Add loadwallet and createwallet RPC load_on_startup options

This maintains a persistent list of wallets stored in settings that will
automatically be loaded on startup. Being able to load a wallet automatically
on startup will be more useful in the GUI when the option to create wallets is
added in #15006, but it's reasonable to expose this feature by RPC as well.

src/interfaces/chain.cpp

@@ -365,6 +365,27 @@ class ChainImpl : public Chain
         RPCRunLater(name, std::move(fn), seconds);
     }
     int rpcSerializationFlags() override { return RPCSerializationFlags(); }
+    util::SettingsValue getSetting(const std::string& name) override
+    {
+        util::SettingsValue result;
+        gArgs.LockSettings([&](const util::Settings& settings) {
+            if (const util::SettingsValue* value = util::FindKey(settings.rw_settings, name)) {
+                result = *value;
+            }
+        });
+        return result;
+    }
+    bool updateSetting(const std::string& name, const util::SettingsValue& value) override
+    {
+        gArgs.LockSettings([&](util::Settings& settings) {
+            if (value.isNull()) {
+                settings.rw_settings.erase(name);
+            } else {
+                settings.rw_settings[name] = value;
+            }
+        });
+        return gArgs.WriteSettingsFile();
+    }
     void requestMempoolTransactions(Notifications& notifications) override
     {
         LOCK2(::cs_main, ::mempool.cs);

src/interfaces/chain.h

@@ -7,6 +7,7 @@
 
 #include <optional.h>               // For Optional and nullopt
 #include <primitives/transaction.h> // For CTransactionRef
+#include <util/settings.h>          // For util::SettingsValue
 
 #include <memory>
 #include <stddef.h>
@@ -248,6 +249,12 @@ class Chain
     //! Current RPC serialization flags.
     virtual int rpcSerializationFlags() = 0;
 
+    // Return <datadir>/settings.json setting value.
+    virtual util::SettingsValue getSetting(const std::string& name) = 0;
+
+    //! Write a setting to <datadir>/settings.json.
+    virtual bool updateSetting(const std::string& name, const util::SettingsValue& value) = 0;
+
     //! Synchronously send TransactionAddedToMempool notifications about all
     //! current mempool transactions to the specified handler and return after
     //! the last one is sent. These notifications aren't coordinated with async

src/rpc/client.cpp

@@ -169,6 +169,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "createwallet", 1, "disable_private_keys"},
     { "createwallet", 2, "blank"},
     { "createwallet", 4, "avoid_reuse"},
+    { "createwallet", 5, "load_on_startup"},
+    { "loadwallet", 1, "load_on_startup"},
     { "getnodeaddresses", 0, "count"},
     { "stop", 0, "wait" },
 };

src/wallet/load.cpp

@@ -12,6 +12,8 @@
 #include <util/translation.h>
 #include <wallet/wallet.h>
 
+#include <univalue.h>
+
 bool VerifyWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files)
 {
     if (gArgs.IsArgSet("-walletdir")) {
@@ -116,3 +118,26 @@ void UnloadWallets()
         UnloadWallet(std::move(wallet));
     }
 }
+
+bool AddWalletSetting(interfaces::Chain& chain, const std::string& wallet_name)
+{
+    util::SettingsValue setting_value = chain.getSetting("wallet");
+    if (!setting_value.isArray()) setting_value.setArray();
+    for (const util::SettingsValue& value : setting_value.getValues()) {
+        if (value.isStr() && value.get_str() == wallet_name) return true;
+    }
+    setting_value.push_back(wallet_name);
+    return chain.updateSetting("wallet", setting_value);
+}
+
+bool RemoveWalletSetting(interfaces::Chain& chain, const std::string& wallet_name)
+{
+    util::SettingsValue setting_value = chain.getSetting("wallet");
+    if (!setting_value.isArray()) return true;
+    util::SettingsValue new_value(util::SettingsValue::VARR);
+    for (const util::SettingsValue& value : setting_value.getValues()) {
+        if (!value.isStr() || value.get_str() != wallet_name) new_value.push_back(value);
+    }
+    if (new_value.size() == setting_value.size()) return true;
+    return chain.updateSetting("wallet", new_value);
+}

src/wallet/load.h

@@ -35,4 +35,10 @@ void StopWallets();
 //! Close all wallets.
 void UnloadWallets();
 
+//! Add wallet name to persistent configuration so it will be loaded on startup.
+bool AddWalletSetting(interfaces::Chain& chain, const std::string& wallet_name);
+
+//! Remove wallet name from persistent configuration so it will not be loaded on startup.
+bool RemoveWalletSetting(interfaces::Chain& chain, const std::string& wallet_name);
+
 #endif // BITCOIN_WALLET_LOAD_H

src/wallet/rpcwallet.cpp

@@ -26,6 +26,7 @@
 #include <util/validation.h>
 #include <wallet/coincontrol.h>
 #include <wallet/feebumper.h>
+#include <wallet/load.h>
 #include <wallet/psbtwallet.h>
 #include <wallet/rpcwallet.h>
 #include <wallet/wallet.h>
@@ -2571,6 +2572,7 @@ static UniValue loadwallet(const JSONRPCRequest& request)
                 "\napplied to the new wallet (eg -zapwallettxes, upgradewallet, rescan, etc).\n",
                 {
                     {"filename", RPCArg::Type::STR, RPCArg::Optional::NO, "The wallet directory or .dat file."},
+                    {"load_on_startup", RPCArg::Type::BOOL, /* default */ "false", "Save wallet name to persistent settings and load on startup."},
                 },
                 RPCResult{
             "{\n"
@@ -2596,11 +2598,21 @@ static UniValue loadwallet(const JSONRPCRequest& request)
         }
     }
 
+    bool load_on_startup = false;
+    if (!request.params[1].isNull() && request.params[1].isBool()) {
+        load_on_startup = request.params[1].get_bool();
+    }
+
     std::string error;
     std::vector<std::string> warning;
     std::shared_ptr<CWallet> const wallet = LoadWallet(*g_rpc_chain, location, error, warning);
     if (!wallet) throw JSONRPCError(RPC_WALLET_ERROR, error);
 
+    if (load_on_startup && !AddWalletSetting(wallet->chain(), location.GetName())) {
+        throw JSONRPCError(RPC_MISC_ERROR, "Wallet loaded, but load-on-startup list could not be written, so wallet "
+                                           "may be not loaded on node restart.");
+    }
+
     UniValue obj(UniValue::VOBJ);
     obj.pushKV("name", wallet->GetName());
     obj.pushKV("warning", Join(warning, "\n"));
@@ -2686,6 +2698,7 @@ static UniValue createwallet(const JSONRPCRequest& request)
             {"blank", RPCArg::Type::BOOL, /* default */ "false", "Create a blank wallet. A blank wallet has no keys or HD seed. One can be set using sethdseed."},
             {"passphrase", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "Encrypt the wallet with this passphrase."},
             {"avoid_reuse", RPCArg::Type::BOOL, /* default */ "false", "Keep track of coin reuse, and treat dirty and clean coins differently with privacy considerations in mind."},
+            {"load_on_startup", RPCArg::Type::BOOL, /* default */ "false", "Save wallet name to persistent settings and load on startup."},
         },
         RPCResult{
             "{\n"
@@ -2722,6 +2735,11 @@ static UniValue createwallet(const JSONRPCRequest& request)
         flags |= WALLET_FLAG_AVOID_REUSE;
     }
 
+    bool load_on_startup = false;
+    if (!request.params[5].isNull() && request.params[5].isBool()) {
+        load_on_startup = request.params[5].get_bool();
+    }
+
     std::string error;
     std::shared_ptr<CWallet> wallet;
     WalletCreationStatus status = CreateWallet(*g_rpc_chain, passphrase, flags, request.params[0].get_str(), error, warnings, wallet);
@@ -2735,6 +2753,11 @@ static UniValue createwallet(const JSONRPCRequest& request)
         // no default case, so the compiler can warn about missing cases
     }
 
+    if (load_on_startup && !AddWalletSetting(wallet->chain(), wallet->GetName())) {
+        throw JSONRPCError(RPC_MISC_ERROR, "Wallet loaded, but load-on-startup list could not be written, so wallet "
+                                           "may be not loaded on node restart.");
+    }
+
     UniValue obj(UniValue::VOBJ);
     obj.pushKV("name", wallet->GetName());
     obj.pushKV("warning", Join(warnings, "\n"));
@@ -2778,7 +2801,12 @@ static UniValue unloadwallet(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_MISC_ERROR, "Requested wallet already unloaded");
     }
 
+    interfaces::Chain& chain = wallet->chain();
     UnloadWallet(std::move(wallet));
+    if (!RemoveWalletSetting(chain, wallet_name)) {
+        throw JSONRPCError(RPC_MISC_ERROR, "Wallet unloaded, but load-on-startup list could not be written, so wallet "
+                                           "may be reloaded on node restart.");
+    }
 
     return NullUniValue;
 }
@@ -4240,7 +4268,7 @@ static const CRPCCommand commands[] =
     { "wallet",             "addmultisigaddress",               &addmultisigaddress,            {"nrequired","keys","label","address_type"} },
     { "wallet",             "backupwallet",                     &backupwallet,                  {"destination"} },
     { "wallet",             "bumpfee",                          &bumpfee,                       {"txid", "options"} },
-    { "wallet",             "createwallet",                     &createwallet,                  {"wallet_name", "disable_private_keys", "blank", "passphrase", "avoid_reuse"} },
+    { "wallet",             "createwallet",                     &createwallet,                  {"wallet_name", "disable_private_keys", "blank", "passphrase", "avoid_reuse", "load_on_startup"} },
     { "wallet",             "dumpprivkey",                      &dumpprivkey,                   {"address"}  },
     { "wallet",             "dumpwallet",                       &dumpwallet,                    {"filename"} },
     { "wallet",             "encryptwallet",                    &encryptwallet,                 {"passphrase"} },
@@ -4272,7 +4300,7 @@ static const CRPCCommand commands[] =
     { "wallet",             "listunspent",                      &listunspent,                   {"minconf","maxconf","addresses","include_unsafe","query_options"} },
     { "wallet",             "listwalletdir",                    &listwalletdir,                 {} },
     { "wallet",             "listwallets",                      &listwallets,                   {} },
-    { "wallet",             "loadwallet",                       &loadwallet,                    {"filename"} },
+    { "wallet",             "loadwallet",                       &loadwallet,                    {"filename", "load_on_startup"} },
     { "wallet",             "lockunspent",                      &lockunspent,                   {"unlock","transactions"} },
     { "wallet",             "removeprunedfunds",                &removeprunedfunds,             {"txid"} },
     { "wallet",             "rescanblockchain",                 &rescanblockchain,              {"start_height", "stop_height"} },

test/functional/test_runner.py

@@ -210,6 +210,7 @@
     'p2p_node_network_limited.py',
     'p2p_permissions.py',
     'feature_blocksdir.py',
+    'wallet_startup.py',
     'feature_config_args.py',
     'rpc_help.py',
     'feature_help.py',

test/functional/wallet_startup.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+# Copyright (c) 2017-2019 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test wallet load on startup.
+
+Verify that a bitcoind node can maintain list of wallets loading on startup
+"""
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+)
+
+
+class WalletStartupTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+        self.supports_cli = True
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def run_test(self):
+        node = self.nodes[0]
+
+        self.nodes[0].createwallet(wallet_name='w0', load_on_startup=True)
+        self.nodes[0].createwallet(wallet_name='w1', load_on_startup=False)
+        self.nodes[0].createwallet(wallet_name='w2', load_on_startup=True)
+        self.nodes[0].createwallet(wallet_name='w3', load_on_startup=False)
+        self.nodes[0].createwallet(wallet_name='w4', load_on_startup=False)
+        self.nodes[0].unloadwallet(wallet_name='w0')
+        self.nodes[0].unloadwallet(wallet_name='w4')
+        self.nodes[0].loadwallet(filename='w4', load_on_startup=True)
+        assert_equal(set(node.listwallets()), set(('', 'w1', 'w2', 'w3', 'w4')))
+        self.stop_nodes()
+        self.start_node(0, [])
+        assert_equal(set(node.listwallets()), set(('w2', 'w4')))
+
+if __name__ == '__main__':
+    WalletStartupTest().main()