wallet: add flag to specify whether or not to include change output

Will allow for more intelligent change policy

common/wallet_tx.c

@@ -152,7 +152,7 @@ struct command_result *wtx_select_utxos(struct wallet_tx *tx,
 	}
 
 	tx->utxos = wallet_select_coins(tx, tx->cmd->ld->wallet,
-					tx->amount,
+					true, tx->amount,
 					fee_rate_per_kw, out_len,
 					maxheight,
 					&fee_estimate, &tx->change);

wallet/test/run-wallet.c

@@ -789,7 +789,7 @@ static bool test_wallet_outputs(struct lightningd *ld, const tal_t *ctx)
 		  "wallet_add_utxo with close_info");
 
 	/* Now select them */
-	utxos = wallet_select_coins(w, w, AMOUNT_SAT(2), 0, 21,
+	utxos = wallet_select_coins(w, w, true, AMOUNT_SAT(2), 0, 21,
 				    0 /* no confirmations required */,
 				    &fee_estimate, &change_satoshis);
 	CHECK(utxos && tal_count(utxos) == 2);
@@ -837,7 +837,7 @@ static bool test_wallet_outputs(struct lightningd *ld, const tal_t *ctx)
 		  "wallet_add_utxo with close_info no commitment_point");
 
 	/* Now select it */
-	utxos = wallet_select_coins(w, w, AMOUNT_SAT(5), 0, 21,
+	utxos = wallet_select_coins(w, w, true, AMOUNT_SAT(5), 0, 21,
 				    0 /* no confirmations required */,
 				    &fee_estimate, &change_satoshis);
 	CHECK(utxos && tal_count(utxos) == 2);

wallet/wallet.c

@@ -433,6 +433,7 @@ static const struct utxo **wallet_select(const tal_t *ctx, struct wallet *w,
 }
 
 const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
+					bool with_change,
 					struct amount_sat sat,
 					const u32 feerate_per_kw,
 					size_t outscriptlen,
@@ -444,7 +445,7 @@ const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
 	const struct utxo **utxo;
 
 	utxo = wallet_select(ctx, w, sat, feerate_per_kw,
-			     outscriptlen, true, maxheight,
+			     outscriptlen, with_change, maxheight,
 			     &satoshi_in, fee_estimate);
 
 	/* Couldn't afford it? */
@@ -452,6 +453,9 @@ const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
 	    || !amount_sat_sub(change, *change, *fee_estimate))
 		return tal_free(utxo);
 
+	if (!with_change)
+		*change = AMOUNT_SAT(0);
+
 	return utxo;
 }
 

wallet/wallet.h

@@ -358,6 +358,7 @@ struct utxo **wallet_get_unconfirmed_closeinfo_utxos(const tal_t *ctx,
 						     struct wallet *w);
 
 const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
+					bool with_change,
 					struct amount_sat value,
 					const u32 feerate_per_kw,
 					size_t outscriptlen,