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

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

On Fri, Aug 03, 2018 at 15:54:24 +0200, Martin Husemann wrote:

> On Fri, Aug 03, 2018 at 08:28:55PM +0700, Robert Elz wrote:
> > Where is the signed arithmetic that was supposedly a probem?
> 
> Ah, stupid C integer promotion rules.  uint16_t is promoted to int
> here, not unsigned int or size_t.

Hmm, i don't think that's true.

  6.3.1.8  Usual arithmetic conversions

  ...
            Otherwise, the integer promotions are performed on both
            operands.   Then the following rules are applied to the
            promoted operands:

                 If both operands  have  the  same  type,  then  no
                 further conversion is needed.

                 Otherwise,  if  both  operands have signed integer
                 types or both have  unsigned  integer  types,  the
                 operand with the type of lesser integer conversion
                 rank is converted to the type of the operand  with
                 greater rank.

ntohs returns unsigned uint16_t, sizeof returns unsigned size_t, so
uint16_t, that has "lesser integer convertion rank" (i.e. it's
smaller) should be converted to size_t automagically.

-uwe