Date: Mon, 30 Jul 2001 22:01:47 +0200 From: Jeroen Ruigrok/Asmodai <asmodai@wxs.nl> To: Bruce Evans <bde@zeta.org.au> Cc: Robert Watson <rwatson@FreeBSD.org>, dd@FreeBSD.org, freebsd-doc@FreeBSD.org, bde@FreeBSD.org, FreeBSD Gnats <freebsd-gnats-submit@freebsd.org> Subject: Re: docs/26003: getgroups(2) lists NGROUPS_MAX but not syslimits.h Message-ID: <20010730220147.H65558@daemon.ninth-circle.org> In-Reply-To: <Pine.BSF.4.21.0104011858330.14800-100000@besplex.bde.org> References: <Pine.NEB.3.96L.1010331222140.65399B-100000@fledge.watson.org> <Pine.BSF.4.21.0104011858330.14800-100000@besplex.bde.org>
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-On [20010401 13:00], Bruce Evans (bde@zeta.org.au) wrote: >On Sat, 31 Mar 2001, Robert Watson wrote: > >> Dunno -- I guess this leads to a number of questions of specification-land >> -- is NGROUPS_MAX supposed to be exposed to the application, if so, how >> should the application go about including things to get the value, etc. >> Bruce might have a good answer, if not a correct one, so I've CC'd him >> :-). > >In POSIX.1-1996: > >1) NGROUPS_MAX is defined in <limits.h>. (<sys/syslimits.h> is BSD > implementation detail, so it shouldn't be documented.) > >2) NGROUPS_MAX is a "Run-Time Increasable Value". This means that > applications may find that the actual maximum number of groups is > larger than their compile time value of NGROUPS_MAX. The run time > maximum is given by sysconf(_SC_NGROUPS_MAX). > >3) Unlike some other POSIX limits, NGROUPS_MAX must be defined at > compile time, although its value is almost useless if its run time > value is larger. A footnote says that future revisions of POSIX.1 > are expected to permit omitting the definition of NGROUPS_MAX from > <limits.h> to indicate that its value is variable. Latest POSIX draft specifies: SYNOPSIS #include <unistd.h> int getgroups(int gidsetsize, gid_t grouplist[]); [...] Applications writers should note that {NGROUPS_MAX} is not necessarily a constant on all implementations. [...] Issue 6 In the SYNOPSIS, the optional include of the <sys/types.h> header is removed. The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification: · The requirement to include <sys/types.h> has been removed. Although <sys/types.h> was required for conforming implementations of previous POSIX specifications, it was not required for UNIX applications. · A return value of 0 is not permitted, because {NGROUPS_MAX} cannot be 0. This is a FIPS requirement. -- Jeroen Ruigrok van der Werven/Asmodai asmodai@[wxs.nl|freebsd.org|xmach.org] Documentation nutter/C-rated Coder, finger asmodai@ninth-circle.dnsalias.net http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/ The human race is challenged more than ever before to demonstrate our mastery -- not over nature but of ourselves... To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-doc" in the body of the message
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