lightning-cli txprepare with a particular syntax provokes FATAL SIGNAL 11

[gabridome]

Issue and Steps to Reproduce

Trying to make lightning-cli txprepare work, I attempted also the following syntax:

lightning-cli txprepare "[{\"bc1hfsk...\":\"all\"}]" slow 1 "[\"e2er...:1\"]"

The output was:

lightning-cli: reading response: socket closed

The log said:

2020-02-17T11:57:17.157Z **BROKEN** lightningd: FATAL SIGNAL 11 (version v0.8.0)
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: common/daemon.c:46 (send_backtrace) 0x557033ce5da1
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: common/daemon.c:54 (crashdump) 0x557033ce5dde
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: (null):0 ((null)) 0x7ff67d1c405f
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: common/wallet_tx.c:208 (wtx_from_utxos) 0x557033ceebe5
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: wallet/walletrpc.c:374 (json_prepare_tx) 0x557033d16e1a
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: wallet/walletrpc.c:415 (json_txprepare) 0x557033d1775d
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: lightningd/jsonrpc.c:588 (command_exec) 0x557033cc4a51
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: lightningd/jsonrpc.c:679 (rpc_command_hook_callback) 0x557033cc6106
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: lightningd/plugin_hook.c:123 (plugin_hook_call_) 0x557033cde6dc
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: lightningd/jsonrpc.c:729 (plugin_hook_call_rpc_command) 0x557033cc5039
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: lightningd/jsonrpc.c:736 (call_rpc_command_hook) 0x557033cc5039
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: common/timeout.c:39 (timer_expired) 0x557033cedd4e
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: lightningd/io_loop_with_timers.c:32 (io_loop_with_timers) 0x557033cc3217
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: lightningd/lightningd.c:855 (main) 0x557033cc76a6
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: (null):0 ((null)) 0x7ff67d1b12e0
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: (null):0 ((null)) 0x557033cb5939
2020-02-17T11:57:17.157Z **BROKEN** lightningd: backtrace: (null):0 ((null)) 0xffffffffffffffff

"version": "v0.8.0"

May I also have an example of which syntax should work?

[darosior]

Was the utxo you passed confirmed ? I'm trying to reproduce this with 0.8.1

[darosior]

Ok looks like it was an unconfirmed utxo, repro test for 0.8 (EDIT: And 0.8.1):

diff --git a/tests/test_wallet.py b/tests/test_wallet.py
index 01f496894..f2044422a 100644
--- a/tests/test_wallet.py
+++ b/tests/test_wallet.py
@@ -348,11 +348,17 @@ def test_txprepare(node_factory, bitcoind, chainparams):
     l1.rpc.txdiscard(prep4['txid'])
 
     # Try passing in a utxo set
-    utxos = [utxo["txid"] + ":" + str(utxo["output"]) for utxo in l1.rpc.listfunds()["outputs"]][:4]
-
+    utxos = [utxo["txid"] + ":" + str(utxo["output"])
+             for utxo in l1.rpc.listfunds()["outputs"]][:4]
     prep5 = l1.rpc.txprepare([{addr:
                              Millisatoshi(amount * 3.5 * 1000)}], utxos=utxos)
 
+    # Try passing unconfirmed utxos
+    unconfirmed_utxo = l1.rpc.withdraw(l1.rpc.newaddr()["bech32"], 10**5)
+    utxos = [unconfirmed_utxo["txid"] + ":0"]
+    prepx = l1.rpc.txprepare([{addr:
+                             Millisatoshi(amount * 3.5 * 1000)}], utxos=utxos)

[darosior]

May I also have an example of which syntax should work?

txprepare doesn't accept unconfirmed utxos.

[gabridome]

RRRight!!! and, at the same time, I had the information I was looking for because in the meanwhile, the tx was confirmed.

So the right format is:

lightning-cli txprepare "[{\"destinationaddress...\":\"all\"}]" slow 1 "[\"txid...:1\"]"

It could be of some help have a mention of the right format as an example in the documentation.