Add bool PSBTInputSigned

Refactor out a "PSBTInputSigned" function to check if a PSBT is signed,
for use in subsequent commits.

Also improve a related comment.

GitHub-Pull: #14588
Rebased-From: 53e6fffb8f5b10f94708d33d667a67cb91c2d09d

1 files changed, 6 insertions, 2 deletions

diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 190c0bf687..945e162355 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -233,10 +233,14 @@ bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreato
     return sigdata.complete;
 }
 
+bool PSBTInputSigned(PSBTInput& input)
+{
+    return !input.final_script_sig.empty() || !input.final_script_witness.IsNull();
+}
+
 bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, SignatureData& sigdata, int index, int sighash)
 {
-    // if this input has a final scriptsig or scriptwitness, don't do anything with it
-    if (!input.final_script_sig.empty() || !input.final_script_witness.IsNull()) {
+    if (PSBTInputSigned(input)) {
         return true;
     }