X-Git-Url: https://git.giacomolli.uk/onechat/blobdiff_plain/0821d23c64f4ffc856760e4914fa39ba2e3260e4..fc0503be49438775c5d08499046852df59bd7377:/file.go?ds=inline

diff --git a/file.go b/file.go
index a7ba5bb..00c8a0c 100644
--- a/file.go
+++ b/file.go
@@ -28,3 +28,47 @@ func writeFileAtomic(path string, data []byte) error {
 
 	return nil
 }
+
+// writeFileDurable replaces path only after syncing its private temporary file.
+// It syncs the directory after rename before it reports success. An error after
+// rename has an uncertain outcome, so callers must stop writes until recovery.
+func writeFileDurable(path string, data []byte) (err error) {
+	file, err := os.CreateTemp(filepath.Dir(path), "."+filepath.Base(path)+".*")
+	if err != nil {
+		return fmt.Errorf("create durable temporary file: %w", err)
+	}
+
+	defer func() {
+		removeErr := os.Remove(file.Name())
+		if removeErr != nil && !errors.Is(removeErr, os.ErrNotExist) {
+			err = errors.Join(err, fmt.Errorf("remove durable temporary file: %w", removeErr))
+		}
+	}()
+
+	_, err = file.Write(data)
+	if err == nil {
+		err = file.Sync()
+	}
+
+	err = errors.Join(err, file.Close())
+	if err != nil {
+		return fmt.Errorf("write durable temporary file: %w", err)
+	}
+
+	err = os.Rename(file.Name(), path)
+	if err != nil {
+		return fmt.Errorf("publish durable file: %w", err)
+	}
+
+	directory, err := os.Open(filepath.Dir(path))
+	if err != nil {
+		return fmt.Errorf("open durable directory: %w", err)
+	}
+
+	err = errors.Join(directory.Sync(), directory.Close())
+	if err != nil {
+		return fmt.Errorf("sync durable directory: %w", err)
+	}
+
+	return nil
+}