[wallet] [rpc] Add `createwallet` RPC

Add a `createwallet` RPC to allow wallets to be created dynamically at
runtime. This functionality is currently only available through RPC and
newly created wallets will not be displayed in the GUI.

src/wallet/rpcwallet.cpp

@@ -3114,6 +3114,52 @@ UniValue loadwallet(const JSONRPCRequest& request)
     return obj;
 }
 
+UniValue createwallet(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() != 1)
+        throw std::runtime_error(
+            "createwallet \"wallet_name\"\n"
+            "\nCreates and loads a new wallet.\n"
+            "\nArguments:\n"
+            "1. \"wallet_name\"    (string, required) The name for the new wallet.\n"
+            "\nResult:\n"
+            "{\n"
+            "  \"name\" :    <wallet_name>,        (string) The wallet name if created successfully.\n"
+            "  \"warning\" : <warning>,            (string) Warning message if wallet was not loaded cleanly.\n"
+            "}\n"
+            "\nExamples:\n"
+            + HelpExampleCli("createwallet", "\"test.dat\"")
+            + HelpExampleRpc("createwallet", "\"test.dat\"")
+        );
+    std::string wallet_name = request.params[0].get_str();
+    std::string error;
+    std::string warning;
+
+    fs::path wallet_path = fs::absolute(wallet_name, GetWalletDir());
+    if (fs::symlink_status(wallet_path).type() != fs::file_not_found) {
+        throw JSONRPCError(RPC_WALLET_ERROR, "Wallet " + wallet_name + " already exists.");
+    }
+
+    // Wallet::Verify will check if we're trying to create a wallet with a duplication name.
+    if (!CWallet::Verify(wallet_name, false, error, warning)) {
+        throw JSONRPCError(RPC_WALLET_ERROR, "Wallet file verification failed: " + error);
+    }
+
+    std::shared_ptr<CWallet> const wallet = CWallet::CreateWalletFromFile(wallet_name, fs::absolute(wallet_name, GetWalletDir()));
+    if (!wallet) {
+        throw JSONRPCError(RPC_WALLET_ERROR, "Wallet creation failed.");
+    }
+    AddWallet(wallet);
+
+    wallet->postInitProcess();
+
+    UniValue obj(UniValue::VOBJ);
+    obj.pushKV("name", wallet->GetName());
+    obj.pushKV("warning", warning);
+
+    return obj;
+}
+
 static UniValue resendwallettransactions(const JSONRPCRequest& request)
 {
     std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
@@ -4315,6 +4361,7 @@ static const CRPCCommand commands[] =
     { "hidden",             "addwitnessaddress",                &addwitnessaddress,             {"address","p2sh"} },
     { "wallet",             "backupwallet",                     &backupwallet,                  {"destination"} },
     { "wallet",             "bumpfee",                          &bumpfee,                       {"txid", "options"} },
+    { "wallet",             "createwallet",                     &createwallet,                  {"filename"} },
     { "wallet",             "dumpprivkey",                      &dumpprivkey,                   {"address"}  },
     { "wallet",             "dumpwallet",                       &dumpwallet,                    {"filename"} },
     { "wallet",             "encryptwallet",                    &encryptwallet,                 {"passphrase"} },