I add readx and writex for reading/writing x bytes for data partition file read/write in case of partial read/write. Current source codes which merely read/write to selinuxfs (psedo file system) have no such problem. But my permanent seboolean feature requires to read/write to /data/security/, during which the partial read/write could happen. This is why I add the readx/writex methods and update my source codes. Please help to review the source codes and give me your insightful comments.