Fix subscribe_multiple datatypes.

client/sub_client.c

@@ -96,7 +96,7 @@ void my_connect_callback(struct mosquitto *mosq, void *obj, int result, int flag
 	cfg = (struct mosq_config *)obj;
 
 	if(!result){
-		mosquitto_subscribe_multiple(mosq, NULL, cfg->topic_count, (const char **)cfg->topics, cfg->qos);
+		mosquitto_subscribe_multiple(mosq, NULL, cfg->topic_count, cfg->topics, cfg->qos);
 
 		for(i=0; i<cfg->unsub_topic_count; i++){
 			mosquitto_unsubscribe(mosq, NULL, cfg->unsub_topics[i]);

lib/actions.c

@@ -105,11 +105,11 @@ int mosquitto_subscribe(struct mosquitto *mosq, int *mid, const char *sub, int q
 	if(mosquitto_sub_topic_check(sub)) return MOSQ_ERR_INVAL;
 	if(mosquitto_validate_utf8(sub, strlen(sub))) return MOSQ_ERR_MALFORMED_UTF8;
 
-	return send__subscribe(mosq, mid, 1, &sub, qos);
+	return send__subscribe(mosq, mid, 1, (char *const *const)&sub, qos);
 }
 
 
-int mosquitto_subscribe_multiple(struct mosquitto *mosq, int *mid, int sub_count, const char **sub, int qos)
+int mosquitto_subscribe_multiple(struct mosquitto *mosq, int *mid, int sub_count, char *const *const sub, int qos)
 {
 	int i;
 

lib/mosquitto.h

@@ -646,6 +646,10 @@ libmosq_EXPORT int mosquitto_subscribe(struct mosquitto *mosq, int *mid, const c
  *	       sent.
  *  sub_count - the count of subscriptions to be made
  *	sub -  array of sub_count pointers, each pointing to a subscription string.
+ *	       The "char *const *const" datatype ensures that neither the array of
+ *	       pointers nor the strings that they point to are mutable. If you aren't
+ *	       familiar with this, just think of it as a safer "char **",
+ *	       equivalent to "const char *" for a simple string pointer.
  *	qos -  the requested Quality of Service for each subscription.
  *
  * Returns:
@@ -655,7 +659,7 @@ libmosq_EXPORT int mosquitto_subscribe(struct mosquitto *mosq, int *mid, const c
  * 	MOSQ_ERR_NO_CONN -        if the client isn't connected to a broker.
  * 	MOSQ_ERR_MALFORMED_UTF8 - if a topic is not valid UTF-8
  */
-int mosquitto_subscribe_multiple(struct mosquitto *mosq, int *mid, int sub_count, const char **sub, int qos);
+int mosquitto_subscribe_multiple(struct mosquitto *mosq, int *mid, int sub_count, char *const *const sub, int qos);
 
 /*
  * Function: mosquitto_unsubscribe

lib/send_mosq.h

@@ -31,7 +31,7 @@ int send__pubcomp(struct mosquitto *mosq, uint16_t mid);
 int send__publish(struct mosquitto *mosq, uint16_t mid, const char *topic, uint32_t payloadlen, const void *payload, int qos, bool retain, bool dup);
 int send__pubrec(struct mosquitto *mosq, uint16_t mid);
 int send__pubrel(struct mosquitto *mosq, uint16_t mid);
-int send__subscribe(struct mosquitto *mosq, int *mid, int topic_count, const char **topic, int topic_qos);
+int send__subscribe(struct mosquitto *mosq, int *mid, int topic_count, char *const *const topic, int topic_qos);
 int send__unsubscribe(struct mosquitto *mosq, int *mid, const char *topic);
 
 #endif

src/handle_connack.c

@@ -76,7 +76,7 @@ int handle__connack(struct mosquitto_db *db, struct mosquitto *context)
 				}
 				for(i=0; i<context->bridge->topic_count; i++){
 					if(context->bridge->topics[i].direction == bd_in || context->bridge->topics[i].direction == bd_both){
-						if(send__subscribe(context, NULL, 1, &context->bridge->topics[i].remote_topic, &context->bridge->topics[i].qos)){
+						if(send__subscribe(context, NULL, 1, &context->bridge->topics[i].remote_topic, context->bridge->topics[i].qos)){
 							return 1;
 						}
 					}else{