lightningd: allow subd_req() to take replycb_data arg.

Useful if it's only to be used for the duration of the callback.

Signed-off-by: Rusty Russell <[email protected]>

Author: rustyrussell

lightningd/subd.c

@@ -142,13 +142,15 @@ static struct subd_req *add_req(const tal_t *ctx,
 				struct subd *sd, int type, size_t num_fds_in,
 				void (*replycb)(struct subd *, const u8 *, const int *,
 						void *),
-				void *replycb_data)
+				void *replycb_data TAKES)
 {
 	struct subd_req *sr = tal(sd, struct subd_req);
 
 	sr->type = type;
 	sr->replycb = replycb;
 	sr->replycb_data = replycb_data;
+	if (taken(replycb_data))
+		tal_steal(sr, replycb_data);
 	sr->num_reply_fds = num_fds_in;
 
 	/* We don't allocate sr off ctx, because we still have to handle the
@@ -852,7 +854,7 @@ struct subd_req *subd_req_(const tal_t *ctx,
 			   const u8 *msg_out,
 			   int fd_out, size_t num_fds_in,
 			   void (*replycb)(struct subd *, const u8 *, const int *, void *),
-			   void *replycb_data)
+			   void *replycb_data TAKES)
 {
 	/* Grab type now in case msg_out is taken() */
 	int type = fromwire_peektype(msg_out);

lightningd/subd.h

@@ -178,7 +178,7 @@ void subd_send_fd(struct subd *sd, int fd);
  * @fd_out: if >=0 fd to pass at the end of the message (closed after)
  * @num_fds_in: how many fds to read in to hand to @replycb if it's a reply.
  * @replycb: callback (inside db transaction) when reply comes in (can free subd)
- * @replycb_data: final arg to hand to @replycb
+ * @replycb_data: final arg to hand to @replycb (can be TAKE())
  *
  * @replycb cannot free @sd, so it returns false to remove it.
  * Note that @replycb is called for replies of type @msg_out + SUBD_REPLY_OFFSET
@@ -196,7 +196,7 @@ struct subd_req *subd_req_(const tal_t *ctx,
 	       const u8 *msg_out,
 	       int fd_out, size_t num_fds_in,
 	       void (*replycb)(struct subd *, const u8 *, const int *, void *),
-	       void *replycb_data);
+	       void *replycb_data TAKES);
 
 /**
  * subd_release_channel - shut down a subdaemon which no longer owns the channel.