use lstat when checking whether file is a symlink

Exclude symlinks from candidates when pruning local files

cmd/backup/main.go

@@ -503,15 +503,35 @@ func (s *script) pruneOldBackups() error {
 	}
 
 	if _, err := os.Stat(s.c.BackupArchive); !os.IsNotExist(err) {
-		candidates, err := filepath.Glob(
-			path.Join(s.c.BackupArchive, fmt.Sprintf("%s*", s.c.BackupPruningPrefix)),
+		globPattern := path.Join(
+			s.c.BackupArchive,
+			fmt.Sprintf("%s*", s.c.BackupPruningPrefix),
 		)
+		globMatches, err := filepath.Glob(globPattern)
 		if err != nil {
 			return fmt.Errorf(
-				"pruneOldBackups: error looking up matching files, starting with: %w", err,
+				"pruneOldBackups: error looking up matching files using pattern %s: %w",
+				globPattern,
+				err,
 			)
 		}
 
+		var candidates []string
+		for _, candidate := range globMatches {
+			fi, err := os.Lstat(candidate)
+			if err != nil {
+				return fmt.Errorf(
+					"pruneOldBackups: error calling Lstat on file %s: %w",
+					candidate,
+					err,
+				)
+			}
+
+			if fi.Mode()&os.ModeSymlink != os.ModeSymlink {
+				candidates = append(candidates, candidate)
+			}
+		}
+
 		var matches []string
 		for _, candidate := range candidates {
 			fi, err := os.Stat(candidate)
@@ -522,16 +542,15 @@ func (s *script) pruneOldBackups() error {
 					err,
 				)
 			}
-
-			if fi.Mode() != os.ModeSymlink && fi.ModTime().Before(deadline) {
+			if fi.ModTime().Before(deadline) {
 				matches = append(matches, candidate)
 			}
 		}
 
 		if len(matches) != 0 && len(matches) != len(candidates) {
 			var removeErrors []error
-			for _, candidate := range matches {
-				if err := os.Remove(candidate); err != nil {
+			for _, match := range matches {
+				if err := os.Remove(match); err != nil {
 					removeErrors = append(removeErrors, err)
 				}
 			}