Merge #14552: wallet: detecting duplicate wallet by comparing the db filename.

591203149f1700f594f781862e88cbbfe83d8d37 wallet: Create IsDatabaseLoaded function (Chun Kuan Lee)
15c93f075a881deb3ad7b1dd8a4516a9b06e5e11 wallet: Add trailing wallet.dat when detecting duplicate wallet if it's a directory. (Chun Kuan Lee)
c456fbd8dfcc748e5ec9feaa57ec0f2900f99cde Refactor: Move m_db pointers into BerkeleyDatabase (Russell Yanofsky)

Pull request description:

  Fix #14538

  Fix crash attempting to load the same wallet with different path strings that resolve to the same absolute path. The primary check which prevents loading the same wallet twice is:

  https://github.com/bitcoin/bitcoin/blob/6b8d0a2164b30eab76e7bccb1ffb056a10fba406/src/wallet/db.cpp#L44

  But this check is skipped if both wallet paths resolve to the same absolute path, due to caching here:

  https://github.com/bitcoin/bitcoin/blob/6b8d0a2164b30eab76e7bccb1ffb056a10fba406/src/wallet/db.cpp#L467

  Meanwhile a secondary check for duplicate wallets is not reliable because it based on a literal comparison, instead of comparison using absolute paths:

  https://github.com/bitcoin/bitcoin/blob/6b8d0a2164b30eab76e7bccb1ffb056a10fba406/src/wallet/wallet.cpp#L3853

  This PR fixes the latter check to compare the absolute path of a new wallet being loaded to absolute paths of wallets already loaded, so there should no longer be any way to load the same wallet more than once.

Tree-SHA512: 2fa01811c160b57be3b76c6b4983556a04bbce71a3f8202429987ec020664a062e897deedcd9248bc04e9baaa2fc7b464e2595dcaeff2af0818387bf1fcdbf6f

3 files changed, 54 insertions, 21 deletions

diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index 74787eb5d2..d75e30d336 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -56,9 +56,8 @@ bool WalletDatabaseFileId::operator==(const WalletDatabaseFileId& rhs) const
     return memcmp(value, &rhs.value, sizeof(value)) == 0;
 }
 
-BerkeleyEnvironment* GetWalletEnv(const fs::path& wallet_path, std::string& database_filename)
+static void SplitWalletPath(const fs::path& wallet_path, fs::path& env_directory, std::string& database_filename)
 {
-    fs::path env_directory;
     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
@@ -71,6 +70,23 @@ BerkeleyEnvironment* GetWalletEnv(const fs::path& wallet_path, std::string& data
         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;
+    return env->second.IsDatabaseLoaded(database_filename);
+}
+
+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);
     // Note: An unused temporary BerkeleyEnvironment object may be created inside the
     // emplace function if the key already exists. This is a little inefficient,
@@ -90,13 +106,13 @@ void BerkeleyEnvironment::Close()
 
     fDbEnvInit = false;
 
-    for (auto& db : mapDb) {
+    for (auto& db : m_databases) {
         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;
+        BerkeleyDatabase& database = db.second.get();
+        if (database.m_db) {
+            database.m_db->close(0);
+            database.m_db.reset();
         }
     }
 
@@ -463,7 +479,7 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo
         if (!env->Open(false /* retry */))
             throw std::runtime_error("BerkeleyBatch: Failed to open database environment.");
 
-        pdb = env->mapDb[strFilename];
+        pdb = database.m_db.get();
         if (pdb == nullptr) {
             int ret;
             std::unique_ptr<Db> pdb_temp = MakeUnique<Db>(env->dbenv.get(), 0);
@@ -508,7 +524,7 @@ BerkeleyBatch::BerkeleyBatch(BerkeleyDatabase& database, const char* pszMode, bo
             }
 
             pdb = pdb_temp.release();
-            env->mapDb[strFilename] = pdb;
+            database.m_db.reset(pdb);
 
             if (fCreate && !Exists(std::string("version"))) {
                 bool fTmp = fReadOnly;
@@ -563,12 +579,13 @@ void BerkeleyEnvironment::CloseDb(const std::string& strFile)
 {
     {
         LOCK(cs_db);
-        if (mapDb[strFile] != nullptr) {
+        auto it = m_databases.find(strFile);
+        assert(it != m_databases.end());
+        BerkeleyDatabase& database = it->second.get();
+        if (database.m_db) {
             // Close the database handle
-            Db* pdb = mapDb[strFile];
-            pdb->close(0);
-            delete pdb;
-            mapDb[strFile] = nullptr;
+            database.m_db->close(0);
+            database.m_db.reset();
         }
     }
 }
@@ -586,7 +603,7 @@ void BerkeleyEnvironment::ReloadDbEnv()
     });
 
     std::vector<std::string> filenames;
-    for (auto it : mapDb) {
+    for (auto it : m_databases) {
         filenames.push_back(it.first);
     }
     // Close the individual Db's
diff --git a/src/wallet/db.h b/src/wallet/db.h
index 8f96483a18..e453d441d7 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -31,6 +31,8 @@ struct WalletDatabaseFileId {
     bool operator==(const WalletDatabaseFileId& rhs) const;
 };
 
+class BerkeleyDatabase;
+
 class BerkeleyEnvironment
 {
 private:
@@ -43,7 +45,7 @@ private:
 public:
     std::unique_ptr<DbEnv> dbenv;
     std::map<std::string, int> mapFileUseCount;
-    std::map<std::string, Db*> mapDb;
+    std::map<std::string, std::reference_wrapper<BerkeleyDatabase>> m_databases;
     std::unordered_map<std::string, WalletDatabaseFileId> m_fileids;
     std::condition_variable_any m_db_in_use;
 
@@ -54,6 +56,7 @@ public:
     void MakeMock();
     bool IsMock() const { return fMockDb; }
     bool IsInitialized() const { return fDbEnvInit; }
+    bool IsDatabaseLoaded(const std::string& db_filename) const { return m_databases.find(db_filename) != m_databases.end(); }
     fs::path Directory() const { return strPath; }
 
     /**
@@ -95,6 +98,9 @@ public:
     }
 };
 
+/** Return whether a wallet database is currently loaded. */
+bool IsWalletLoaded(const fs::path& wallet_path);
+
 /** Get BerkeleyEnvironment and database filename given a wallet path. */
 BerkeleyEnvironment* GetWalletEnv(const fs::path& wallet_path, std::string& database_filename);
 
@@ -115,6 +121,8 @@ public:
         nUpdateCounter(0), nLastSeen(0), nLastFlushed(0), nLastWalletUpdate(0)
     {
         env = GetWalletEnv(wallet_path, strFile);
+        auto inserted = env->m_databases.emplace(strFile, std::ref(*this));
+        assert(inserted.second);
         if (mock) {
             env->Close();
             env->Reset();
@@ -122,6 +130,13 @@ public:
         }
     }
 
+    ~BerkeleyDatabase() {
+        if (env) {
+            size_t erased = env->m_databases.erase(strFile);
+            assert(erased == 1);
+        }
+    }
+
     /** Return object for accessing database at specified path. */
     static std::unique_ptr<BerkeleyDatabase> Create(const fs::path& path)
     {
@@ -161,6 +176,9 @@ public:
     unsigned int nLastFlushed;
     int64_t nLastWalletUpdate;
 
+    /** Database pointer. This is initialized lazily and reset during flushes, so it can be null. */
+    std::unique_ptr<Db> m_db;
+
 private:
     /** BerkeleyDB specific */
     BerkeleyEnvironment *env;
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 8ea4c5c495..360d0f177c 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3872,11 +3872,9 @@ bool CWallet::Verify(interfaces::Chain& chain, const WalletLocation& location, b
     }
 
     // Make sure that the wallet path doesn't clash with an existing wallet path
-    for (auto wallet : GetWallets()) {
-        if (wallet->GetLocation().GetPath() == wallet_path) {
-            error_string = strprintf("Error loading wallet %s. Duplicate -wallet filename specified.", location.GetName());
-            return false;
-        }
+    if (IsWalletLoaded(wallet_path)) {
+        error_string = strprintf("Error loading wallet %s. Duplicate -wallet filename specified.", location.GetName());
+        return false;
     }
 
     try {