List a file:// destination through a symlinked directory (closes #296)

List and ListStream walked the destination with afero.Walk, which uses
Lstat and so reported a symlinked metadata/ or blobs/ directory as one
file, while Put, Get and Stat follow the link. The store then listed as
empty, and prune removed the local snapshot records and deleted every
blob. Both listings now walk a view of the filesystem without its Lstat
method, so afero falls back to Stat and enters the link.

A symlink loop is not detected: it is followed until the system refuses
the path for too many levels of links, and the listing fails.

Model: opus-5-5

README.md

@@ -412,8 +412,7 @@ destination store.
 entirely. Remote storage is unaffected; the next backup will do a full
 scan and re-deduplicate against existing remote blobs, and the local
 index will re-bind to the currently configured storage destination.
-Use this after changing `storage_url`, or `s3.endpoint`, `s3.bucket` or
-`s3.prefix`, to a different destination.
+Use this after changing `storage_url` to a different destination.
 * `--force`: Skip confirmation prompt
 
 ---

TODO.md

@@ -22,24 +22,15 @@ the tag exists and is exercised; what is left is merging `next` to
 
 # Completed Steps
 
-- 2026-10-13: Made Ctrl-C or SIGTERM during a local index write end the
-  command as interrupted
-  ([issue #301](https://git.eeqj.de/sneak/vaultik/issues/301)). Once the
-  run is cancelled, `database/sql` rolls an open transaction back itself,
-  so the rollback in `WithTx` failed with `sql.ErrTxDone` and the process
-  exited 1 with `FATAL: failed to rollback transaction`, skipping the
-  interrupted exit and message. That result is no longer an error, and a
-  rollback that does fail is returned with the transaction's error
-  instead of ending the process.
-
-- 2026-10-12: Bound the local index to the destination an `s3.*` config
-  names ([issue #298](https://git.eeqj.de/sneak/vaultik/issues/298)).
-  Only `storage_url` was checked, so after `s3.bucket` or `s3.prefix`
-  changed, the next backup treated every chunk as already stored,
-  uploaded nothing, and completed a snapshot that could not be restored.
-  Without `storage_url`, the local index is now bound to `s3.endpoint`,
-  `s3.bucket` and `s3.prefix`, and a change is refused as a changed
-  `storage_url` is.
+- 2026-10-12: Made a `file://` destination list through a symlinked
+  directory ([issue #296](https://git.eeqj.de/sneak/vaultik/issues/296)).
+  A `metadata/` or `blobs/` directory that was a symlink to a directory
+  elsewhere was listed as one file, so the destination store listed as
+  empty while backups and restores still worked through the link.
+  `prune` then removed the local snapshot records and deleted every blob,
+  and `remote info` and `remote nuke` found no blobs. The listings now
+  read through the link as `Get` and `Stat` do; a link pointing back up
+  the tree makes them fail.
 
 - 2026-10-12: Rejected a retention duration longer than about 292 years
   ([issue #289](https://git.eeqj.de/sneak/vaultik/issues/289)). The

internal/database/repositories.go

@@ -3,7 +3,6 @@ package database
 import (
 	"context"
 	"database/sql"
-	"errors"
 	"fmt"
 )
 
@@ -61,24 +60,22 @@ func (r *Repositories) WithTx(ctx context.Context, fn TxFunc) error {
 
 	defer func() {
 		if p := recover(); p != nil {
-			// The panic is the failure to report, so a rollback error
-			// is dropped.
-			_ = tx.Rollback()
+			rollbackErr := tx.Rollback()
+			if rollbackErr != nil {
+				Fatalf("failed to rollback transaction: %v", rollbackErr)
+			}
 
 			panic(p)
+		} else if err != nil {
+			rollbackErr := tx.Rollback()
+			if rollbackErr != nil {
+				Fatalf("failed to rollback transaction: %v", rollbackErr)
+			}
 		}
 	}()
 
 	err = fn(ctx, tx)
 	if err != nil {
-		// Once ctx is cancelled, database/sql rolls the transaction
-		// back itself and Rollback returns sql.ErrTxDone.
-		rollbackErr := tx.Rollback()
-		if rollbackErr != nil && !errors.Is(rollbackErr, sql.ErrTxDone) {
-			return fmt.Errorf("%w; rolling back transaction: %w",
-				err, rollbackErr)
-		}
-
 		return err
 	}
 

internal/database/repositories_test.go

@@ -235,64 +235,6 @@ func TestRepositoriesTransactionRollback(t *testing.T) {
 	}
 }
 
-// When the context is cancelled during the body, database/sql rolls the
-// transaction back itself, so WithTx's own rollback finds it already
-// done. WithTx must still return the body's error.
-func TestRepositoriesTransactionContextCancelled(t *testing.T) {
-	t.Parallel()
-
-	db, cleanup := setupTestDB(t)
-	defer cleanup()
-
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	repos := database.NewRepositories(db)
-
-	err := repos.WithTx(ctx, func(ctx context.Context, tx *sql.Tx) error {
-		file := &database.File{
-			Path:  "/test/cancelled_file.txt",
-			MTime: time.Now().Truncate(time.Second),
-			Size:  1024,
-			Mode:  0644,
-			UID:   1000,
-			GID:   1000,
-		}
-
-		err := repos.Files.Create(ctx, tx, file)
-		if err != nil {
-			return err
-		}
-
-		cancel()
-
-		// database/sql rolls back from a goroutine of its own; wait
-		// until it has, so the test does not depend on that race.
-		for {
-			_, err = tx.ExecContext(context.WithoutCancel(ctx), "SELECT 1")
-			if errors.Is(err, sql.ErrTxDone) {
-				return ctx.Err()
-			}
-
-			time.Sleep(time.Millisecond)
-		}
-	})
-	if !errors.Is(err, context.Canceled) {
-		t.Fatalf("expected context.Canceled, got: %v", err)
-	}
-
-	file, err := repos.Files.GetByPath(
-		context.Background(), "/test/cancelled_file.txt",
-	)
-	if err != nil {
-		t.Fatalf("error checking for file: %v", err)
-	}
-
-	if file != nil {
-		t.Error("file should not exist after the cancelled transaction")
-	}
-}
-
 func TestRepositoriesReadTransaction(t *testing.T) {
 	t.Parallel()
 

internal/storage/file.go

@@ -120,9 +120,9 @@ func (f *FileStorer) Delete(_ context.Context, key string) error {
 	return nil
 }
 
-// List returns all keys with the given prefix. It fails when the
-// destination directory is missing; a missing prefix under it is an
-// empty listing.
+// List returns all keys with the given prefix, reading through symlinked
+// directories. It fails when the destination directory is missing; a
+// missing prefix under it is an empty listing.
 func (f *FileStorer) List(ctx context.Context, prefix string) ([]string, error) {
 	var keys []string
 
@@ -143,7 +143,7 @@ func (f *FileStorer) List(ctx context.Context, prefix string) ([]string, error)
 		return keys, nil // Empty list for non-existent prefix
 	}
 
-	err = afero.Walk(f.fs, basePath, func(path string, info os.FileInfo, err error) error {
+	err = f.walk(basePath, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err
 		}
@@ -176,7 +176,8 @@ func (f *FileStorer) List(ctx context.Context, prefix string) ([]string, error)
 }
 
 // ListStream returns a channel of ObjectInfo for large result sets. Like
-// List, it sends an error when the destination directory is missing.
+// List, it reads through symlinked directories and sends an error when
+// the destination directory is missing.
 func (f *FileStorer) ListStream(ctx context.Context, prefix string) <-chan ObjectInfo {
 	ch := make(chan ObjectInfo)
 
@@ -204,7 +205,7 @@ func (f *FileStorer) ListStream(ctx context.Context, prefix string) <-chan Objec
 			return // Empty channel for non-existent prefix
 		}
 
-		_ = afero.Walk(f.fs, basePath, func(path string, info os.FileInfo, err error) error {
+		_ = f.walk(basePath, func(path string, info os.FileInfo, err error) error {
 			// Check context cancellation
 			select {
 			case <-ctx.Done():
@@ -352,6 +353,17 @@ func (f *FileStorer) writeAtomic(
 	return nil
 }
 
+// walk is afero.Walk, except that it reads through a symlinked directory
+// the way Get and Stat do, where afero.Walk reports the link as one file.
+// afero.Walk uses Lstat, which does not follow a link, whenever the
+// filesystem has one; the struct below carries only the afero.Fs methods,
+// so the walk uses Stat instead. A link back up the tree is followed until
+// the operating system refuses the path for too many levels of links, and
+// the walk then fails.
+func (f *FileStorer) walk(root string, fn filepath.WalkFunc) error {
+	return afero.Walk(struct{ afero.Fs }{f.fs}, root, fn)
+}
+
 // fullPath returns the full filesystem path for a key.
 func (f *FileStorer) fullPath(key string) string {
 	return filepath.Join(f.basePath, key)

internal/storage/file_backend_test.go

@@ -4,7 +4,10 @@ import (
 	"context"
 	"errors"
 	"io/fs"
+	"os"
 	"path/filepath"
+	"reflect"
+	"strings"
 	"testing"
 
 	"sneak.berlin/go/vaultik/internal/storage"
@@ -60,3 +63,100 @@ func TestFileStorerListMissingDestination(t *testing.T) {
 		t.Errorf("ListStream error = %v, want a not-exist error", streamErr)
 	}
 }
+
+// TestFileStorerListsThroughSymlinkedDirectory checks that List and
+// ListStream read through a symlinked metadata/ or blobs/ directory, as Get
+// and Stat do, instead of listing the link as one key. Listing the whole
+// destination meets the link part-way through the walk; listing its prefix
+// starts the walk at the link.
+func TestFileStorerListsThroughSymlinkedDirectory(t *testing.T) {
+	t.Parallel()
+
+	for _, dir := range []string{"metadata", "blobs"} {
+		t.Run(dir, func(t *testing.T) {
+			t.Parallel()
+
+			base := t.TempDir()
+			key := dir + "/aa/bb/object"
+
+			s, err := storage.NewFileStorer(base)
+			if err != nil {
+				t.Fatalf("NewFileStorer: %v", err)
+			}
+
+			err = s.Put(context.Background(), key, strings.NewReader("data"))
+			if err != nil {
+				t.Fatalf("Put: %v", err)
+			}
+
+			linkPath := filepath.Join(base, dir)
+			movedPath := filepath.Join(t.TempDir(), dir)
+
+			err = os.Rename(linkPath, movedPath)
+			if err != nil {
+				t.Fatalf("moving %s away: %v", dir, err)
+			}
+
+			err = os.Symlink(movedPath, linkPath)
+			if err != nil {
+				t.Fatalf("linking %s: %v", dir, err)
+			}
+
+			want := []string{key}
+
+			for _, prefix := range []string{"", dir + "/"} {
+				got := listSorted(t, s, prefix)
+				if !reflect.DeepEqual(got, want) {
+					t.Errorf("List(%q) = %v, want %v", prefix, got, want)
+				}
+
+				got = listStreamKeys(t, s, prefix)
+				if !reflect.DeepEqual(got, want) {
+					t.Errorf("ListStream(%q) = %v, want %v", prefix, got, want)
+				}
+			}
+		})
+	}
+}
+
+// TestFileStorerListFailsOnSymlinkLoop checks that a symlink pointing back
+// at the destination makes List and ListStream fail instead of walking it
+// forever.
+func TestFileStorerListFailsOnSymlinkLoop(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	base := t.TempDir()
+
+	s, err := storage.NewFileStorer(base)
+	if err != nil {
+		t.Fatalf("NewFileStorer: %v", err)
+	}
+
+	err = s.Put(ctx, testBlobKey, strings.NewReader("data"))
+	if err != nil {
+		t.Fatalf("Put: %v", err)
+	}
+
+	err = os.Symlink(base, filepath.Join(base, "blobs", "loop"))
+	if err != nil {
+		t.Fatalf("Symlink: %v", err)
+	}
+
+	keys, err := s.List(ctx, "blobs/")
+	if err == nil {
+		t.Errorf("List = %d keys and no error, want an error", len(keys))
+	}
+
+	var streamErr error
+
+	for object := range s.ListStream(ctx, "blobs/") {
+		if object.Err != nil {
+			streamErr = object.Err
+		}
+	}
+
+	if streamErr == nil {
+		t.Error("ListStream sent no error, want one")
+	}
+}

internal/vaultik/storage_bind.go

@@ -9,7 +9,7 @@ import (
 )
 
 // errStorageBindingMismatch is returned when the local index database is
-// bound to a different destination than the configured one.
+// bound to a different destination than the configured storage_url.
 var errStorageBindingMismatch = errors.New(
 	"local index is bound to a different backup destination")
 
@@ -24,9 +24,8 @@ var errStorageBindingMismatch = errors.New(
 //
 // Behaviour:
 //   - On first use (empty stored value), record the configured
-//     destination (storage_url, or the s3.* endpoint, bucket and
-//     prefix) and log the binding.
-//   - When the stored value matches the configured destination, do
+//     storage_url and log the binding.
+//   - When the stored value matches the configured storage_url, do
 //     nothing and return nil.
 //   - When the two differ, refuse with an error that tells the user
 //     how to recover (revert the config, or run `vaultik database
@@ -47,10 +46,12 @@ func (v *Vaultik) EnsureStorageBinding() error {
 
 	configured := v.Config.StorageURL
 	if configured == "" {
-		// The s3.* form: bind on its endpoint, bucket and prefix,
-		// written the way storage_url would name the same destination.
-		s3 := v.Config.S3
-		configured = "s3://" + s3.Bucket + "/" + s3.Prefix + "?endpoint=" + s3.Endpoint
+		// Some legacy configs still use the split s3.* keys instead of
+		// storage_url. Falling back to a synthetic URL for those would
+		// hide the fact that the binding is loose. Instead, treat
+		// unset as "nothing to bind against" — the check is
+		// necessarily best-effort for those configs.
+		return nil
 	}
 
 	stored, err := v.Repositories.LocalMeta.Get(v.ctx, database.LocalMetaKeyStorageURL)
@@ -95,8 +96,7 @@ func buildBindingMismatchMessage(stored, configured string) string {
 		"future snapshots referencing blobs that don't exist at the new destination.\n" +
 		"\n" +
 		"To proceed, either:\n" +
-		"  - revert storage_url (or the s3.* endpoint, bucket and prefix) in your\n" +
-		"    config to the bound destination, or\n" +
+		"  - revert storage_url in your config to the bound destination, or\n" +
 		"  - run 'vaultik database delete' to discard the local index and rebuild it\n" +
 		"    from a fresh full backup against the new destination"
 }

internal/vaultik/storage_bind_test.go

@@ -76,51 +76,3 @@ func TestEnsureStorageBinding_MismatchRefuses(t *testing.T) {
 	assert.Contains(t, err.Error(), "file:///mnt/backups/new")
 	assert.Contains(t, err.Error(), "vaultik database delete")
 }
-
-// A config with no storage_url names its destination with s3.endpoint,
-// s3.bucket and s3.prefix; a change to any of them must be refused just
-// as a changed storage_url is.
-func TestEnsureStorageBinding_S3FieldsChangeRefuses(t *testing.T) {
-	log.Initialize(log.Config{})
-	t.Parallel()
-
-	bound := config.S3Config{
-		Endpoint: "https://s3.example.com",
-		Bucket:   "bucket-a",
-		Prefix:   "backups",
-	}
-
-	tests := []struct {
-		name    string
-		changed config.S3Config
-	}{
-		{"bucket", config.S3Config{
-			Endpoint: bound.Endpoint, Bucket: "bucket-b", Prefix: bound.Prefix,
-		}},
-		{"prefix", config.S3Config{
-			Endpoint: bound.Endpoint, Bucket: bound.Bucket, Prefix: "other",
-		}},
-		{"endpoint", config.S3Config{
-			Endpoint: "https://s3.other.com", Bucket: bound.Bucket, Prefix: bound.Prefix,
-		}},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			tv, _ := buildBindTestVaultik(t, "")
-
-			tv.Config.S3 = bound
-			require.NoError(t, tv.EnsureStorageBinding(), "first use binds")
-			require.NoError(t, tv.EnsureStorageBinding(), "same destination passes")
-
-			tv.Config.S3 = tt.changed
-			err := tv.EnsureStorageBinding()
-			require.Error(t, err)
-			assert.Contains(t, err.Error(),
-				"local index is bound to a different backup destination")
-			assert.Contains(t, err.Error(), "vaultik database delete")
-		})
-	}
-}

internal/vaultik/symlinked_destination_test.go

@@ -0,0 +1,63 @@
+package vaultik_test
+
+import (
+	"context"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// TestPruneDeletesNothingThroughSymlinkedDirectory checks that prune keeps
+// every blob and the local snapshot record when the metadata/ or blobs/
+// directory of a file:// destination is a symlink to a directory elsewhere
+// (https://git.eeqj.de/sneak/vaultik/issues/296). A backup writes through
+// such a link, so prune has to list through it too.
+func TestPruneDeletesNothingThroughSymlinkedDirectory(t *testing.T) {
+	log.Initialize(log.Config{})
+	t.Parallel()
+
+	for _, dir := range []string{"metadata", "blobs"} {
+		t.Run(dir, func(t *testing.T) {
+			t.Parallel()
+
+			ctx := context.Background()
+			storeDir := filepath.Join(t.TempDir(), "store")
+			v, repos, _ := backUpToFileDestination(ctx, t, storeDir)
+
+			var blobFiles []string
+
+			err := filepath.WalkDir(filepath.Join(storeDir, "blobs"),
+				func(path string, entry fs.DirEntry, err error) error {
+					if err == nil && !entry.IsDir() {
+						blobFiles = append(blobFiles, path)
+					}
+
+					return err
+				})
+			require.NoError(t, err)
+			require.NotEmpty(t, blobFiles)
+
+			linkPath := filepath.Join(storeDir, dir)
+			movedPath := filepath.Join(t.TempDir(), dir)
+			require.NoError(t, os.Rename(linkPath, movedPath))
+			require.NoError(t, os.Symlink(movedPath, linkPath))
+
+			require.NoError(t, v.Prune(&vaultik.PruneOptions{Force: true}))
+
+			// When blobs/ is the link, these paths run through it.
+			for _, blobFile := range blobFiles {
+				assert.FileExists(t, blobFile, "prune must delete no blob")
+			}
+
+			snapshots, err := repos.Snapshots.ListRecent(ctx, listRecentTestLimit)
+			require.NoError(t, err)
+			assert.Len(t, snapshots, 1, "prune must delete no local snapshot record")
+		})
+	}
+}