Merge bitcoin/bitcoin#22541: Add a new RPC command: restorewallet

5fe8100ff36fed6d50c2a25b028f57b25af3504c Change the wallet_backup.py test to use the restorewallet RPC command instead of restoring wallets manually. (lsilva01)
ae23faba6fc5cabc896f1175456d1018576f912d Add a new RPC command: restorewallet (lsilva01)

Pull request description:

  As far as I know, there is no command to restore the wallet from a backup file.
  The only way to do this is to replace the `wallet.dat` of a newly created wallet with the backup file, which is hardly an intuitive way.

  This PR implements the `restorewallet` RPC command which restores the wallet from the backup file.

  To test:
  First create a backup file:
  `$ bitcoin-cli -rpcwallet="wallet-01" backupwallet /home/Backups/wallet-01.bak`

  Then restore it in another wallet:
  `$ bitcoin-cli  restorewallet "restored-wallet-01" /home/Backups/wallet-01.bak`

ACKs for top commit:
  achow101:
    re-ACK 5fe8100ff36fed6d50c2a25b028f57b25af3504c
  prayank23:
    tACK https://github.com/bitcoin/bitcoin/commit/5fe8100ff36fed6d50c2a25b028f57b25af3504c
  meshcollider:
    utACK 5fe8100ff36fed6d50c2a25b028f57b25af3504c

Tree-SHA512: 9639df4d8ad32f255f5b868320dc69878bd9aceb3b471b49dfad500b67681e2d354292b5410982fbf18e25a44ed0c06fd4a0dd010e82807c2e00ff32e84047a1

3 files changed, 125 insertions, 40 deletions

diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
index 9b5d181c4e..4357ab2bb3 100644
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -187,6 +187,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "createwallet", 5, "descriptors"},
     { "createwallet", 6, "load_on_startup"},
     { "createwallet", 7, "external_signer"},
+    { "restorewallet", 2, "load_on_startup"},
     { "loadwallet", 1, "load_on_startup"},
     { "unloadwallet", 1, "load_on_startup"},
     { "getnodeaddresses", 0, "count"},
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 2e2300f887..2a5b547858 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2572,6 +2572,37 @@ static RPCHelpMan listwallets()
     };
 }
 
+static std::tuple<std::shared_ptr<CWallet>, std::vector<bilingual_str>> LoadWalletHelper(WalletContext& context, UniValue load_on_start_param, const std::string wallet_name)
+{
+    DatabaseOptions options;
+    DatabaseStatus status;
+    options.require_existing = true;
+    bilingual_str error;
+    std::vector<bilingual_str> warnings;
+    std::optional<bool> load_on_start = load_on_start_param.isNull() ? std::nullopt : std::optional<bool>(load_on_start_param.get_bool());
+    std::shared_ptr<CWallet> const wallet = LoadWallet(*context.chain, wallet_name, load_on_start, options, status, error, warnings);
+
+    if (!wallet) {
+        // Map bad format to not found, since bad format is returned when the
+        // wallet directory exists, but doesn't contain a data file.
+        RPCErrorCode code = RPC_WALLET_ERROR;
+        switch (status) {
+            case DatabaseStatus::FAILED_NOT_FOUND:
+            case DatabaseStatus::FAILED_BAD_FORMAT:
+                code = RPC_WALLET_NOT_FOUND;
+                break;
+            case DatabaseStatus::FAILED_ALREADY_LOADED:
+                code = RPC_WALLET_ALREADY_LOADED;
+                break;
+            default: // RPC_WALLET_ERROR is returned for all other cases.
+                break;
+        }
+        throw JSONRPCError(code, error.original);
+    }
+
+    return { wallet, warnings };
+}
+
 static RPCHelpMan loadwallet()
 {
     return RPCHelpMan{"loadwallet",
@@ -2598,30 +2629,7 @@ static RPCHelpMan loadwallet()
     WalletContext& context = EnsureWalletContext(request.context);
     const std::string name(request.params[0].get_str());
 
-    DatabaseOptions options;
-    DatabaseStatus status;
-    options.require_existing = true;
-    bilingual_str error;
-    std::vector<bilingual_str> warnings;
-    std::optional<bool> load_on_start = request.params[1].isNull() ? std::nullopt : std::optional<bool>(request.params[1].get_bool());
-    std::shared_ptr<CWallet> const wallet = LoadWallet(*context.chain, name, load_on_start, options, status, error, warnings);
-    if (!wallet) {
-        // Map bad format to not found, since bad format is returned when the
-        // wallet directory exists, but doesn't contain a data file.
-        RPCErrorCode code = RPC_WALLET_ERROR;
-        switch (status) {
-            case DatabaseStatus::FAILED_NOT_FOUND:
-            case DatabaseStatus::FAILED_BAD_FORMAT:
-                code = RPC_WALLET_NOT_FOUND;
-                break;
-            case DatabaseStatus::FAILED_ALREADY_LOADED:
-                code = RPC_WALLET_ALREADY_LOADED;
-                break;
-            default: // RPC_WALLET_ERROR is returned for all other cases.
-                break;
-        }
-        throw JSONRPCError(code, error.original);
-    }
+    auto [wallet, warnings] = LoadWalletHelper(context, request.params[1], name);
 
     UniValue obj(UniValue::VOBJ);
     obj.pushKV("name", wallet->GetName());
@@ -2795,6 +2803,68 @@ static RPCHelpMan createwallet()
     };
 }
 
+static RPCHelpMan restorewallet()
+{
+    return RPCHelpMan{
+        "restorewallet",
+        "\nRestore and loads a wallet from backup.\n",
+        {
+            {"wallet_name", RPCArg::Type::STR, RPCArg::Optional::NO, "The name that will be applied to the restored wallet"},
+            {"backup_file", RPCArg::Type::STR, RPCArg::Optional::NO, "The backup file that will be used to restore the wallet."},
+            {"load_on_startup", RPCArg::Type::BOOL, RPCArg::Optional::OMITTED_NAMED_ARG, "Save wallet name to persistent settings and load on startup. True to add wallet to startup list, false to remove, null to leave unchanged."},
+        },
+        RPCResult{
+            RPCResult::Type::OBJ, "", "",
+            {
+                {RPCResult::Type::STR, "name", "The wallet name if restored successfully."},
+                {RPCResult::Type::STR, "warning", "Warning message if wallet was not loaded cleanly."},
+            }
+        },
+        RPCExamples{
+            HelpExampleCli("restorewallet", "\"testwallet\" \"home\\backups\\backup-file.bak\"")
+            + HelpExampleRpc("restorewallet", "\"testwallet\" \"home\\backups\\backup-file.bak\"")
+            + HelpExampleCliNamed("restorewallet", {{"wallet_name", "testwallet"}, {"backup_file", "home\\backups\\backup-file.bak\""}, {"load_on_startup", true}})
+            + HelpExampleRpcNamed("restorewallet", {{"wallet_name", "testwallet"}, {"backup_file", "home\\backups\\backup-file.bak\""}, {"load_on_startup", true}})
+        },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+{
+
+    WalletContext& context = EnsureWalletContext(request.context);
+
+    std::string backup_file = request.params[1].get_str();
+
+    if (!fs::exists(backup_file)) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Backup file does not exist");
+    }
+
+    std::string wallet_name = request.params[0].get_str();
+
+    const fs::path wallet_path = fsbridge::AbsPathJoin(GetWalletDir(), wallet_name);
+
+    if (fs::exists(wallet_path)) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Wallet name already exists.");
+    }
+
+    if (!TryCreateDirectories(wallet_path)) {
+        throw JSONRPCError(RPC_WALLET_ERROR, strprintf("Failed to create database path '%s'. Database already exists.", wallet_path.string()));
+    }
+
+    auto wallet_file = wallet_path / "wallet.dat";
+
+    fs::copy_file(backup_file, wallet_file, fs::copy_option::fail_if_exists);
+
+    auto [wallet, warnings] = LoadWalletHelper(context, request.params[2], wallet_name);
+
+    UniValue obj(UniValue::VOBJ);
+    obj.pushKV("name", wallet->GetName());
+    obj.pushKV("warning", Join(warnings, Untranslated("\n")).original);
+
+    return obj;
+
+},
+    };
+}
+
 static RPCHelpMan unloadwallet()
 {
     return RPCHelpMan{"unloadwallet",
@@ -4639,6 +4709,7 @@ static const CRPCCommand commands[] =
     { "wallet",             &bumpfee,                        },
     { "wallet",             &psbtbumpfee,                    },
     { "wallet",             &createwallet,                   },
+    { "wallet",             &restorewallet,                  },
     { "wallet",             &dumpprivkey,                    },
     { "wallet",             &dumpwallet,                     },
     { "wallet",             &encryptwallet,                  },
diff --git a/test/functional/wallet_backup.py b/test/functional/wallet_backup.py
index 05a0ef0ea1..c7a983556d 100755
--- a/test/functional/wallet_backup.py
+++ b/test/functional/wallet_backup.py
@@ -111,6 +111,18 @@ class WalletBackupTest(BitcoinTestFramework):
         os.remove(os.path.join(self.nodes[1].datadir, self.chain, 'wallets', self.default_wallet_name, self.wallet_data_filename))
         os.remove(os.path.join(self.nodes[2].datadir, self.chain, 'wallets', self.default_wallet_name, self.wallet_data_filename))
 
+    def restore_nonexistent_wallet(self):
+        node = self.nodes[3]
+        nonexistent_wallet_file = os.path.join(self.nodes[0].datadir, 'nonexistent_wallet.bak')
+        wallet_name = "res0"
+        assert_raises_rpc_error(-8, "Backup file does not exist", node.restorewallet, wallet_name, nonexistent_wallet_file)
+
+    def restore_wallet_existent_name(self):
+        node = self.nodes[3]
+        wallet_file = os.path.join(self.nodes[0].datadir, 'wallet.bak')
+        wallet_name = "res0"
+        assert_raises_rpc_error(-8, "Wallet name already exists.", node.restorewallet, wallet_name, wallet_file)
+
     def init_three(self):
         self.init_wallet(0)
         self.init_wallet(1)
@@ -169,26 +181,27 @@ class WalletBackupTest(BitcoinTestFramework):
         ##
         # Test restoring spender wallets from backups
         ##
-        self.log.info("Restoring using wallet.dat")
-        self.stop_three()
-        self.erase_three()
+        self.log.info("Restoring wallets on node 3 using backup files")
 
-        # Start node2 with no chain
-        shutil.rmtree(os.path.join(self.nodes[2].datadir, self.chain, 'blocks'))
-        shutil.rmtree(os.path.join(self.nodes[2].datadir, self.chain, 'chainstate'))
+        self.restore_nonexistent_wallet()
 
-        # Restore wallets from backup
-        shutil.copyfile(os.path.join(self.nodes[0].datadir, 'wallet.bak'), os.path.join(self.nodes[0].datadir, self.chain, 'wallets', self.default_wallet_name, self.wallet_data_filename))
-        shutil.copyfile(os.path.join(self.nodes[1].datadir, 'wallet.bak'), os.path.join(self.nodes[1].datadir, self.chain, 'wallets', self.default_wallet_name, self.wallet_data_filename))
-        shutil.copyfile(os.path.join(self.nodes[2].datadir, 'wallet.bak'), os.path.join(self.nodes[2].datadir, self.chain, 'wallets', self.default_wallet_name, self.wallet_data_filename))
+        backup_file_0 = os.path.join(self.nodes[0].datadir, 'wallet.bak')
+        backup_file_1 = os.path.join(self.nodes[1].datadir, 'wallet.bak')
+        backup_file_2 = os.path.join(self.nodes[2].datadir, 'wallet.bak')
 
-        self.log.info("Re-starting nodes")
-        self.start_three()
-        self.sync_blocks()
+        self.nodes[3].restorewallet("res0", backup_file_0)
+        self.nodes[3].restorewallet("res1", backup_file_1)
+        self.nodes[3].restorewallet("res2", backup_file_2)
+
+        res0_rpc = self.nodes[3].get_wallet_rpc("res0")
+        res1_rpc = self.nodes[3].get_wallet_rpc("res1")
+        res2_rpc = self.nodes[3].get_wallet_rpc("res2")
+
+        assert_equal(res0_rpc.getbalance(), balance0)
+        assert_equal(res1_rpc.getbalance(), balance1)
+        assert_equal(res2_rpc.getbalance(), balance2)
 
-        assert_equal(self.nodes[0].getbalance(), balance0)
-        assert_equal(self.nodes[1].getbalance(), balance1)
-        assert_equal(self.nodes[2].getbalance(), balance2)
+        self.restore_wallet_existent_name()
 
         if not self.options.descriptors:
             self.log.info("Restoring using dumped wallet")