Merge #12803: Make BaseSignatureCreator a pure interface

be67831 Make DummySignatureCreator a singleton (Pieter Wuille)
190b8d2 Make BaseSignatureCreator a pure interface (Pieter Wuille)

Pull request description:

  * Removes the `m_provider` field from `BaseSignatureCreator`. Instead both a `SigningProvider` (which provides keys and scripts) and a `BaseSignatureCreator` (which implements the transaction-specific (or other) signing logic) are passed into and down in `ProduceSignature`, making the two concepts orthogonal.
  * Makes `BaseSignatureCreator` a pure interface without constructor, making it easier to implement new derivations of it (for example for message signing).
  * As `DummySignatureCreator` now becomes a stateless object, turn it into a singleton `DUMMY_SIGNATURE_CREATOR`.

Tree-SHA512: 5f1f4512e4ea7d02a31df7b9ede55008efa716c5b74a2630ca1c2fc6599584d8bf5f5641487266127f4b3788033803539fbd22b03ef1219c83c10da2d3da3dcd

1 files changed, 7 insertions, 17 deletions

diff --git a/src/script/sign.h b/src/script/sign.h
index c301f0544f..cf3651c1de 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -26,19 +26,14 @@ public:
     virtual bool GetKey(const CKeyID &address, CKey& key) const =0;
 };
 
-/** Virtual base class for signature creators. */
+/** Interface for signature creators. */
 class BaseSignatureCreator {
-protected:
-    const SigningProvider* m_provider;
-
 public:
-    explicit BaseSignatureCreator(const SigningProvider* provider) : m_provider(provider) {}
-    const SigningProvider& Provider() const { return *m_provider; }
     virtual ~BaseSignatureCreator() {}
     virtual const BaseSignatureChecker& Checker() const =0;
 
     /** Create a singular (non-script) signature. */
-    virtual bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const =0;
+    virtual bool CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const =0;
 };
 
 /** A signature creator for transactions. */
@@ -50,25 +45,20 @@ class TransactionSignatureCreator : public BaseSignatureCreator {
     const TransactionSignatureChecker checker;
 
 public:
-    TransactionSignatureCreator(const SigningProvider* provider, const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn=SIGHASH_ALL);
+    TransactionSignatureCreator(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn=SIGHASH_ALL);
     const BaseSignatureChecker& Checker() const override { return checker; }
-    bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const override;
+    bool CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const override;
 };
 
 class MutableTransactionSignatureCreator : public TransactionSignatureCreator {
     CTransaction tx;
 
 public:
-    MutableTransactionSignatureCreator(const SigningProvider* provider, const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn) : TransactionSignatureCreator(provider, &tx, nInIn, amountIn, nHashTypeIn), tx(*txToIn) {}
+    MutableTransactionSignatureCreator(const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn) : TransactionSignatureCreator(&tx, nInIn, amountIn, nHashTypeIn), tx(*txToIn) {}
 };
 
 /** A signature creator that just produces 72-byte empty signatures. */
-class DummySignatureCreator : public BaseSignatureCreator {
-public:
-    explicit DummySignatureCreator(const SigningProvider* provider) : BaseSignatureCreator(provider) {}
-    const BaseSignatureChecker& Checker() const override;
-    bool CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const override;
-};
+extern const BaseSignatureCreator& DUMMY_SIGNATURE_CREATOR;
 
 struct SignatureData {
     CScript scriptSig;
@@ -79,7 +69,7 @@ struct SignatureData {
 };
 
 /** Produce a script signature using a generic signature creator. */
-bool ProduceSignature(const BaseSignatureCreator& creator, const CScript& scriptPubKey, SignatureData& sigdata);
+bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreator& creator, const CScript& scriptPubKey, SignatureData& sigdata);
 
 /** Produce a script signature for a transaction. */
 bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType);