s.checkWrite(safeCanonicalPath());
s.checkWrite(sname); s.checkWrite(dname);
  public boolean renameTo (File dest)  {    SecurityManager s = System.getSecurityManager();    if (s != null)      {	// FIXME: JCL doesn't specify which path to check.  We check the	// source since we can canonicalize it.	s.checkWrite(safeCanonicalPath());      }    return performRenameTo (dest);  }