Merge bitcoin#22805: refactor: use CWallet const shared pointers in dump{privkey,wallet}

d150fe3 refactor: use `CWallet` const shared pointers in dump{privkey,wallet} RPCs (Sebastian Falbesoner)
ec2792d refactor: use const `LegacyScriptPubKeyMan` references in dump{privkey,wallet} RPCs (Sebastian Falbesoner)
29905c0 refactor: avoid multiple key->metadata lookups in dumpwallet RPC (Sebastian Falbesoner)

Pull request description:

  ~~This PR is based on bitcoin#22787 ("refactor: actual immutable pointing"), which should be reviewed first.~~ (merged by now)

  It aims to make the CWallet shared pointers actually immutable also for the `dumpprivkey` and `dumpwallet` RPC methods. For doing that, some more preparations are needed; we need a const-counterpart to the helper `EnsureLegacyScriptPubKeyMan` that accepts a const CWallet pointer and accordingly also returns a const `LegacyScriptPubKeyMan` instance. The metadata lookup in `dumpwallet` is changed to not need a mutable `ScriptPubKeyMan` instance by avoiding using the `operator[]` in its mapKeyMetadata map, which also avoids repeated lookups.

ACKs for top commit:
  laanwj:
    Code review ACK d150fe3

Tree-SHA512: 90ac05e21f40c6d0ebb479a71c545da2fd89940b9ca3409d9f932abc983bf8830d34c45086e68880d0d1e994846fbefee7534eec142ff4268e0fa28a1a411d36

Author: laanwj

src/wallet/rpcdump.cpp

@@ -57,7 +57,7 @@ static std::string DecodeDumpString(const std::string &str) {
     return ret.str();
 }
 
-static bool GetWalletAddressesForKey(LegacyScriptPubKeyMan* spk_man, const CWallet& wallet, const CKeyID& keyid, std::string& strAddr, std::string& strLabel) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
+static bool GetWalletAddressesForKey(const LegacyScriptPubKeyMan* spk_man, const CWallet& wallet, const CKeyID& keyid, std::string& strAddr, std::string& strLabel) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet)
 {
     bool fLabelFound = false;
     CKey key;
@@ -681,10 +681,10 @@ RPCHelpMan dumpprivkey()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
-    LegacyScriptPubKeyMan& spk_man = EnsureLegacyScriptPubKeyMan(*pwallet);
+    const LegacyScriptPubKeyMan& spk_man = EnsureConstLegacyScriptPubKeyMan(*pwallet);
 
     LOCK2(pwallet->cs_wallet, spk_man.cs_KeyStore);
 
@@ -731,11 +731,11 @@ RPCHelpMan dumpwallet()
                 },
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
-    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
+    const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return NullUniValue;
 
-    CWallet& wallet = *pwallet;
-    LegacyScriptPubKeyMan& spk_man = EnsureLegacyScriptPubKeyMan(wallet);
+    const CWallet& wallet = *pwallet;
+    const LegacyScriptPubKeyMan& spk_man = EnsureConstLegacyScriptPubKeyMan(wallet);
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -809,19 +809,22 @@ RPCHelpMan dumpwallet()
         std::string strLabel;
         CKey key;
         if (spk_man.GetKey(keyid, key)) {
+            CKeyMetadata metadata;
+            const auto it{spk_man.mapKeyMetadata.find(keyid)};
+            if (it != spk_man.mapKeyMetadata.end()) metadata = it->second;
             file << strprintf("%s %s ", EncodeSecret(key), strTime);
             if (GetWalletAddressesForKey(&spk_man, wallet, keyid, strAddr, strLabel)) {
                 file << strprintf("label=%s", strLabel);
             } else if (keyid == seed_id) {
                 file << "hdseed=1";
             } else if (mapKeyPool.count(keyid)) {
                 file << "reserve=1";
-            } else if (spk_man.mapKeyMetadata[keyid].hdKeypath == "s") {
+            } else if (metadata.hdKeypath == "s") {
                 file << "inactivehdseed=1";
             } else {
                 file << "change=1";
             }
-            file << strprintf(" # addr=%s%s\n", strAddr, (spk_man.mapKeyMetadata[keyid].has_key_origin ? " hdkeypath="+WriteHDKeypath(spk_man.mapKeyMetadata[keyid].key_origin.path) : ""));
+            file << strprintf(" # addr=%s%s\n", strAddr, (metadata.has_key_origin ? " hdkeypath="+WriteHDKeypath(metadata.key_origin.path) : ""));
         }
     }
     file << "\n";

src/wallet/rpcwallet.cpp

@@ -150,6 +150,15 @@ LegacyScriptPubKeyMan& EnsureLegacyScriptPubKeyMan(CWallet& wallet, bool also_cr
     return *spk_man;
 }
 
+const LegacyScriptPubKeyMan& EnsureConstLegacyScriptPubKeyMan(const CWallet& wallet)
+{
+    const LegacyScriptPubKeyMan* spk_man = wallet.GetLegacyScriptPubKeyMan();
+    if (!spk_man) {
+        throw JSONRPCError(RPC_WALLET_ERROR, "This type of wallet does not support this command");
+    }
+    return *spk_man;
+}
+
 static void WalletTxToJSON(const CWallet& wallet, const CWalletTx& wtx, UniValue& entry)
 {
     interfaces::Chain& chain = wallet.chain();

src/wallet/rpcwallet.h

@@ -34,6 +34,7 @@ std::shared_ptr<CWallet> GetWalletForJSONRPCRequest(const JSONRPCRequest& reques
 void EnsureWalletIsUnlocked(const CWallet&);
 WalletContext& EnsureWalletContext(const std::any& context);
 LegacyScriptPubKeyMan& EnsureLegacyScriptPubKeyMan(CWallet& wallet, bool also_create = false);
+const LegacyScriptPubKeyMan& EnsureConstLegacyScriptPubKeyMan(const CWallet& wallet);
 
 RPCHelpMan getaddressinfo();
 RPCHelpMan signrawtransactionwithwallet();