wallet: Fix migration of wallets with pathnames.

davidgumberg · luke-jr · commit fee79e70d933 · 2026-01-21T20:42:12.000Z
Co-authored-by: Russell Yanofsky <russ@yanofsky.org> Github-Pull: bitcoin#32273 Rebased-From: 70f1c99
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
@@ -4546,9 +4546,20 @@ util::Result<MigrationResult> MigrateLegacyToDescriptor(std::shared_ptr<CWallet>
         return util::Error{_("Error: This wallet is already a descriptor wallet")};
     }
 
-    // Make a backup of the DB
+    // Make a backup of the DB in the wallet's directory with a unique filename
+    // using the wallet name and current timestamp. The backup filename is based
+    // on the name of the parent directory containing the wallet data in most
+    // cases, but in the case where the wallet name is a path to a data file,
+    // the name of the data file is used, and in the case where the wallet name
+    // is blank, "default_wallet" is used.
     fs::path this_wallet_dir = fs::absolute(fs::PathFromString(local_wallet->GetDatabase().Filename())).parent_path();
-    fs::path backup_filename = fs::PathFromString(strprintf("%s_%d.legacy.bak", MigrationPrefixName(*local_wallet), GetTime()));
+    const std::string backup_prefix = wallet_name.empty() ? MigrationPrefixName(*local_wallet) : [&] {
+        // fs::weakly_canonical resolves relative specifiers and remove trailing slashes.
+        const auto legacy_wallet_path = fs::weakly_canonical(GetWalletDir() / fs::PathFromString(wallet_name));
+        return fs::PathToString(legacy_wallet_path.filename());
+    }();
+
+    fs::path backup_filename = fs::PathFromString(strprintf("%s_%d.legacy.bak", backup_prefix, GetTime()));
     fs::path backup_path = this_wallet_dir / backup_filename;
     if (!local_wallet->BackupWallet(fs::PathToString(backup_path))) {
         if (was_loaded) {
diff --git a/test/functional/wallet_migration.py b/test/functional/wallet_migration.py
@@ -636,7 +636,7 @@ def test_migration_failure(self, wallet_name):
         assert Path(old_path / "wallet.dat").exists()
         assert Path(master_path / "wallet.dat").exists()
 
-        backup_prefix = "default_wallet" if is_default else wallet_name
+        backup_prefix = "default_wallet" if is_default else os.path.basename(os.path.abspath(master_path))
         backup_path = master_path / f"{backup_prefix}_{mocked_time}.legacy.bak"
         assert backup_path.exists()
 
