lib/rules kr_rules_init(): allow not overwriting the DB

daemon/lua/kres-gen-30.lua

@@ -497,7 +497,7 @@ int kr_cache_remove(struct kr_cache *, const knot_dname_t *, uint16_t);
 int kr_cache_remove_subtree(struct kr_cache *, const knot_dname_t *, _Bool, int);
 int kr_cache_commit(struct kr_cache *);
 uint32_t packet_ttl(const knot_pkt_t *);
-int kr_rules_init(const char *, size_t);
+int kr_rules_init(const char *, size_t, _Bool);
 int kr_rules_commit(_Bool);
 int kr_view_insert_action(const char *, const char *, kr_proto_set, const char *);
 int kr_view_select_action(const struct kr_request *, knot_db_val_t *);

daemon/lua/kres-gen-31.lua

@@ -497,7 +497,7 @@ int kr_cache_remove(struct kr_cache *, const knot_dname_t *, uint16_t);
 int kr_cache_remove_subtree(struct kr_cache *, const knot_dname_t *, _Bool, int);
 int kr_cache_commit(struct kr_cache *);
 uint32_t packet_ttl(const knot_pkt_t *);
-int kr_rules_init(const char *, size_t);
+int kr_rules_init(const char *, size_t, _Bool);
 int kr_rules_commit(_Bool);
 int kr_view_insert_action(const char *, const char *, kr_proto_set, const char *);
 int kr_view_select_action(const struct kr_request *, knot_db_val_t *);

daemon/lua/kres-gen-32.lua

@@ -498,7 +498,7 @@ int kr_cache_remove(struct kr_cache *, const knot_dname_t *, uint16_t);
 int kr_cache_remove_subtree(struct kr_cache *, const knot_dname_t *, _Bool, int);
 int kr_cache_commit(struct kr_cache *);
 uint32_t packet_ttl(const knot_pkt_t *);
-int kr_rules_init(const char *, size_t);
+int kr_rules_init(const char *, size_t, _Bool);
 int kr_rules_commit(_Bool);
 int kr_view_insert_action(const char *, const char *, kr_proto_set, const char *);
 int kr_view_select_action(const struct kr_request *, knot_db_val_t *);

lib/rules/api.c

@@ -141,9 +141,9 @@ int kr_rules_init_ensure(void)
 {
 	if (the_rules)
 		return kr_ok();
-	return kr_rules_init(NULL, 0);
+	return kr_rules_init(NULL, 0, true);
 }
-int kr_rules_init(const char *path, size_t maxsize)
+int kr_rules_init(const char *path, size_t maxsize, bool overwrite)
 {
 	if (the_rules)
 		return kr_error(EINVAL);
@@ -157,22 +157,17 @@ int kr_rules_init(const char *path, size_t maxsize)
 		// FIXME: the file will be sparse, but we still need to choose its size somehow.
 		// Later we might improve it to auto-resize in case of running out of space.
 		// Caveat: mdb_env_set_mapsize() can only be called without transactions open.
-		.maxsize = maxsize ? maxsize :
-			(size_t)(sizeof(size_t) > 4 ? 2048 : 500) * 1024*1024,
+		.maxsize = !overwrite ? 0 :
+			(maxsize ? maxsize : (size_t)(sizeof(size_t) > 4 ? 2048 : 500) * 1024*1024),
 	};
 	int ret = the_rules->api->open(&the_rules->db, &the_rules->stats, &opts, NULL);
-	/* No persistence - we always refill from config for now.
-	 * LATER:
-	 *  - Make it include versioning?
-	 *  - "\0stamp" key when loading config(s)?
-	 *  - Don't clear ruleset data that doesn't come directly from config;
-	 *    and add marks for that, etc.
-	 *    (after there actually are any kinds of rules like that)
-	 */
-	if (ret == 0) ret = ruledb_op(clear);
+
+	if (ret == 0 && overwrite) ret = ruledb_op(clear);
 	if (ret != 0) goto failure;
 	kr_require(the_rules->db);
 
+	if (!overwrite) return kr_ok(); // we assume that the caller ensured OK contents
+
 	ret = tag_names_default();
 	if (ret != 0) goto failure;
 

lib/rules/api.h

@@ -19,11 +19,13 @@ typedef uint64_t kr_rule_tags_t;
 
 /** Open the rule DB.
  *
- * You can call this to override the path or size (NULL/0 -> default).
- * Not allowed if already open (EINVAL), so this optional call has to come
- * before writing anything into the DB. */
+ * You can call this to override the path or size (NULL/0 -> default)
+ * or choose not to overwrite the DB with just the defaults.
+ *
+ * \return error code.  Not allowed if already open (EINVAL),
+ * so this optional call has to come before writing anything into the DB. */
 KR_EXPORT
-int kr_rules_init(const char *path, size_t maxsize);
+int kr_rules_init(const char *path, size_t maxsize, bool overwrite);
 /** kr_rules_init() but OK if already open, and not allowing to override defaults. */
 KR_EXPORT
 int kr_rules_init_ensure(void);

lib/rules/impl.h

@@ -20,7 +20,7 @@ extern struct kr_rules *the_rules;
 
 #define ENSURE_the_rules \
 	if (!the_rules) { \
-		int ret = kr_rules_init(NULL, 0); \
+		int ret = kr_rules_init(NULL, 0, true); \
 		if (ret) return ret; \
 	}