Abstract out UpdatePSBTOutput from FillPSBT

1 files changed, 19 insertions, 0 deletions

diff --git a/src/psbt.cpp b/src/psbt.cpp
index 97bda51a63..2362d4d497 100644
--- a/src/psbt.cpp
+++ b/src/psbt.cpp
@@ -215,6 +215,25 @@ bool PSBTInputSigned(const PSBTInput& input)
     return !input.final_script_sig.empty() || !input.final_script_witness.IsNull();
 }
 
+void UpdatePSBTOutput(const SigningProvider& provider, PartiallySignedTransaction& psbt, int index)
+{
+    const CTxOut& out = psbt.tx->vout.at(index);
+    PSBTOutput& psbt_out = psbt.outputs.at(index);
+
+    // Fill a SignatureData with output info
+    SignatureData sigdata;
+    psbt_out.FillSignatureData(sigdata);
+
+    // Construct a would-be spend of this output, to update sigdata with.
+    // Note that ProduceSignature is used to fill in metadata (not actual signatures),
+    // so provider does not need to provide any private keys (it can be a HidingSigningProvider).
+    MutableTransactionSignatureCreator creator(psbt.tx.get_ptr(), /* index */ 0, out.nValue, SIGHASH_ALL);
+    ProduceSignature(provider, creator, out.scriptPubKey, sigdata);
+
+    // Put redeem_script, witness_script, key paths, into PSBTOutput.
+    psbt_out.FromSignatureData(sigdata);
+}
+
 bool SignPSBTInput(const SigningProvider& provider, PartiallySignedTransaction& psbt, int index, int sighash, SignatureData* out_sigdata, bool use_dummy)
 {
     PSBTInput& input = psbt.inputs.at(index);