ubusd: don't free messages in ubus_send_msg() anymore

This makes it clear that `ubus_msg_send()` is only
about sending and queue-ing messages, and has nothing
to do with free-ing.

It can be a bit misleading/confusing when trying to go
through the code and make assumptions about whether a
buffer is free'd in ubus_send_msg(), or is free'd outside.

In `ubusd_proto_receive_message()` the `ubus_msg_free()`
is now called before the `if (ret == -1)` check.
That way, all callbacks will have their messages free'd,
which is what's desired, but confusing, because:
* ubusd_handle_invoke() called ubus_msg_free() before returning -1
* ubusd_handle_notify() called ubus_msg_free() before returning -1
* ubusd_handle_response() called ubus_msg_send(,,free=true) before returning -1
* ubus_msg_send() would call ubus_msg_send(,,free=false)
* all other callback callers would `ubus_msg_send(,,free=true)`
  (free the buffers in ubus_msg_send() )

In all other places, where `ubus_msg_send(,,free=true)`
an explicit `ubus_msg_free()` was added.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

5 files changed, 21 insertions, 23 deletions

diff --git a/ubusd.c b/ubusd.c
index f060b38..ba1ff07 100644
--- a/ubusd.c
+++ b/ubusd.c
@@ -146,7 +146,7 @@ static void ubus_msg_enqueue(struct ubus_client *cl, struct ubus_msg_buf *ub)
 }
 
 /* takes the msgbuf reference */
-void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free)
+void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub)
 {
 	int written;
 
@@ -160,7 +160,7 @@ void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free)
 			written = 0;
 
 		if (written >= ub->len + sizeof(ub->hdr))
-			goto out;
+			return;
 
 		cl->txq_ofs = written;
 
@@ -168,10 +168,6 @@ void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free)
 		uloop_fd_add(&cl->sock, ULOOP_READ | ULOOP_WRITE | ULOOP_EDGE_TRIGGER);
 	}
 	ubus_msg_enqueue(cl, ub);
-
-out:
-	if (free)
-		ubus_msg_free(ub);
 }
 
 static struct ubus_msg_buf *ubus_msg_head(struct ubus_client *cl)
diff --git a/ubusd.h b/ubusd.h
index 5031ed4..991a59f 100644
--- a/ubusd.h
+++ b/ubusd.h
@@ -67,7 +67,7 @@ struct ubus_path {
 extern const char *ubusd_acl_dir;
 
 struct ubus_msg_buf *ubus_msg_new(void *data, int len, bool shared);
-void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub, bool free);
+void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub);
 void ubus_msg_free(struct ubus_msg_buf *ub);
 struct blob_attr **ubus_parse_msg(struct blob_attr *msg);
 
diff --git a/ubusd_event.c b/ubusd_event.c
index 984f341..0469c20 100644
--- a/ubusd_event.c
+++ b/ubusd_event.c
@@ -129,7 +129,7 @@ static void ubusd_send_event_msg(struct ubus_msg_buf **ub, struct ubus_client *c
 	*objid_ptr = htonl(obj->id.id);
 
 	(*ub)->hdr.seq = ++event_seq;
-	ubus_msg_send(obj->client, *ub, false);
+	ubus_msg_send(obj->client, *ub);
 }
 
 static bool strmatch_len(const char *s1, const char *s2, int *len)
diff --git a/ubusd_monitor.c b/ubusd_monitor.c
index 82d0333..a192206 100644
--- a/ubusd_monitor.c
+++ b/ubusd_monitor.c
@@ -76,7 +76,8 @@ ubusd_monitor_message(struct ubus_client *cl, struct ubus_msg_buf *ub, bool send
 		ub = ubus_msg_new(mb.head, blob_raw_len(mb.head), true);
 		ub->hdr.type = UBUS_MSG_MONITOR;
 		ub->hdr.seq = ++m->seq;
-		ubus_msg_send(m->cl, ub, true);
+		ubus_msg_send(m->cl, ub);
+		ubus_msg_free(ub);
 	}
 }
 
diff --git a/ubusd_proto.c b/ubusd_proto.c
index 72da7a7..441d084 100644
--- a/ubusd_proto.c
+++ b/ubusd_proto.c
@@ -89,7 +89,8 @@ ubus_proto_send_msg_from_blob(struct ubus_client *cl, struct ubus_msg_buf *ub,
 	ub->hdr.type = type;
 	ub->fd = fd;
 
-	ubus_msg_send(cl, ub, true);
+	ubus_msg_send(cl, ub);
+	ubus_msg_free(ub);
 }
 
 static bool ubusd_send_hello(struct ubus_client *cl)
@@ -102,14 +103,15 @@ static bool ubusd_send_hello(struct ubus_client *cl)
 		return false;
 
 	ubus_msg_init(ub, UBUS_MSG_HELLO, 0, cl->id.id);
-	ubus_msg_send(cl, ub, true);
+	ubus_msg_send(cl, ub);
+	ubus_msg_free(ub);
 	return true;
 }
 
 static int ubusd_send_pong(struct ubus_client *cl, struct ubus_msg_buf *ub, struct blob_attr **attr)
 {
 	ub->hdr.type = UBUS_MSG_DATA;
-	ubus_msg_send(cl, ub, false);
+	ubus_msg_send(cl, ub);
 	return 0;
 }
 
@@ -274,7 +276,6 @@ static int ubusd_handle_invoke(struct ubus_client *cl, struct ubus_msg_buf *ub,
 	blob_buf_init(&b, 0);
 
 	ubusd_forward_invoke(cl, obj, method, ub, attr[UBUS_ATTR_DATA]);
-	ubus_msg_free(ub);
 
 	return -1;
 }
@@ -322,7 +323,6 @@ static int ubusd_handle_notify(struct ubus_client *cl, struct ubus_msg_buf *ub,
 			blob_put_int8(&b, UBUS_ATTR_NO_REPLY, 1);
 		ubusd_forward_invoke(cl, s->subscriber, method, ub, attr[UBUS_ATTR_DATA]);
 	}
-	ubus_msg_free(ub);
 
 	return -1;
 }
@@ -359,11 +359,8 @@ static int ubusd_handle_response(struct ubus_client *cl, struct ubus_msg_buf *ub
 		goto error;
 
 	ub->hdr.peer = blob_get_u32(attr[UBUS_ATTR_OBJID]);
-	ubus_msg_send(cl, ub, true);
-	return -1;
-
+	ubus_msg_send(cl, ub);
 error:
-	ubus_msg_free(ub);
 	return -1;
 }
 
@@ -454,18 +451,20 @@ void ubusd_proto_receive_message(struct ubus_client *cl, struct ubus_msg_buf *ub
 	if (ub->hdr.type != UBUS_MSG_STATUS && ub->hdr.type != UBUS_MSG_INVOKE)
 		ubus_msg_close_fd(ub);
 
+	/* Note: no callback should free the `ub` buffer
+	         that's always done right after the callback finishes */
 	if (cb)
 		ret = cb(cl, ub, ubus_parse_msg(ub->data));
 	else
 		ret = UBUS_STATUS_INVALID_COMMAND;
 
+	ubus_msg_free(ub);
+
 	if (ret == -1)
 		return;
 
-	ubus_msg_free(ub);
-
 	*retmsg_data = htonl(ret);
-	ubus_msg_send(cl, retmsg, false);
+	ubus_msg_send(cl, retmsg);
 }
 
 struct ubus_client *ubusd_proto_new_client(int fd, uloop_fd_handler cb)
@@ -526,7 +525,8 @@ void ubus_notify_subscription(struct ubus_object *obj)
 		return;
 
 	ubus_msg_init(ub, UBUS_MSG_NOTIFY, ++obj->invoke_seq, 0);
-	ubus_msg_send(obj->client, ub, true);
+	ubus_msg_send(obj->client, ub);
+	ubus_msg_free(ub);
 }
 
 void ubus_notify_unsubscribe(struct ubus_subscription *s)
@@ -540,7 +540,8 @@ void ubus_notify_unsubscribe(struct ubus_subscription *s)
 	ub = ubus_msg_from_blob(false);
 	if (ub != NULL) {
 		ubus_msg_init(ub, UBUS_MSG_UNSUBSCRIBE, ++s->subscriber->invoke_seq, 0);
-		ubus_msg_send(s->subscriber->client, ub, true);
+		ubus_msg_send(s->subscriber->client, ub);
+		ubus_msg_free(ub);
 	}
 
 	ubus_unsubscribe(s);