Date: Wed, 20 Jun 2007 08:34:46 -0400 (EDT) From: Daniel Eischen <deischen@freebsd.org> To: Stefan Farfeleder <stefan@fafoe.narf.at> Cc: current@freebsd.org Subject: socklen_t (Re: Multicast problems [PATCH]) Message-ID: <Pine.GSO.4.64.0706200824530.4695@sea.ntplx.net> In-Reply-To: <20070620110702.GB929@lizard.fafoe.narf.at> References: <E1I0E3b-0000kk-Ky@clue.co.za> <46765CB9.9020105@incunabulum.net> <Pine.GSO.4.64.0706180833080.23884@sea.ntplx.net> <4676C30E.7040300@incunabulum.net> <Pine.GSO.4.64.0706181344060.24865@sea.ntplx.net> <4676C952.5000607@incunabulum.net> <4676D168.3050502@incunabulum.net> <4678529A.3080308@incunabulum.net> <Pine.GSO.4.64.0706191823040.1099@sea.ntplx.net> <20070620110702.GB929@lizard.fafoe.narf.at>
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On Wed, 20 Jun 2007, Stefan Farfeleder wrote: > On Tue, Jun 19, 2007 at 06:36:39PM -0400, Daniel Eischen wrote: > >> POSIX states that: >> >> o The <sys/socket.h> header shall define the type socklen_t, >> which is an integer type of width of at least 32 bits; see >> APPLICATION USAGE. >> >> and goes on to state: >> >> o The <sys/socket.h> header shall define the unsigned integer >> type sa_family_t. >> >> This seems to imply that our socklen_t should not be an unsigned >> integer (uint32_t), but a signed integer. In APPLICATION USAGE, >> POSIX states: > > I don't understand how you come to that conclusion. Why does not > mentioning whether socklen_t is signed or unsigned imply it should be > signed? Because it explicitly says unsigned for sa_family_t and does not say unsigned for socklen_t. To me, "integer" means a C (signed) integer. The fact that older APIs and implementations used "int" might support the argument to use int32_t just for compatibility reasons. As it stands now, portable code has to have some sort of autoconfig to determine whether or not to use socklen_t or int. I don't see how you can do this with #ifdefs unless you know OS version numbers and when socklen_t first got introduced. >> To forestall portability problems, it is recommended that >> applications not use values larger than 23^1 -1 for the >> socklen_t type. > > That just means that those values will wrap to negative values if > socklen_t is a signed integer type. -- DE
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