Determine wallet file type based on file magic

src/wallet/bdb.cpp

@@ -813,7 +813,7 @@ bool ExistsBerkeleyDatabase(const fs::path& path)
     fs::path env_directory;
     std::string data_filename;
     SplitWalletPath(path, env_directory, data_filename);
-    return IsBerkeleyBtree(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)
@@ -839,3 +839,28 @@ 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;
+}

src/wallet/bdb.h

@@ -87,7 +87,7 @@ public:
 std::shared_ptr<BerkeleyEnvironment> GetWalletEnv(const fs::path& wallet_path, std::string& database_filename);
 
 /** Check format of database file */
-bool IsBerkeleyBtree(const fs::path& path);
+bool IsBDBFile(const fs::path& path);
 
 class BerkeleyBatch;
 

src/wallet/db.h

@@ -8,6 +8,7 @@
 
 #include <clientversion.h>
 #include <fs.h>
+#include <optional.h>
 #include <streams.h>
 #include <support/allocators/secure.h>
 #include <util/memory.h>
@@ -194,11 +195,13 @@ public:
 
 enum class DatabaseFormat {
     BERKELEY,
+    SQLITE,
 };
 
 struct DatabaseOptions {
     bool require_existing = false;
     bool require_create = false;
+    Optional<DatabaseFormat> require_format;
     uint64_t create_flags = 0;
     SecureString create_passphrase;
     bool verify = true;

src/wallet/sqlite.cpp

@@ -502,7 +502,8 @@ bool SQLiteBatch::TxnAbort()
 
 bool ExistsSQLiteDatabase(const fs::path& path)
 {
-    return false;
+    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)
@@ -526,3 +527,26 @@ 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);
+    file.close();
+
+    // Check the magic, see https://sqlite.org/fileformat2.html
+    std::string magic_str(magic);
+    return magic_str == std::string("SQLite format 3");
+}

src/wallet/sqlite.h

@@ -116,5 +116,6 @@ 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

src/wallet/walletdb.cpp

@@ -15,6 +15,7 @@
 #include <util/time.h>
 #include <util/translation.h>
 #include <wallet/bdb.h>
+#include <wallet/sqlite.h>
 #include <wallet/wallet.h>
 
 #include <atomic>
@@ -1011,6 +1012,14 @@ std::unique_ptr<WalletDatabase> MakeDatabase(const fs::path& path, const Databas
         if (ExistsBerkeleyDatabase(path)) {
             format = DatabaseFormat::BERKELEY;
         }
+        if (ExistsSQLiteDatabase(path)) {
+            if (format) {
+                error = Untranslated(strprintf("Failed to load database path '%s'. Data is in ambiguous format.", path.string()));
+                status = DatabaseStatus::FAILED_BAD_FORMAT;
+                return nullptr;
+            }
+            format = DatabaseFormat::SQLITE;
+        }
     } 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;
@@ -1029,6 +1038,20 @@ std::unique_ptr<WalletDatabase> MakeDatabase(const fs::path& path, const Databas
         return nullptr;
     }
 
+    // A db already exists so format is set, but options also specifies the format, so make sure they agree
+    if (format && options.require_format && format != options.require_format) {
+        error = Untranslated(strprintf("Failed to load database path '%s'. Data is not in required format.", path.string()));
+        status = DatabaseStatus::FAILED_BAD_FORMAT;
+        return nullptr;
+    }
+
+    // Format is not set when a db doesn't already exist, so use the format specified by the options if it is set.
+    if (!format && options.require_format) format = options.require_format;
+
+    if (format && format == DatabaseFormat::SQLITE) {
+        return MakeSQLiteDatabase(path, options, status, error);
+    }
+
     return MakeBerkeleyDatabase(path, options, status, error);
 }
 

src/wallet/walletutil.cpp

@@ -7,6 +7,8 @@
 #include <logging.h>
 #include <util/system.h>
 
+bool ExistsBerkeleyDatabase(const fs::path& path);
+
 fs::path GetWalletDir()
 {
     fs::path path;
@@ -29,31 +31,6 @@ fs::path GetWalletDir()
     return path;
 }
 
-bool IsBerkeleyBtree(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;
-}
-
 std::vector<fs::path> ListWalletDir()
 {
     const fs::path wallet_dir = GetWalletDir();
@@ -71,10 +48,10 @@ std::vector<fs::path> ListWalletDir()
         // 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 && IsBerkeleyBtree(it->path() / "wallet.dat")) {
+        if (it->status().type() == fs::directory_file && ExistsBerkeleyDatabase(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 && IsBerkeleyBtree(it->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.