Errno 13 can be caused by the high level error codes ERROR_ACCESS_DENIED and ERROR_SHARING_VIOLATION in Windows. As I understand it, ERROR_ACCESS_DENIED alone can be caused by any of these underlying Windows status codes:
STATUS_INVALID_LOCK_SEQUENCE 0xc000001e
STATUS_INVALID_VIEW_SIZE 0xc000001f
STATUS_ALREADY_COMMITTED 0xc0000021
STATUS_ACCESS_DENIED 0xc0000022
STATUS_PORT_CONNECTION_REFUSED 0xc0000041
STATUS_THREAD_IS_TERMINATING 0xc000004b
STATUS_DELETE_PENDING 0xc0000056
STATUS_FILE_IS_A_DIRECTORY 0xc00000ba
STATUS_FILE_RENAMED 0xc00000d5
STATUS_PROCESS_IS_TERMINATING 0xc000010a
STATUS_CANNOT_DELETE 0xc0000121
STATUS_FILE_DELETED 0xc0000123
Encrypting File System
STATUS_ENCRYPTION_FAILED 0xc000028a
STATUS_DECRYPTION_FAILED 0xc000028b
STATUS_NO_RECOVERY_POLICY 0xc000028d
STATUS_NO_EFS 0xc000028e
STATUS_WRONG_EFS 0xc000028f
STATUS_NO_USER_KEYS 0xc0000290
Hopefully it won't always be STATUS_ACCESS_DENIED.