIT */
-	{ "commit", 1, sizeof(struct git_commit)},
+	{ "commit", sizeof(git_commit), NULL, git_commit__parse, git_commit__free },
 
 	/* 2 = GIT_OBJ_TREE */
-	{ "tree", 1, sizeof(struct git_tree) },
+	{ "tree", sizeof(git_tree), NULL, git_tree__parse, git_tree__free },
 
 	/* 3 = GIT_OBJ_BLOB */
-	{ "blob", 1, sizeof(struct git_blob) },
+	{ "blob", sizeof(git_blob), git_blob__from_odb_object, NULL, git_blob__free },
 
 	/* 4 = GIT_OBJ_TAG */
-	{ "tag", 1, sizeof(struct git_tag) },
+	{ "tag", sizeof(git_tag), NULL, git_tag__parse, git_tag__free },
 
 	/* 5 = GIT_OBJ__EXT2 */
-	{ "", 0, 0 },
-
+	{ "", 0, NULL, NULL, NULL },
 	/* 6 = GIT_OBJ_OFS_DELTA */
-	{ "OFS_DELTA", 0, 0 },
-
+	{ "OFS_DELTA", 0, NULL, NULL, NULL },
 	/* 7 = GIT_OBJ_REF_DELTA */
-	{ "REF_DELTA", 0, 0	}
+	{ "REF_DELTA", 0, NULL, NULL, NULL },
 };
 
-static int create_object(git_object **object_out, git_otype type)
-{
-	git_object *object = NULL;
-
-	assert(object_out);
-
-	*object_out = NULL;
-
-	switch (type) {
-	case GIT_OBJ_COMMIT:
-	case GIT_OBJ_TAG:
-	case GIT_OBJ_BLOB:
-	case GIT_OBJ_TREE:
-		object = git__malloc(git_object__size(type));
-		GITERR_CHECK_ALLOC(object);
-		memset(object, 0x0, git_object__size(type));
-		break;
-
-	default:
-		giterr_set(GITERR_INVALID, "The given type is invalid");
-		return -1;
-	}
-
-	*object_out = object;
-	return 0;
-}
-
 int git_object__from_odb_object(
 	git_object **object_out,
 	git_repository *repo,
@@ -82,46 +58,47 @@ int git_object__from_odb_object(
 	git_otype type)
 {
 	int error;
+	size_t object_size;
+	git_object_def *def;
 	git_object *object = NULL;
 
+	assert(object_out);
+	*object_out = NULL;
+
+	/* Validate type match */
 	if (type != GIT_OBJ_ANY && type != odb_obj->cached.type) {
 		giterr_set(GITERR_INVALID,
 			"The requested type does not match the type in the ODB");
 		return GIT_ENOTFOUND;
 	}
 
-	if ((error = create_object(&object, odb_obj->cached.type)) < 0)
-		return error;
+	if ((object_size = git_object__size(odb_obj->cached.type)) == 0) {
+		giterr_set(GITERR_INVALID, "The requested type is invalid");
+		return GIT_ENOTFOUND;
+	}
+
+	/* Allocate and initialize base object */
+	object = git__calloc(1, object_size);
+	GITERR_CHECK_ALLOC(object);
 
-	/* Initialize parent object */
 	git_oid_cpy(&object->cached.oid, &odb_obj->cached.oid);
-	object->cached.size = odb_obj->cached.size;
 	object->cached.type = odb_obj->cached.type;
+	object->cached.size = odb_obj->cached.size;
 	object->repo = repo;
 
-	switch (object->cached.type) {
-	case GIT_OBJ_COMMIT:
-		error = git_commit__parse((git_commit *)object, odb_obj);
-		break;
-
-	case GIT_OBJ_TREE:
-		error = git_tree__parse((git_tree *)object, odb_obj);
-		break;
-
-	case GIT_OBJ_TAG:
-		error = git_tag__parse((git_tag *)object, odb_obj);
-		break;
+	/* Parse raw object data */
+	def = &git_objects_table[odb_obj->cached.type];
+	assert(def->free && (def->from_odb || def->parse));
 
-	case GIT_OBJ_BLOB:
-		error = git_blob__parse((git_blob *)object, odb_obj);
-		break;
-
-	default:
-		break;
+	if (def->from_odb) {
+		error = def->from_odb(object, odb_obj);
+	} else {
+		const char *data = (const char *)git_odb_object_data(odb_obj);
+		error = def->parse(object, data, data + git_odb_object_size(odb_obj));
 	}
 
 	if (error < 0) {
-		git_object__free(object);
+		def->free(object);
 		return error;
 	}
 
@@ -129,6 +106,17 @@ int git_object__from_odb_object(
 	return 0;
 }
 
+void git_object__free(void *obj)
+{
+	git_otype type = ((git_object *)obj)->cached.type;
+
+	if (type < 0 || ((size_t)type) >= ARRAY_SIZE(git_objects_table) ||
+		!git_objects_table[type].free)
+		git__free(obj);
+	else
+		git_objects_table[type].free(obj);
+}
+
 int git_object_lookup_prefix(
 	git_object **object_out,
 	git_repository *repo,
@@ -222,35 +210,6 @@ int git_object_lookup(git_object **object_out, git_repository *repo, const git_o
 	return git_object_lookup_prefix(object_out, repo, id, GIT_OID_HEXSZ, type);
 }
 
-void git_object__free(void *_obj)
-{
-	git_object *object = (git_object *)_obj;
-
-	assert(object);
-
-	switch (object->cached.type) {
-	case GIT_OBJ_COMMIT:
-		git_commit__free((git_commit *)object);
-		break;
-
-	case GIT_OBJ_TREE:
-		git_tree__free((git_tree *)object);
-		break;
-
-	case GIT_OBJ_TAG:
-		git_tag__free((git_tag *)object);
-		break;
-
-	case GIT_OBJ_BLOB:
-		git_blob__free((git_blob *)object);
-		break;
-
-	default:
-		git__free(object);
-		break;
-	}
-}
-
 void git_object_free(git_object *object)
 {
 	if (object == NULL)
@@ -304,7 +263,7 @@ int git_object_typeisloose(git_otype type)
 	if (type < 0 || ((size_t) type) >= ARRAY_SIZE(git_objects_table))
 		return 0;
 
-	return git_objects_table[type].loose;
+	return (git_objects_table[type].size > 0) ? 1 : 0;
 }
 
 size_t git_object__size(git_otype type)