feat: restart to apply update, privileged helper, rollback

internal/infrastructure/update/atomicFile.go

@@ -0,0 +1,46 @@
+package update
+
+import (
+	"encoding/json"
+	"errors"
+	"io/fs"
+	"os"
+)
+
+const readableFilePermissions = 0o644
+
+func writeFileAtomically(path string, content []byte, permissions os.FileMode) error {
+	temporary := path + ".tmp"
+	if err := os.WriteFile(temporary, content, permissions); err != nil {
+		return err
+	}
+	if err := os.Rename(temporary, path); err != nil {
+		_ = os.Remove(temporary)
+		return err
+	}
+	return nil
+}
+
+func writeJSONAtomically(path string, value any, permissions os.FileMode) error {
+	content, err := json.Marshal(value)
+	if err != nil {
+		return err
+	}
+	return writeFileAtomically(path, content, permissions)
+}
+
+func removeFile(path string) (bool, error) {
+	err := os.Remove(path)
+	if err == nil {
+		return true, nil
+	}
+	if errors.Is(err, fs.ErrNotExist) {
+		return false, nil
+	}
+	return false, err
+}
+
+func removeIfPresent(path string) error {
+	_, err := removeFile(path)
+	return err
+}