TODO.md

@@ -22,6 +22,14 @@ the tag exists and is exercised; what is left is merging `next` to
 
 # Completed Steps
 
+- 2026-10-06: Made a backup record the real uid and gid of files,
+  directories and symlinks
+  ([issue #216](https://git.eeqj.de/sneak/vaultik/issues/216)). The
+  scanner asked the stat result for `Uid()` and `Gid()` methods, which
+  `*syscall.Stat_t` does not have, so every entry was stored as `0:0`
+  and a restore as root gave every file to root. It now reads the
+  `Uid` and `Gid` fields of `*syscall.Stat_t`.
+
 - 2026-10-06: Made a `file://` destination whose directory is missing
   count as one that cannot be listed
   ([issue #220](https://git.eeqj.de/sneak/vaultik/issues/220)). The file

internal/snapshot/scanner.go

@@ -11,6 +11,7 @@ import (
 	"runtime"
 	"strings"
 	"sync"
+	"syscall"
 	"time"
 
 	"github.com/dustin/go-humanize"
@@ -1142,12 +1143,9 @@ func (s *Scanner) buildSymlinkEntry(path string, info os.FileInfo) *database.Fil
 	}
 
 	var uid, gid uint32
-	if stat, ok := info.Sys().(interface {
-		Uid() uint32
-		Gid() uint32
-	}); ok {
-		uid = stat.Uid()
-		gid = stat.Gid()
+	if stat, ok := info.Sys().(*syscall.Stat_t); ok {
+		uid = stat.Uid
+		gid = stat.Gid
 	}
 
 	return &database.File{
@@ -1166,12 +1164,9 @@ func (s *Scanner) buildSymlinkEntry(path string, info os.FileInfo) *database.Fil
 // buildDirectoryEntry creates a File record for a directory.
 func (s *Scanner) buildDirectoryEntry(path string, info os.FileInfo) *database.File {
 	var uid, gid uint32
-	if stat, ok := info.Sys().(interface {
-		Uid() uint32
-		Gid() uint32
-	}); ok {
-		uid = stat.Uid()
-		gid = stat.Gid()
+	if stat, ok := info.Sys().(*syscall.Stat_t); ok {
+		uid = stat.Uid
+		gid = stat.Gid
 	}
 
 	return &database.File{
@@ -1204,16 +1199,10 @@ func (s *Scanner) recordNonRegularFile(ctx context.Context, ftp *FileToProcess)
 func (s *Scanner) checkFileInMemory(
 	path string, info os.FileInfo, knownFiles map[string]*database.File,
 ) (*database.File, bool) {
-	// Get file stats
-	stat, ok := info.Sys().(interface {
-		Uid() uint32
-		Gid() uint32
-	})
-
 	var uid, gid uint32
-	if ok {
-		uid = stat.Uid()
-		gid = stat.Gid()
+	if stat, ok := info.Sys().(*syscall.Stat_t); ok {
+		uid = stat.Uid
+		gid = stat.Gid
 	}
 
 	// Check against in-memory map first to get existing ID if available

internal/snapshot/scanner_test.go

@@ -307,3 +307,80 @@ func TestScannerLargeFile(t *testing.T) {
 		}
 	}
 }
+
+// TestScannerRecordsOwnership backs up real files on disk and checks that
+// the uid and gid of a file, a directory and a symlink are recorded.
+// When the tests run as root both sides are 0, so only a run as another
+// user can catch ownership recorded as 0.
+func TestScannerRecordsOwnership(t *testing.T) {
+	t.Parallel()
+
+	sourceDir := t.TempDir()
+	filePath := filepath.Join(sourceDir, "file.txt")
+	dirPath := filepath.Join(sourceDir, "subdir")
+	linkPath := filepath.Join(sourceDir, "link")
+
+	err := os.WriteFile(filePath, []byte("owned"), 0o600)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = os.Mkdir(dirPath, 0o700)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = os.Symlink("file.txt", linkPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	db, err := database.NewTestDB()
+	if err != nil {
+		t.Fatalf("failed to create test database: %v", err)
+	}
+
+	defer func() {
+		err := db.Close()
+		if err != nil {
+			t.Errorf("failed to close database: %v", err)
+		}
+	}()
+
+	repos := database.NewRepositories(db)
+
+	scanner := snapshot.NewScanner(snapshot.ScannerConfig{
+		FS:               afero.NewOsFs(),
+		ChunkSize:        int64(1024 * 16),
+		Repositories:     repos,
+		MaxBlobSize:      int64(1024 * 1024),
+		CompressionLevel: 3,
+		AgeRecipients:    []string{testAgePublicKey},
+	})
+
+	ctx := context.Background()
+	snapshotID := "test-snapshot-ownership"
+
+	createTestSnapshotRecord(ctx, t, repos, snapshotID)
+
+	_, err = scanner.Scan(ctx, sourceDir, snapshotID)
+	if err != nil {
+		t.Fatalf("scan failed: %v", err)
+	}
+
+	for _, path := range []string{filePath, dirPath, linkPath} {
+		file, err := repos.Files.GetByPath(ctx, path)
+		if err != nil {
+			t.Fatalf("failed to get %s: %v", path, err)
+		}
+
+		if file == nil {
+			t.Fatalf("%s was not recorded", path)
+		}
+
+		if int(file.UID) != os.Getuid() || int(file.GID) != os.Getgid() {
+			t.Errorf("%s recorded as uid %d gid %d, want uid %d gid %d",
+				path, file.UID, file.GID, os.Getuid(), os.Getgid())
+		}
+	}
+}