writev(2) and IOV_MAX confusion

Andre Oppermann andre at freebsd.org
Mon Feb 16 07:40:05 PST 2004


David Schultz wrote:
> 
> On Mon, Feb 16, 2004, Andre Oppermann wrote:
> > The is a big confusion over the correct definition of IOV_MAX in relation
> > to writev(2).  The man page for write(2)/writev(2) says you only have to
> > include <sys/uio.h> to get everything.  Unfortunatly IOV_MAX is not (no
> > longer?) defined there but in <sys/syslimits.h>.  Both Net- and OpenBSD
> > still define it in <sys/uio.h> but NetBSD only for compatibility.  For
> > them the correct place seems to be <sys/syslimits.h> too but only when
> > _XOPEN_SOURCE is defined.
> >
> > What is the correct place for IOV_MAX?  And what has to be adjusted, the
> > man page or the .h files?
> 
> In POSIX, you get IOV_MAX only by including <limits.h>, and
> FreeBSD's <limits.h> includes <sys/syslimits.h>, so the code is
> correct here.  As far as I can tell, the man page doesn't say
> anything about what you have to include to get IOV_MAX, but I
> suppose it could be more clear.

Yes, the write(2) man page is missing any reference to <limits.h>.
I'd say the man page should mention that.

-- 
Andre


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