wire_sync_write: support take()

We often want it to free the message after writing.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/daemon_conn.c

@@ -46,7 +46,7 @@ bool daemon_conn_sync_flush(struct daemon_conn *dc)
 		if (fd >= 0) {
 			if (!fdpass_send(io_conn_fd(dc->conn), fd))
 				return false;
-		} else if (!wire_sync_write(io_conn_fd(dc->conn), msg))
+		} else if (!wire_sync_write(io_conn_fd(dc->conn), take(msg)))
 			return false;
 	}
 	return true;

lightningd/opening/opening.c

@@ -187,7 +187,7 @@ static u8 *read_next_peer_msg(struct state *state, const tal_t *ctx)
 			tal_free(pong);
 		} else if (gossip_msg(msg)) {
 			/* We relay gossip to gossipd, but don't relay from */
-			if (!wire_sync_write(GOSSIP_FD, msg))
+			if (!wire_sync_write(GOSSIP_FD, take(msg)))
 				peer_failed(PEER_FD, &state->cs, NULL,
 					    WIRE_OPENING_PEER_WRITE_FAILED,
 					    "Relaying gossip message");

lightningd/status.c

@@ -65,9 +65,8 @@ static void status_send_with_hdr(u16 type, const void *p, size_t len)
 		tal_resize(&msg, 65535);
 
 	if (status_fd >= 0) {
-		if (!wire_sync_write(status_fd, msg))
+		if (!wire_sync_write(status_fd, take(msg)))
 			err(1, "Writing out status %u len %zu", type, len);
-		tal_free(msg);
 	} else {
 		daemon_conn_send(status_conn, take(msg));
 	}

wire/wire_sync.c

@@ -3,13 +3,18 @@
 #include <ccan/endian/endian.h>
 #include <ccan/read_write_all/read_write_all.h>
 
-bool wire_sync_write(int fd, const void *msg)
+bool wire_sync_write(int fd, const void *msg TAKES)
 {
 	be16 be_len = cpu_to_be16(tal_count(msg));
+	bool ret;
 
 	assert(be16_to_cpu(be_len) == tal_count(msg));
-	return write_all(fd, &be_len, sizeof(be_len))
+	ret = write_all(fd, &be_len, sizeof(be_len))
 		&& write_all(fd, msg, tal_count(msg));
+
+	if (taken(msg))
+		tal_free(msg);
+	return ret;
 }
 
 u8 *wire_sync_read(const tal_t *ctx, int fd)

wire/wire_sync.h

@@ -4,7 +4,7 @@
 #include <ccan/short_types/short_types.h>
 #include <ccan/tal/tal.h>
 
-bool wire_sync_write(int fd, const void *msg);
+bool wire_sync_write(int fd, const void *msg TAKES);
 u8 *wire_sync_read(const tal_t *ctx, int fd);
 
 #endif /* LIGHTNING_WIRE_WIRE_SYNC_H */