Allow wallet files in multiple directories

Remove requirement that two wallet files can only be opened at the same time if
they are contained in the same directory.

This change mostly consists of updates to function signatures (updating
functions to take fs::path arguments, instead of combinations of strings,
fs::path, and CDBEnv / CWalletDBWrapper arguments).

13 files changed, 201 insertions, 151 deletions

diff --git a/src/bench/coin_selection.cpp b/src/bench/coin_selection.cpp
index 6f438b60e9..98965840c7 100644
--- a/src/bench/coin_selection.cpp
+++ b/src/bench/coin_selection.cpp
@@ -32,7 +32,7 @@ static void addCoin(const CAmount& nValue, const CWallet& wallet, std::vector<CO
 // (https://github.com/bitcoin/bitcoin/issues/7883#issuecomment-224807484)
 static void CoinSelection(benchmark::State& state)
 {
-    const CWallet wallet;
+    const CWallet wallet("dummy", CWalletDBWrapper::CreateDummy());
     std::vector<COutput> vCoins;
     LOCK(wallet.cs_wallet);
 
diff --git a/src/qt/test/wallettests.cpp b/src/qt/test/wallettests.cpp
index cd49292138..af4e36c04f 100644
--- a/src/qt/test/wallettests.cpp
+++ b/src/qt/test/wallettests.cpp
@@ -157,9 +157,7 @@ void TestGUI()
     for (int i = 0; i < 5; ++i) {
         test.CreateAndProcessBlock({}, GetScriptForRawPubKey(test.coinbaseKey.GetPubKey()));
     }
-    bitdb.MakeMock();
-    std::unique_ptr<CWalletDBWrapper> dbw(new CWalletDBWrapper(&bitdb, "wallet_test.dat"));
-    CWallet wallet(std::move(dbw));
+    CWallet wallet("mock", CWalletDBWrapper::CreateMock());
     bool firstRun;
     wallet.LoadWallet(firstRun);
     {
@@ -260,9 +258,6 @@ void TestGUI()
     QPushButton* removeRequestButton = receiveCoinsDialog.findChild<QPushButton*>("removeRequestButton");
     removeRequestButton->click();
     QCOMPARE(requestTableModel->rowCount({}), currentRowCount-1);
-
-    bitdb.Flush(true);
-    bitdb.Reset();
 }
 
 }
diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index 23c6279128..88463d10b2 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -52,20 +52,44 @@ void CheckUniqueFileid(const CDBEnv& env, const std::string& filename, Db& db)
         }
     }
 }
+
+CCriticalSection cs_db;
+std::map<std::string, CDBEnv> g_dbenvs; //!< Map from directory name to open db environment.
 } // namespace
 
+CDBEnv* GetWalletEnv(const fs::path& wallet_path, std::string& database_filename)
+{
+    fs::path env_directory = wallet_path.parent_path();
+    database_filename = wallet_path.filename().string();
+    LOCK(cs_db);
+    // Note: An ununsed temporary CDBEnv object may be created inside the
+    // emplace function if the key already exists. This is a little inefficient,
+    // but not a big concern since the map will be changed in the future to hold
+    // pointers instead of objects, anyway.
+    return &g_dbenvs.emplace(std::piecewise_construct, std::forward_as_tuple(env_directory.string()), std::forward_as_tuple(env_directory)).first->second;
+}
+
 //
 // CDB
 //
 
-CDBEnv bitdb;
-
-void CDBEnv::EnvShutdown()
+void CDBEnv::Close()
 {
     if (!fDbEnvInit)
         return;
 
     fDbEnvInit = false;
+
+    for (auto& db : mapDb) {
+        auto count = mapFileUseCount.find(db.first);
+        assert(count == mapFileUseCount.end() || count->second == 0);
+        if (db.second) {
+            db.second->close(0);
+            delete db.second;
+            db.second = nullptr;
+        }
+    }
+
     int ret = dbenv->close(0);
     if (ret != 0)
         LogPrintf("CDBEnv::EnvShutdown: Error %d shutting down database environment: %s\n", ret, DbEnv::strerror(ret));
@@ -80,29 +104,24 @@ void CDBEnv::Reset()
     fMockDb = false;
 }
 
-CDBEnv::CDBEnv()
+CDBEnv::CDBEnv(const fs::path& dir_path) : strPath(dir_path.string())
 {
     Reset();
 }
 
 CDBEnv::~CDBEnv()
 {
-    EnvShutdown();
+    Close();
 }
 
-void CDBEnv::Close()
-{
-    EnvShutdown();
-}
-
-bool CDBEnv::Open(const fs::path& pathIn, bool retry)
+bool CDBEnv::Open(bool retry)
 {
     if (fDbEnvInit)
         return true;
 
     boost::this_thread::interruption_point();
 
-    strPath = pathIn.string();
+    fs::path pathIn = strPath;
     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;
@@ -150,7 +169,7 @@ bool CDBEnv::Open(const fs::path& pathIn, bool retry)
                 // 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(pathIn, false)) {
+            if (!Open(false /* retry */)) {
                 // if it still fails, it probably means we can't even create the database env
                 return false;
             }
@@ -209,12 +228,15 @@ CDBEnv::VerifyResult CDBEnv::Verify(const std::string& strFile, recoverFunc_type
         return RECOVER_FAIL;
 
     // Try to recover:
-    bool fRecovered = (*recoverFunc)(strFile, out_backup_filename);
+    bool fRecovered = (*recoverFunc)(fs::path(strPath) / strFile, out_backup_filename);
     return (fRecovered ? RECOVER_OK : RECOVER_FAIL);
 }
 
-bool CDB::Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& newFilename)
+bool CDB::Recover(const fs::path& file_path, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& newFilename)
 {
+    std::string filename;
+    CDBEnv* env = GetWalletEnv(file_path, filename);
+
     // Recovery procedure:
     // move wallet file to walletfilename.timestamp.bak
     // Call Salvage with fAggressive=true to
@@ -225,7 +247,7 @@ bool CDB::Recover(const std::string& filename, void *callbackDataIn, bool (*reco
     int64_t now = GetTime();
     newFilename = strprintf("%s.%d.bak", filename, now);
 
-    int result = bitdb.dbenv->dbrename(nullptr, filename.c_str(), nullptr,
+    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);
@@ -236,7 +258,7 @@ bool CDB::Recover(const std::string& filename, void *callbackDataIn, bool (*reco
     }
 
     std::vector<CDBEnv::KeyValPair> salvagedData;
-    bool fSuccess = bitdb.Salvage(newFilename, true, salvagedData);
+    bool fSuccess = env->Salvage(newFilename, true, salvagedData);
     if (salvagedData.empty())
     {
         LogPrintf("Salvage(aggressive) found no records in %s.\n", newFilename);
@@ -244,7 +266,7 @@ bool CDB::Recover(const std::string& filename, void *callbackDataIn, bool (*reco
     }
     LogPrintf("Salvage(aggressive) found %u records\n", salvagedData.size());
 
-    std::unique_ptr<Db> pdbCopy = MakeUnique<Db>(bitdb.dbenv.get(), 0);
+    std::unique_ptr<Db> pdbCopy = MakeUnique<Db>(env->dbenv.get(), 0);
     int ret = pdbCopy->open(nullptr,               // Txn pointer
                             filename.c_str(),   // Filename
                             "main",             // Logical db name
@@ -257,7 +279,7 @@ bool CDB::Recover(const std::string& filename, void *callbackDataIn, bool (*reco
         return false;
     }
 
-    DbTxn* ptxn = bitdb.TxnBegin();
+    DbTxn* ptxn = env->TxnBegin();
     for (CDBEnv::KeyValPair& row : salvagedData)
     {
         if (recoverKVcallback)
@@ -279,8 +301,12 @@ bool CDB::Recover(const std::string& filename, void *callbackDataIn, bool (*reco
     return fSuccess;
 }
 
-bool CDB::VerifyEnvironment(const std::string& walletFile, const fs::path& walletDir, std::string& errorStr)
+bool CDB::VerifyEnvironment(const fs::path& file_path, std::string& errorStr)
 {
+    std::string walletFile;
+    CDBEnv* 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);
 
@@ -291,7 +317,7 @@ bool CDB::VerifyEnvironment(const std::string& walletFile, const fs::path& walle
         return false;
     }
 
-    if (!bitdb.Open(walletDir, true)) {
+    if (!env->Open(true /* retry */)) {
         errorStr = strprintf(_("Error initializing wallet database environment %s!"), walletDir);
         return false;
     }
@@ -299,12 +325,16 @@ bool CDB::VerifyEnvironment(const std::string& walletFile, const fs::path& walle
     return true;
 }
 
-bool CDB::VerifyDatabaseFile(const std::string& walletFile, const fs::path& walletDir, std::string& warningStr, std::string& errorStr, CDBEnv::recoverFunc_type recoverFunc)
+bool CDB::VerifyDatabaseFile(const fs::path& file_path, std::string& warningStr, std::string& errorStr, CDBEnv::recoverFunc_type recoverFunc)
 {
+    std::string walletFile;
+    CDBEnv* env = GetWalletEnv(file_path, walletFile);
+    fs::path walletDir = env->Directory();
+
     if (fs::exists(walletDir / walletFile))
     {
         std::string backup_filename;
-        CDBEnv::VerifyResult r = bitdb.Verify(walletFile, recoverFunc, backup_filename);
+        CDBEnv::VerifyResult r = env->Verify(walletFile, recoverFunc, backup_filename);
         if (r == CDBEnv::RECOVER_OK)
         {
             warningStr = strprintf(_("Warning: Wallet file corrupt, data salvaged!"
@@ -414,8 +444,8 @@ CDB::CDB(CWalletDBWrapper& dbw, const char* pszMode, bool fFlushOnCloseIn) : pdb
         nFlags |= DB_CREATE;
 
     {
-        LOCK(env->cs_db);
-        if (!env->Open(GetWalletDir()))
+        LOCK(cs_db);
+        if (!env->Open(false /* retry */))
             throw std::runtime_error("CDB: Failed to open database environment.");
 
         pdb = env->mapDb[strFilename];
@@ -442,7 +472,25 @@ CDB::CDB(CWalletDBWrapper& dbw, const char* pszMode, bool fFlushOnCloseIn) : pdb
             if (ret != 0) {
                 throw std::runtime_error(strprintf("CDB: Error %d, can't open database %s", ret, strFilename));
             }
-            CheckUniqueFileid(*env, strFilename, *pdb_temp);
+
+            // 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 (auto& env : g_dbenvs) {
+                CheckUniqueFileid(env.second, strFilename, *pdb_temp);
+            }
 
             pdb = pdb_temp.release();
             env->mapDb[strFilename] = pdb;
@@ -490,7 +538,7 @@ void CDB::Close()
         Flush();
 
     {
-        LOCK(env->cs_db);
+        LOCK(cs_db);
         --env->mapFileUseCount[strFile];
     }
 }
@@ -518,7 +566,7 @@ bool CDB::Rewrite(CWalletDBWrapper& dbw, const char* pszSkip)
     const std::string& strFile = dbw.strFile;
     while (true) {
         {
-            LOCK(env->cs_db);
+            LOCK(cs_db);
             if (!env->mapFileUseCount.count(strFile) || env->mapFileUseCount[strFile] == 0) {
                 // Flush log data to the dat file
                 env->CloseDb(strFile);
@@ -646,7 +694,7 @@ bool CDB::PeriodicFlush(CWalletDBWrapper& dbw)
     bool ret = false;
     CDBEnv *env = dbw.env;
     const std::string& strFile = dbw.strFile;
-    TRY_LOCK(bitdb.cs_db,lockDb);
+    TRY_LOCK(cs_db, lockDb);
     if (lockDb)
     {
         // Don't do this if any databases are in use
@@ -694,7 +742,7 @@ bool CWalletDBWrapper::Backup(const std::string& strDest)
     while (true)
     {
         {
-            LOCK(env->cs_db);
+            LOCK(cs_db);
             if (!env->mapFileUseCount.count(strFile) || env->mapFileUseCount[strFile] == 0)
             {
                 // Flush log data to the dat file
diff --git a/src/wallet/db.h b/src/wallet/db.h
index 787135e400..b1ce451534 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -11,6 +11,7 @@
 #include <serialize.h>
 #include <streams.h>
 #include <sync.h>
+#include <util.h>
 #include <version.h>
 
 #include <atomic>
@@ -32,20 +33,19 @@ private:
     // shutdown problems/crashes caused by a static initialized internal pointer.
     std::string strPath;
 
-    void EnvShutdown();
-
 public:
-    mutable CCriticalSection cs_db;
     std::unique_ptr<DbEnv> dbenv;
     std::map<std::string, int> mapFileUseCount;
     std::map<std::string, Db*> mapDb;
 
-    CDBEnv();
+    CDBEnv(const fs::path& env_directory);
     ~CDBEnv();
     void Reset();
 
     void MakeMock();
     bool IsMock() const { return fMockDb; }
+    bool IsInitialized() const { return fDbEnvInit; }
+    fs::path Directory() const { return strPath; }
 
     /**
      * Verify that database file strFile is OK. If it is not,
@@ -56,7 +56,7 @@ public:
     enum VerifyResult { VERIFY_OK,
                         RECOVER_OK,
                         RECOVER_FAIL };
-    typedef bool (*recoverFunc_type)(const std::string& strFile, std::string& out_backup_filename);
+    typedef bool (*recoverFunc_type)(const fs::path& file_path, std::string& out_backup_filename);
     VerifyResult Verify(const std::string& strFile, recoverFunc_type recoverFunc, std::string& out_backup_filename);
     /**
      * Salvage data from a file that Verify says is bad.
@@ -68,7 +68,7 @@ public:
     typedef std::pair<std::vector<unsigned char>, std::vector<unsigned char> > KeyValPair;
     bool Salvage(const std::string& strFile, bool fAggressive, std::vector<KeyValPair>& vResult);
 
-    bool Open(const fs::path& path, bool retry = 0);
+    bool Open(bool retry);
     void Close();
     void Flush(bool fShutdown);
     void CheckpointLSN(const std::string& strFile);
@@ -85,7 +85,8 @@ public:
     }
 };
 
-extern CDBEnv bitdb;
+/** Get CDBEnv and database filename given a wallet path. */
+CDBEnv* GetWalletEnv(const fs::path& wallet_path, std::string& database_filename);
 
 /** An instance of this class represents one database.
  * For BerkeleyDB this is just a (env, strFile) tuple.
@@ -100,9 +101,33 @@ public:
     }
 
     /** Create DB handle to real database */
-    CWalletDBWrapper(CDBEnv *env_in, const std::string &strFile_in) :
-        nUpdateCounter(0), nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0), env(env_in), strFile(strFile_in)
+    CWalletDBWrapper(const fs::path& wallet_path, bool mock = false) :
+        nUpdateCounter(0), nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0)
     {
+        env = GetWalletEnv(wallet_path, strFile);
+        if (mock) {
+            env->Close();
+            env->Reset();
+            env->MakeMock();
+        }
+    }
+
+    /** Return object for accessing database at specified path. */
+    static std::unique_ptr<CWalletDBWrapper> Create(const fs::path& path)
+    {
+        return MakeUnique<CWalletDBWrapper>(path);
+    }
+
+    /** Return object for accessing dummy database with no read/write capabilities. */
+    static std::unique_ptr<CWalletDBWrapper> CreateDummy()
+    {
+        return MakeUnique<CWalletDBWrapper>();
+    }
+
+    /** Return object for accessing temporary in-memory database. */
+    static std::unique_ptr<CWalletDBWrapper> CreateMock()
+    {
+        return MakeUnique<CWalletDBWrapper>("", true /* mock */);
     }
 
     /** Rewrite the entire database on disk, with the exception of key pszSkip if non-zero
@@ -113,10 +138,6 @@ public:
      */
     bool Backup(const std::string& strDest);
 
-    /** Get a name for this database, for debugging etc.
-     */
-    std::string GetName() const { return strFile; }
-
     /** Make sure all changes are flushed to disk.
      */
     void Flush(bool shutdown);
@@ -161,15 +182,15 @@ public:
 
     void Flush();
     void Close();
-    static bool Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename);
+    static bool Recover(const fs::path& file_path, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename);
 
     /* flush the wallet passively (TRY_LOCK)
        ideal to be called periodically */
     static bool PeriodicFlush(CWalletDBWrapper& dbw);
     /* verifies the database environment */
-    static bool VerifyEnvironment(const std::string& walletFile, const fs::path& walletDir, std::string& errorStr);
+    static bool VerifyEnvironment(const fs::path& file_path, std::string& errorStr);
     /* verifies the database file */
-    static bool VerifyDatabaseFile(const std::string& walletFile, const fs::path& walletDir, std::string& warningStr, std::string& errorStr, CDBEnv::recoverFunc_type recoverFunc);
+    static bool VerifyDatabaseFile(const fs::path& file_path, std::string& warningStr, std::string& errorStr, CDBEnv::recoverFunc_type recoverFunc);
 
 public:
     template <typename K, typename T>
@@ -329,7 +350,7 @@ public:
     {
         if (!pdb || activeTxn)
             return false;
-        DbTxn* ptxn = bitdb.TxnBegin();
+        DbTxn* ptxn = env->TxnBegin();
         if (!ptxn)
             return false;
         activeTxn = ptxn;
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index 9ac48bff77..6e243c0a09 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -249,21 +249,21 @@ bool VerifyWallets()
         }
 
         std::string strError;
-        if (!CWalletDB::VerifyEnvironment(walletFile, GetWalletDir().string(), strError)) {
+        if (!CWalletDB::VerifyEnvironment(wallet_path, strError)) {
             return InitError(strError);
         }
 
         if (gArgs.GetBoolArg("-salvagewallet", false)) {
             // Recover readable keypairs:
-            CWallet dummyWallet;
+            CWallet dummyWallet("dummy", CWalletDBWrapper::CreateDummy());
             std::string backup_filename;
-            if (!CWalletDB::Recover(walletFile, (void *)&dummyWallet, CWalletDB::RecoverKeysOnlyFilter, backup_filename)) {
+            if (!CWalletDB::Recover(wallet_path, (void *)&dummyWallet, CWalletDB::RecoverKeysOnlyFilter, backup_filename)) {
                 return false;
             }
         }
 
         std::string strWarning;
-        bool dbV = CWalletDB::VerifyDatabaseFile(walletFile, GetWalletDir().string(), strWarning, strError);
+        bool dbV = CWalletDB::VerifyDatabaseFile(wallet_path, strWarning, strError);
         if (!strWarning.empty()) {
             InitWarning(strWarning);
         }
@@ -284,7 +284,7 @@ bool OpenWallets()
     }
 
     for (const std::string& walletFile : gArgs.GetArgs("-wallet")) {
-        CWallet * const pwallet = CWallet::CreateWalletFromFile(walletFile);
+        CWallet * const pwallet = CWallet::CreateWalletFromFile(walletFile, fs::absolute(walletFile, GetWalletDir()));
         if (!pwallet) {
             return false;
         }
diff --git a/src/wallet/test/accounting_tests.cpp b/src/wallet/test/accounting_tests.cpp
index cafd69d075..17b8637a8b 100644
--- a/src/wallet/test/accounting_tests.cpp
+++ b/src/wallet/test/accounting_tests.cpp
@@ -13,13 +13,13 @@
 BOOST_FIXTURE_TEST_SUITE(accounting_tests, WalletTestingSetup)
 
 static void
-GetResults(CWallet *wallet, std::map<CAmount, CAccountingEntry>& results)
+GetResults(CWallet& wallet, std::map<CAmount, CAccountingEntry>& results)
 {
     std::list<CAccountingEntry> aes;
 
     results.clear();
-    BOOST_CHECK(wallet->ReorderTransactions() == DB_LOAD_OK);
-    wallet->ListAccountCreditDebit("", aes);
+    BOOST_CHECK(wallet.ReorderTransactions() == DB_LOAD_OK);
+    wallet.ListAccountCreditDebit("", aes);
     for (CAccountingEntry& ae : aes)
     {
         results[ae.nOrderPos] = ae;
@@ -33,28 +33,28 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
     CAccountingEntry ae;
     std::map<CAmount, CAccountingEntry> results;
 
-    LOCK(pwalletMain->cs_wallet);
+    LOCK(m_wallet.cs_wallet);
 
     ae.strAccount = "";
     ae.nCreditDebit = 1;
     ae.nTime = 1333333333;
     ae.strOtherAccount = "b";
     ae.strComment = "";
-    pwalletMain->AddAccountingEntry(ae);
+    m_wallet.AddAccountingEntry(ae);
 
     wtx.mapValue["comment"] = "z";
-    pwalletMain->AddToWallet(wtx);
-    vpwtx.push_back(&pwalletMain->mapWallet[wtx.GetHash()]);
+    m_wallet.AddToWallet(wtx);
+    vpwtx.push_back(&m_wallet.mapWallet[wtx.GetHash()]);
     vpwtx[0]->nTimeReceived = (unsigned int)1333333335;
     vpwtx[0]->nOrderPos = -1;
 
     ae.nTime = 1333333336;
     ae.strOtherAccount = "c";
-    pwalletMain->AddAccountingEntry(ae);
+    m_wallet.AddAccountingEntry(ae);
 
-    GetResults(pwalletMain.get(), results);
+    GetResults(m_wallet, results);
 
-    BOOST_CHECK(pwalletMain->nOrderPosNext == 3);
+    BOOST_CHECK(m_wallet.nOrderPosNext == 3);
     BOOST_CHECK(2 == results.size());
     BOOST_CHECK(results[0].nTime == 1333333333);
     BOOST_CHECK(results[0].strComment.empty());
@@ -65,13 +65,13 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
 
     ae.nTime = 1333333330;
     ae.strOtherAccount = "d";
-    ae.nOrderPos = pwalletMain->IncOrderPosNext();
-    pwalletMain->AddAccountingEntry(ae);
+    ae.nOrderPos = m_wallet.IncOrderPosNext();
+    m_wallet.AddAccountingEntry(ae);
 
-    GetResults(pwalletMain.get(), results);
+    GetResults(m_wallet, results);
 
     BOOST_CHECK(results.size() == 3);
-    BOOST_CHECK(pwalletMain->nOrderPosNext == 4);
+    BOOST_CHECK(m_wallet.nOrderPosNext == 4);
     BOOST_CHECK(results[0].nTime == 1333333333);
     BOOST_CHECK(1 == vpwtx[0]->nOrderPos);
     BOOST_CHECK(results[2].nTime == 1333333336);
@@ -85,8 +85,8 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
         --tx.nLockTime;  // Just to change the hash :)
         wtx.SetTx(MakeTransactionRef(std::move(tx)));
     }
-    pwalletMain->AddToWallet(wtx);
-    vpwtx.push_back(&pwalletMain->mapWallet[wtx.GetHash()]);
+    m_wallet.AddToWallet(wtx);
+    vpwtx.push_back(&m_wallet.mapWallet[wtx.GetHash()]);
     vpwtx[1]->nTimeReceived = (unsigned int)1333333336;
 
     wtx.mapValue["comment"] = "x";
@@ -95,15 +95,15 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
         --tx.nLockTime;  // Just to change the hash :)
         wtx.SetTx(MakeTransactionRef(std::move(tx)));
     }
-    pwalletMain->AddToWallet(wtx);
-    vpwtx.push_back(&pwalletMain->mapWallet[wtx.GetHash()]);
+    m_wallet.AddToWallet(wtx);
+    vpwtx.push_back(&m_wallet.mapWallet[wtx.GetHash()]);
     vpwtx[2]->nTimeReceived = (unsigned int)1333333329;
     vpwtx[2]->nOrderPos = -1;
 
-    GetResults(pwalletMain.get(), results);
+    GetResults(m_wallet, results);
 
     BOOST_CHECK(results.size() == 3);
-    BOOST_CHECK(pwalletMain->nOrderPosNext == 6);
+    BOOST_CHECK(m_wallet.nOrderPosNext == 6);
     BOOST_CHECK(0 == vpwtx[2]->nOrderPos);
     BOOST_CHECK(results[1].nTime == 1333333333);
     BOOST_CHECK(2 == vpwtx[0]->nOrderPos);
@@ -116,12 +116,12 @@ BOOST_AUTO_TEST_CASE(acc_orderupgrade)
     ae.nTime = 1333333334;
     ae.strOtherAccount = "e";
     ae.nOrderPos = -1;
-    pwalletMain->AddAccountingEntry(ae);
+    m_wallet.AddAccountingEntry(ae);
 
-    GetResults(pwalletMain.get(), results);
+    GetResults(m_wallet, results);
 
     BOOST_CHECK(results.size() == 4);
-    BOOST_CHECK(pwalletMain->nOrderPosNext == 7);
+    BOOST_CHECK(m_wallet.nOrderPosNext == 7);
     BOOST_CHECK(0 == vpwtx[2]->nOrderPos);
     BOOST_CHECK(results[1].nTime == 1333333333);
     BOOST_CHECK(2 == vpwtx[0]->nOrderPos);
diff --git a/src/wallet/test/wallet_test_fixture.cpp b/src/wallet/test/wallet_test_fixture.cpp
index 18abf9a9db..77ccd0b8d8 100644
--- a/src/wallet/test/wallet_test_fixture.cpp
+++ b/src/wallet/test/wallet_test_fixture.cpp
@@ -6,26 +6,21 @@
 
 #include <rpc/server.h>
 #include <wallet/db.h>
+#include <wallet/wallet.h>
 
 WalletTestingSetup::WalletTestingSetup(const std::string& chainName):
-    TestingSetup(chainName)
+    TestingSetup(chainName), m_wallet("mock", CWalletDBWrapper::CreateMock())
 {
-    bitdb.MakeMock();
     bool fFirstRun;
     g_address_type = OUTPUT_TYPE_DEFAULT;
     g_change_type = OUTPUT_TYPE_DEFAULT;
-    std::unique_ptr<CWalletDBWrapper> dbw(new CWalletDBWrapper(&bitdb, "wallet_test.dat"));
-    pwalletMain = MakeUnique<CWallet>(std::move(dbw));
-    pwalletMain->LoadWallet(fFirstRun);
-    RegisterValidationInterface(pwalletMain.get());
+    m_wallet.LoadWallet(fFirstRun);
+    RegisterValidationInterface(&m_wallet);
 
     RegisterWalletRPCCommands(tableRPC);
 }
 
 WalletTestingSetup::~WalletTestingSetup()
 {
-    UnregisterValidationInterface(pwalletMain.get());
-
-    bitdb.Flush(true);
-    bitdb.Reset();
+    UnregisterValidationInterface(&m_wallet);
 }
diff --git a/src/wallet/test/wallet_test_fixture.h b/src/wallet/test/wallet_test_fixture.h
index c03aec7f87..663836a955 100644
--- a/src/wallet/test/wallet_test_fixture.h
+++ b/src/wallet/test/wallet_test_fixture.h
@@ -15,7 +15,7 @@ struct WalletTestingSetup: public TestingSetup {
     explicit WalletTestingSetup(const std::string& chainName = CBaseChainParams::MAIN);
     ~WalletTestingSetup();
 
-    std::unique_ptr<CWallet> pwalletMain;
+    CWallet m_wallet;
 };
 
 #endif
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 9db5d63922..41348b50a4 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -36,7 +36,7 @@ typedef std::set<CInputCoin> CoinSet;
 
 BOOST_FIXTURE_TEST_SUITE(wallet_tests, WalletTestingSetup)
 
-static const CWallet testWallet;
+static const CWallet testWallet("dummy", CWalletDBWrapper::CreateDummy());
 static std::vector<COutput> vCoins;
 
 static void add_coin(const CAmount& nValue, int nAge = 6*24, bool fIsFromMe = false, int nInput=0)
@@ -382,7 +382,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     // Verify ScanForWalletTransactions picks up transactions in both the old
     // and new block files.
     {
-        CWallet wallet;
+        CWallet wallet("dummy", CWalletDBWrapper::CreateDummy());
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(&wallet);
         reserver.reserve();
@@ -397,7 +397,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     // Verify ScanForWalletTransactions only picks transactions in the new block
     // file.
     {
-        CWallet wallet;
+        CWallet wallet("dummy", CWalletDBWrapper::CreateDummy());
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(&wallet);
         reserver.reserve();
@@ -409,7 +409,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     // before the missing block, and success for a key whose creation time is
     // after.
     {
-        CWallet wallet;
+        CWallet wallet("dummy", CWalletDBWrapper::CreateDummy());
         vpwallets.insert(vpwallets.begin(), &wallet);
         UniValue keys;
         keys.setArray();
@@ -471,7 +471,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
 
     // Import key into wallet and call dumpwallet to create backup file.
     {
-        CWallet wallet;
+        CWallet wallet("dummy", CWalletDBWrapper::CreateDummy());
         LOCK(wallet.cs_wallet);
         wallet.mapKeyMetadata[coinbaseKey.GetPubKey().GetID()].nCreateTime = KEY_TIME;
         wallet.AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
@@ -486,7 +486,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
     // Call importwallet RPC and verify all blocks with timestamps >= BLOCK_TIME
     // were scanned, and no prior blocks were scanned.
     {
-        CWallet wallet;
+        CWallet wallet("dummy", CWalletDBWrapper::CreateDummy());
 
         JSONRPCRequest request;
         request.params.setArray();
@@ -516,7 +516,7 @@ BOOST_FIXTURE_TEST_CASE(importwallet_rescan, TestChain100Setup)
 // debit functions.
 BOOST_FIXTURE_TEST_CASE(coin_mark_dirty_immature_credit, TestChain100Setup)
 {
-    CWallet wallet;
+    CWallet wallet("dummy", CWalletDBWrapper::CreateDummy());
     CWalletTx wtx(&wallet, MakeTransactionRef(coinbaseTxns.back()));
     LOCK2(cs_main, wallet.cs_wallet);
     wtx.hashBlock = chainActive.Tip()->GetBlockHash();
@@ -562,27 +562,25 @@ static int64_t AddTx(CWallet& wallet, uint32_t lockTime, int64_t mockTime, int64
 // expanded to cover more corner cases of smart time logic.
 BOOST_AUTO_TEST_CASE(ComputeTimeSmart)
 {
-    CWallet wallet;
-
     // New transaction should use clock time if lower than block time.
-    BOOST_CHECK_EQUAL(AddTx(wallet, 1, 100, 120), 100);
+    BOOST_CHECK_EQUAL(AddTx(m_wallet, 1, 100, 120), 100);
 
     // Test that updating existing transaction does not change smart time.
-    BOOST_CHECK_EQUAL(AddTx(wallet, 1, 200, 220), 100);
+    BOOST_CHECK_EQUAL(AddTx(m_wallet, 1, 200, 220), 100);
 
     // New transaction should use clock time if there's no block time.
-    BOOST_CHECK_EQUAL(AddTx(wallet, 2, 300, 0), 300);
+    BOOST_CHECK_EQUAL(AddTx(m_wallet, 2, 300, 0), 300);
 
     // New transaction should use block time if lower than clock time.
-    BOOST_CHECK_EQUAL(AddTx(wallet, 3, 420, 400), 400);
+    BOOST_CHECK_EQUAL(AddTx(m_wallet, 3, 420, 400), 400);
 
     // New transaction should use latest entry time if higher than
     // min(block time, clock time).
-    BOOST_CHECK_EQUAL(AddTx(wallet, 4, 500, 390), 400);
+    BOOST_CHECK_EQUAL(AddTx(m_wallet, 4, 500, 390), 400);
 
     // If there are future entries, new transaction should use time of the
     // newest entry that is no more than 300 seconds ahead of the clock time.
-    BOOST_CHECK_EQUAL(AddTx(wallet, 5, 50, 600), 300);
+    BOOST_CHECK_EQUAL(AddTx(m_wallet, 5, 50, 600), 300);
 
     // Reset mock time for other tests.
     SetMockTime(0);
@@ -591,12 +589,12 @@ BOOST_AUTO_TEST_CASE(ComputeTimeSmart)
 BOOST_AUTO_TEST_CASE(LoadReceiveRequests)
 {
     CTxDestination dest = CKeyID();
-    LOCK(pwalletMain->cs_wallet);
-    pwalletMain->AddDestData(dest, "misc", "val_misc");
-    pwalletMain->AddDestData(dest, "rr0", "val_rr0");
-    pwalletMain->AddDestData(dest, "rr1", "val_rr1");
+    LOCK(m_wallet.cs_wallet);
+    m_wallet.AddDestData(dest, "misc", "val_misc");
+    m_wallet.AddDestData(dest, "rr0", "val_rr0");
+    m_wallet.AddDestData(dest, "rr1", "val_rr1");
 
-    auto values = pwalletMain->GetDestValues("rr");
+    auto values = m_wallet.GetDestValues("rr");
     BOOST_CHECK_EQUAL(values.size(), 2);
     BOOST_CHECK_EQUAL(values[0], "val_rr0");
     BOOST_CHECK_EQUAL(values[1], "val_rr1");
@@ -608,10 +606,9 @@ public:
     ListCoinsTestingSetup()
     {
         CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
-        ::bitdb.MakeMock();
         g_address_type = OUTPUT_TYPE_DEFAULT;
         g_change_type = OUTPUT_TYPE_DEFAULT;
-        wallet.reset(new CWallet(std::unique_ptr<CWalletDBWrapper>(new CWalletDBWrapper(&bitdb, "wallet_test.dat"))));
+        wallet = MakeUnique<CWallet>("mock", CWalletDBWrapper::CreateMock());
         bool firstRun;
         wallet->LoadWallet(firstRun);
         AddKey(*wallet, coinbaseKey);
@@ -623,8 +620,6 @@ public:
     ~ListCoinsTestingSetup()
     {
         wallet.reset();
-        ::bitdb.Flush(true);
-        ::bitdb.Reset();
     }
 
     CWalletTx& AddTx(CRecipient recipient)
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index bb7be2df33..b1e2181ec7 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3908,16 +3908,17 @@ std::vector<std::string> CWallet::GetDestValues(const std::string& prefix) const
     return values;
 }
 
-CWallet* CWallet::CreateWalletFromFile(const std::string walletFile)
+CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path& path)
 {
+    const std::string& walletFile = name;
+
     // needed to restore wallet transaction meta data after -zapwallettxes
     std::vector<CWalletTx> vWtx;
 
     if (gArgs.GetBoolArg("-zapwallettxes", false)) {
         uiInterface.InitMessage(_("Zapping all transactions from wallet..."));
 
-        std::unique_ptr<CWalletDBWrapper> dbw(new CWalletDBWrapper(&bitdb, walletFile));
-        std::unique_ptr<CWallet> tempWallet = MakeUnique<CWallet>(std::move(dbw));
+        std::unique_ptr<CWallet> tempWallet = MakeUnique<CWallet>(name, CWalletDBWrapper::Create(path));
         DBErrors nZapWalletRet = tempWallet->ZapWalletTx(vWtx);
         if (nZapWalletRet != DB_LOAD_OK) {
             InitError(strprintf(_("Error loading %s: Wallet corrupted"), walletFile));
@@ -3929,8 +3930,7 @@ CWallet* CWallet::CreateWalletFromFile(const std::string walletFile)
 
     int64_t nStart = GetTimeMillis();
     bool fFirstRun = true;
-    std::unique_ptr<CWalletDBWrapper> dbw(new CWalletDBWrapper(&bitdb, walletFile));
-    CWallet *walletInstance = new CWallet(std::move(dbw));
+    CWallet *walletInstance = new CWallet(name, CWalletDBWrapper::Create(path));
     DBErrors nLoadWalletRet = walletInstance->LoadWallet(fFirstRun);
     if (nLoadWalletRet != DB_LOAD_OK)
     {
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 4db45f16ef..76a411d81b 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -15,6 +15,7 @@
 #include <validationinterface.h>
 #include <script/ismine.h>
 #include <script/sign.h>
+#include <util.h>
 #include <wallet/crypter.h>
 #include <wallet/walletdb.h>
 #include <wallet/rpcwallet.h>
@@ -737,6 +738,14 @@ private:
      */
     bool AddWatchOnly(const CScript& dest) override;
 
+    /**
+     * Wallet filename from wallet=<path> command line or config option.
+     * Used in debug logs and to send RPCs to the right wallet instance when
+     * more than one wallet is loaded.
+     */
+    std::string m_name;
+
+    /** Internal database handle. */
     std::unique_ptr<CWalletDBWrapper> dbw;
 
     /**
@@ -768,14 +777,7 @@ public:
 
     /** Get a name for this wallet for logging/debugging purposes.
      */
-    std::string GetName() const
-    {
-        if (dbw) {
-            return dbw->GetName();
-        } else {
-            return "dummy";
-        }
-    }
+    const std::string& GetName() const { return m_name; }
 
     void LoadKeyPool(int64_t nIndex, const CKeyPool &keypool);
 
@@ -789,14 +791,8 @@ public:
     MasterKeyMap mapMasterKeys;
     unsigned int nMasterKeyMaxID;
 
-    // Create wallet with dummy database handle
-    CWallet(): dbw(new CWalletDBWrapper())
-    {
-        SetNull();
-    }
-
-    // Create wallet with passed-in database handle
-    explicit CWallet(std::unique_ptr<CWalletDBWrapper> dbw_in) : dbw(std::move(dbw_in))
+    /** Construct wallet with specified name and database implementation. */
+    CWallet(std::string name, std::unique_ptr<CWalletDBWrapper> dbw) : m_name(std::move(name)), dbw(std::move(dbw))
     {
         SetNull();
     }
@@ -1116,7 +1112,7 @@ public:
     bool MarkReplaced(const uint256& originalHash, const uint256& newHash);
 
     /* Initializes the wallet, returns a new CWallet instance or a null pointer in case of an error */
-    static CWallet* CreateWalletFromFile(const std::string walletFile);
+    static CWallet* CreateWalletFromFile(const std::string& name, const fs::path& path);
 
     /**
      * Wallet post-init setup
diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index dd6835a06f..46e4c12a7a 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -771,16 +771,16 @@ void MaybeCompactWalletDB()
 //
 // Try to (very carefully!) recover wallet file if there is a problem.
 //
-bool CWalletDB::Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename)
+bool CWalletDB::Recover(const fs::path& wallet_path, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename)
 {
-    return CDB::Recover(filename, callbackDataIn, recoverKVcallback, out_backup_filename);
+    return CDB::Recover(wallet_path, callbackDataIn, recoverKVcallback, out_backup_filename);
 }
 
-bool CWalletDB::Recover(const std::string& filename, std::string& out_backup_filename)
+bool CWalletDB::Recover(const fs::path& wallet_path, std::string& out_backup_filename)
 {
     // recover without a key filter callback
     // results in recovering all record types
-    return CWalletDB::Recover(filename, nullptr, nullptr, out_backup_filename);
+    return CWalletDB::Recover(wallet_path, nullptr, nullptr, out_backup_filename);
 }
 
 bool CWalletDB::RecoverKeysOnlyFilter(void *callbackData, CDataStream ssKey, CDataStream ssValue)
@@ -806,14 +806,14 @@ bool CWalletDB::RecoverKeysOnlyFilter(void *callbackData, CDataStream ssKey, CDa
     return true;
 }
 
-bool CWalletDB::VerifyEnvironment(const std::string& walletFile, const fs::path& walletDir, std::string& errorStr)
+bool CWalletDB::VerifyEnvironment(const fs::path& wallet_path, std::string& errorStr)
 {
-    return CDB::VerifyEnvironment(walletFile, walletDir, errorStr);
+    return CDB::VerifyEnvironment(wallet_path, errorStr);
 }
 
-bool CWalletDB::VerifyDatabaseFile(const std::string& walletFile, const fs::path& walletDir, std::string& warningStr, std::string& errorStr)
+bool CWalletDB::VerifyDatabaseFile(const fs::path& wallet_path, std::string& warningStr, std::string& errorStr)
 {
-    return CDB::VerifyDatabaseFile(walletFile, walletDir, warningStr, errorStr, CWalletDB::Recover);
+    return CDB::VerifyDatabaseFile(wallet_path, warningStr, errorStr, CWalletDB::Recover);
 }
 
 bool CWalletDB::WriteDestData(const std::string &address, const std::string &key, const std::string &value)
diff --git a/src/wallet/walletdb.h b/src/wallet/walletdb.h
index 3691cfcb57..7d754c7284 100644
--- a/src/wallet/walletdb.h
+++ b/src/wallet/walletdb.h
@@ -218,17 +218,17 @@ public:
     DBErrors ZapWalletTx(std::vector<CWalletTx>& vWtx);
     DBErrors ZapSelectTx(std::vector<uint256>& vHashIn, std::vector<uint256>& vHashOut);
     /* Try to (very carefully!) recover wallet database (with a possible key type filter) */
-    static bool Recover(const std::string& filename, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename);
+    static bool Recover(const fs::path& wallet_path, void *callbackDataIn, bool (*recoverKVcallback)(void* callbackData, CDataStream ssKey, CDataStream ssValue), std::string& out_backup_filename);
     /* Recover convenience-function to bypass the key filter callback, called when verify fails, recovers everything */
-    static bool Recover(const std::string& filename, std::string& out_backup_filename);
+    static bool Recover(const fs::path& wallet_path, std::string& out_backup_filename);
     /* Recover filter (used as callback), will only let keys (cryptographical keys) as KV/key-type pass through */
     static bool RecoverKeysOnlyFilter(void *callbackData, CDataStream ssKey, CDataStream ssValue);
     /* Function to determine if a certain KV/key-type is a key (cryptographical key) type */
     static bool IsKeyType(const std::string& strType);
     /* verifies the database environment */
-    static bool VerifyEnvironment(const std::string& walletFile, const fs::path& walletDir, std::string& errorStr);
+    static bool VerifyEnvironment(const fs::path& wallet_path, std::string& errorStr);
     /* verifies the database file */
-    static bool VerifyDatabaseFile(const std::string& walletFile, const fs::path& walletDir, std::string& warningStr, std::string& errorStr);
+    static bool VerifyDatabaseFile(const fs::path& wallet_path, std::string& warningStr, std::string& errorStr);
 
     //! write the hdchain model (external chain child index counter)
     bool WriteHDChain(const CHDChain& chain);