Re: CVS commit: src/external/bsd/dhcpcd/dist/src

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Fri, 3 Aug 2018 15:54:24 +0200
    From:        Martin Husemann <martin%duskware.de@localhost>
    Message-ID:  <20180803135424.GC23831%mail.duskware.de@localhost>

  | Ah, stupid C integer promotion rules. uint16_t is promoted to int
  | here, not unsigned int or size_t.

Even with that, there should be no problem, in

	signed - unsigned

the '-' should be an unsigned - and the result should
be unsigned.   There is no signed arithmetic being done
here to cause an undefined result.

That's the same rule that makes

	strlen(s) + 1

be a size_t rather than a ssize_t or whatever.   Otherwise we'd
need to be adding casts to every operation like that, just in case
strlen(s) == MAX_INT and the " +1 " would cause overflow, and
undefined operation.    No thanks.

Whether there need to be any attention to the possibility
of a malformed packet I will leave for Roy to decide (I am
assuming probably not) but that added cast just looks to be
a bandaid for a broken compiler (sanitiser).

kre