diff --git a/src/util/system.cpp b/src/util/system.cpp
index 4784b92217..7b9ac9f198 100644
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -1,1383 +1,1389 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <fs.h>
 #include <util/system.h>
 
 #include <chainparamsbase.h>
 #include <fs.h>
 #include <random.h>
 #include <serialize.h>
 #include <util/strencodings.h>
 #include <util/time.h>
 
 #include <boost/thread.hpp>
 
 #include <cstdarg>
 #include <memory>
 
 #if (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
 #include <pthread.h>
 #include <pthread_np.h>
 #endif
 
 #ifndef WIN32
 // for posix_fallocate
 #ifdef __linux__
 
 #ifdef _POSIX_C_SOURCE
 #undef _POSIX_C_SOURCE
 #endif
 
 #define _POSIX_C_SOURCE 200112L
 
 #endif // __linux__
 
 #include <algorithm>
 #include <fcntl.h>
 #include <sched.h>
 #include <sys/resource.h>
 #include <sys/stat.h>
 
 #else
 
 #ifdef _MSC_VER
 #pragma warning(disable : 4786)
 #pragma warning(disable : 4804)
 #pragma warning(disable : 4805)
 #pragma warning(disable : 4717)
 #endif
 
 #ifdef _WIN32_WINNT
 #undef _WIN32_WINNT
 #endif
 #define _WIN32_WINNT 0x0501
 
 #ifdef _WIN32_IE
 #undef _WIN32_IE
 #endif
 #define _WIN32_IE 0x0501
 
 #define WIN32_LEAN_AND_MEAN 1
 #ifndef NOMINMAX
 #define NOMINMAX
 #endif
 #include <codecvt>
 
 #include <io.h> /* for _commit */
 #include <shellapi.h>
 #include <shlobj.h>
 #endif
 
 #ifdef HAVE_SYS_PRCTL_H
 #include <sys/prctl.h>
 #endif
 
 #ifdef HAVE_MALLOPT_ARENA_MAX
 #include <malloc.h>
 #endif
 
 // Application startup time (used for uptime calculation)
 const int64_t nStartupTime = GetTime();
 
 const char *const BITCOIN_CONF_FILENAME = "bitcoin.conf";
 const char *const BITCOIN_PID_FILENAME = "bitcoind.pid";
 
 ArgsManager gArgs;
 
 /**
  * A map that contains all the currently held directory locks. After successful
  * locking, these will be held here until the global destructor cleans them up
  * and thus automatically unlocks them, or ReleaseDirectoryLocks is called.
  */
 static std::map<std::string, std::unique_ptr<fsbridge::FileLock>> dir_locks;
 /** Mutex to protect dir_locks. */
 static std::mutex cs_dir_locks;
 
 bool LockDirectory(const fs::path &directory, const std::string lockfile_name,
                    bool probe_only) {
     std::lock_guard<std::mutex> ulock(cs_dir_locks);
     fs::path pathLockFile = directory / lockfile_name;
 
     // If a lock for this directory already exists in the map, don't try to
     // re-lock it
     if (dir_locks.count(pathLockFile.string())) {
         return true;
     }
 
     // Create empty lock file if it doesn't exist.
     FILE *file = fsbridge::fopen(pathLockFile, "a");
     if (file) {
         fclose(file);
     }
     auto lock = std::make_unique<fsbridge::FileLock>(pathLockFile);
     if (!lock->TryLock()) {
         return error("Error while attempting to lock directory %s: %s",
                      directory.string(), lock->GetReason());
     }
     if (!probe_only) {
         // Lock successful and we're not just probing, put it into the map
         dir_locks.emplace(pathLockFile.string(), std::move(lock));
     }
     return true;
 }
 
+void UnlockDirectory(const fs::path &directory,
+                     const std::string &lockfile_name) {
+    std::lock_guard<std::mutex> lock(cs_dir_locks);
+    dir_locks.erase((directory / lockfile_name).string());
+}
+
 void ReleaseDirectoryLocks() {
     std::lock_guard<std::mutex> ulock(cs_dir_locks);
     dir_locks.clear();
 }
 
 bool DirIsWritable(const fs::path &directory) {
     fs::path tmpFile = directory / fs::unique_path();
 
     FILE *file = fsbridge::fopen(tmpFile, "a");
     if (!file) {
         return false;
     }
 
     fclose(file);
     remove(tmpFile);
 
     return true;
 }
 
 bool CheckDiskSpace(const fs::path &dir, uint64_t additional_bytes) {
     // 50 MiB
     constexpr uint64_t min_disk_space = 52428800;
 
     uint64_t free_bytes_available = fs::space(dir).available;
     return free_bytes_available >= min_disk_space + additional_bytes;
 }
 
 /**
  * Interpret a string argument as a boolean.
  *
  * The definition of atoi() requires that non-numeric string values like "foo",
  * return 0. This means that if a user unintentionally supplies a non-integer
  * argument here, the return value is always false. This means that -foo=false
  * does what the user probably expects, but -foo=true is well defined but does
  * not do what they probably expected.
  *
  * The return value of atoi() is undefined when given input not representable as
  * an int. On most systems this means string value between "-2147483648" and
  * "2147483647" are well defined (this method will return true). Setting
  * -txindex=2147483648 on most systems, however, is probably undefined.
  *
  * For a more extensive discussion of this topic (and a wide range of opinions
  * on the Right Way to change this code), see PR12713.
  */
 static bool InterpretBool(const std::string &strValue) {
     if (strValue.empty()) {
         return true;
     }
     return (atoi(strValue) != 0);
 }
 
 /** Internal helper functions for ArgsManager */
 class ArgsManagerHelper {
 public:
     typedef std::map<std::string, std::vector<std::string>> MapArgs;
 
     /** Determine whether to use config settings in the default section,
      *  See also comments around ArgsManager::ArgsManager() below. */
     static inline bool UseDefaultSection(const ArgsManager &am,
                                          const std::string &arg)
         EXCLUSIVE_LOCKS_REQUIRED(am.cs_args) {
         return (am.m_network == CBaseChainParams::MAIN ||
                 am.m_network_only_args.count(arg) == 0);
     }
 
     /** Convert regular argument into the network-specific setting */
     static inline std::string NetworkArg(const ArgsManager &am,
                                          const std::string &arg) {
         assert(arg.length() > 1 && arg[0] == '-');
         return "-" + am.m_network + "." + arg.substr(1);
     }
 
     /** Find arguments in a map and add them to a vector */
     static inline void AddArgs(std::vector<std::string> &res,
                                const MapArgs &map_args,
                                const std::string &arg) {
         auto it = map_args.find(arg);
         if (it != map_args.end()) {
             res.insert(res.end(), it->second.begin(), it->second.end());
         }
     }
 
     /**
      * Return true/false if an argument is set in a map, and also
      * return the first (or last) of the possibly multiple values it has
      */
     static inline std::pair<bool, std::string>
     GetArgHelper(const MapArgs &map_args, const std::string &arg,
                  bool getLast = false) {
         auto it = map_args.find(arg);
 
         if (it == map_args.end() || it->second.empty()) {
             return std::make_pair(false, std::string());
         }
 
         if (getLast) {
             return std::make_pair(true, it->second.back());
         } else {
             return std::make_pair(true, it->second.front());
         }
     }
 
     /**
      * Get the string value of an argument, returning a pair of a boolean
      * indicating the argument was found, and the value for the argument
      * if it was found (or the empty string if not found).
      */
     static inline std::pair<bool, std::string> GetArg(const ArgsManager &am,
                                                       const std::string &arg) {
         LOCK(am.cs_args);
         std::pair<bool, std::string> found_result(false, std::string());
 
         // We pass "true" to GetArgHelper in order to return the last
         // argument value seen from the command line (so "bitcoind -foo=bar
         // -foo=baz" gives GetArg(am,"foo")=={true,"baz"}
         found_result = GetArgHelper(am.m_override_args, arg, true);
         if (found_result.first) {
             return found_result;
         }
 
         // But in contrast we return the first argument seen in a config file,
         // so "foo=bar \n foo=baz" in the config file gives
         // GetArg(am,"foo")={true,"bar"}
         if (!am.m_network.empty()) {
             found_result = GetArgHelper(am.m_config_args, NetworkArg(am, arg));
             if (found_result.first) {
                 return found_result;
             }
         }
 
         if (UseDefaultSection(am, arg)) {
             found_result = GetArgHelper(am.m_config_args, arg);
             if (found_result.first) {
                 return found_result;
             }
         }
 
         return found_result;
     }
 
     /* Special test for -testnet and -regtest args, because we don't want to be
      * confused by craziness like "[regtest] testnet=1"
      */
     static inline bool GetNetBoolArg(const ArgsManager &am,
                                      const std::string &net_arg)
         EXCLUSIVE_LOCKS_REQUIRED(am.cs_args) {
         std::pair<bool, std::string> found_result(false, std::string());
         found_result = GetArgHelper(am.m_override_args, net_arg, true);
         if (!found_result.first) {
             found_result = GetArgHelper(am.m_config_args, net_arg, true);
             if (!found_result.first) {
                 // not set
                 return false;
             }
         }
         // is set, so evaluate
         return InterpretBool(found_result.second);
     }
 };
 
 /**
  * Interpret -nofoo as if the user supplied -foo=0.
  *
  * This method also tracks when the -no form was supplied, and if so, checks
  * whether there was a double-negative (-nofoo=0 -> -foo=1).
  *
  * If there was not a double negative, it removes the "no" from the key, and
  * returns true, indicating the caller should clear the args vector to indicate
  * a negated option.
  *
  * If there was a double negative, it removes "no" from the key, sets the value
  * to "1" and returns false.
  *
  * If there was no "no", it leaves key and value untouched and returns false.
  *
  * Where an option was negated can be later checked using the IsArgNegated()
  * method. One use case for this is to have a way to disable options that are
  * not normally boolean (e.g. using -nodebuglogfile to request that debug log
  * output is not sent to any file at all).
  */
 static bool InterpretNegatedOption(std::string &key, std::string &val) {
     assert(key[0] == '-');
 
     size_t option_index = key.find('.');
     if (option_index == std::string::npos) {
         option_index = 1;
     } else {
         ++option_index;
     }
     if (key.substr(option_index, 2) == "no") {
         bool bool_val = InterpretBool(val);
         key.erase(option_index, 2);
         if (!bool_val) {
             // Double negatives like -nofoo=0 are supported (but discouraged)
             LogPrintf(
                 "Warning: parsed potentially confusing double-negative %s=%s\n",
                 key, val);
             val = "1";
         } else {
             return true;
         }
     }
     return false;
 }
 
 ArgsManager::ArgsManager()
     : /* These options would cause cross-contamination if values for mainnet
        * were used while running on regtest/testnet (or vice-versa).
        * Setting them as section_only_args ensures that sharing a config file
        * between mainnet and regtest/testnet won't cause problems due to these
        * parameters by accident. */
       m_network_only_args{
           "-addnode", "-connect", "-port",   "-bind",
           "-rpcport", "-rpcbind", "-wallet",
       } {
     // nothing to do
 }
 
 void ArgsManager::WarnForSectionOnlyArgs() {
     LOCK(cs_args);
 
     // if there's no section selected, don't worry
     if (m_network.empty()) {
         return;
     }
 
     // if it's okay to use the default section for this network, don't worry
     if (m_network == CBaseChainParams::MAIN) {
         return;
     }
 
     for (const auto &arg : m_network_only_args) {
         std::pair<bool, std::string> found_result;
 
         // if this option is overridden it's fine
         found_result = ArgsManagerHelper::GetArgHelper(m_override_args, arg);
         if (found_result.first) {
             continue;
         }
 
         // if there's a network-specific value for this option, it's fine
         found_result = ArgsManagerHelper::GetArgHelper(
             m_config_args, ArgsManagerHelper::NetworkArg(*this, arg));
         if (found_result.first) {
             continue;
         }
 
         // if there isn't a default value for this option, it's fine
         found_result = ArgsManagerHelper::GetArgHelper(m_config_args, arg);
         if (!found_result.first) {
             continue;
         }
 
         // otherwise, issue a warning
         LogPrintf("Warning: Config setting for %s only applied on %s network "
                   "when in [%s] section.\n",
                   arg, m_network, m_network);
     }
 }
 
 void ArgsManager::SelectConfigNetwork(const std::string &network) {
     LOCK(cs_args);
     m_network = network;
 }
 
 bool ParseKeyValue(std::string &key, std::string &val) {
     size_t is_index = key.find('=');
     if (is_index != std::string::npos) {
         val = key.substr(is_index + 1);
         key.erase(is_index);
     }
 #ifdef WIN32
     std::transform(key.begin(), key.end(), key.begin(), ::tolower);
     if (key[0] == '/') {
         key[0] = '-';
     }
 #endif
 
     if (key[0] != '-') {
         return false;
     }
 
     // Transform --foo to -foo
     if (key.length() > 1 && key[1] == '-') {
         key.erase(0, 1);
     }
     return true;
 }
 
 bool ArgsManager::ParseParameters(int argc, const char *const argv[],
                                   std::string &error) {
     LOCK(cs_args);
     m_override_args.clear();
 
     for (int i = 1; i < argc; i++) {
         std::string key(argv[i]);
         std::string val;
         if (!ParseKeyValue(key, val)) {
             break;
         }
 
         // Check for -nofoo
         if (InterpretNegatedOption(key, val)) {
             m_override_args[key].clear();
         } else {
             m_override_args[key].push_back(val);
         }
 
         // Check that the arg is known
         if (!(IsSwitchChar(key[0]) && key.size() == 1)) {
             if (!IsArgKnown(key)) {
                 error = strprintf("Invalid parameter %s", key.c_str());
                 return false;
             }
         }
     }
 
     // we do not allow -includeconf from command line, so we clear it here
     auto it = m_override_args.find("-includeconf");
     if (it != m_override_args.end()) {
         if (it->second.size() > 0) {
             for (const auto &ic : it->second) {
                 error += "-includeconf cannot be used from commandline; "
                          "-includeconf=" +
                          ic + "\n";
             }
             return false;
         }
     }
     return true;
 }
 
 bool ArgsManager::IsArgKnown(const std::string &key) const {
     size_t option_index = key.find('.');
     std::string arg_no_net;
     if (option_index == std::string::npos) {
         arg_no_net = key;
     } else {
         arg_no_net =
             std::string("-") + key.substr(option_index + 1, std::string::npos);
     }
 
     LOCK(cs_args);
     for (const auto &arg_map : m_available_args) {
         if (arg_map.second.count(arg_no_net)) {
             return true;
         }
     }
     return false;
 }
 
 std::vector<std::string> ArgsManager::GetArgs(const std::string &strArg) const {
     std::vector<std::string> result = {};
     // special case
     if (IsArgNegated(strArg)) {
         return result;
     }
 
     LOCK(cs_args);
 
     ArgsManagerHelper::AddArgs(result, m_override_args, strArg);
     if (!m_network.empty()) {
         ArgsManagerHelper::AddArgs(
             result, m_config_args,
             ArgsManagerHelper::NetworkArg(*this, strArg));
     }
 
     if (ArgsManagerHelper::UseDefaultSection(*this, strArg)) {
         ArgsManagerHelper::AddArgs(result, m_config_args, strArg);
     }
 
     return result;
 }
 
 bool ArgsManager::IsArgSet(const std::string &strArg) const {
     // special case
     if (IsArgNegated(strArg)) {
         return true;
     }
     return ArgsManagerHelper::GetArg(*this, strArg).first;
 }
 
 bool ArgsManager::IsArgNegated(const std::string &strArg) const {
     LOCK(cs_args);
 
     const auto &ov = m_override_args.find(strArg);
     if (ov != m_override_args.end()) {
         return ov->second.empty();
     }
 
     if (!m_network.empty()) {
         const auto &cfs =
             m_config_args.find(ArgsManagerHelper::NetworkArg(*this, strArg));
         if (cfs != m_config_args.end()) {
             return cfs->second.empty();
         }
     }
 
     const auto &cf = m_config_args.find(strArg);
     if (cf != m_config_args.end()) {
         return cf->second.empty();
     }
 
     return false;
 }
 
 std::string ArgsManager::GetArg(const std::string &strArg,
                                 const std::string &strDefault) const {
     if (IsArgNegated(strArg)) {
         return "0";
     }
     std::pair<bool, std::string> found_res =
         ArgsManagerHelper::GetArg(*this, strArg);
     if (found_res.first) {
         return found_res.second;
     }
     return strDefault;
 }
 
 int64_t ArgsManager::GetArg(const std::string &strArg, int64_t nDefault) const {
     if (IsArgNegated(strArg)) {
         return 0;
     }
     std::pair<bool, std::string> found_res =
         ArgsManagerHelper::GetArg(*this, strArg);
     if (found_res.first) {
         return atoi64(found_res.second);
     }
     return nDefault;
 }
 
 bool ArgsManager::GetBoolArg(const std::string &strArg, bool fDefault) const {
     if (IsArgNegated(strArg)) {
         return false;
     }
     std::pair<bool, std::string> found_res =
         ArgsManagerHelper::GetArg(*this, strArg);
     if (found_res.first) {
         return InterpretBool(found_res.second);
     }
     return fDefault;
 }
 
 bool ArgsManager::SoftSetArg(const std::string &strArg,
                              const std::string &strValue) {
     LOCK(cs_args);
     if (IsArgSet(strArg)) {
         return false;
     }
     ForceSetArg(strArg, strValue);
     return true;
 }
 
 bool ArgsManager::SoftSetBoolArg(const std::string &strArg, bool fValue) {
     if (fValue) {
         return SoftSetArg(strArg, std::string("1"));
     } else {
         return SoftSetArg(strArg, std::string("0"));
     }
 }
 
 void ArgsManager::ForceSetArg(const std::string &strArg,
                               const std::string &strValue) {
     LOCK(cs_args);
     m_override_args[strArg] = {strValue};
 }
 
 /**
  * This function is only used for testing purpose so
  * so we should not worry about element uniqueness and
  * integrity of mapMultiArgs data structure
  */
 void ArgsManager::ForceSetMultiArg(const std::string &strArg,
                                    const std::string &strValue) {
     LOCK(cs_args);
     m_override_args[strArg].push_back(strValue);
 }
 
 void ArgsManager::AddArg(const std::string &name, const std::string &help,
                          const bool debug_only, const OptionsCategory &cat) {
     // Split arg name from its help param
     size_t eq_index = name.find('=');
     if (eq_index == std::string::npos) {
         eq_index = name.size();
     }
 
     LOCK(cs_args);
     std::map<std::string, Arg> &arg_map = m_available_args[cat];
     auto ret = arg_map.emplace(
         name.substr(0, eq_index),
         Arg(name.substr(eq_index, name.size() - eq_index), help, debug_only));
     // Make sure an insertion actually happened.
     assert(ret.second);
 }
 
 void ArgsManager::AddHiddenArgs(const std::vector<std::string> &names) {
     for (const std::string &name : names) {
         AddArg(name, "", false, OptionsCategory::HIDDEN);
     }
 }
 
 void ArgsManager::ClearArg(const std::string &strArg) {
     LOCK(cs_args);
     m_override_args.erase(strArg);
     m_config_args.erase(strArg);
 }
 
 std::string ArgsManager::GetHelpMessage() const {
     const bool show_debug = gArgs.GetBoolArg("-help-debug", false);
 
     std::string usage = "";
     LOCK(cs_args);
     for (const auto &arg_map : m_available_args) {
         switch (arg_map.first) {
             case OptionsCategory::OPTIONS:
                 usage += HelpMessageGroup("Options:");
                 break;
             case OptionsCategory::CONNECTION:
                 usage += HelpMessageGroup("Connection options:");
                 break;
             case OptionsCategory::ZMQ:
                 usage += HelpMessageGroup("ZeroMQ notification options:");
                 break;
             case OptionsCategory::DEBUG_TEST:
                 usage += HelpMessageGroup("Debugging/Testing options:");
                 break;
             case OptionsCategory::NODE_RELAY:
                 usage += HelpMessageGroup("Node relay options:");
                 break;
             case OptionsCategory::BLOCK_CREATION:
                 usage += HelpMessageGroup("Block creation options:");
                 break;
             case OptionsCategory::RPC:
                 usage += HelpMessageGroup("RPC server options:");
                 break;
             case OptionsCategory::WALLET:
                 usage += HelpMessageGroup("Wallet options:");
                 break;
             case OptionsCategory::WALLET_DEBUG_TEST:
                 if (show_debug) {
                     usage +=
                         HelpMessageGroup("Wallet debugging/testing options:");
                 }
                 break;
             case OptionsCategory::CHAINPARAMS:
                 usage += HelpMessageGroup("Chain selection options:");
                 break;
             case OptionsCategory::GUI:
                 usage += HelpMessageGroup("UI Options:");
                 break;
             case OptionsCategory::COMMANDS:
                 usage += HelpMessageGroup("Commands:");
                 break;
             case OptionsCategory::REGISTER_COMMANDS:
                 usage += HelpMessageGroup("Register Commands:");
                 break;
             default:
                 break;
         }
 
         // When we get to the hidden options, stop
         if (arg_map.first == OptionsCategory::HIDDEN) {
             break;
         }
 
         for (const auto &arg : arg_map.second) {
             if (show_debug || !arg.second.m_debug_only) {
                 std::string name;
                 if (arg.second.m_help_param.empty()) {
                     name = arg.first;
                 } else {
                     name = arg.first + arg.second.m_help_param;
                 }
                 usage += HelpMessageOpt(name, arg.second.m_help_text);
             }
         }
     }
     return usage;
 }
 
 bool HelpRequested(const ArgsManager &args) {
     return args.IsArgSet("-?") || args.IsArgSet("-h") || args.IsArgSet("-help");
 }
 
 static const int screenWidth = 79;
 static const int optIndent = 2;
 static const int msgIndent = 7;
 
 std::string HelpMessageGroup(const std::string &message) {
     return std::string(message) + std::string("\n\n");
 }
 
 std::string HelpMessageOpt(const std::string &option,
                            const std::string &message) {
     return std::string(optIndent, ' ') + std::string(option) +
            std::string("\n") + std::string(msgIndent, ' ') +
            FormatParagraph(message, screenWidth - msgIndent, msgIndent) +
            std::string("\n\n");
 }
 
 static std::string FormatException(const std::exception *pex,
                                    const char *pszThread) {
 #ifdef WIN32
     char pszModule[MAX_PATH] = "";
     GetModuleFileNameA(nullptr, pszModule, sizeof(pszModule));
 #else
     const char *pszModule = "bitcoin";
 #endif
     if (pex) {
         return strprintf("EXCEPTION: %s       \n%s       \n%s in %s       \n",
                          typeid(*pex).name(), pex->what(), pszModule,
                          pszThread);
     } else {
         return strprintf("UNKNOWN EXCEPTION       \n%s in %s       \n",
                          pszModule, pszThread);
     }
 }
 
 void PrintExceptionContinue(const std::exception *pex, const char *pszThread) {
     std::string message = FormatException(pex, pszThread);
     LogPrintf("\n\n************************\n%s\n", message);
     fprintf(stderr, "\n\n************************\n%s\n", message.c_str());
 }
 
 fs::path GetDefaultDataDir() {
 // Windows < Vista: C:\Documents and Settings\Username\Application Data\Bitcoin
 // Windows >= Vista: C:\Users\Username\AppData\Roaming\Bitcoin
 // Mac: ~/Library/Application Support/Bitcoin
 // Unix: ~/.bitcoin
 #ifdef WIN32
     // Windows
     return GetSpecialFolderPath(CSIDL_APPDATA) / "Bitcoin";
 #else
     fs::path pathRet;
     char *pszHome = getenv("HOME");
     if (pszHome == nullptr || strlen(pszHome) == 0) {
         pathRet = fs::path("/");
     } else {
         pathRet = fs::path(pszHome);
     }
 #ifdef MAC_OSX
     // Mac
     return pathRet / "Library/Application Support/Bitcoin";
 #else
     // Unix
     return pathRet / ".bitcoin";
 #endif
 #endif
 }
 
 static fs::path g_blocks_path_cache_net_specific;
 static fs::path pathCached;
 static fs::path pathCachedNetSpecific;
 static CCriticalSection csPathCached;
 
 const fs::path &GetBlocksDir() {
     LOCK(csPathCached);
 
     fs::path &path = g_blocks_path_cache_net_specific;
 
     // This can be called during exceptions by LogPrintf(), so we cache the
     // value so we don't have to do memory allocations after that.
     if (!path.empty()) {
         return path;
     }
 
     if (gArgs.IsArgSet("-blocksdir")) {
         path = fs::system_complete(gArgs.GetArg("-blocksdir", ""));
         if (!fs::is_directory(path)) {
             path = "";
             return path;
         }
     } else {
         path = GetDataDir(false);
     }
 
     path /= BaseParams().DataDir();
     path /= "blocks";
     fs::create_directories(path);
     return path;
 }
 
 const fs::path &GetDataDir(bool fNetSpecific) {
     LOCK(csPathCached);
 
     fs::path &path = fNetSpecific ? pathCachedNetSpecific : pathCached;
 
     // This can be called during exceptions by LogPrintf(), so we cache the
     // value so we don't have to do memory allocations after that.
     if (!path.empty()) {
         return path;
     }
 
     if (gArgs.IsArgSet("-datadir")) {
         path = fs::system_complete(gArgs.GetArg("-datadir", ""));
         if (!fs::is_directory(path)) {
             path = "";
             return path;
         }
     } else {
         path = GetDefaultDataDir();
     }
 
     if (fNetSpecific) {
         path /= BaseParams().DataDir();
     }
 
     if (fs::create_directories(path)) {
         // This is the first run, create wallets subdirectory too
         //
         // TODO: this is an ugly way to create the wallets/ directory and
         // really shouldn't be done here. Once this is fixed, please
         // also remove the corresponding line in bitcoind.cpp AppInit.
         // See more info at:
         // https://reviews.bitcoinabc.org/D3312
         fs::create_directories(path / "wallets");
     }
 
     return path;
 }
 
 void ClearDatadirCache() {
     LOCK(csPathCached);
 
     pathCached = fs::path();
     pathCachedNetSpecific = fs::path();
     g_blocks_path_cache_net_specific = fs::path();
 }
 
 fs::path GetConfigFile(const std::string &confPath) {
     return AbsPathForConfigVal(fs::path(confPath), false);
 }
 
 static std::string TrimString(const std::string &str,
                               const std::string &pattern) {
     std::string::size_type front = str.find_first_not_of(pattern);
     if (front == std::string::npos) {
         return std::string();
     }
     std::string::size_type end = str.find_last_not_of(pattern);
     return str.substr(front, end - front + 1);
 }
 
 static bool
 GetConfigOptions(std::istream &stream, std::string &error,
                  std::vector<std::pair<std::string, std::string>> &options) {
     std::string str, prefix;
     std::string::size_type pos;
     int linenr = 1;
     while (std::getline(stream, str)) {
         bool used_hash = false;
         if ((pos = str.find('#')) != std::string::npos) {
             str = str.substr(0, pos);
             used_hash = true;
         }
         const static std::string pattern = " \t\r\n";
         str = TrimString(str, pattern);
         if (!str.empty()) {
             if (*str.begin() == '[' && *str.rbegin() == ']') {
                 prefix = str.substr(1, str.size() - 2) + '.';
             } else if (*str.begin() == '-') {
                 error = strprintf(
                     "parse error on line %i: %s, options in configuration file "
                     "must be specified without leading -",
                     linenr, str);
                 return false;
             } else if ((pos = str.find('=')) != std::string::npos) {
                 std::string name =
                     prefix + TrimString(str.substr(0, pos), pattern);
                 std::string value = TrimString(str.substr(pos + 1), pattern);
                 if (used_hash && name == "rpcpassword") {
                     error = strprintf(
                         "parse error on line %i, using # in rpcpassword can be "
                         "ambiguous and should be avoided",
                         linenr);
                     return false;
                 }
                 options.emplace_back(name, value);
             } else {
                 error = strprintf("parse error on line %i: %s", linenr, str);
                 if (str.size() >= 2 && str.substr(0, 2) == "no") {
                     error += strprintf(", if you intended to specify a negated "
                                        "option, use %s=1 instead",
                                        str);
                 }
                 return false;
             }
         }
         ++linenr;
     }
     return true;
 }
 
 bool ArgsManager::ReadConfigStream(std::istream &stream, std::string &error,
                                    bool ignore_invalid_keys) {
     LOCK(cs_args);
     std::vector<std::pair<std::string, std::string>> options;
     if (!GetConfigOptions(stream, error, options)) {
         return false;
     }
     for (const std::pair<std::string, std::string> &option : options) {
         std::string strKey = std::string("-") + option.first;
         std::string strValue = option.second;
 
         if (InterpretNegatedOption(strKey, strValue)) {
             m_config_args[strKey].clear();
         } else {
             m_config_args[strKey].push_back(strValue);
         }
 
         // Check that the arg is known
         if (!IsArgKnown(strKey) && !ignore_invalid_keys) {
             error = strprintf("Invalid configuration value %s",
                               option.first.c_str());
             return false;
         }
     }
     return true;
 }
 
 bool ArgsManager::ReadConfigFiles(std::string &error,
                                   bool ignore_invalid_keys) {
     {
         LOCK(cs_args);
         m_config_args.clear();
     }
 
     const std::string confPath = GetArg("-conf", BITCOIN_CONF_FILENAME);
     fs::ifstream stream(GetConfigFile(confPath));
 
     // ok to not have a config file
     if (stream.good()) {
         if (!ReadConfigStream(stream, error, ignore_invalid_keys)) {
             return false;
         }
         // if there is an -includeconf in the override args, but it is empty,
         // that means the user passed '-noincludeconf' on the command line, in
         // which case we should not include anything
         bool emptyIncludeConf;
         {
             LOCK(cs_args);
             emptyIncludeConf = m_override_args.count("-includeconf") == 0;
         }
         if (emptyIncludeConf) {
             std::string chain_id = GetChainName();
             std::vector<std::string> includeconf(GetArgs("-includeconf"));
             {
                 // We haven't set m_network yet (that happens in
                 // SelectParams()), so manually check for network.includeconf
                 // args.
                 std::vector<std::string> includeconf_net(
                     GetArgs(std::string("-") + chain_id + ".includeconf"));
                 includeconf.insert(includeconf.end(), includeconf_net.begin(),
                                    includeconf_net.end());
             }
 
             // Remove -includeconf from configuration, so we can warn about
             // recursion later
             {
                 LOCK(cs_args);
                 m_config_args.erase("-includeconf");
                 m_config_args.erase(std::string("-") + chain_id +
                                     ".includeconf");
             }
 
             for (const std::string &to_include : includeconf) {
                 fs::ifstream include_config(GetConfigFile(to_include));
                 if (include_config.good()) {
                     if (!ReadConfigStream(include_config, error,
                                           ignore_invalid_keys)) {
                         return false;
                     }
                     LogPrintf("Included configuration file %s\n",
                               to_include.c_str());
                 } else {
                     error =
                         "Failed to include configuration file " + to_include;
                     return false;
                 }
             }
 
             // Warn about recursive -includeconf
             includeconf = GetArgs("-includeconf");
             {
                 std::vector<std::string> includeconf_net(
                     GetArgs(std::string("-") + chain_id + ".includeconf"));
                 includeconf.insert(includeconf.end(), includeconf_net.begin(),
                                    includeconf_net.end());
                 std::string chain_id_final = GetChainName();
                 if (chain_id_final != chain_id) {
                     // Also warn about recursive includeconf for the chain that
                     // was specified in one of the includeconfs
                     includeconf_net = GetArgs(std::string("-") +
                                               chain_id_final + ".includeconf");
                     includeconf.insert(includeconf.end(),
                                        includeconf_net.begin(),
                                        includeconf_net.end());
                 }
             }
             for (const std::string &to_include : includeconf) {
                 fprintf(stderr,
                         "warning: -includeconf cannot be used from included "
                         "files; ignoring -includeconf=%s\n",
                         to_include.c_str());
             }
         }
     }
 
     // If datadir is changed in .conf file:
     ClearDatadirCache();
     if (!fs::is_directory(GetDataDir(false))) {
         error = strprintf("specified data directory \"%s\" does not exist.",
                           gArgs.GetArg("-datadir", "").c_str());
         return false;
     }
     return true;
 }
 
 std::string ArgsManager::GetChainName() const {
     LOCK(cs_args);
     bool fRegTest = ArgsManagerHelper::GetNetBoolArg(*this, "-regtest");
     bool fTestNet = ArgsManagerHelper::GetNetBoolArg(*this, "-testnet");
 
     if (fTestNet && fRegTest) {
         throw std::runtime_error(
             "Invalid combination of -regtest and -testnet.");
     }
     if (fRegTest) {
         return CBaseChainParams::REGTEST;
     }
     if (fTestNet) {
         return CBaseChainParams::TESTNET;
     }
     return CBaseChainParams::MAIN;
 }
 
 #ifndef WIN32
 fs::path GetPidFile() {
     return AbsPathForConfigVal(
         fs::path(gArgs.GetArg("-pid", BITCOIN_PID_FILENAME)));
 }
 
 void CreatePidFile(const fs::path &path, pid_t pid) {
     FILE *file = fsbridge::fopen(path, "w");
     if (file) {
         fprintf(file, "%d\n", pid);
         fclose(file);
     }
 }
 #endif
 
 bool RenameOver(fs::path src, fs::path dest) {
 #ifdef WIN32
     return MoveFileExA(src.string().c_str(), dest.string().c_str(),
                        MOVEFILE_REPLACE_EXISTING) != 0;
 #else
     int rc = std::rename(src.string().c_str(), dest.string().c_str());
     return (rc == 0);
 #endif /* WIN32 */
 }
 
 /**
  * Ignores exceptions thrown by Boost's create_directories if the requested
  * directory exists. Specifically handles case where path p exists, but it
  * wasn't possible for the user to write to the parent directory.
  */
 bool TryCreateDirectories(const fs::path &p) {
     try {
         return fs::create_directories(p);
     } catch (const fs::filesystem_error &) {
         if (!fs::exists(p) || !fs::is_directory(p)) {
             throw;
         }
     }
 
     // create_directory didn't create the directory, it had to have existed
     // already.
     return false;
 }
 
 bool FileCommit(FILE *file) {
     // harmless if redundantly called
     if (fflush(file) != 0) {
         LogPrintf("%s: fflush failed: %d\n", __func__, errno);
         return false;
     }
 #ifdef WIN32
     HANDLE hFile = (HANDLE)_get_osfhandle(_fileno(file));
     if (FlushFileBuffers(hFile) == 0) {
         LogPrintf("%s: FlushFileBuffers failed: %d\n", __func__,
                   GetLastError());
         return false;
     }
 #else
 #if defined(__linux__) || defined(__NetBSD__)
     // Ignore EINVAL for filesystems that don't support sync
     if (fdatasync(fileno(file)) != 0 && errno != EINVAL) {
         LogPrintf("%s: fdatasync failed: %d\n", __func__, errno);
         return false;
     }
 #elif defined(MAC_OSX) && defined(F_FULLFSYNC)
     // Manpage says "value other than -1" is returned on success
     if (fcntl(fileno(file), F_FULLFSYNC, 0) == -1) {
         LogPrintf("%s: fcntl F_FULLFSYNC failed: %d\n", __func__, errno);
         return false;
     }
 #else
     if (fsync(fileno(file)) != 0 && errno != EINVAL) {
         LogPrintf("%s: fsync failed: %d\n", __func__, errno);
         return false;
     }
 #endif
 #endif
     return true;
 }
 
 bool TruncateFile(FILE *file, unsigned int length) {
 #if defined(WIN32)
     return _chsize(_fileno(file), length) == 0;
 #else
     return ftruncate(fileno(file), length) == 0;
 #endif
 }
 
 /**
  * This function tries to raise the file descriptor limit to the requested
  * number. It returns the actual file descriptor limit (which may be more or
  * less than nMinFD)
  */
 int RaiseFileDescriptorLimit(int nMinFD) {
 #if defined(WIN32)
     return 2048;
 #else
     struct rlimit limitFD;
     if (getrlimit(RLIMIT_NOFILE, &limitFD) != -1) {
         if (limitFD.rlim_cur < (rlim_t)nMinFD) {
             limitFD.rlim_cur = nMinFD;
             if (limitFD.rlim_cur > limitFD.rlim_max) {
                 limitFD.rlim_cur = limitFD.rlim_max;
             }
             setrlimit(RLIMIT_NOFILE, &limitFD);
             getrlimit(RLIMIT_NOFILE, &limitFD);
         }
         return limitFD.rlim_cur;
     }
     // getrlimit failed, assume it's fine.
     return nMinFD;
 #endif
 }
 
 /**
  * This function tries to make a particular range of a file allocated
  * (corresponding to disk space) it is advisory, and the range specified in the
  * arguments will never contain live data.
  */
 void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length) {
 #if defined(WIN32)
     // Windows-specific version.
     HANDLE hFile = (HANDLE)_get_osfhandle(_fileno(file));
     LARGE_INTEGER nFileSize;
     int64_t nEndPos = (int64_t)offset + length;
     nFileSize.u.LowPart = nEndPos & 0xFFFFFFFF;
     nFileSize.u.HighPart = nEndPos >> 32;
     SetFilePointerEx(hFile, nFileSize, 0, FILE_BEGIN);
     SetEndOfFile(hFile);
 #elif defined(MAC_OSX)
     // OSX specific version.
     fstore_t fst;
     fst.fst_flags = F_ALLOCATECONTIG;
     fst.fst_posmode = F_PEOFPOSMODE;
     fst.fst_offset = 0;
     fst.fst_length = (off_t)offset + length;
     fst.fst_bytesalloc = 0;
     if (fcntl(fileno(file), F_PREALLOCATE, &fst) == -1) {
         fst.fst_flags = F_ALLOCATEALL;
         fcntl(fileno(file), F_PREALLOCATE, &fst);
     }
     ftruncate(fileno(file), fst.fst_length);
 #elif defined(__linux__)
     // Version using posix_fallocate.
     off_t nEndPos = (off_t)offset + length;
     posix_fallocate(fileno(file), 0, nEndPos);
 #else
     // Fallback version
     // TODO: just write one byte per block
     static const char buf[65536] = {};
     if (fseek(file, offset, SEEK_SET)) {
         return;
     }
     while (length > 0) {
         unsigned int now = 65536;
         if (length < now) {
             now = length;
         }
         // Allowed to fail; this function is advisory anyway.
         fwrite(buf, 1, now, file);
         length -= now;
     }
 #endif
 }
 
 #ifdef WIN32
 fs::path GetSpecialFolderPath(int nFolder, bool fCreate) {
     char pszPath[MAX_PATH] = "";
 
     if (SHGetSpecialFolderPathA(nullptr, pszPath, nFolder, fCreate)) {
         return fs::path(pszPath);
     }
 
     LogPrintf(
         "SHGetSpecialFolderPathA() failed, could not obtain requested path.\n");
     return fs::path("");
 }
 #endif
 
 void runCommand(const std::string &strCommand) {
     if (strCommand.empty()) {
         return;
     }
 #ifndef WIN32
     int nErr = ::system(strCommand.c_str());
 #else
     int nErr = ::_wsystem(
         std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>, wchar_t>()
             .from_bytes(strCommand)
             .c_str());
 #endif
     if (nErr) {
         LogPrintf("runCommand error: system(%s) returned %d\n", strCommand,
                   nErr);
     }
 }
 
 void RenameThread(const char *name) {
 #if defined(PR_SET_NAME)
     // Only the first 15 characters are used (16 - NUL terminator)
     ::prctl(PR_SET_NAME, name, 0, 0, 0);
 #elif (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
     pthread_set_name_np(pthread_self(), name);
 
 #elif defined(MAC_OSX)
     pthread_setname_np(name);
 #else
     // Prevent warnings for unused parameters...
     (void)name;
 #endif
 }
 
 void SetupEnvironment() {
 #ifdef HAVE_MALLOPT_ARENA_MAX
     // glibc-specific: On 32-bit systems set the number of arenas to 1. By
     // default, since glibc 2.10, the C library will create up to two heap
     // arenas per core. This is known to cause excessive virtual address space
     // usage in our usage. Work around it by setting the maximum number of
     // arenas to 1.
     if (sizeof(void *) == 4) {
         mallopt(M_ARENA_MAX, 1);
     }
 #endif
 // On most POSIX systems (e.g. Linux, but not BSD) the environment's locale may
 // be invalid, in which case the "C" locale is used as fallback.
 #if !defined(WIN32) && !defined(MAC_OSX) && !defined(__FreeBSD__) &&           \
     !defined(__OpenBSD__)
     try {
         // Raises a runtime error if current locale is invalid.
         std::locale("");
     } catch (const std::runtime_error &) {
         setenv("LC_ALL", "C", 1);
     }
 #elif defined(WIN32)
     // Set the default input/output charset is utf-8
     SetConsoleCP(CP_UTF8);
     SetConsoleOutputCP(CP_UTF8);
 #endif
     // The path locale is lazy initialized and to avoid deinitialization errors
     // in multithreading environments, it is set explicitly by the main thread.
     // A dummy locale is used to extract the internal default locale, used by
     // fs::path, which is then used to explicitly imbue the path.
     std::locale loc = fs::path::imbue(std::locale::classic());
 #ifndef WIN32
     fs::path::imbue(loc);
 #else
     fs::path::imbue(std::locale(loc, new std::codecvt_utf8_utf16<wchar_t>()));
 #endif
 }
 
 bool SetupNetworking() {
 #ifdef WIN32
     // Initialize Windows Sockets.
     WSADATA wsadata;
     int ret = WSAStartup(MAKEWORD(2, 2), &wsadata);
     if (ret != NO_ERROR || LOBYTE(wsadata.wVersion) != 2 ||
         HIBYTE(wsadata.wVersion) != 2) {
         return false;
     }
 #endif
     return true;
 }
 
 int GetNumCores() {
     return boost::thread::physical_concurrency();
 }
 
 std::string CopyrightHolders(const std::string &strPrefix) {
     return strPrefix +
            strprintf(_(COPYRIGHT_HOLDERS), _(COPYRIGHT_HOLDERS_SUBSTITUTION));
 }
 
 // Obtain the application startup time (used for uptime calculation)
 int64_t GetStartupTime() {
     return nStartupTime;
 }
 
 fs::path AbsPathForConfigVal(const fs::path &path, bool net_specific) {
     return fs::absolute(path, GetDataDir(net_specific));
 }
 
 int ScheduleBatchPriority() {
 #ifdef SCHED_BATCH
     const static sched_param param{};
     if (int ret = pthread_setschedparam(pthread_self(), SCHED_BATCH, &param)) {
         LogPrintf("Failed to pthread_setschedparam: %s\n", strerror(errno));
         return ret;
     }
     return 0;
 #else
     return 1;
 #endif
 }
 
 namespace util {
 #ifdef WIN32
 WinCmdLineArgs::WinCmdLineArgs() {
     wchar_t **wargv = CommandLineToArgvW(GetCommandLineW(), &argc);
     std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>, wchar_t> utf8_cvt;
     argv = new char *[argc];
     args.resize(argc);
     for (int i = 0; i < argc; i++) {
         args[i] = utf8_cvt.to_bytes(wargv[i]);
         argv[i] = &*args[i].begin();
     }
     LocalFree(wargv);
 }
 
 WinCmdLineArgs::~WinCmdLineArgs() {
     delete[] argv;
 }
 
 std::pair<int, char **> WinCmdLineArgs::get() {
     return std::make_pair(argc, argv);
 }
 #endif
 } // namespace util
diff --git a/src/util/system.h b/src/util/system.h
index dc7edf291d..627b2d8ddf 100644
--- a/src/util/system.h
+++ b/src/util/system.h
@@ -1,397 +1,399 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 /**
  * Server/client environment: argument handling, config file parsing,
  * thread wrappers, startup time
  */
 #ifndef BITCOIN_UTIL_SYSTEM_H
 #define BITCOIN_UTIL_SYSTEM_H
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <attributes.h>
 #include <compat.h>
 #include <compat/assumptions.h>
 #include <fs.h>
 #include <logging.h>
 #include <sync.h>
 #include <tinyformat.h>
 #include <util/time.h>
 
 #include <boost/thread/condition_variable.hpp> // for boost::thread_interrupted
 
 #include <atomic>
 #include <cstdint>
 #include <exception>
 #include <map>
 #include <set>
 #include <string>
 #include <unordered_set>
 #include <utility>
 #include <vector>
 
 // Application startup time (used for uptime calculation)
 int64_t GetStartupTime();
 
 extern const char *const BITCOIN_CONF_FILENAME;
 extern const char *const BITCOIN_PID_FILENAME;
 
 /** Translate a message to the native language of the user. */
 const extern std::function<std::string(const char *)> G_TRANSLATION_FUN;
 
 /**
  * Translation function.
  * If no translation function is set, simply return the input.
  */
 inline std::string _(const char *psz) {
     return G_TRANSLATION_FUN ? (G_TRANSLATION_FUN)(psz) : psz;
 }
 
 void SetupEnvironment();
 bool SetupNetworking();
 
 template <typename... Args> bool error(const char *fmt, const Args &... args) {
     LogPrintf("ERROR: %s\n", tfm::format(fmt, args...));
     return false;
 }
 
 void PrintExceptionContinue(const std::exception *pex, const char *pszThread);
 bool FileCommit(FILE *file);
 bool TruncateFile(FILE *file, unsigned int length);
 int RaiseFileDescriptorLimit(int nMinFD);
 void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length);
 bool RenameOver(fs::path src, fs::path dest);
 bool LockDirectory(const fs::path &directory, const std::string lockfile_name,
                    bool probe_only = false);
+void UnlockDirectory(const fs::path &directory,
+                     const std::string &lockfile_name);
 bool DirIsWritable(const fs::path &directory);
 bool CheckDiskSpace(const fs::path &dir, uint64_t additional_bytes = 0);
 
 /**
  * Release all directory locks. This is used for unit testing only, at runtime
  * the global destructor will take care of the locks.
  */
 void ReleaseDirectoryLocks();
 
 bool TryCreateDirectories(const fs::path &p);
 fs::path GetDefaultDataDir();
 // The blocks directory is always net specific.
 const fs::path &GetBlocksDir();
 const fs::path &GetDataDir(bool fNetSpecific = true);
 void ClearDatadirCache();
 fs::path GetConfigFile(const std::string &confPath);
 #ifndef WIN32
 fs::path GetPidFile();
 void CreatePidFile(const fs::path &path, pid_t pid);
 #endif
 #ifdef WIN32
 fs::path GetSpecialFolderPath(int nFolder, bool fCreate = true);
 #endif
 void runCommand(const std::string &strCommand);
 
 NODISCARD bool ParseKeyValue(std::string &key, std::string &val);
 
 /**
  * Most paths passed as configuration arguments are treated as relative to
  * the datadir if they are not absolute.
  *
  * @param path The path to be conditionally prefixed with datadir.
  * @param net_specific Forwarded to GetDataDir().
  * @return The normalized path.
  */
 fs::path AbsPathForConfigVal(const fs::path &path, bool net_specific = true);
 
 inline bool IsSwitchChar(char c) {
 #ifdef WIN32
     return c == '-' || c == '/';
 #else
     return c == '-';
 #endif
 }
 
 enum class OptionsCategory {
     OPTIONS,
     CONNECTION,
     WALLET,
     WALLET_DEBUG_TEST,
     ZMQ,
     DEBUG_TEST,
     CHAINPARAMS,
     NODE_RELAY,
     BLOCK_CREATION,
     RPC,
     GUI,
     COMMANDS,
     REGISTER_COMMANDS,
 
     // Always the last option to avoid printing these in the help
     HIDDEN,
 };
 
 class ArgsManager {
 protected:
     friend class ArgsManagerHelper;
 
     struct Arg {
         std::string m_help_param;
         std::string m_help_text;
         bool m_debug_only;
 
         Arg(const std::string &help_param, const std::string &help_text,
             bool debug_only)
             : m_help_param(help_param), m_help_text(help_text),
               m_debug_only(debug_only){};
     };
 
     mutable CCriticalSection cs_args;
     std::map<std::string, std::vector<std::string>>
         m_override_args GUARDED_BY(cs_args);
     std::map<std::string, std::vector<std::string>>
         m_config_args GUARDED_BY(cs_args);
     std::string m_network GUARDED_BY(cs_args);
     std::set<std::string> m_network_only_args GUARDED_BY(cs_args);
     std::map<OptionsCategory, std::map<std::string, Arg>>
         m_available_args GUARDED_BY(cs_args);
 
     bool ReadConfigStream(std::istream &stream, std::string &error,
                           bool ignore_invalid_keys = false);
 
 public:
     ArgsManager();
 
     /**
      * Select the network in use
      */
     void SelectConfigNetwork(const std::string &network);
 
     NODISCARD bool ParseParameters(int argc, const char *const argv[],
                                    std::string &error);
     bool ReadConfigFiles(std::string &error, bool ignore_invalid_keys = false);
 
     /**
      * Log warnings for options in m_section_only_args when they are specified
      * in the default section but not overridden on the command line or in a
      * network-specific section in the config file.
      */
     void WarnForSectionOnlyArgs();
 
     /**
      * Return a vector of strings of the given argument
      *
      * @param strArg Argument to get (e.g. "-foo")
      * @return command-line arguments
      */
     std::vector<std::string> GetArgs(const std::string &strArg) const;
 
     /**
      * Return true if the given argument has been manually set.
      *
      * @param strArg Argument to get (e.g. "-foo")
      * @return true if the argument has been set
      */
     bool IsArgSet(const std::string &strArg) const;
 
     /**
      * Return true if the argument was originally passed as a negated option,
      * i.e. -nofoo.
      *
      * @param strArg Argument to get (e.g. "-foo")
      * @return true if the argument was passed negated
      */
     bool IsArgNegated(const std::string &strArg) const;
 
     /**
      * Return string argument or default value.
      *
      * @param strArg Argument to get (e.g. "-foo")
      * @param default (e.g. "1")
      * @return command-line argument or default value
      */
     std::string GetArg(const std::string &strArg,
                        const std::string &strDefault) const;
 
     /**
      * Return integer argument or default value.
      *
      * @param strArg Argument to get (e.g. "-foo")
      * @param default (e.g. 1)
      * @return command-line argument (0 if invalid number) or default value
      */
     int64_t GetArg(const std::string &strArg, int64_t nDefault) const;
 
     /**
      * Return boolean argument or default value.
      *
      * @param strArg Argument to get (e.g. "-foo")
      * @param default (true or false)
      * @return command-line argument or default value
      */
     bool GetBoolArg(const std::string &strArg, bool fDefault) const;
 
     /**
      * Set an argument if it doesn't already have a value.
      *
      * @param strArg Argument to set (e.g. "-foo")
      * @param strValue Value (e.g. "1")
      * @return true if argument gets set, false if it already had a value
      */
     bool SoftSetArg(const std::string &strArg, const std::string &strValue);
 
     /**
      * Set a boolean argument if it doesn't already have a value.
      *
      * @param strArg Argument to set (e.g. "-foo")
      * @param fValue Value (e.g. false)
      * @return true if argument gets set, false if it already had a value
      */
     bool SoftSetBoolArg(const std::string &strArg, bool fValue);
 
     // Forces an arg setting. Called by SoftSetArg() if the arg hasn't already
     // been set. Also called directly in testing.
     void ForceSetArg(const std::string &strArg, const std::string &strValue);
 
     // Forces a multi arg setting, used only in testing
     void ForceSetMultiArg(const std::string &strArg,
                           const std::string &strValue);
 
     /**
      * Looks for -regtest, -testnet and returns the appropriate BIP70 chain
      * name.
      * @return CBaseChainParams::MAIN by default; raises runtime error if an
      * invalid combination is given.
      */
     std::string GetChainName() const;
 
     /**
      * Add argument
      */
     void AddArg(const std::string &name, const std::string &help,
                 const bool debug_only, const OptionsCategory &cat);
 
     // Remove an arg setting, used only in testing
     void ClearArg(const std::string &strArg);
 
     /**
      * Add many hidden arguments
      */
     void AddHiddenArgs(const std::vector<std::string> &args);
 
     /**
      * Clear available arguments
      */
     void ClearArgs() {
         LOCK(cs_args);
         m_available_args.clear();
     }
 
     /**
      * Get the help string
      */
     std::string GetHelpMessage() const;
 
     /**
      * Check whether we know of this arg
      */
     bool IsArgKnown(const std::string &key) const;
 };
 
 extern ArgsManager gArgs;
 
 /**
  * @return true if help has been requested via a command-line arg
  */
 bool HelpRequested(const ArgsManager &args);
 
 /**
  * Format a string to be used as group of options in help messages.
  *
  * @param message Group name (e.g. "RPC server options:")
  * @return the formatted string
  */
 std::string HelpMessageGroup(const std::string &message);
 
 /**
  * Format a string to be used as option description in help messages.
  *
  * @param option Option message (e.g. "-rpcuser=<user>")
  * @param message Option description (e.g. "Username for JSON-RPC connections")
  * @return the formatted string
  */
 std::string HelpMessageOpt(const std::string &option,
                            const std::string &message);
 
 /**
  * Return the number of physical cores available on the current system.
  * @note This does not count virtual cores, such as those provided by
  * HyperThreading when boost is newer than 1.56.
  */
 int GetNumCores();
 
 void RenameThread(const char *name);
 
 /**
  * .. and a wrapper that just calls func once
  */
 template <typename Callable> void TraceThread(const char *name, Callable func) {
     std::string s = strprintf("bitcoin-%s", name);
     RenameThread(s.c_str());
     try {
         LogPrintf("%s thread start\n", name);
         func();
         LogPrintf("%s thread exit\n", name);
     } catch (const boost::thread_interrupted &) {
         LogPrintf("%s thread interrupt\n", name);
         throw;
     } catch (const std::exception &e) {
         PrintExceptionContinue(&e, name);
         throw;
     } catch (...) {
         PrintExceptionContinue(nullptr, name);
         throw;
     }
 }
 
 std::string CopyrightHolders(const std::string &strPrefix);
 
 namespace util {
 
 //! Simplification of std insertion
 template <typename Tdst, typename Tsrc>
 inline void insert(Tdst &dst, const Tsrc &src) {
     dst.insert(dst.begin(), src.begin(), src.end());
 }
 template <typename TsetT, typename Tsrc>
 inline void insert(std::set<TsetT> &dst, const Tsrc &src) {
     dst.insert(src.begin(), src.end());
 }
 
 #ifdef WIN32
 class WinCmdLineArgs {
 public:
     WinCmdLineArgs();
     ~WinCmdLineArgs();
     std::pair<int, char **> get();
 
 private:
     int argc;
     char **argv;
     std::vector<std::string> args;
 };
 #endif
 
 } // namespace util
 
 /**
  * On platforms that support it, tell the kernel the calling thread is
  * CPU-intensive and non-interactive. See SCHED_BATCH in sched(7) for details.
  *
  * @return The return value of sched_setschedule(), or 1 on systems without
  * sched_setchedule().
  */
 int ScheduleBatchPriority();
 
 #endif // BITCOIN_UTIL_SYSTEM_H
diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index 29dc2bc6e6..17686f526f 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -1,968 +1,977 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <wallet/db.h>
 
 #include <addrman.h>
 #include <fs.h>
 #include <hash.h>
 #include <protocol.h>
 #include <util/strencodings.h>
 #include <util/system.h>
 #include <wallet/walletutil.h>
 
 #include <boost/thread.hpp> // boost::this_thread::interruption_point() (mingw)
 
 #include <cstdint>
 #ifndef WIN32
 #include <sys/stat.h>
 #endif
 
 namespace {
 //! Make sure database has a unique fileid within the environment. If it
 //! doesn't, throw an error. BDB caches do not work properly when more than one
 //! open database has the same fileid (values written to one database may show
 //! up in reads to other databases).
 //!
 //! BerkeleyDB generates unique fileids by default
 //! (https://docs.oracle.com/cd/E17275_01/html/programmer_reference/program_copy.html),
 //! so bitcoin should never create different databases with the same fileid, but
 //! this error can be triggered if users manually copy database files.
 void CheckUniqueFileid(const BerkeleyEnvironment &env,
                        const std::string &filename, Db &db,
                        WalletDatabaseFileId &fileid) {
     if (env.IsMock()) {
         return;
     }
 
     int ret = db.get_mpf()->get_fileid(fileid.value);
     if (ret != 0) {
         throw std::runtime_error(strprintf(
             "BerkeleyBatch: Can't open database %s (get_fileid failed with %d)",
             filename, ret));
     }
 
     for (const auto &item : env.m_fileids) {
         if (fileid == item.second && &fileid != &item.second) {
             throw std::runtime_error(strprintf(
                 "BerkeleyBatch: Can't open database %s (duplicates fileid %s "
                 "from %s)",
                 filename,
                 HexStr(std::begin(item.second.value),
                        std::end(item.second.value)),
                 item.first));
         }
     }
 }
 
 CCriticalSection cs_db;
 
 //!< Map from directory name to db environment.
 std::map<std::string, std::weak_ptr<BerkeleyEnvironment>>
     g_dbenvs GUARDED_BY(cs_db);
 } // namespace
 
 bool WalletDatabaseFileId::operator==(const WalletDatabaseFileId &rhs) const {
     return memcmp(value, &rhs.value, sizeof(value)) == 0;
 }
 
 static void SplitWalletPath(const fs::path &wallet_path,
                             fs::path &env_directory,
                             std::string &database_filename) {
     if (fs::is_regular_file(wallet_path)) {
         // Special case for backwards compatibility: if wallet path points to an
         // existing file, treat it as the path to a BDB data file in a parent
         // directory that also contains BDB log files.
         env_directory = wallet_path.parent_path();
         database_filename = wallet_path.filename().string();
     } else {
         // Normal case: Interpret wallet path as a directory path containing
         // data and log files.
         env_directory = wallet_path;
         database_filename = "wallet.dat";
     }
 }
 
 bool IsWalletLoaded(const fs::path &wallet_path) {
     fs::path env_directory;
     std::string database_filename;
     SplitWalletPath(wallet_path, env_directory, database_filename);
 
     LOCK(cs_db);
     auto env = g_dbenvs.find(env_directory.string());
     if (env == g_dbenvs.end()) {
         return false;
     }
 
     auto database = env->second.lock();
     return database && database->IsDatabaseLoaded(database_filename);
 }
 
 /**
  * @param[in] wallet_path Path to wallet directory. Or (for backwards
  * compatibility only) a path to a berkeley btree data file inside a wallet
  * directory.
  * @param[out] database_filename Filename of berkeley btree data file inside the
  * wallet directory.
  * @return A shared pointer to the BerkeleyEnvironment object for the wallet
  * directory, never empty because ~BerkeleyEnvironment erases the weak pointer
  * from the g_dbenvs map.
  * @post A new BerkeleyEnvironment weak pointer is inserted into g_dbenvs if the
  * directory path key was not already in the map.
  */
 std::shared_ptr<BerkeleyEnvironment>
 GetWalletEnv(const fs::path &wallet_path, std::string &database_filename) {
     fs::path env_directory;
     SplitWalletPath(wallet_path, env_directory, database_filename);
     LOCK(cs_db);
     auto inserted = g_dbenvs.emplace(env_directory.string(),
                                      std::weak_ptr<BerkeleyEnvironment>());
     if (inserted.second) {
         auto env =
             std::make_shared<BerkeleyEnvironment>(env_directory.string());
         inserted.first->second = env;
         return env;
     }
     return inserted.first->second.lock();
 }
 
 //
 // BerkeleyBatch
 //
 
 void BerkeleyEnvironment::Close() {
     if (!fDbEnvInit) {
         return;
     }
 
     fDbEnvInit = false;
 
     for (auto &db : m_databases) {
         auto count = mapFileUseCount.find(db.first);
         assert(count == mapFileUseCount.end() || count->second == 0);
         BerkeleyDatabase &database = db.second.get();
         if (database.m_db) {
             database.m_db->close(0);
             database.m_db.reset();
         }
     }
 
+    FILE *error_file = nullptr;
+    dbenv->get_errfile(&error_file);
+
     int ret = dbenv->close(0);
     if (ret != 0) {
         LogPrintf("BerkeleyEnvironment::Close: Error %d closing database "
                   "environment: %s\n",
                   ret, DbEnv::strerror(ret));
     }
     if (!fMockDb) {
         DbEnv(u_int32_t(0)).remove(strPath.c_str(), 0);
     }
+
+    if (error_file) {
+        fclose(error_file);
+    }
+
+    UnlockDirectory(strPath, ".walletlock");
 }
 
 void BerkeleyEnvironment::Reset() {
     dbenv.reset(new DbEnv(DB_CXX_NO_EXCEPTIONS));
     fDbEnvInit = false;
     fMockDb = false;
 }
 
 BerkeleyEnvironment::BerkeleyEnvironment(const fs::path &dir_path)
     : strPath(dir_path.string()) {
     Reset();
 }
 
 BerkeleyEnvironment::~BerkeleyEnvironment() {
     LOCK(cs_db);
     g_dbenvs.erase(strPath);
     Close();
 }
 
 bool BerkeleyEnvironment::Open(bool retry) {
     if (fDbEnvInit) {
         return true;
     }
 
     boost::this_thread::interruption_point();
 
     fs::path pathIn = strPath;
     TryCreateDirectories(pathIn);
     if (!LockDirectory(pathIn, ".walletlock")) {
         LogPrintf("Cannot obtain a lock on wallet directory %s. Another "
                   "instance of bitcoin may be using it.\n",
                   strPath);
         return false;
     }
 
     fs::path pathLogDir = pathIn / "database";
     TryCreateDirectories(pathLogDir);
     fs::path pathErrorFile = pathIn / "db.log";
     LogPrintf("BerkeleyEnvironment::Open: LogDir=%s ErrorFile=%s\n",
               pathLogDir.string(), pathErrorFile.string());
 
     unsigned int nEnvFlags = 0;
     if (gArgs.GetBoolArg("-privdb", DEFAULT_WALLET_PRIVDB)) {
         nEnvFlags |= DB_PRIVATE;
     }
 
     dbenv->set_lg_dir(pathLogDir.string().c_str());
     // 1 MiB should be enough for just the wallet
     dbenv->set_cachesize(0, 0x100000, 1);
     dbenv->set_lg_bsize(0x10000);
     dbenv->set_lg_max(1048576);
     dbenv->set_lk_max_locks(40000);
     dbenv->set_lk_max_objects(40000);
     /// debug
     dbenv->set_errfile(fsbridge::fopen(pathErrorFile, "a"));
     dbenv->set_flags(DB_AUTO_COMMIT, 1);
     dbenv->set_flags(DB_TXN_WRITE_NOSYNC, 1);
     dbenv->log_set_config(DB_LOG_AUTO_REMOVE, 1);
     int ret =
         dbenv->open(strPath.c_str(),
                     DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL |
                         DB_INIT_TXN | DB_THREAD | DB_RECOVER | nEnvFlags,
                     S_IRUSR | S_IWUSR);
     if (ret != 0) {
         LogPrintf("BerkeleyEnvironment::Open: Error %d opening database "
                   "environment: %s\n",
                   ret, DbEnv::strerror(ret));
         int ret2 = dbenv->close(0);
         if (ret2 != 0) {
             LogPrintf("BerkeleyEnvironment::Open: Error %d closing failed "
                       "database environment: %s\n",
                       ret2, DbEnv::strerror(ret2));
         }
         Reset();
         if (retry) {
             // try moving the database env out of the way
             fs::path pathDatabaseBak =
                 pathIn / strprintf("database.%d.bak", GetTime());
             try {
                 fs::rename(pathLogDir, pathDatabaseBak);
                 LogPrintf("Moved old %s to %s. Retrying.\n",
                           pathLogDir.string(), pathDatabaseBak.string());
             } catch (const fs::filesystem_error &) {
                 // failure is ok (well, not really, but it's not worse than what
                 // we started with)
             }
             // try opening it again one more time
             if (!Open(false /* retry */)) {
                 // if it still fails, it probably means we can't even create the
                 // database env
                 return false;
             }
         } else {
             return false;
         }
     }
 
     fDbEnvInit = true;
     fMockDb = false;
     return true;
 }
 
 //! Construct an in-memory mock Berkeley environment for testing and as a
 //! place-holder for g_dbenvs emplace
 BerkeleyEnvironment::BerkeleyEnvironment() {
     Reset();
 
     boost::this_thread::interruption_point();
 
     LogPrint(BCLog::DB, "BerkeleyEnvironment::MakeMock\n");
 
     dbenv->set_cachesize(1, 0, 1);
     dbenv->set_lg_bsize(10485760 * 4);
     dbenv->set_lg_max(10485760);
     dbenv->set_lk_max_locks(10000);
     dbenv->set_lk_max_objects(10000);
     dbenv->set_flags(DB_AUTO_COMMIT, 1);
     dbenv->log_set_config(DB_LOG_IN_MEMORY, 1);
     int ret =
         dbenv->open(nullptr,
                     DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL |
                         DB_INIT_TXN | DB_THREAD | DB_PRIVATE,
                     S_IRUSR | S_IWUSR);
     if (ret > 0) {
         throw std::runtime_error(
             strprintf("BerkeleyEnvironment::MakeMock: Error %d opening "
                       "database environment.",
                       ret));
     }
 
     fDbEnvInit = true;
     fMockDb = true;
 }
 
 BerkeleyEnvironment::VerifyResult
 BerkeleyEnvironment::Verify(const std::string &strFile,
                             recoverFunc_type recoverFunc,
                             std::string &out_backup_filename) {
     LOCK(cs_db);
     assert(mapFileUseCount.count(strFile) == 0);
 
     Db db(dbenv.get(), 0);
     int result = db.verify(strFile.c_str(), nullptr, nullptr, 0);
     if (result == 0) {
         return VerifyResult::VERIFY_OK;
     } else if (recoverFunc == nullptr) {
         return VerifyResult::RECOVER_FAIL;
     }
 
     // Try to recover:
     bool fRecovered =
         (*recoverFunc)(fs::path(strPath) / strFile, out_backup_filename);
     return (fRecovered ? VerifyResult::RECOVER_OK : VerifyResult::RECOVER_FAIL);
 }
 
 bool BerkeleyBatch::Recover(const fs::path &file_path, void *callbackDataIn,
                             bool (*recoverKVcallback)(void *callbackData,
                                                       CDataStream ssKey,
                                                       CDataStream ssValue),
                             std::string &newFilename) {
     std::string filename;
     std::shared_ptr<BerkeleyEnvironment> env =
         GetWalletEnv(file_path, filename);
 
     // Recovery procedure:
     // Move wallet file to walletfilename.timestamp.bak
     // Call Salvage with fAggressive=true to get as much data as possible.
     // Rewrite salvaged data to fresh wallet file.
     // Set -rescan so any missing transactions will be found.
     int64_t now = GetTime();
     newFilename = strprintf("%s.%d.bak", filename, now);
 
     int result = env->dbenv->dbrename(nullptr, filename.c_str(), nullptr,
                                       newFilename.c_str(), DB_AUTO_COMMIT);
     if (result == 0) {
         LogPrintf("Renamed %s to %s\n", filename, newFilename);
     } else {
         LogPrintf("Failed to rename %s to %s\n", filename, newFilename);
         return false;
     }
 
     std::vector<BerkeleyEnvironment::KeyValPair> salvagedData;
     bool fSuccess = env->Salvage(newFilename, true, salvagedData);
     if (salvagedData.empty()) {
         LogPrintf("Salvage(aggressive) found no records in %s.\n", newFilename);
         return false;
     }
     LogPrintf("Salvage(aggressive) found %u records\n", salvagedData.size());
 
     std::unique_ptr<Db> pdbCopy = std::make_unique<Db>(env->dbenv.get(), 0);
     int ret = pdbCopy->open(nullptr,          // Txn pointer
                             filename.c_str(), // Filename
                             "main",           // Logical db name
                             DB_BTREE,         // Database type
                             DB_CREATE,        // Flags
                             0);
     if (ret > 0) {
         LogPrintf("Cannot create database file %s\n", filename);
         pdbCopy->close(0);
         return false;
     }
 
     DbTxn *ptxn = env->TxnBegin();
     for (BerkeleyEnvironment::KeyValPair &row : salvagedData) {
         if (recoverKVcallback) {
             CDataStream ssKey(row.first, SER_DISK, CLIENT_VERSION);
             CDataStream ssValue(row.second, SER_DISK, CLIENT_VERSION);
             if (!(*recoverKVcallback)(callbackDataIn, ssKey, ssValue)) {
                 continue;
             }
         }
         Dbt datKey(&row.first[0], row.first.size());
         Dbt datValue(&row.second[0], row.second.size());
         int ret2 = pdbCopy->put(ptxn, &datKey, &datValue, DB_NOOVERWRITE);
         if (ret2 > 0) {
             fSuccess = false;
         }
     }
     ptxn->commit(0);
     pdbCopy->close(0);
 
     return fSuccess;
 }
 
 bool BerkeleyBatch::VerifyEnvironment(const fs::path &file_path,
                                       std::string &errorStr) {
     std::string walletFile;
     std::shared_ptr<BerkeleyEnvironment> env =
         GetWalletEnv(file_path, walletFile);
     fs::path walletDir = env->Directory();
 
     LogPrintf("Using BerkeleyDB version %s\n", DbEnv::version(0, 0, 0));
     LogPrintf("Using wallet %s\n", walletFile);
 
     // Wallet file must be a plain filename without a directory
     if (walletFile != fs::basename(walletFile) + fs::extension(walletFile)) {
         errorStr = strprintf(_("Wallet %s resides outside wallet directory %s"),
                              walletFile, walletDir.string());
         return false;
     }
 
     if (!env->Open(true /* retry */)) {
         errorStr = strprintf(
             _("Error initializing wallet database environment %s!"), walletDir);
         return false;
     }
 
     return true;
 }
 
 bool BerkeleyBatch::VerifyDatabaseFile(
     const fs::path &file_path, std::string &warningStr, std::string &errorStr,
     BerkeleyEnvironment::recoverFunc_type recoverFunc) {
     std::string walletFile;
     std::shared_ptr<BerkeleyEnvironment> env =
         GetWalletEnv(file_path, walletFile);
     fs::path walletDir = env->Directory();
 
     if (fs::exists(walletDir / walletFile)) {
         std::string backup_filename;
         BerkeleyEnvironment::VerifyResult r =
             env->Verify(walletFile, recoverFunc, backup_filename);
         if (r == BerkeleyEnvironment::VerifyResult::RECOVER_OK) {
             warningStr = strprintf(
                 _("Warning: Wallet file corrupt, data salvaged! Original %s "
                   "saved as %s in %s; if your balance or transactions are "
                   "incorrect you should restore from a backup."),
                 walletFile, backup_filename, walletDir);
         }
         if (r == BerkeleyEnvironment::VerifyResult::RECOVER_FAIL) {
             errorStr = strprintf(_("%s corrupt, salvage failed"), walletFile);
             return false;
         }
     }
     // also return true if files does not exists
     return true;
 }
 
 /* End of headers, beginning of key/value data */
 static const char *HEADER_END = "HEADER=END";
 /* End of key/value data */
 static const char *DATA_END = "DATA=END";
 
 bool BerkeleyEnvironment::Salvage(
     const std::string &strFile, bool fAggressive,
     std::vector<BerkeleyEnvironment::KeyValPair> &vResult) {
     LOCK(cs_db);
     assert(mapFileUseCount.count(strFile) == 0);
 
     u_int32_t flags = DB_SALVAGE;
     if (fAggressive) {
         flags |= DB_AGGRESSIVE;
     }
 
     std::stringstream strDump;
 
     Db db(dbenv.get(), 0);
     int result = db.verify(strFile.c_str(), nullptr, &strDump, flags);
     if (result == DB_VERIFY_BAD) {
         LogPrintf("BerkeleyEnvironment::Salvage: Database salvage found "
                   "errors, all data may not be recoverable.\n");
         if (!fAggressive) {
             LogPrintf("BerkeleyEnvironment::Salvage: Rerun with aggressive "
                       "mode to ignore errors and continue.\n");
             return false;
         }
     }
     if (result != 0 && result != DB_VERIFY_BAD) {
         LogPrintf("BerkeleyEnvironment::Salvage: Database salvage failed with "
                   "result %d.\n",
                   result);
         return false;
     }
 
     // Format of bdb dump is ascii lines:
     // header lines...
     // HEADER=END
     //  hexadecimal key
     //  hexadecimal value
     //  ... repeated
     // DATA=END
 
     std::string strLine;
     while (!strDump.eof() && strLine != HEADER_END) {
         // Skip past header
         getline(strDump, strLine);
     }
 
     std::string keyHex, valueHex;
     while (!strDump.eof() && keyHex != DATA_END) {
         getline(strDump, keyHex);
         if (keyHex != DATA_END) {
             if (strDump.eof()) {
                 break;
             }
             getline(strDump, valueHex);
             if (valueHex == DATA_END) {
                 LogPrintf("BerkeleyEnvironment::Salvage: WARNING: Number of "
                           "keys in data does not match number of values.\n");
                 break;
             }
             vResult.push_back(make_pair(ParseHex(keyHex), ParseHex(valueHex)));
         }
     }
 
     if (keyHex != DATA_END) {
         LogPrintf("BerkeleyEnvironment::Salvage: WARNING: Unexpected end of "
                   "file while reading salvage output.\n");
         return false;
     }
 
     return (result == 0);
 }
 
 void BerkeleyEnvironment::CheckpointLSN(const std::string &strFile) {
     dbenv->txn_checkpoint(0, 0, 0);
     if (fMockDb) {
         return;
     }
     dbenv->lsn_reset(strFile.c_str(), 0);
 }
 
 BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase &database, const char *pszMode,
                              bool fFlushOnCloseIn)
     : pdb(nullptr), activeTxn(nullptr) {
     fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));
     fFlushOnClose = fFlushOnCloseIn;
     env = database.env.get();
     if (database.IsDummy()) {
         return;
     }
 
     const std::string &strFilename = database.strFile;
 
     bool fCreate = strchr(pszMode, 'c') != nullptr;
     unsigned int nFlags = DB_THREAD;
     if (fCreate) {
         nFlags |= DB_CREATE;
     }
 
     {
         LOCK(cs_db);
         if (!env->Open(false /* retry */)) {
             throw std::runtime_error(
                 "BerkeleyBatch: Failed to open database environment.");
         }
 
         pdb = database.m_db.get();
         if (pdb == nullptr) {
             int ret;
             std::unique_ptr<Db> pdb_temp =
                 std::make_unique<Db>(env->dbenv.get(), 0);
 
             bool fMockDb = env->IsMock();
             if (fMockDb) {
                 DbMpoolFile *mpf = pdb_temp->get_mpf();
                 ret = mpf->set_flags(DB_MPOOL_NOFILE, 1);
                 if (ret != 0) {
                     throw std::runtime_error(
                         strprintf("BerkeleyBatch: Failed to configure for no "
                                   "temp file backing for database %s",
                                   strFilename));
                 }
             }
 
             ret = pdb_temp->open(
                 nullptr,                                 // Txn pointer
                 fMockDb ? nullptr : strFilename.c_str(), // Filename
                 fMockDb ? strFilename.c_str() : "main",  // Logical db name
                 DB_BTREE,                                // Database type
                 nFlags,                                  // Flags
                 0);
 
             if (ret != 0) {
                 throw std::runtime_error(
                     strprintf("BerkeleyBatch: Error %d, can't open database %s",
                               ret, strFilename));
             }
 
             // Call CheckUniqueFileid on the containing BDB environment to
             // avoid BDB data consistency bugs that happen when different data
             // files in the same environment have the same fileid.
             //
             // Also call CheckUniqueFileid on all the other g_dbenvs to prevent
             // bitcoin from opening the same data file through another
             // environment when the file is referenced through equivalent but
             // not obviously identical symlinked or hard linked or bind mounted
             // paths. In the future a more relaxed check for equal inode and
             // device ids could be done instead, which would allow opening
             // different backup copies of a wallet at the same time. Maybe even
             // more ideally, an exclusive lock for accessing the database could
             // be implemented, so no equality checks are needed at all. (Newer
             // versions of BDB have an set_lk_exclusive method for this
             // purpose, but the older version we use does not.)
             for (const auto &dbenv : g_dbenvs) {
                 CheckUniqueFileid(*dbenv.second.lock().get(), strFilename,
                                   *pdb_temp, this->env->m_fileids[strFilename]);
             }
 
             pdb = pdb_temp.release();
             database.m_db.reset(pdb);
 
             if (fCreate && !Exists(std::string("version"))) {
                 bool fTmp = fReadOnly;
                 fReadOnly = false;
                 WriteVersion(CLIENT_VERSION);
                 fReadOnly = fTmp;
             }
         }
         ++env->mapFileUseCount[strFilename];
         strFile = strFilename;
     }
 }
 
 void BerkeleyBatch::Flush() {
     if (activeTxn) {
         return;
     }
 
     // Flush database activity from memory pool to disk log
     unsigned int nMinutes = 0;
     if (fReadOnly) {
         nMinutes = 1;
     }
 
     env->dbenv->txn_checkpoint(
         nMinutes ? gArgs.GetArg("-dblogsize", DEFAULT_WALLET_DBLOGSIZE) * 1024
                  : 0,
         nMinutes, 0);
 }
 
 void BerkeleyDatabase::IncrementUpdateCounter() {
     ++nUpdateCounter;
 }
 
 void BerkeleyBatch::Close() {
     if (!pdb) {
         return;
     }
     if (activeTxn) {
         activeTxn->abort();
     }
     activeTxn = nullptr;
     pdb = nullptr;
 
     if (fFlushOnClose) {
         Flush();
     }
 
     {
         LOCK(cs_db);
         --env->mapFileUseCount[strFile];
     }
     env->m_db_in_use.notify_all();
 }
 
 void BerkeleyEnvironment::CloseDb(const std::string &strFile) {
     LOCK(cs_db);
     auto it = m_databases.find(strFile);
     assert(it != m_databases.end());
     BerkeleyDatabase &database = it->second.get();
     if (database.m_db) {
         // Close the database handle
         database.m_db->close(0);
         database.m_db.reset();
     }
 }
 
 void BerkeleyEnvironment::ReloadDbEnv() {
     // Make sure that no Db's are in use
     AssertLockNotHeld(cs_db);
     std::unique_lock<CCriticalSection> lock(cs_db);
     m_db_in_use.wait(lock, [this]() {
         for (auto &count : mapFileUseCount) {
             if (count.second > 0) {
                 return false;
             }
         }
         return true;
     });
 
     std::vector<std::string> filenames;
     for (auto it : m_databases) {
         filenames.push_back(it.first);
     }
     // Close the individual Db's
     for (const std::string &filename : filenames) {
         CloseDb(filename);
     }
     // Reset the environment
     // This will flush and close the environment
     Flush(true);
     Reset();
     Open(true);
 }
 
 bool BerkeleyBatch::Rewrite(BerkeleyDatabase &database, const char *pszSkip) {
     if (database.IsDummy()) {
         return true;
     }
     BerkeleyEnvironment *env = database.env.get();
     const std::string &strFile = database.strFile;
     while (true) {
         {
             LOCK(cs_db);
             if (!env->mapFileUseCount.count(strFile) ||
                 env->mapFileUseCount[strFile] == 0) {
                 // Flush log data to the dat file
                 env->CloseDb(strFile);
                 env->CheckpointLSN(strFile);
                 env->mapFileUseCount.erase(strFile);
 
                 bool fSuccess = true;
                 LogPrintf("BerkeleyBatch::Rewrite: Rewriting %s...\n", strFile);
                 std::string strFileRes = strFile + ".rewrite";
                 {
                     // surround usage of db with extra {}
                     BerkeleyBatch db(database, "r");
                     std::unique_ptr<Db> pdbCopy =
                         std::make_unique<Db>(env->dbenv.get(), 0);
 
                     int ret = pdbCopy->open(nullptr,            // Txn pointer
                                             strFileRes.c_str(), // Filename
                                             "main",    // Logical db name
                                             DB_BTREE,  // Database type
                                             DB_CREATE, // Flags
                                             0);
                     if (ret > 0) {
                         LogPrintf("BerkeleyBatch::Rewrite: Can't create "
                                   "database file %s\n",
                                   strFileRes);
                         fSuccess = false;
                     }
 
                     Dbc *pcursor = db.GetCursor();
                     if (pcursor)
                         while (fSuccess) {
                             CDataStream ssKey(SER_DISK, CLIENT_VERSION);
                             CDataStream ssValue(SER_DISK, CLIENT_VERSION);
                             int ret1 = db.ReadAtCursor(pcursor, ssKey, ssValue);
                             if (ret1 == DB_NOTFOUND) {
                                 pcursor->close();
                                 break;
                             }
                             if (ret1 != 0) {
                                 pcursor->close();
                                 fSuccess = false;
                                 break;
                             }
                             if (pszSkip &&
                                 strncmp(ssKey.data(), pszSkip,
                                         std::min(ssKey.size(),
                                                  strlen(pszSkip))) == 0) {
                                 continue;
                             }
                             if (strncmp(ssKey.data(), "\x07version", 8) == 0) {
                                 // Update version:
                                 ssValue.clear();
                                 ssValue << CLIENT_VERSION;
                             }
                             Dbt datKey(ssKey.data(), ssKey.size());
                             Dbt datValue(ssValue.data(), ssValue.size());
                             int ret2 = pdbCopy->put(nullptr, &datKey, &datValue,
                                                     DB_NOOVERWRITE);
                             if (ret2 > 0) {
                                 fSuccess = false;
                             }
                         }
                     if (fSuccess) {
                         db.Close();
                         env->CloseDb(strFile);
                         if (pdbCopy->close(0)) {
                             fSuccess = false;
                         }
                     } else {
                         pdbCopy->close(0);
                     }
                 }
                 if (fSuccess) {
                     Db dbA(env->dbenv.get(), 0);
                     if (dbA.remove(strFile.c_str(), nullptr, 0)) {
                         fSuccess = false;
                     }
                     Db dbB(env->dbenv.get(), 0);
                     if (dbB.rename(strFileRes.c_str(), nullptr, strFile.c_str(),
                                    0)) {
                         fSuccess = false;
                     }
                 }
                 if (!fSuccess) {
                     LogPrintf("BerkeleyBatch::Rewrite: Failed to rewrite "
                               "database file %s\n",
                               strFileRes);
                 }
                 return fSuccess;
             }
         }
         MilliSleep(100);
     }
 }
 
 void BerkeleyEnvironment::Flush(bool fShutdown) {
     int64_t nStart = GetTimeMillis();
     // Flush log data to the actual data file on all files that are not in use
     LogPrint(BCLog::DB, "BerkeleyEnvironment::Flush: [%s] Flush(%s)%s\n",
              strPath, fShutdown ? "true" : "false",
              fDbEnvInit ? "" : " database not started");
     if (!fDbEnvInit) {
         return;
     }
     {
         LOCK(cs_db);
         std::map<std::string, int>::iterator mi = mapFileUseCount.begin();
         while (mi != mapFileUseCount.end()) {
             std::string strFile = (*mi).first;
             int nRefCount = (*mi).second;
             LogPrint(
                 BCLog::DB,
                 "BerkeleyEnvironment::Flush: Flushing %s (refcount = %d)...\n",
                 strFile, nRefCount);
             if (nRefCount == 0) {
                 // Move log data to the dat file
                 CloseDb(strFile);
                 LogPrint(BCLog::DB,
                          "BerkeleyEnvironment::Flush: %s checkpoint\n",
                          strFile);
                 dbenv->txn_checkpoint(0, 0, 0);
                 LogPrint(BCLog::DB, "BerkeleyEnvironment::Flush: %s detach\n",
                          strFile);
                 if (!fMockDb) {
                     dbenv->lsn_reset(strFile.c_str(), 0);
                 }
                 LogPrint(BCLog::DB, "BerkeleyEnvironment::Flush: %s closed\n",
                          strFile);
                 mapFileUseCount.erase(mi++);
             } else {
                 mi++;
             }
         }
         LogPrint(BCLog::DB,
                  "BerkeleyEnvironment::Flush: Flush(%s)%s took %15dms\n",
                  fShutdown ? "true" : "false",
                  fDbEnvInit ? "" : " database not started",
                  GetTimeMillis() - nStart);
         if (fShutdown) {
             char **listp;
             if (mapFileUseCount.empty()) {
                 dbenv->log_archive(&listp, DB_ARCH_REMOVE);
                 Close();
                 if (!fMockDb) {
                     fs::remove_all(fs::path(strPath) / "database");
                 }
             }
         }
     }
 }
 
 bool BerkeleyBatch::PeriodicFlush(BerkeleyDatabase &database) {
     if (database.IsDummy()) {
         return true;
     }
     bool ret = false;
     BerkeleyEnvironment *env = database.env.get();
     const std::string &strFile = database.strFile;
     TRY_LOCK(cs_db, lockDb);
     if (lockDb) {
         // Don't do this if any databases are in use
         int nRefCount = 0;
         std::map<std::string, int>::iterator mit = env->mapFileUseCount.begin();
         while (mit != env->mapFileUseCount.end()) {
             nRefCount += (*mit).second;
             mit++;
         }
 
         if (nRefCount == 0) {
             boost::this_thread::interruption_point();
             std::map<std::string, int>::iterator mi =
                 env->mapFileUseCount.find(strFile);
             if (mi != env->mapFileUseCount.end()) {
                 LogPrint(BCLog::DB, "Flushing %s\n", strFile);
                 int64_t nStart = GetTimeMillis();
 
                 // Flush wallet file so it's self contained
                 env->CloseDb(strFile);
                 env->CheckpointLSN(strFile);
 
                 env->mapFileUseCount.erase(mi++);
                 LogPrint(BCLog::DB, "Flushed %s %dms\n", strFile,
                          GetTimeMillis() - nStart);
                 ret = true;
             }
         }
     }
 
     return ret;
 }
 
 bool BerkeleyDatabase::Rewrite(const char *pszSkip) {
     return BerkeleyBatch::Rewrite(*this, pszSkip);
 }
 
 bool BerkeleyDatabase::Backup(const std::string &strDest) {
     if (IsDummy()) {
         return false;
     }
     while (true) {
         {
             LOCK(cs_db);
             if (!env->mapFileUseCount.count(strFile) ||
                 env->mapFileUseCount[strFile] == 0) {
                 // Flush log data to the dat file
                 env->CloseDb(strFile);
                 env->CheckpointLSN(strFile);
                 env->mapFileUseCount.erase(strFile);
 
                 // Copy wallet file.
                 fs::path pathSrc = env->Directory() / strFile;
                 fs::path pathDest(strDest);
                 if (fs::is_directory(pathDest)) {
                     pathDest /= strFile;
                 }
 
                 try {
                     if (fs::equivalent(pathSrc, pathDest)) {
                         LogPrintf("cannot backup to wallet source file %s\n",
                                   pathDest.string());
                         return false;
                     }
 
                     fs::copy_file(pathSrc, pathDest,
                                   fs::copy_option::overwrite_if_exists);
                     LogPrintf("copied %s to %s\n", strFile, pathDest.string());
                     return true;
                 } catch (const fs::filesystem_error &e) {
                     LogPrintf("error copying %s to %s - %s\n", strFile,
                               pathDest.string(), e.what());
                     return false;
                 }
             }
         }
         MilliSleep(100);
     }
 }
 
 void BerkeleyDatabase::Flush(bool shutdown) {
     if (!IsDummy()) {
         env->Flush(shutdown);
         if (shutdown) {
             LOCK(cs_db);
             g_dbenvs.erase(env->Directory().string());
             env = nullptr;
         } else {
             // TODO: To avoid g_dbenvs.erase erasing the environment prematurely
             // after the first database shutdown when multiple databases are
             // open in the same environment, should replace raw database `env`
             // pointers with shared or weak pointers, or else separate the
             // database and environment shutdowns so environments can be shut
             // down after databases.
             env->m_fileids.erase(strFile);
         }
     }
 }
 
 void BerkeleyDatabase::ReloadDbEnv() {
     if (!IsDummy()) {
         env->ReloadDbEnv();
     }
 }
diff --git a/test/functional/wallet_multiwallet.py b/test/functional/wallet_multiwallet.py
index 239ca28c0a..a920045971 100755
--- a/test/functional/wallet_multiwallet.py
+++ b/test/functional/wallet_multiwallet.py
@@ -1,323 +1,332 @@
 #!/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 multiwallet.
 
 Verify that a bitcoind node can load multiple wallet files
 """
 import os
 import shutil
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.test_node import ErrorMatch
 from test_framework.util import (
     assert_equal,
     assert_raises_rpc_error,
 )
 
 
 class MultiWalletTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 2
         self.supports_cli = True
 
     def run_test(self):
         node = self.nodes[0]
 
         data_dir = lambda *p: os.path.join(node.datadir, 'regtest', *p)
         wallet_dir = lambda *p: data_dir('wallets', *p)
 
         def wallet(name): return node.get_wallet_rpc(name)
 
         def wallet_file(name):
             if os.path.isdir(wallet_dir(name)):
                 return wallet_dir(name, "wallet.dat")
             return wallet_dir(name)
 
         # check wallet.dat is created
         self.stop_nodes()
         assert_equal(os.path.isfile(wallet_dir('wallet.dat')), True)
 
         # create symlink to verify wallet directory path can be referenced
         # through symlink
         os.mkdir(wallet_dir('w7'))
         os.symlink('w7', wallet_dir('w7_symlink'))
 
         # rename wallet.dat to make sure plain wallet file paths (as opposed to
         # directory paths) can be loaded
         os.rename(wallet_dir("wallet.dat"), wallet_dir("w8"))
 
         # create another dummy wallet for use in testing backups later
         self.start_node(0, [])
         self.stop_nodes()
         empty_wallet = os.path.join(self.options.tmpdir, 'empty.dat')
         os.rename(wallet_dir("wallet.dat"), empty_wallet)
 
         # restart node with a mix of wallet names:
         #   w1, w2, w3 - to verify new wallets created when non-existing paths specified
         #   w          - to verify wallet name matching works when one wallet path is prefix of another
         #   sub/w5     - to verify relative wallet path is created correctly
         #   extern/w6  - to verify absolute wallet path is created correctly
         #   w7_symlink - to verify symlinked wallet path is initialized correctly
         #   w8         - to verify existing wallet file is loaded correctly
         #   ''         - to verify default wallet file is created correctly
         wallet_names = ['w1', 'w2', 'w3', 'w', 'sub/w5',
                         os.path.join(self.options.tmpdir, 'extern/w6'), 'w7_symlink', 'w8', '']
         extra_args = ['-wallet={}'.format(n) for n in wallet_names]
         self.start_node(0, extra_args)
         assert_equal(set(node.listwallets()), set(wallet_names))
 
         # check that all requested wallets were created
         self.stop_node(0)
         for wallet_name in wallet_names:
             assert_equal(os.path.isfile(wallet_file(wallet_name)), True)
 
         # should not initialize if wallet path can't be created
         exp_stderr = "boost::filesystem::create_directory: (The system cannot find the path specified|Not a directory):"
         self.nodes[0].assert_start_raises_init_error(
             ['-wallet=wallet.dat/bad'], exp_stderr, match=ErrorMatch.PARTIAL_REGEX)
 
         self.nodes[0].assert_start_raises_init_error(
             ['-walletdir=wallets'], 'Error: Specified -walletdir "wallets" does not exist')
         self.nodes[0].assert_start_raises_init_error(
             ['-walletdir=wallets'], 'Error: Specified -walletdir "wallets" is a relative path', cwd=data_dir())
         self.nodes[0].assert_start_raises_init_error(
             ['-walletdir=debug.log'], 'Error: Specified -walletdir "debug.log" is not a directory', cwd=data_dir())
 
         # should not initialize if there are duplicate wallets
         self.nodes[0].assert_start_raises_init_error(
             ['-wallet=w1', '-wallet=w1'], 'Error: Error loading wallet w1. Duplicate -wallet filename specified.')
 
         # should not initialize if one wallet is a copy of another
         shutil.copyfile(wallet_dir('w8'), wallet_dir('w8_copy'))
         exp_stderr = r"BerkeleyBatch: Can't open database w8_copy \(duplicates fileid \w+ from w8\)"
         self.nodes[0].assert_start_raises_init_error(
             ['-wallet=w8', '-wallet=w8_copy'], exp_stderr, match=ErrorMatch.PARTIAL_REGEX)
 
         # should not initialize if wallet file is a symlink
         os.symlink('w8', wallet_dir('w8_symlink'))
         self.nodes[0].assert_start_raises_init_error(
             ['-wallet=w8_symlink'], r'Error: Invalid -wallet path \'w8_symlink\'\. .*', match=ErrorMatch.FULL_REGEX)
 
         # should not initialize if the specified walletdir does not exist
         self.nodes[0].assert_start_raises_init_error(
             ['-walletdir=bad'], 'Error: Specified -walletdir "bad" does not exist')
         # should not initialize if the specified walletdir is not a directory
         not_a_dir = wallet_dir('notadir')
         open(not_a_dir, 'a', encoding="utf8").close()
         self.nodes[0].assert_start_raises_init_error(
             ['-walletdir=' + not_a_dir], 'Error: Specified -walletdir "' + not_a_dir + '" is not a directory')
 
         # if wallets/ doesn't exist, datadir should be the default wallet dir
         wallet_dir2 = data_dir('walletdir')
         os.rename(wallet_dir(), wallet_dir2)
         self.start_node(0, ['-wallet=w4', '-wallet=w5'])
         assert_equal(set(node.listwallets()), {"w4", "w5"})
         w5 = wallet("w5")
         w5.generate(1)
 
         # now if wallets/ exists again, but the rootdir is specified as the walletdir, w4 and w5 should still be loaded
         os.rename(wallet_dir2, wallet_dir())
         self.restart_node(0, ['-wallet=w4', '-wallet=w5',
                               '-walletdir=' + data_dir()])
         assert_equal(set(node.listwallets()), {"w4", "w5"})
         w5 = wallet("w5")
         w5_info = w5.getwalletinfo()
         assert_equal(w5_info['immature_balance'], 50)
 
         competing_wallet_dir = os.path.join(
             self.options.tmpdir, 'competing_walletdir')
         os.mkdir(competing_wallet_dir)
         self.restart_node(0, ['-walletdir=' + competing_wallet_dir])
         exp_stderr = r"Error: Error initializing wallet database environment \"\S+competing_walletdir\"!"
         self.nodes[1].assert_start_raises_init_error(
             ['-walletdir=' + competing_wallet_dir], exp_stderr, match=ErrorMatch.PARTIAL_REGEX)
 
         self.restart_node(0, extra_args)
 
         wallets = [wallet(w) for w in wallet_names]
         wallet_bad = wallet("bad")
 
         # check wallet names and balances
         wallets[0].generate(1)
         for wallet_name, wallet in zip(wallet_names, wallets):
             info = wallet.getwalletinfo()
             assert_equal(info['immature_balance'],
                          50 if wallet is wallets[0] else 0)
             assert_equal(info['walletname'], wallet_name)
 
         # accessing invalid wallet fails
         assert_raises_rpc_error(-18, "Requested wallet does not exist or is not loaded",
                                 wallet_bad.getwalletinfo)
 
         # accessing wallet RPC without using wallet endpoint fails
         assert_raises_rpc_error(-19, "Wallet file not specified (must request wallet RPC through /wallet/<filename> uri-path).",
                                 node.getwalletinfo)
 
         w1, w2, w3, w4, *_ = wallets
         w1.generate(101)
         assert_equal(w1.getbalance(), 100)
         assert_equal(w2.getbalance(), 0)
         assert_equal(w3.getbalance(), 0)
         assert_equal(w4.getbalance(), 0)
 
         w1.sendtoaddress(w2.getnewaddress(), 1)
         w1.sendtoaddress(w3.getnewaddress(), 2)
         w1.sendtoaddress(w4.getnewaddress(), 3)
         w1.generate(1)
         assert_equal(w2.getbalance(), 1)
         assert_equal(w3.getbalance(), 2)
         assert_equal(w4.getbalance(), 3)
 
         batch = w1.batch([w1.getblockchaininfo.get_request(),
                           w1.getwalletinfo.get_request()])
         assert_equal(batch[0]["result"]["chain"], "regtest")
         assert_equal(batch[1]["result"]["walletname"], "w1")
 
         self.log.info('Check for per-wallet settxfee call')
         assert_equal(w1.getwalletinfo()['paytxfee'], 0)
         assert_equal(w2.getwalletinfo()['paytxfee'], 0)
         w2.settxfee(4.0)
         assert_equal(w1.getwalletinfo()['paytxfee'], 0)
         assert_equal(w2.getwalletinfo()['paytxfee'], 4.0)
 
         self.log.info("Test dynamic wallet loading")
 
         self.restart_node(0, ['-nowallet'])
         assert_equal(node.listwallets(), [])
         assert_raises_rpc_error(-32601, "Method not found", node.getwalletinfo)
 
         self.log.info("Load first wallet")
         loadwallet_name = node.loadwallet(wallet_names[0])
         assert_equal(loadwallet_name['name'], wallet_names[0])
         assert_equal(node.listwallets(), wallet_names[0:1])
         node.getwalletinfo()
         w1 = node.get_wallet_rpc(wallet_names[0])
         w1.getwalletinfo()
 
         self.log.info("Load second wallet")
         loadwallet_name = node.loadwallet(wallet_names[1])
         assert_equal(loadwallet_name['name'], wallet_names[1])
         assert_equal(node.listwallets(), wallet_names[0:2])
         assert_raises_rpc_error(-19,
                                 "Wallet file not specified", node.getwalletinfo)
         w2 = node.get_wallet_rpc(wallet_names[1])
         w2.getwalletinfo()
 
         self.log.info("Load remaining wallets")
         for wallet_name in wallet_names[2:]:
             loadwallet_name = self.nodes[0].loadwallet(wallet_name)
             assert_equal(loadwallet_name['name'], wallet_name)
 
         assert_equal(set(self.nodes[0].listwallets()), set(wallet_names))
 
         # Fail to load if wallet doesn't exist
         assert_raises_rpc_error(-18, 'Wallet wallets not found.',
                                 self.nodes[0].loadwallet, 'wallets')
 
         # Fail to load duplicate wallets
         assert_raises_rpc_error(-4, 'Wallet file verification failed: Error loading wallet w1. Duplicate -wallet filename specified.',
                                 self.nodes[0].loadwallet, wallet_names[0])
 
         # Fail to load duplicate wallets by different ways (directory and filepath)
         assert_raises_rpc_error(-4, "Wallet file verification failed: Error loading wallet wallet.dat. Duplicate -wallet filename specified.",
                                 self.nodes[0].loadwallet, 'wallet.dat')
 
         # Fail to load if one wallet is a copy of another
         assert_raises_rpc_error(-1, "BerkeleyBatch: Can't open database w8_copy (duplicates fileid",
                                 self.nodes[0].loadwallet, 'w8_copy')
 
         # Fail to load if one wallet is a copy of another.
         # Test this twice to make sure that we don't re-introduce https://github.com/bitcoin/bitcoin/issues/14304
         assert_raises_rpc_error(-1, "BerkeleyBatch: Can't open database w8_copy (duplicates fileid",
                                 self.nodes[0].loadwallet, 'w8_copy')
 
         # Fail to load if wallet file is a symlink
         assert_raises_rpc_error(-4, "Wallet file verification failed: Invalid -wallet path 'w8_symlink'",
                                 self.nodes[0].loadwallet, 'w8_symlink')
 
         # Fail to load if a directory is specified that doesn't contain a wallet
         os.mkdir(wallet_dir('empty_wallet_dir'))
         assert_raises_rpc_error(-18, "Directory empty_wallet_dir does not contain a wallet.dat file",
                                 self.nodes[0].loadwallet, 'empty_wallet_dir')
 
         self.log.info("Test dynamic wallet creation.")
 
         # Fail to create a wallet if it already exists.
         assert_raises_rpc_error(-4, "Wallet w2 already exists.",
                                 self.nodes[0].createwallet, 'w2')
 
         # Successfully create a wallet with a new name
         loadwallet_name = self.nodes[0].createwallet('w9')
         assert_equal(loadwallet_name['name'], 'w9')
         w9 = node.get_wallet_rpc('w9')
         assert_equal(w9.getwalletinfo()['walletname'], 'w9')
 
         assert 'w9' in self.nodes[0].listwallets()
 
         # Successfully create a wallet using a full path
         new_wallet_dir = os.path.join(self.options.tmpdir, 'new_walletdir')
         new_wallet_name = os.path.join(new_wallet_dir, 'w10')
         loadwallet_name = self.nodes[0].createwallet(new_wallet_name)
         assert_equal(loadwallet_name['name'], new_wallet_name)
         w10 = node.get_wallet_rpc(new_wallet_name)
         assert_equal(w10.getwalletinfo()['walletname'], new_wallet_name)
 
         assert new_wallet_name in self.nodes[0].listwallets()
 
         self.log.info("Test dynamic wallet unloading")
 
         # Test `unloadwallet` errors
         assert_raises_rpc_error(-1, "JSON value is not a string as expected",
                                 self.nodes[0].unloadwallet)
         assert_raises_rpc_error(-18, "Requested wallet does not exist or is not loaded",
                                 self.nodes[0].unloadwallet, "dummy")
         assert_raises_rpc_error(-18, "Requested wallet does not exist or is not loaded",
                                 node.get_wallet_rpc("dummy").unloadwallet)
         assert_raises_rpc_error(-8, "Cannot unload the requested wallet",
                                 w1.unloadwallet, "w2"),
 
         # Successfully unload the specified wallet name
         self.nodes[0].unloadwallet("w1")
         assert 'w1' not in self.nodes[0].listwallets()
 
         # Successfully unload the wallet referenced by the request endpoint
         w2.unloadwallet()
         assert 'w2' not in self.nodes[0].listwallets()
 
         # Successfully unload all wallets
         for wallet_name in self.nodes[0].listwallets():
             self.nodes[0].unloadwallet(wallet_name)
         assert_equal(self.nodes[0].listwallets(), [])
         assert_raises_rpc_error(-32601, "Method not found (wallet method is disabled because no wallet is loaded)",
                                 self.nodes[0].getwalletinfo)
 
         # Successfully load a previously unloaded wallet
         self.nodes[0].loadwallet('w1')
         assert_equal(self.nodes[0].listwallets(), ['w1'])
         assert_equal(w1.getwalletinfo()['walletname'], 'w1')
 
         # Test backing up and restoring wallets
         self.log.info("Test wallet backup")
         self.restart_node(0, ['-nowallet'])
         for wallet_name in wallet_names:
             self.nodes[0].loadwallet(wallet_name)
         for wallet_name in wallet_names:
             rpc = self.nodes[0].get_wallet_rpc(wallet_name)
             addr = rpc.getnewaddress()
             backup = os.path.join(self.options.tmpdir, 'backup.dat')
             rpc.backupwallet(backup)
             self.nodes[0].unloadwallet(wallet_name)
             shutil.copyfile(empty_wallet, wallet_file(wallet_name))
             self.nodes[0].loadwallet(wallet_name)
             assert_equal(rpc.getaddressinfo(addr)['ismine'], False)
             self.nodes[0].unloadwallet(wallet_name)
             shutil.copyfile(backup, wallet_file(wallet_name))
             self.nodes[0].loadwallet(wallet_name)
             assert_equal(rpc.getaddressinfo(addr)['ismine'], True)
 
+        # Test .walletlock file is closed
+        self.start_node(1)
+        wallet = os.path.join(self.options.tmpdir, 'my_wallet')
+        self.nodes[0].createwallet(wallet)
+        assert_raises_rpc_error(-4, "Error initializing wallet database environment",
+                                self.nodes[1].loadwallet, wallet)
+        self.nodes[0].unloadwallet(wallet)
+        self.nodes[1].loadwallet(wallet)
+
 
 if __name__ == '__main__':
     MultiWalletTest().main()