rem: make_printable_str (const unsigned char *s, size_t len)
add: make_printable_str (char const *s, size_t len)
context: make_printable_str (const unsigned char *s, size_t len){  /* Worst case is that every character expands to a backslash     followed by a 3-character octal escape sequence.  */  char *printable_buf = xmalloc (4 * len + 1);  char *p = printable_buf;  size_t i;  for (i = 0; i < len; i++)    {      char buf[5];      char *tmp = NULL;      switch (s[i])	{	case '\\':	  tmp = "\\";	  break;	case '\007':	  tmp = "\\a";	  break;	case '\b':	  tmp = "\\b";	  break;	case '\f':	  tmp = "\\f";	  break;	case '\n':	  tmp = "\\n";	  break;	case '\r':	  tmp = "\\r";	  break;	case '\t':	  tmp = "\\t";	  break;	case '\v':	  tmp = "\\v";	  break;	default:	  if (ISPRINT (s[i]))	    {	      buf[0] = s[i];	      buf[1] = '\0';	    }	  else	    sprintf (buf, "\\%03o", s[i]);	  tmp = buf;	  break;	}      p = stpcpy (p, tmp);    }  return printable_buf;}