wallet: Return any eventual outpoint scid when marking it spent

Just return the short_channel_id matching the outpoint that we just marked as
spent.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

lightningd/chaintopology.c

@@ -406,13 +406,17 @@ static void updates_complete(struct chain_topology *topo)
  */
 static void topo_update_spends(struct chain_topology *topo, struct block *b)
 {
+	const struct short_channel_id *scid;
 	for (size_t i = 0; i < tal_count(b->full_txs); i++) {
 		const struct bitcoin_tx *tx = b->full_txs[i];
 		for (size_t j = 0; j < tal_count(tx->input); j++) {
 			const struct bitcoin_tx_input *input = &tx->input[j];
-			wallet_outpoint_spend(topo->wallet, b->height,
+			scid = wallet_outpoint_spend(topo->wallet, tmpctx,
-					      &input->txid,
+						     b->height, &input->txid,
 						     input->index);
+			if (scid) {
+				tal_free(scid);
+			}
 		}
 	}
 }

wallet/wallet.c

@@ -2016,10 +2016,13 @@ void wallet_blocks_rollback(struct wallet *w, u32 height)
 	db_exec_prepared(w->db, stmt);
 }
 
-void wallet_outpoint_spend(struct wallet *w, const u32 blockheight,
+const struct short_channel_id *
+wallet_outpoint_spend(struct wallet *w, const tal_t *ctx, const u32 blockheight,
 		      const struct bitcoin_txid *txid, const u32 outnum)
 {
+	struct short_channel_id *scid;
 	sqlite3_stmt *stmt;
+	int res;
 	if (outpointfilter_matches(w->owned_outpoints, txid, outnum)) {
 		stmt = db_prepare(w->db,
 				  "UPDATE outputs "
@@ -2046,7 +2049,29 @@ void wallet_outpoint_spend(struct wallet *w, const u32 blockheight,
 		sqlite3_bind_int(stmt, 3, outnum);
 
 		db_exec_prepared(w->db, stmt);
+
+		if (sqlite3_changes(w->db->sql) == 0) {
+			return NULL;
 		}
+
+		/* Now look for the outpoint's short_channel_id */
+		stmt = db_prepare(w->db,
+				  "SELECT blockheight, txindex "
+				  "FROM utxoset "
+				  "WHERE txid = ? AND outnum = ?");
+		sqlite3_bind_sha256_double(stmt, 1, &txid->shad);
+		sqlite3_bind_int(stmt, 2, outnum);
+
+		res = sqlite3_step(stmt);
+		assert(res == SQLITE_ROW);
+
+		scid = tal(ctx, struct short_channel_id);
+		mk_short_channel_id(scid, sqlite3_column_int(stmt, 0),
+				    sqlite3_column_int(stmt, 1), outnum);
+		sqlite3_finalize(stmt);
+		return scid;
+	}
+	return NULL;
 }
 
 void wallet_utxoset_add(struct wallet *w, const struct bitcoin_tx *tx,

wallet/wallet.h

@@ -790,7 +790,17 @@ void wallet_block_remove(struct wallet *w, struct block *b);
  */
 void wallet_blocks_rollback(struct wallet *w, u32 height);
 
-void wallet_outpoint_spend(struct wallet *w, const u32 blockheight,
+/**
+ * Mark an outpoint as spent, both in the owned as well as the UTXO set
+ *
+ * Given the outpoint (txid, outnum), and the blockheight, mark the
+ * corresponding DB entries as spent at the blockheight.
+ *
+ * @return scid The short_channel_id corresponding to the spent outpoint, if
+ *         any.
+ */
+const struct short_channel_id *
+wallet_outpoint_spend(struct wallet *w, const tal_t *ctx, const u32 blockheight,
 		      const struct bitcoin_txid *txid, const u32 outnum);
 
 struct outpoint *wallet_outpoint_for_scid(struct wallet *w, tal_t *ctx,