MT#55283 glib_json_builder_add_str hack

Avoids allocating and duplicating the string. Should be safe as all
strings that use it are allocated in read-write memory.

Requires changing some struct members to non-const.

Change-Id: Idc81a84a1454898c76d8514666c385307043bb6f

daemon/janus.c

@@ -334,14 +334,14 @@ static void janus_add_publisher_details(JsonBuilder *builder, struct call_monolo
 	json_builder_set_member_name(builder, "streams");
 	json_builder_begin_array(builder);
 
-	const str *a_codec = NULL, *v_codec = NULL;
+	str *a_codec = NULL, *v_codec = NULL;
 
 	for (unsigned int i = 0; i < ml->medias->len; i++) {
 		struct call_media *media = ml->medias->pdata[i];
 		if (!media)
 			continue;
 
-		const str *codec = NULL;
+		str *codec = NULL;
 		for (__auto_type k = media->codecs.codec_prefs.head; k; k = k->next) {
 			rtp_payload_type *pt = k->data;
 			codec = &pt->encoding;

include/call.h

@@ -381,7 +381,7 @@ struct endpoint_map {
 	unsigned int		unique_id;
 	struct endpoint		endpoint;
 	unsigned int		num_ports;
-	const struct logical_intf *logical_intf;
+	struct logical_intf	*logical_intf;
 	sfd_intf_list_q		intf_sfds; /* list of struct sfd_intf_list - contains stream_fd list */
 	unsigned int		wildcard:1;
 };
@@ -487,7 +487,7 @@ struct call_media {
 	const struct transport_protocol *protocol;
 	str			format_str;
 	sockfamily_t		*desired_family;
-	const struct logical_intf *logical_intf;
+	struct logical_intf	*logical_intf;
 
 	struct ice_agent	*ice_agent;
 
@@ -583,7 +583,7 @@ struct call_monologue {
 	struct timeval		terminated;		/* for CDR */
 	enum termination_reason	term_reason;
 	sockfamily_t		*desired_family;
-	const struct logical_intf *logical_intf;
+	struct logical_intf	*logical_intf;
 	GHashTable 		*associated_tags;
 	GHashTable		*subscribers_ht;	/* for quick lookup */
 	medias_arr		*medias;

include/helpers.h

@@ -100,13 +100,11 @@ INLINE char *glib_json_print(JsonBuilder *builder) {
 
 	return result;
 }
-INLINE void glib_json_builder_add_str(JsonBuilder *builder, const str *s) {
-	// this is not optimal at all, but necessary due to glib's lack of "add_string_len_value" or similar
-	char *b = g_malloc(s->len + 1);
-	memcpy(b, s->s, s->len);
-	b[s->len] = '\0';
-	json_builder_add_string_value(builder, b);
-	g_free(b);
+INLINE void glib_json_builder_add_str(JsonBuilder *builder, str *s) {
+	char ori = s->s[s->len];
+	s->s[s->len] = '\0';
+	json_builder_add_string_value(builder, s->s);
+	s->s[s->len] = ori;
 }
 
 

include/media_socket.h

@@ -156,7 +156,7 @@ struct local_intf {
 	struct intf_spec		*spec;
 	struct intf_address		advertised_address;
 	unsigned int			unique_id; /* starting with 0 - serves as preference */
-	const struct logical_intf	*logical;
+	struct logical_intf		*logical;
 	str				ice_foundation;
 
 	struct interface_stats_block	*stats;