Persist plugin: Simplify cases where we don't take a copy.

Some members of the persist plugin interface are only used to find a
client struct, for example. There is no need for the plugin to allocate
a new copy and the broker to free it in that case.

include/mosquitto_broker.h

@@ -255,7 +255,6 @@ struct mosquitto_evt_persist_subscription {
  * it may change in a future minor release. */
 struct mosquitto_evt_persist_client_msg {
 	const char *client_id;
-	char *plugin_client_id;
 	uint64_t cmsg_id;
 	uint64_t store_id;
 	uint32_t subscription_identifier;
@@ -282,8 +281,6 @@ struct mosquitto_evt_persist_base_msg {
 	const char *source_username;
 	char *plugin_topic;
 	void *plugin_payload;
-	char *plugin_source_id;
-	char *plugin_source_username;
 	const mosquitto_property *properties;
 	mosquitto_property *plugin_properties;
 	uint32_t payloadlen;

plugins/persist-sqlite/restore.c

@@ -216,25 +216,8 @@ static int msg_restore(struct mosquitto_sqlite *ms)
 				continue;
 			}
 		}
-		str = (const char *)sqlite3_column_text(stmt, 4);
-		if(str){
-			msg.plugin_source_id = strdup(str);
-			if(!msg.plugin_source_id){
-				free(msg.plugin_topic);
-				failed++;
-				continue;
-			}
-		}
-		str = (const char *)sqlite3_column_text(stmt, 5);
-		if(str){
-			msg.plugin_source_username = strdup(str);
-			if(!msg.plugin_source_username){
-				free(msg.plugin_topic);
-				free(msg.plugin_source_id);
-				failed++;
-				continue;
-			}
-		}
+		msg.source_id = (const char *)sqlite3_column_text(stmt, 4);
+		msg.source_username = (const char *)sqlite3_column_text(stmt, 5);
 		payload = (const void *)sqlite3_column_blob(stmt, 3);
 		msg.payloadlen = (uint32_t)sqlite3_column_int(stmt, 6);
 		if(payload && msg.payloadlen){
@@ -242,8 +225,6 @@ static int msg_restore(struct mosquitto_sqlite *ms)
 			if(!msg.plugin_payload){
 				free(msg.plugin_topic);
 				free(msg.plugin_topic);
-				free(msg.plugin_source_id);
-				free(msg.plugin_source_username);
 				failed++;
 				continue;
 			}
@@ -277,7 +258,6 @@ static int client_msg_restore(struct mosquitto_sqlite *ms)
 	struct mosquitto_evt_persist_client_msg msg;
 	int rc;
 	long count = 0, failed = 0;
-	const char *str;
 
 	rc = sqlite3_prepare_v2(ms->db,
 			"SELECT client_id, store_id, dup, direction, mid, qos, retain, state "
@@ -291,10 +271,7 @@ static int client_msg_restore(struct mosquitto_sqlite *ms)
 
 	memset(&msg, 0, sizeof(msg));
 	while(sqlite3_step(stmt) == SQLITE_ROW){
-		str = (const char *)sqlite3_column_text(stmt, 0);
-		if(str){
-			msg.plugin_client_id = strdup(str);
-		}
+		msg.client_id = (const char *)sqlite3_column_text(stmt, 0);
 		msg.store_id = (uint64_t)sqlite3_column_int64(stmt, 1);
 		msg.dup = sqlite3_column_int(stmt, 2);
 		msg.direction = (uint8_t)sqlite3_column_int(stmt, 3);

src/plugin_public.c

@@ -614,13 +614,11 @@ int mosquitto_persist_client_msg_add(struct mosquitto_evt_persist_client_msg *cl
 	struct mosquitto *context;
 	struct mosquitto_base_msg *base_msg;
 
-	if(client_msg == NULL || client_msg->plugin_client_id == NULL){
-		free(client_msg->plugin_client_id);
+	if(client_msg == NULL || client_msg->client_id == NULL){
 		return MOSQ_ERR_INVAL;
 	}
 
-	HASH_FIND(hh_id, db.contexts_by_id, client_msg->plugin_client_id, strlen(client_msg->plugin_client_id), context);
-	free(client_msg->plugin_client_id);
+	HASH_FIND(hh_id, db.contexts_by_id, client_msg->client_id, strlen(client_msg->client_id), context);
 	if(context == NULL){
 		return MOSQ_ERR_NOT_FOUND;
 	}
@@ -646,9 +644,9 @@ int mosquitto_persist_client_msg_delete(struct mosquitto_evt_persist_client_msg
 {
 	struct mosquitto *context;
 
-	if(client_msg == NULL || client_msg->plugin_client_id == NULL) return MOSQ_ERR_INVAL;
+	if(client_msg == NULL || client_msg->client_id == NULL) return MOSQ_ERR_INVAL;
 
-	HASH_FIND(hh_id, db.contexts_by_id, client_msg->plugin_client_id, strlen(client_msg->plugin_client_id), context);
+	HASH_FIND(hh_id, db.contexts_by_id, client_msg->client_id, strlen(client_msg->client_id), context);
 	if(context == NULL){
 		return MOSQ_ERR_NOT_FOUND;
 	}
@@ -666,9 +664,9 @@ int mosquitto_persist_client_msg_update(struct mosquitto_evt_persist_client_msg
 {
 	struct mosquitto *context;
 
-	if(client_msg == NULL || client_msg->plugin_client_id == NULL) return MOSQ_ERR_INVAL;
+	if(client_msg == NULL || client_msg->client_id == NULL) return MOSQ_ERR_INVAL;
 
-	HASH_FIND(hh_id, db.contexts_by_id, client_msg->plugin_client_id, strlen(client_msg->plugin_client_id), context);
+	HASH_FIND(hh_id, db.contexts_by_id, client_msg->client_id, strlen(client_msg->client_id), context);
 	if(context == NULL){
 		return MOSQ_ERR_NOT_FOUND;
 	}
@@ -730,8 +728,10 @@ int mosquitto_persist_base_msg_add(struct mosquitto_evt_persist_base_msg *msg)
 
 	memset(&context, 0, sizeof(context));
 
-	context.id = msg->plugin_source_id;
-	context.username = msg->plugin_source_username;
+	/* db__message_store only takes a copy of .id and .username, so it is reasonably safe
+	 * to cast the const char * to char * */
+	context.id = (char *)msg->source_id;
+	context.username = (char *)msg->source_username;
 
 	if(msg->expiry_time == 0){
 		message_expiry_interval = 0;
@@ -771,8 +771,6 @@ int mosquitto_persist_base_msg_add(struct mosquitto_evt_persist_base_msg *msg)
 		}
 	}
 	rc = db__message_store(&context, base_msg, message_expiry_interval, msg->store_id, mosq_mo_broker);
-	free(context.id);
-	free(context.username);
 	return rc;
 
 error: