psbt: add psbt to bitcoin tx struct

bitcoin/tx.c

@@ -429,6 +429,7 @@ struct bitcoin_tx *bitcoin_tx(const tal_t *ctx,
 			      varint_t input_count, varint_t output_count,
 			      u32 nlocktime)
 {
+	int ret;
 	struct bitcoin_tx *tx = tal(ctx, struct bitcoin_tx);
 	assert(chainparams);
 
@@ -447,6 +448,12 @@ struct bitcoin_tx *bitcoin_tx(const tal_t *ctx,
 	tx->wtx->version = 2;
 	tx->output_witscripts = tal_arrz(tx, struct witscript*, output_count);
 	tx->chainparams = chainparams;
+
+	ret = wally_psbt_init_alloc(input_count, output_count,
+				    0, &tx->psbt);
+	assert(ret == WALLY_OK);
+	ret = wally_psbt_set_global_tx(tx->psbt, tx->wtx);
+
 	return tx;
 }
 
@@ -467,7 +474,7 @@ struct bitcoin_tx *pull_bitcoin_tx(const tal_t *ctx, const u8 **cursor,
 				   size_t *max)
 {
 	size_t wsize;
-	int flags = WALLY_TX_FLAG_USE_WITNESS;
+	int flags = WALLY_TX_FLAG_USE_WITNESS, ret;
 	struct bitcoin_tx *tx = tal(ctx, struct bitcoin_tx);
 
 	if (chainparams->is_elements)
@@ -494,6 +501,12 @@ struct bitcoin_tx *pull_bitcoin_tx(const tal_t *ctx, const u8 **cursor,
 	    tal_arrz(tx, struct amount_sat *, tx->wtx->inputs_allocation_len);
 	tx->chainparams = chainparams;
 
+	ret = wally_psbt_init_alloc(tx->wtx->num_inputs, tx->wtx->num_outputs,
+				    0, &tx->psbt);
+	assert(ret == WALLY_OK);
+	ret = wally_psbt_set_global_tx(tx->psbt, tx->wtx);
+
+
 	*cursor += wsize;
 	*max -= wsize;
 	return tx;

bitcoin/tx.h

@@ -8,9 +8,11 @@
 #include <ccan/structeq/structeq.h>
 #include <ccan/tal/tal.h>
 #include <common/amount.h>
+#include <wally_psbt.h>
 #include <wally_transaction.h>
 
 #define BITCOIN_TX_DEFAULT_SEQUENCE 0xFFFFFFFF
+struct wally_psbt;
 
 struct witscript {
     u8 *ptr;
@@ -33,6 +35,9 @@ struct bitcoin_tx {
 
 	/* Keep a reference to the ruleset we have to abide by */
 	const struct chainparams *chainparams;
+
+	/* psbt struct */
+	struct wally_psbt *psbt;
 };
 
 struct bitcoin_tx_output {

common/permute_tx.c

@@ -1,6 +1,7 @@
 #include "permute_tx.h"
 #include <stdbool.h>
 #include <string.h>
+#include <wally_psbt.h>
 
 static bool input_better(const struct wally_tx_input *a,
 			 const struct wally_tx_input *b)