onchaind: fix bug when grinding feerates with multiple possibilities.

Fixes: #2820
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

onchaind/onchaind.c

@@ -169,8 +169,15 @@ static bool set_htlc_timeout_fee(struct bitcoin_tx *tx,
 	 *    1. Multiply `feerate_per_kw` by 663 and divide by 1000 (rounding
 	 *    down).
 	 */
-	if (amount_sat_eq(fee, AMOUNT_SAT(UINT64_MAX)))
+	if (amount_sat_eq(fee, AMOUNT_SAT(UINT64_MAX))) {
-		return grind_htlc_tx_fee(&fee, tx, remotesig, wscript, 663);
+		struct amount_sat grindfee;
+		if (grind_htlc_tx_fee(&grindfee, tx, remotesig, wscript, 663)) {
+			/* Cache this for next time */
+			fee = grindfee;
+			return true;
+		}
+		return false;
+	}
 
 	if (!amount_sat_sub(&amount, amount, fee))
 		status_failed(STATUS_FAIL_INTERNAL_ERROR,

onchaind/test/run-grind_feerate-bug.c

@@ -85,6 +85,10 @@ bool shachain_get_secret(const struct shachain *shachain UNNEEDED,
 			 u64 commit_num UNNEEDED,
 			 struct secret *preimage UNNEEDED)
 { fprintf(stderr, "shachain_get_secret called!\n"); abort(); }
+/* Generated stub for status_failed */
+void status_failed(enum status_failreason code UNNEEDED,
+		   const char *fmt UNNEEDED, ...)
+{ fprintf(stderr, "status_failed called!\n"); abort(); }
 /* Generated stub for status_setup_sync */
 void status_setup_sync(int fd UNNEEDED)
 { fprintf(stderr, "status_setup_sync called!\n"); abort(); }
@@ -228,16 +232,6 @@ struct bitcoin_tx *htlc_timeout_tx(const tal_t *ctx,
 	return tx;
 }
 
-void status_failed(enum status_failreason code UNNEEDED,
-		   const char *fmt, ...)
-{
-	/* FIXME! */
-	fprintf(stderr, "XFAIL: %s!\n", fmt);
-	tal_free(tmpctx);
-	secp256k1_context_destroy(secp256k1_ctx);
-	exit(0);
-}
-
 int main(void)
 {
 	struct bitcoin_signature remotesig;