From 5aaeb6cf877055c47fa2bbd2ea5e8d3d2033933b Mon Sep 17 00:00:00 2001
From: Russell Yanofsky <russ@yanofsky.org>
Date: Fri, 30 Oct 2020 16:11:28 -0400
Subject: [PATCH 1/5] MOVEONLY: Move IsBDBFile, IsSQLiteFile, and ListWalletDir

This commit does not change to any code and behavior. It it is easily reviewed
with the --color-moved=dimmed_zebra git diff option.

Motivation for this change is to:

- Consolidate redundant functions
  IsBDBFile /ExistsBerkeleyDatabase / SplitWalletPath, and
  IsSQLiteFile / ExistsSQLiteDatabase in the next commits

- Detect SQLite wallets consistently regardless whether bitcoin is built with
  SQLite support in the next commits

- Avoid attempting to open SQLite databases with the BDB library when bitcoin
  is built without SQLite support in the next commits
---
 src/wallet/bdb.cpp        |  25 --------
 src/wallet/bdb.h          |   3 -
 src/wallet/db.cpp         | 118 ++++++++++++++++++++++++++++++++++++++
 src/wallet/db.h           |   3 +
 src/wallet/sqlite.cpp     |  34 -----------
 src/wallet/sqlite.h       |   1 -
 src/wallet/walletutil.cpp |  55 ------------------
 7 files changed, 121 insertions(+), 118 deletions(-)

diff --git a/src/wallet/bdb.cpp b/src/wallet/bdb.cpp
index 85aae0170d8..c289f94c786 100644
--- a/src/wallet/bdb.cpp
+++ b/src/wallet/bdb.cpp
@@ -839,28 +839,3 @@ std::unique_ptr<BerkeleyDatabase> MakeBerkeleyDatabase(const fs::path& path, con
     status = DatabaseStatus::SUCCESS;
     return db;
 }
-
-bool IsBDBFile(const fs::path& path)
-{
-    if (!fs::exists(path)) return false;
-
-    // A Berkeley DB Btree file has at least 4K.
-    // This check also prevents opening lock files.
-    boost::system::error_code ec;
-    auto size = fs::file_size(path, ec);
-    if (ec) LogPrintf("%s: %s %s\n", __func__, ec.message(), path.string());
-    if (size < 4096) return false;
-
-    fsbridge::ifstream file(path, std::ios::binary);
-    if (!file.is_open()) return false;
-
-    file.seekg(12, std::ios::beg); // Magic bytes start at offset 12
-    uint32_t data = 0;
-    file.read((char*) &data, sizeof(data)); // Read 4 bytes of file to compare against magic
-
-    // Berkeley DB Btree magic bytes, from:
-    //  https://github.com/file/file/blob/5824af38469ec1ca9ac3ffd251e7afe9dc11e227/magic/Magdir/database#L74-L75
-    //  - big endian systems - 00 05 31 62
-    //  - little endian systems - 62 31 05 00
-    return data == 0x00053162 || data == 0x62310500;
-}
diff --git a/src/wallet/bdb.h b/src/wallet/bdb.h
index 4f97665f086..935d0f947db 100644
--- a/src/wallet/bdb.h
+++ b/src/wallet/bdb.h
@@ -86,9 +86,6 @@ public:
 /** Get BerkeleyEnvironment and database filename given a wallet path. */
 std::shared_ptr<BerkeleyEnvironment> GetWalletEnv(const fs::path& wallet_path, std::string& database_filename);
 
-/** Check format of database file */
-bool IsBDBFile(const fs::path& path);
-
 class BerkeleyBatch;
 
 /** An instance of this class represents one database.
diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index bd1d1147303..85aeaeb3ab4 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -3,11 +3,70 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#include <chainparams.h>
 #include <fs.h>
+#include <logging.h>
 #include <wallet/db.h>
 
 #include <string>
 
+fs::path GetWalletDir();
+
+#ifdef USE_BDB
+bool ExistsBerkeleyDatabase(const fs::path& path);
+#else
+#   define ExistsBerkeleyDatabase(path)  (false)
+#endif
+#ifdef USE_SQLITE
+bool ExistsSQLiteDatabase(const fs::path& path);
+#else
+#   define ExistsSQLiteDatabase(path)  (false)
+#endif
+
+std::vector<fs::path> ListWalletDir()
+{
+    const fs::path wallet_dir = GetWalletDir();
+    const size_t offset = wallet_dir.string().size() + 1;
+    std::vector<fs::path> paths;
+    boost::system::error_code ec;
+
+    for (auto it = fs::recursive_directory_iterator(wallet_dir, ec); it != fs::recursive_directory_iterator(); it.increment(ec)) {
+        if (ec) {
+            LogPrintf("%s: %s %s\n", __func__, ec.message(), it->path().string());
+            continue;
+        }
+
+        try {
+            // Get wallet path relative to walletdir by removing walletdir from the wallet path.
+            // This can be replaced by boost::filesystem::lexically_relative once boost is bumped to 1.60.
+            const fs::path path = it->path().string().substr(offset);
+
+            if (it->status().type() == fs::directory_file &&
+                (ExistsBerkeleyDatabase(it->path()) || ExistsSQLiteDatabase(it->path()))) {
+                // Found a directory which contains wallet.dat btree file, add it as a wallet.
+                paths.emplace_back(path);
+            } else if (it.level() == 0 && it->symlink_status().type() == fs::regular_file && ExistsBerkeleyDatabase(it->path())) {
+                if (it->path().filename() == "wallet.dat") {
+                    // Found top-level wallet.dat btree file, add top level directory ""
+                    // as a wallet.
+                    paths.emplace_back();
+                } else {
+                    // Found top-level btree file not called wallet.dat. Current bitcoin
+                    // software will never create these files but will allow them to be
+                    // opened in a shared database environment for backwards compatibility.
+                    // Add it to the list of available wallets.
+                    paths.emplace_back(path);
+                }
+            }
+        } catch (const std::exception& e) {
+            LogPrintf("%s: Error scanning %s: %s\n", __func__, it->path().string(), e.what());
+            it.no_push();
+        }
+    }
+
+    return paths;
+}
+
 void SplitWalletPath(const fs::path& wallet_path, fs::path& env_directory, std::string& database_filename)
 {
     if (fs::is_regular_file(wallet_path)) {
@@ -23,3 +82,62 @@ void SplitWalletPath(const fs::path& wallet_path, fs::path& env_directory, std::
         database_filename = "wallet.dat";
     }
 }
+
+bool IsBDBFile(const fs::path& path)
+{
+    if (!fs::exists(path)) return false;
+
+    // A Berkeley DB Btree file has at least 4K.
+    // This check also prevents opening lock files.
+    boost::system::error_code ec;
+    auto size = fs::file_size(path, ec);
+    if (ec) LogPrintf("%s: %s %s\n", __func__, ec.message(), path.string());
+    if (size < 4096) return false;
+
+    fsbridge::ifstream file(path, std::ios::binary);
+    if (!file.is_open()) return false;
+
+    file.seekg(12, std::ios::beg); // Magic bytes start at offset 12
+    uint32_t data = 0;
+    file.read((char*) &data, sizeof(data)); // Read 4 bytes of file to compare against magic
+
+    // Berkeley DB Btree magic bytes, from:
+    //  https://github.com/file/file/blob/5824af38469ec1ca9ac3ffd251e7afe9dc11e227/magic/Magdir/database#L74-L75
+    //  - big endian systems - 00 05 31 62
+    //  - little endian systems - 62 31 05 00
+    return data == 0x00053162 || data == 0x62310500;
+}
+
+bool IsSQLiteFile(const fs::path& path)
+{
+    if (!fs::exists(path)) return false;
+
+    // A SQLite Database file is at least 512 bytes.
+    boost::system::error_code ec;
+    auto size = fs::file_size(path, ec);
+    if (ec) LogPrintf("%s: %s %s\n", __func__, ec.message(), path.string());
+    if (size < 512) return false;
+
+    fsbridge::ifstream file(path, std::ios::binary);
+    if (!file.is_open()) return false;
+
+    // Magic is at beginning and is 16 bytes long
+    char magic[16];
+    file.read(magic, 16);
+
+    // Application id is at offset 68 and 4 bytes long
+    file.seekg(68, std::ios::beg);
+    char app_id[4];
+    file.read(app_id, 4);
+
+    file.close();
+
+    // Check the magic, see https://sqlite.org/fileformat2.html
+    std::string magic_str(magic, 16);
+    if (magic_str != std::string("SQLite format 3", 16)) {
+        return false;
+    }
+
+    // Check the application id matches our network magic
+    return memcmp(Params().MessageStart(), app_id, 4) == 0;
+}
diff --git a/src/wallet/db.h b/src/wallet/db.h
index 940d1cd2422..cc13f887b06 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -225,4 +225,7 @@ enum class DatabaseStatus {
 
 std::unique_ptr<WalletDatabase> MakeDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
 
+bool IsBDBFile(const fs::path& path);
+bool IsSQLiteFile(const fs::path& path);
+
 #endif // BITCOIN_WALLET_DB_H
diff --git a/src/wallet/sqlite.cpp b/src/wallet/sqlite.cpp
index d278d96476d..69d96dd27c6 100644
--- a/src/wallet/sqlite.cpp
+++ b/src/wallet/sqlite.cpp
@@ -596,37 +596,3 @@ std::string SQLiteDatabaseVersion()
 {
     return std::string(sqlite3_libversion());
 }
-
-bool IsSQLiteFile(const fs::path& path)
-{
-    if (!fs::exists(path)) return false;
-
-    // A SQLite Database file is at least 512 bytes.
-    boost::system::error_code ec;
-    auto size = fs::file_size(path, ec);
-    if (ec) LogPrintf("%s: %s %s\n", __func__, ec.message(), path.string());
-    if (size < 512) return false;
-
-    fsbridge::ifstream file(path, std::ios::binary);
-    if (!file.is_open()) return false;
-
-    // Magic is at beginning and is 16 bytes long
-    char magic[16];
-    file.read(magic, 16);
-
-    // Application id is at offset 68 and 4 bytes long
-    file.seekg(68, std::ios::beg);
-    char app_id[4];
-    file.read(app_id, 4);
-
-    file.close();
-
-    // Check the magic, see https://sqlite.org/fileformat2.html
-    std::string magic_str(magic, 16);
-    if (magic_str != std::string("SQLite format 3", 16)) {
-        return false;
-    }
-
-    // Check the application id matches our network magic
-    return memcmp(Params().MessageStart(), app_id, 4) == 0;
-}
diff --git a/src/wallet/sqlite.h b/src/wallet/sqlite.h
index 693a2ef55a3..3cb11614db9 100644
--- a/src/wallet/sqlite.h
+++ b/src/wallet/sqlite.h
@@ -117,6 +117,5 @@ bool ExistsSQLiteDatabase(const fs::path& path);
 std::unique_ptr<SQLiteDatabase> MakeSQLiteDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
 
 std::string SQLiteDatabaseVersion();
-bool IsSQLiteFile(const fs::path& path);
 
 #endif // BITCOIN_WALLET_SQLITE_H
diff --git a/src/wallet/walletutil.cpp b/src/wallet/walletutil.cpp
index d6e6f015db2..16ddad3a84f 100644
--- a/src/wallet/walletutil.cpp
+++ b/src/wallet/walletutil.cpp
@@ -7,17 +7,6 @@
 #include <logging.h>
 #include <util/system.h>
 
-#ifdef USE_BDB
-bool ExistsBerkeleyDatabase(const fs::path& path);
-#else
-#   define ExistsBerkeleyDatabase(path)  (false)
-#endif
-#ifdef USE_SQLITE
-bool ExistsSQLiteDatabase(const fs::path& path);
-#else
-#   define ExistsSQLiteDatabase(path)  (false)
-#endif
-
 fs::path GetWalletDir()
 {
     fs::path path;
@@ -40,50 +29,6 @@ fs::path GetWalletDir()
     return path;
 }
 
-std::vector<fs::path> ListWalletDir()
-{
-    const fs::path wallet_dir = GetWalletDir();
-    const size_t offset = wallet_dir.string().size() + 1;
-    std::vector<fs::path> paths;
-    boost::system::error_code ec;
-
-    for (auto it = fs::recursive_directory_iterator(wallet_dir, ec); it != fs::recursive_directory_iterator(); it.increment(ec)) {
-        if (ec) {
-            LogPrintf("%s: %s %s\n", __func__, ec.message(), it->path().string());
-            continue;
-        }
-
-        try {
-            // Get wallet path relative to walletdir by removing walletdir from the wallet path.
-            // This can be replaced by boost::filesystem::lexically_relative once boost is bumped to 1.60.
-            const fs::path path = it->path().string().substr(offset);
-
-            if (it->status().type() == fs::directory_file &&
-                (ExistsBerkeleyDatabase(it->path()) || ExistsSQLiteDatabase(it->path()))) {
-                // Found a directory which contains wallet.dat btree file, add it as a wallet.
-                paths.emplace_back(path);
-            } else if (it.level() == 0 && it->symlink_status().type() == fs::regular_file && ExistsBerkeleyDatabase(it->path())) {
-                if (it->path().filename() == "wallet.dat") {
-                    // Found top-level wallet.dat btree file, add top level directory ""
-                    // as a wallet.
-                    paths.emplace_back();
-                } else {
-                    // Found top-level btree file not called wallet.dat. Current bitcoin
-                    // software will never create these files but will allow them to be
-                    // opened in a shared database environment for backwards compatibility.
-                    // Add it to the list of available wallets.
-                    paths.emplace_back(path);
-                }
-            }
-        } catch (const std::exception& e) {
-            LogPrintf("%s: Error scanning %s: %s\n", __func__, it->path().string(), e.what());
-            it.no_push();
-        }
-    }
-
-    return paths;
-}
-
 bool IsFeatureSupported(int wallet_version, int feature_version)
 {
     return wallet_version >= feature_version;

From 6ee9cbdd18a70894f89dd268c276d5eb47a34827 Mon Sep 17 00:00:00 2001
From: Russell Yanofsky <russ@yanofsky.org>
Date: Fri, 30 Oct 2020 16:25:56 -0400
Subject: [PATCH 2/5] refactor: Replace ListWalletDir() function with
 ListDatabases()

No change to behavior. This is just cleanup after previous MOVEONLY commit to
make db.h list function fit conventions of surrounding functions.
---
 src/wallet/db.cpp         | 5 +----
 src/wallet/db.h           | 3 +++
 src/wallet/interfaces.cpp | 2 +-
 src/wallet/rpcwallet.cpp  | 2 +-
 src/wallet/walletutil.h   | 3 ---
 5 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index 85aeaeb3ab4..e8b8b8abc12 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -10,8 +10,6 @@
 
 #include <string>
 
-fs::path GetWalletDir();
-
 #ifdef USE_BDB
 bool ExistsBerkeleyDatabase(const fs::path& path);
 #else
@@ -23,9 +21,8 @@ bool ExistsSQLiteDatabase(const fs::path& path);
 #   define ExistsSQLiteDatabase(path)  (false)
 #endif
 
-std::vector<fs::path> ListWalletDir()
+std::vector<fs::path> ListDatabases(const fs::path& wallet_dir)
 {
-    const fs::path wallet_dir = GetWalletDir();
     const size_t offset = wallet_dir.string().size() + 1;
     std::vector<fs::path> paths;
     boost::system::error_code ec;
diff --git a/src/wallet/db.h b/src/wallet/db.h
index cc13f887b06..3d18e5cec0e 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -223,6 +223,9 @@ enum class DatabaseStatus {
     FAILED_ENCRYPT,
 };
 
+/** Recursively list database paths in directory. */
+std::vector<fs::path> ListDatabases(const fs::path& path);
+
 std::unique_ptr<WalletDatabase> MakeDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
 
 bool IsBDBFile(const fs::path& path);
diff --git a/src/wallet/interfaces.cpp b/src/wallet/interfaces.cpp
index 3fbba9ab921..46ef6eee3ec 100644
--- a/src/wallet/interfaces.cpp
+++ b/src/wallet/interfaces.cpp
@@ -551,7 +551,7 @@ public:
     std::vector<std::string> listWalletDir() override
     {
         std::vector<std::string> paths;
-        for (auto& path : ListWalletDir()) {
+        for (auto& path : ListDatabases(GetWalletDir())) {
             paths.push_back(path.string());
         }
         return paths;
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 7ea6a214b24..3802bb452a2 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2537,7 +2537,7 @@ static RPCHelpMan listwalletdir()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     UniValue wallets(UniValue::VARR);
-    for (const auto& path : ListWalletDir()) {
+    for (const auto& path : ListDatabases(GetWalletDir())) {
         UniValue wallet(UniValue::VOBJ);
         wallet.pushKV("name", path.string());
         wallets.push_back(wallet);
diff --git a/src/wallet/walletutil.h b/src/wallet/walletutil.h
index 27521abd81c..d4143ceff47 100644
--- a/src/wallet/walletutil.h
+++ b/src/wallet/walletutil.h
@@ -65,9 +65,6 @@ enum WalletFlags : uint64_t {
 //! Get the path of the wallet directory.
 fs::path GetWalletDir();
 
-//! Get wallets in wallet directory.
-std::vector<fs::path> ListWalletDir();
-
 /** Descriptor with some wallet metadata */
 class WalletDescriptor
 {

From 6a7a63644cd2fc56538d323cc0d5c1d7945247fd Mon Sep 17 00:00:00 2001
From: Russell Yanofsky <russ@yanofsky.org>
Date: Fri, 30 Oct 2020 16:28:44 -0400
Subject: [PATCH 3/5] refactor: Drop call to GetWalletEnv in wallet salvage
 code

No observable change in behavior. This just avoids a redundant environment
lookup. Motivation is to be able to simplify the GetWalletEnv implementation in
an upcoming commit.
---
 src/wallet/salvage.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/wallet/salvage.cpp b/src/wallet/salvage.cpp
index da5ca7858f2..09a9ec68cd0 100644
--- a/src/wallet/salvage.cpp
+++ b/src/wallet/salvage.cpp
@@ -32,8 +32,9 @@ bool RecoverDatabaseFile(const fs::path& file_path, bilingual_str& error, std::v
     std::unique_ptr<WalletDatabase> database = MakeDatabase(file_path, options, status, error);
     if (!database) return false;
 
-    std::string filename;
-    std::shared_ptr<BerkeleyEnvironment> env = GetWalletEnv(file_path, filename);
+    BerkeleyDatabase& berkeley_database = static_cast<BerkeleyDatabase&>(*database);
+    std::string filename = berkeley_database.Filename();
+    std::shared_ptr<BerkeleyEnvironment> env = berkeley_database.env;
 
     if (!env->Open(error)) {
         return false;

From d70dc89e78ee6355e0bc37cc36cfc04ef7a86885 Mon Sep 17 00:00:00 2001
From: Russell Yanofsky <russ@yanofsky.org>
Date: Fri, 30 Oct 2020 16:41:23 -0400
Subject: [PATCH 4/5] refactor: Consolidate redundant wallet database path and
 exists functions

No change in behavior. Just remove a little bit of code, reduce macro usage,
remove duplicative functions, and make BDB and SQLite implementations more
consistent with each other.
---
 src/wallet/bdb.cpp           | 20 +++++---------------
 src/wallet/bdb.h             |  7 ++-----
 src/wallet/db.cpp            | 36 ++++++++++++++++++------------------
 src/wallet/db.h              |  2 ++
 src/wallet/sqlite.cpp        | 11 ++---------
 src/wallet/sqlite.h          |  1 -
 src/wallet/test/db_tests.cpp |  7 +++++++
 src/wallet/walletdb.cpp      |  8 ++------
 8 files changed, 38 insertions(+), 54 deletions(-)

diff --git a/src/wallet/bdb.cpp b/src/wallet/bdb.cpp
index c289f94c786..6ed48593fb6 100644
--- a/src/wallet/bdb.cpp
+++ b/src/wallet/bdb.cpp
@@ -53,16 +53,13 @@ bool WalletDatabaseFileId::operator==(const WalletDatabaseFileId& rhs) const
 }
 
 /**
- * @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.
+ * @param[in] env_directory Path to environment 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)
+std::shared_ptr<BerkeleyEnvironment> GetBerkeleyEnv(const fs::path& env_directory)
 {
-    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) {
@@ -808,21 +805,14 @@ std::unique_ptr<DatabaseBatch> BerkeleyDatabase::MakeBatch(bool flush_on_close)
     return MakeUnique<BerkeleyBatch>(*this, false, flush_on_close);
 }
 
-bool ExistsBerkeleyDatabase(const fs::path& path)
-{
-    fs::path env_directory;
-    std::string data_filename;
-    SplitWalletPath(path, env_directory, data_filename);
-    return IsBDBFile(env_directory / data_filename);
-}
-
 std::unique_ptr<BerkeleyDatabase> MakeBerkeleyDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error)
 {
+    fs::path data_file = BDBDataFile(path);
     std::unique_ptr<BerkeleyDatabase> db;
     {
         LOCK(cs_db); // Lock env.m_databases until insert in BerkeleyDatabase constructor
-        std::string data_filename;
-        std::shared_ptr<BerkeleyEnvironment> env = GetWalletEnv(path, data_filename);
+        std::string data_filename = data_file.filename().string();
+        std::shared_ptr<BerkeleyEnvironment> env = GetBerkeleyEnv(data_file.parent_path());
         if (env->m_databases.count(data_filename)) {
             error = Untranslated(strprintf("Refusing to load database. Data file '%s' is already loaded.", (env->Directory() / data_filename).string()));
             status = DatabaseStatus::FAILED_ALREADY_LOADED;
diff --git a/src/wallet/bdb.h b/src/wallet/bdb.h
index 935d0f947db..bf1617d67f9 100644
--- a/src/wallet/bdb.h
+++ b/src/wallet/bdb.h
@@ -83,8 +83,8 @@ public:
     }
 };
 
-/** Get BerkeleyEnvironment and database filename given a wallet path. */
-std::shared_ptr<BerkeleyEnvironment> GetWalletEnv(const fs::path& wallet_path, std::string& database_filename);
+/** Get BerkeleyEnvironment given a directory path. */
+std::shared_ptr<BerkeleyEnvironment> GetBerkeleyEnv(const fs::path& env_directory);
 
 class BerkeleyBatch;
 
@@ -223,9 +223,6 @@ public:
 
 std::string BerkeleyDatabaseVersion();
 
-//! Check if Berkeley database exists at specified path.
-bool ExistsBerkeleyDatabase(const fs::path& path);
-
 //! Return object giving access to Berkeley database at specified path.
 std::unique_ptr<BerkeleyDatabase> MakeBerkeleyDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
 
diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index e8b8b8abc12..425b14b8f9f 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -10,17 +10,6 @@
 
 #include <string>
 
-#ifdef USE_BDB
-bool ExistsBerkeleyDatabase(const fs::path& path);
-#else
-#   define ExistsBerkeleyDatabase(path)  (false)
-#endif
-#ifdef USE_SQLITE
-bool ExistsSQLiteDatabase(const fs::path& path);
-#else
-#   define ExistsSQLiteDatabase(path)  (false)
-#endif
-
 std::vector<fs::path> ListDatabases(const fs::path& wallet_dir)
 {
     const size_t offset = wallet_dir.string().size() + 1;
@@ -39,10 +28,10 @@ std::vector<fs::path> ListDatabases(const fs::path& wallet_dir)
             const fs::path path = it->path().string().substr(offset);
 
             if (it->status().type() == fs::directory_file &&
-                (ExistsBerkeleyDatabase(it->path()) || ExistsSQLiteDatabase(it->path()))) {
+                (IsBDBFile(BDBDataFile(it->path())) || IsSQLiteFile(SQLiteDataFile(it->path())))) {
                 // Found a directory which contains wallet.dat btree file, add it as a wallet.
                 paths.emplace_back(path);
-            } else if (it.level() == 0 && it->symlink_status().type() == fs::regular_file && ExistsBerkeleyDatabase(it->path())) {
+            } else if (it.level() == 0 && it->symlink_status().type() == fs::regular_file && IsBDBFile(it->path())) {
                 if (it->path().filename() == "wallet.dat") {
                     // Found top-level wallet.dat btree file, add top level directory ""
                     // as a wallet.
@@ -64,24 +53,31 @@ std::vector<fs::path> ListDatabases(const fs::path& wallet_dir)
     return paths;
 }
 
-void SplitWalletPath(const fs::path& wallet_path, fs::path& env_directory, std::string& database_filename)
+fs::path BDBDataFile(const fs::path& wallet_path)
 {
     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();
+        return wallet_path;
     } else {
         // Normal case: Interpret wallet path as a directory path containing
         // data and log files.
-        env_directory = wallet_path;
-        database_filename = "wallet.dat";
+        return wallet_path / "wallet.dat";
     }
 }
 
+fs::path SQLiteDataFile(const fs::path& path)
+{
+    return path / "wallet.dat";
+}
+
 bool IsBDBFile(const fs::path& path)
 {
+#ifndef USE_BDB
+    return false;
+#endif
+
     if (!fs::exists(path)) return false;
 
     // A Berkeley DB Btree file has at least 4K.
@@ -107,6 +103,10 @@ bool IsBDBFile(const fs::path& path)
 
 bool IsSQLiteFile(const fs::path& path)
 {
+#ifndef USE_SQLITE
+    return false;
+#endif
+
     if (!fs::exists(path)) return false;
 
     // A SQLite Database file is at least 512 bytes.
diff --git a/src/wallet/db.h b/src/wallet/db.h
index 3d18e5cec0e..2c75486a44b 100644
--- a/src/wallet/db.h
+++ b/src/wallet/db.h
@@ -228,6 +228,8 @@ std::vector<fs::path> ListDatabases(const fs::path& path);
 
 std::unique_ptr<WalletDatabase> MakeDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
 
+fs::path BDBDataFile(const fs::path& path);
+fs::path SQLiteDataFile(const fs::path& path);
 bool IsBDBFile(const fs::path& path);
 bool IsSQLiteFile(const fs::path& path);
 
diff --git a/src/wallet/sqlite.cpp b/src/wallet/sqlite.cpp
index 69d96dd27c6..0fb3b1d3c41 100644
--- a/src/wallet/sqlite.cpp
+++ b/src/wallet/sqlite.cpp
@@ -17,7 +17,6 @@
 #include <sqlite3.h>
 #include <stdint.h>
 
-static const char* const DATABASE_FILENAME = "wallet.dat";
 static constexpr int32_t WALLET_SCHEMA_VERSION = 0;
 
 static Mutex g_sqlite_mutex;
@@ -568,17 +567,11 @@ bool SQLiteBatch::TxnAbort()
     return res == SQLITE_OK;
 }
 
-bool ExistsSQLiteDatabase(const fs::path& path)
-{
-    const fs::path file = path / DATABASE_FILENAME;
-    return fs::symlink_status(file).type() == fs::regular_file && IsSQLiteFile(file);
-}
-
 std::unique_ptr<SQLiteDatabase> MakeSQLiteDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error)
 {
-    const fs::path file = path / DATABASE_FILENAME;
     try {
-        auto db = MakeUnique<SQLiteDatabase>(path, file);
+        fs::path data_file = SQLiteDataFile(path);
+        auto db = MakeUnique<SQLiteDatabase>(data_file.parent_path(), data_file);
         if (options.verify && !db->Verify(error)) {
             status = DatabaseStatus::FAILED_VERIFY;
             return nullptr;
diff --git a/src/wallet/sqlite.h b/src/wallet/sqlite.h
index 3cb11614db9..442563184e3 100644
--- a/src/wallet/sqlite.h
+++ b/src/wallet/sqlite.h
@@ -113,7 +113,6 @@ public:
     sqlite3* m_db{nullptr};
 };
 
-bool ExistsSQLiteDatabase(const fs::path& path);
 std::unique_ptr<SQLiteDatabase> MakeSQLiteDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
 
 std::string SQLiteDatabaseVersion();
diff --git a/src/wallet/test/db_tests.cpp b/src/wallet/test/db_tests.cpp
index 8f0083cd2e4..1a28852a6bb 100644
--- a/src/wallet/test/db_tests.cpp
+++ b/src/wallet/test/db_tests.cpp
@@ -13,6 +13,13 @@
 
 BOOST_FIXTURE_TEST_SUITE(db_tests, BasicTestingSetup)
 
+static std::shared_ptr<BerkeleyEnvironment> GetWalletEnv(const fs::path& path, std::string& database_filename)
+{
+    fs::path data_file = BDBDataFile(path);
+    database_filename = data_file.filename().string();
+    return GetBerkeleyEnv(data_file.parent_path());
+}
+
 BOOST_AUTO_TEST_CASE(getwalletenv_file)
 {
     std::string test_name = "test_name.dat";
diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index c0521d33865..5b72a019396 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -1013,13 +1013,10 @@ std::unique_ptr<WalletDatabase> MakeDatabase(const fs::path& path, const Databas
 
     Optional<DatabaseFormat> format;
     if (exists) {
-#ifdef USE_BDB
-        if (ExistsBerkeleyDatabase(path)) {
+        if (IsBDBFile(BDBDataFile(path))) {
             format = DatabaseFormat::BERKELEY;
         }
-#endif
-#ifdef USE_SQLITE
-        if (ExistsSQLiteDatabase(path)) {
+        if (IsSQLiteFile(SQLiteDataFile(path))) {
             if (format) {
                 error = Untranslated(strprintf("Failed to load database path '%s'. Data is in ambiguous format.", path.string()));
                 status = DatabaseStatus::FAILED_BAD_FORMAT;
@@ -1027,7 +1024,6 @@ std::unique_ptr<WalletDatabase> MakeDatabase(const fs::path& path, const Databas
             }
             format = DatabaseFormat::SQLITE;
         }
-#endif
     } else if (options.require_existing) {
         error = Untranslated(strprintf("Failed to load database path '%s'. Path does not exist.", path.string()));
         status = DatabaseStatus::FAILED_NOT_FOUND;

From f3d870fc2271bf45e0269e5ae135bced1a26f620 Mon Sep 17 00:00:00 2001
From: Russell Yanofsky <russ@yanofsky.org>
Date: Fri, 30 Oct 2020 16:48:04 -0400
Subject: [PATCH 5/5] wallet: List all wallets in non-SQLite or non-BDB builds

This commit does not change behavior when bitcoin is built normally with both
the SQLite and BDB libraries. It just makes non-SQLite and non-BDB builds
more similar to the normal build. Specifically:

- It makes wallet directory lists always include all wallets so wallets don't
  appear missing depending on the build.

- It now triggers specific "Build does not support SQLite database format" and
  "Build does not support Berkeley DB database format" errors if a wallet can't
  be loaded instead of the more ambiguous and scary "Data is not in recognized
  format" error.
---
 src/wallet/db.cpp | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
index 425b14b8f9f..cd49baeb786 100644
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -74,10 +74,6 @@ fs::path SQLiteDataFile(const fs::path& path)
 
 bool IsBDBFile(const fs::path& path)
 {
-#ifndef USE_BDB
-    return false;
-#endif
-
     if (!fs::exists(path)) return false;
 
     // A Berkeley DB Btree file has at least 4K.
@@ -103,10 +99,6 @@ bool IsBDBFile(const fs::path& path)
 
 bool IsSQLiteFile(const fs::path& path)
 {
-#ifndef USE_SQLITE
-    return false;
-#endif
-
     if (!fs::exists(path)) return false;
 
     // A SQLite Database file is at least 512 bytes.