// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Copyright (c) 2017-2022 The Bitcoin 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 <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(item.second.value), item.first));
        }
    }
}

RecursiveMutex 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;
    }

    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();

    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(nullptr, nullptr, nullptr));
    LogPrintf("Using wallet %s\n", walletFile);

    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<RecursiveMutex> 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) {
            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,
                                  fsbridge::get_overwrite_if_exists_option());
                    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(),
                              fsbridge::get_filesystem_error_message(e));
                    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();
    }
}
