Merge bitcoin/bitcoin#23065: Allow UTXO locks to be written to wallet DB

d96b000e94d72d041689c5c47e374df2ebc0e011 Make GUI UTXO lock/unlock persistent (Samuel Dobson)
077154fe698f5556ad6e26ef49c9024c2f07ff68 Add release note for lockunspent change (Samuel Dobson)
719ae927dcdb60c0f9902fa79796256035228c4e Update lockunspent tests for lock persistence (Samuel Dobson)
f13fc16295c19a156f2974d2d73fba56d52fc161 Allow lockunspent to store the lock in the wallet DB (Samuel Dobson)
c52789365e5dbcb25aa5f1775de4d318da79e5a7 Allow locked UTXOs to be store in the wallet database (Samuel Dobson)

Pull request description:

  Addresses and closes #22368

  As per that issue (and its predecessor #14907), there seems to be some interest in allowing unspent outputs to be locked persistently. This PR does so by adding a flag to lockunspent to store the change in the wallet database. Defaults to false, so there is no change in default behaviour.

  Edit: GUI commit changes default behaviour. UTXOs locked/unlocked via the GUI are now persistent.

ACKs for top commit:
  achow101:
    ACK d96b000e94d72d041689c5c47e374df2ebc0e011
  kristapsk:
    ACK d96b000e94d72d041689c5c47e374df2ebc0e011
  lsilva01:
    Tested ACK https://github.com/bitcoin/bitcoin/pull/23065/commits/d96b000e94d72d041689c5c47e374df2ebc0e011 on Ubuntu 20.04
  prayank23:
    ACK https://github.com/bitcoin/bitcoin/pull/23065/commits/d96b000e94d72d041689c5c47e374df2ebc0e011

Tree-SHA512: 957a5bbfe7f763036796906ccb1598feb6c14c5975838be1ba24a198840bf59e83233165cb112cebae909b6b25bf27275a4d7fa425923ef6c788ff671d7a89a8

9 files changed, 86 insertions, 28 deletions

diff --git a/src/interfaces/wallet.h b/src/interfaces/wallet.h
index a85db04b8b..6766e0510f 100644
--- a/src/interfaces/wallet.h
+++ b/src/interfaces/wallet.h
@@ -122,10 +122,10 @@ public:
     virtual bool displayAddress(const CTxDestination& dest) = 0;
 
     //! Lock coin.
-    virtual void lockCoin(const COutPoint& output) = 0;
+    virtual bool lockCoin(const COutPoint& output, const bool write_to_db) = 0;
 
     //! Unlock coin.
-    virtual void unlockCoin(const COutPoint& output) = 0;
+    virtual bool unlockCoin(const COutPoint& output) = 0;
 
     //! Return whether coin is locked.
     virtual bool isLockedCoin(const COutPoint& output) = 0;
diff --git a/src/qt/coincontroldialog.cpp b/src/qt/coincontroldialog.cpp
index d2a9365890..86dbd05b1a 100644
--- a/src/qt/coincontroldialog.cpp
+++ b/src/qt/coincontroldialog.cpp
@@ -241,7 +241,7 @@ void CoinControlDialog::lockCoin()
         contextMenuItem->setCheckState(COLUMN_CHECKBOX, Qt::Unchecked);
 
     COutPoint outpt(uint256S(contextMenuItem->data(COLUMN_ADDRESS, TxHashRole).toString().toStdString()), contextMenuItem->data(COLUMN_ADDRESS, VOutRole).toUInt());
-    model->wallet().lockCoin(outpt);
+    model->wallet().lockCoin(outpt, /* write_to_db = */ true);
     contextMenuItem->setDisabled(true);
     contextMenuItem->setIcon(COLUMN_CHECKBOX, platformStyle->SingleColorIcon(":/icons/lock_closed"));
     updateLabelLocked();
diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
index d6943e066a..93e49cb9a8 100644
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -131,6 +131,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "gettxoutsetinfo", 2, "use_index"},
     { "lockunspent", 0, "unlock" },
     { "lockunspent", 1, "transactions" },
+    { "lockunspent", 2, "persistent" },
     { "send", 0, "outputs" },
     { "send", 1, "conf_target" },
     { "send", 3, "fee_rate"},
diff --git a/src/wallet/interfaces.cpp b/src/wallet/interfaces.cpp
index 9a8c1e3c02..d9fc6de79b 100644
--- a/src/wallet/interfaces.cpp
+++ b/src/wallet/interfaces.cpp
@@ -214,15 +214,17 @@ public:
         LOCK(m_wallet->cs_wallet);
         return m_wallet->DisplayAddress(dest);
     }
-    void lockCoin(const COutPoint& output) override
+    bool lockCoin(const COutPoint& output, const bool write_to_db) override
     {
         LOCK(m_wallet->cs_wallet);
-        return m_wallet->LockCoin(output);
+        std::unique_ptr<WalletBatch> batch = write_to_db ? std::make_unique<WalletBatch>(m_wallet->GetDatabase()) : nullptr;
+        return m_wallet->LockCoin(output, batch.get());
     }
-    void unlockCoin(const COutPoint& output) override
+    bool unlockCoin(const COutPoint& output) override
     {
         LOCK(m_wallet->cs_wallet);
-        return m_wallet->UnlockCoin(output);
+        std::unique_ptr<WalletBatch> batch = std::make_unique<WalletBatch>(m_wallet->GetDatabase());
+        return m_wallet->UnlockCoin(output, batch.get());
     }
     bool isLockedCoin(const COutPoint& output) override
     {
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 77757e79a3..c101f6560d 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2140,8 +2140,9 @@ static RPCHelpMan lockunspent()
                 "If no transaction outputs are specified when unlocking then all current locked transaction outputs are unlocked.\n"
                 "A locked transaction output will not be chosen by automatic coin selection, when spending bitcoins.\n"
                 "Manually selected coins are automatically unlocked.\n"
-                "Locks are stored in memory only. Nodes start with zero locked outputs, and the locked output list\n"
-                "is always cleared (by virtue of process exit) when a node stops or fails.\n"
+                "Locks are stored in memory only, unless persistent=true, in which case they will be written to the\n"
+                "wallet database and loaded on node start. Unwritten (persistent=false) locks are always cleared\n"
+                "(by virtue of process exit) when a node stops or fails. Unlocking will clear both persistent and not.\n"
                 "Also see the listunspent call\n",
                 {
                     {"unlock", RPCArg::Type::BOOL, RPCArg::Optional::NO, "Whether to unlock (true) or lock (false) the specified transactions"},
@@ -2155,6 +2156,7 @@ static RPCHelpMan lockunspent()
                             },
                         },
                     },
+                    {"persistent", RPCArg::Type::BOOL, RPCArg::Default{false}, "Whether to write/erase this lock in the wallet database, or keep the change in memory only. Ignored for unlocking."},
                 },
                 RPCResult{
                     RPCResult::Type::BOOL, "", "Whether the command was successful or not"
@@ -2168,6 +2170,8 @@ static RPCHelpMan lockunspent()
             + HelpExampleCli("listlockunspent", "") +
             "\nUnlock the transaction again\n"
             + HelpExampleCli("lockunspent", "true \"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":1}]\"") +
+            "\nLock the transaction persistently in the wallet database\n"
+            + HelpExampleCli("lockunspent", "false \"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":1}]\" true") +
             "\nAs a JSON-RPC call\n"
             + HelpExampleRpc("lockunspent", "false, \"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":1}]\"")
                 },
@@ -2186,9 +2190,13 @@ static RPCHelpMan lockunspent()
 
     bool fUnlock = request.params[0].get_bool();
 
+    const bool persistent{request.params[2].isNull() ? false : request.params[2].get_bool()};
+
     if (request.params[1].isNull()) {
-        if (fUnlock)
-            pwallet->UnlockAllCoins();
+        if (fUnlock) {
+            if (!pwallet->UnlockAllCoins())
+                throw JSONRPCError(RPC_WALLET_ERROR, "Unlocking coins failed");
+        }
         return true;
     }
 
@@ -2239,17 +2247,24 @@ static RPCHelpMan lockunspent()
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, expected locked output");
         }
 
-        if (!fUnlock && is_locked) {
+        if (!fUnlock && is_locked && !persistent) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, output already locked");
         }
 
         outputs.push_back(outpt);
     }
 
+    std::unique_ptr<WalletBatch> batch = nullptr;
+    // Unlock is always persistent
+    if (fUnlock || persistent) batch = std::make_unique<WalletBatch>(pwallet->GetDatabase());
+
     // Atomically set (un)locked status for the outputs.
     for (const COutPoint& outpt : outputs) {
-        if (fUnlock) pwallet->UnlockCoin(outpt);
-        else pwallet->LockCoin(outpt);
+        if (fUnlock) {
+            if (!pwallet->UnlockCoin(outpt, batch.get())) throw JSONRPCError(RPC_WALLET_ERROR, "Unlocking coin failed");
+        } else {
+            if (!pwallet->LockCoin(outpt, batch.get())) throw JSONRPCError(RPC_WALLET_ERROR, "Locking coin failed");
+        }
     }
 
     return true;
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 70349b2455..a9610d05a4 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -589,11 +589,16 @@ bool CWallet::IsSpent(const uint256& hash, unsigned int n) const
     return false;
 }
 
-void CWallet::AddToSpends(const COutPoint& outpoint, const uint256& wtxid)
+void CWallet::AddToSpends(const COutPoint& outpoint, const uint256& wtxid, WalletBatch* batch)
 {
     mapTxSpends.insert(std::make_pair(outpoint, wtxid));
 
-    setLockedCoins.erase(outpoint);
+    if (batch) {
+        UnlockCoin(outpoint, batch);
+    } else {
+        WalletBatch temp_batch(GetDatabase());
+        UnlockCoin(outpoint, &temp_batch);
+    }
 
     std::pair<TxSpends::iterator, TxSpends::iterator> range;
     range = mapTxSpends.equal_range(outpoint);
@@ -601,7 +606,7 @@ void CWallet::AddToSpends(const COutPoint& outpoint, const uint256& wtxid)
 }
 
 
-void CWallet::AddToSpends(const uint256& wtxid)
+void CWallet::AddToSpends(const uint256& wtxid, WalletBatch* batch)
 {
     auto it = mapWallet.find(wtxid);
     assert(it != mapWallet.end());
@@ -610,7 +615,7 @@ void CWallet::AddToSpends(const uint256& wtxid)
         return;
 
     for (const CTxIn& txin : thisTx.tx->vin)
-        AddToSpends(txin.prevout, wtxid);
+        AddToSpends(txin.prevout, wtxid, batch);
 }
 
 bool CWallet::EncryptWallet(const SecureString& strWalletPassphrase)
@@ -910,7 +915,7 @@ CWalletTx* CWallet::AddToWallet(CTransactionRef tx, const CWalletTx::Confirmatio
         wtx.nOrderPos = IncOrderPosNext(&batch);
         wtx.m_it_wtxOrdered = wtxOrdered.insert(std::make_pair(wtx.nOrderPos, &wtx));
         wtx.nTimeSmart = ComputeTimeSmart(wtx);
-        AddToSpends(hash);
+        AddToSpends(hash, &batch);
     }
 
     if (!fInsertedNew)
@@ -2260,22 +2265,36 @@ bool CWallet::DisplayAddress(const CTxDestination& dest)
     return signer_spk_man->DisplayAddress(scriptPubKey, signer);
 }
 
-void CWallet::LockCoin(const COutPoint& output)
+bool CWallet::LockCoin(const COutPoint& output, WalletBatch* batch)
 {
     AssertLockHeld(cs_wallet);
     setLockedCoins.insert(output);
+    if (batch) {
+        return batch->WriteLockedUTXO(output);
+    }
+    return true;
 }
 
-void CWallet::UnlockCoin(const COutPoint& output)
+bool CWallet::UnlockCoin(const COutPoint& output, WalletBatch* batch)
 {
     AssertLockHeld(cs_wallet);
-    setLockedCoins.erase(output);
+    bool was_locked = setLockedCoins.erase(output);
+    if (batch && was_locked) {
+        return batch->EraseLockedUTXO(output);
+    }
+    return true;
 }
 
-void CWallet::UnlockAllCoins()
+bool CWallet::UnlockAllCoins()
 {
     AssertLockHeld(cs_wallet);
+    bool success = true;
+    WalletBatch batch(GetDatabase());
+    for (auto it = setLockedCoins.begin(); it != setLockedCoins.end(); ++it) {
+        success &= batch.EraseLockedUTXO(*it);
+    }
     setLockedCoins.clear();
+    return success;
 }
 
 bool CWallet::IsLockedCoin(uint256 hash, unsigned int n) const
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 2dc9eff712..6b4bcf31c4 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -256,8 +256,8 @@ private:
      */
     typedef std::multimap<COutPoint, uint256> TxSpends;
     TxSpends mapTxSpends GUARDED_BY(cs_wallet);
-    void AddToSpends(const COutPoint& outpoint, const uint256& wtxid) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
-    void AddToSpends(const uint256& wtxid) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    void AddToSpends(const COutPoint& outpoint, const uint256& wtxid, WalletBatch* batch = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    void AddToSpends(const uint256& wtxid, WalletBatch* batch = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /**
      * Add a transaction to the wallet, or update it.  pIndex and posInBlock should
@@ -449,9 +449,9 @@ public:
     bool DisplayAddress(const CTxDestination& dest) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     bool IsLockedCoin(uint256 hash, unsigned int n) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
-    void LockCoin(const COutPoint& output) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
-    void UnlockCoin(const COutPoint& output) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
-    void UnlockAllCoins() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    bool LockCoin(const COutPoint& output, WalletBatch* batch = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    bool UnlockCoin(const COutPoint& output, WalletBatch* batch = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    bool UnlockAllCoins() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void ListLockedCoins(std::vector<COutPoint>& vOutpts) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /*
diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index 03464cd2c8..c697534c06 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -40,6 +40,7 @@ const std::string FLAGS{"flags"};
 const std::string HDCHAIN{"hdchain"};
 const std::string KEYMETA{"keymeta"};
 const std::string KEY{"key"};
+const std::string LOCKED_UTXO{"lockedutxo"};
 const std::string MASTER_KEY{"mkey"};
 const std::string MINVERSION{"minversion"};
 const std::string NAME{"name"};
@@ -284,6 +285,16 @@ bool WalletBatch::WriteDescriptorCacheItems(const uint256& desc_id, const Descri
     return true;
 }
 
+bool WalletBatch::WriteLockedUTXO(const COutPoint& output)
+{
+    return WriteIC(std::make_pair(DBKeys::LOCKED_UTXO, std::make_pair(output.hash, output.n)), uint8_t{'1'});
+}
+
+bool WalletBatch::EraseLockedUTXO(const COutPoint& output)
+{
+    return EraseIC(std::make_pair(DBKeys::LOCKED_UTXO, std::make_pair(output.hash, output.n)));
+}
+
 class CWalletScanState {
 public:
     unsigned int nKeys{0};
@@ -701,6 +712,12 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
 
             wss.m_descriptor_crypt_keys.insert(std::make_pair(std::make_pair(desc_id, pubkey.GetID()), std::make_pair(pubkey, privkey)));
             wss.fIsEncrypted = true;
+        } else if (strType == DBKeys::LOCKED_UTXO) {
+            uint256 hash;
+            uint32_t n;
+            ssKey >> hash;
+            ssKey >> n;
+            pwallet->LockCoin(COutPoint(hash, n));
         } else if (strType != DBKeys::BESTBLOCK && strType != DBKeys::BESTBLOCK_NOMERKLE &&
                    strType != DBKeys::MINVERSION && strType != DBKeys::ACENTRY &&
                    strType != DBKeys::VERSION && strType != DBKeys::SETTINGS &&
diff --git a/src/wallet/walletdb.h b/src/wallet/walletdb.h
index 25c2ec5909..a549c8039c 100644
--- a/src/wallet/walletdb.h
+++ b/src/wallet/walletdb.h
@@ -65,6 +65,7 @@ extern const std::string FLAGS;
 extern const std::string HDCHAIN;
 extern const std::string KEY;
 extern const std::string KEYMETA;
+extern const std::string LOCKED_UTXO;
 extern const std::string MASTER_KEY;
 extern const std::string MINVERSION;
 extern const std::string NAME;
@@ -250,6 +251,9 @@ public:
     bool WriteDescriptorLastHardenedCache(const CExtPubKey& xpub, const uint256& desc_id, uint32_t key_exp_index);
     bool WriteDescriptorCacheItems(const uint256& desc_id, const DescriptorCache& cache);
 
+    bool WriteLockedUTXO(const COutPoint& output);
+    bool EraseLockedUTXO(const COutPoint& output);
+
     /// Write destination data key,value tuple to database
     bool WriteDestData(const std::string &address, const std::string &key, const std::string &value);
     /// Erase destination data tuple from wallet database