Date: Wed, 18 Jul 2001 20:51:34 +0300 From: Peter Pentchev <roam@orbitel.bg> To: Sheldon Hearn <sheldonh@starjuice.net> Cc: freebsd-hackers@FreeBSD.org Subject: Re: Weird <stdarg.h> problem in 4.3-STABLE Message-ID: <20010718205134.D635@ringworld.oblivion.bg> In-Reply-To: <20010718204715.C635@ringworld.oblivion.bg>; from roam@orbitel.bg on Wed, Jul 18, 2001 at 08:47:15PM %2B0300 References: <11254.995477648@axl.seasidesoftware.co.za> <20010718204715.C635@ringworld.oblivion.bg>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, Jul 18, 2001 at 08:47:15PM +0300, Peter Pentchev wrote:
> On Wed, Jul 18, 2001 at 07:34:08PM +0200, Sheldon Hearn wrote:
> >
> > Hi folks,
> >
> > I'm busy developing a libdaemon implementation and have come unstuck on
> > a weird problem with functions using variable argument lists in FreeBSD
> > 4.3-STABLE.
> >
> > What I really want is a static inline void function declared in a header
> > file and included in various source files, looking something like this:
> >
> > static inline void
> > xdaemonwarn(char *fmt, ...)
> > {
> > va_list ap;
> >
> > va_start(ap, fmt);
> > if (!daemon_quiet)
> > warn(fmt, ap);
> > va_end(ap);
> >
> > return;
> > }
>
> Errrrrr. Snipped the rest, since this code snippet contains
> an important mistake.
>
> warn() does not take a va_list as an argument.
> Try using vwarn(fmt, ap) instead, and your function looks fine.
To elaborate a bit: a va_list is a pointer to a memory area where
the arguments are stored; a '...' means that this actual memory
area lies on the stack. Thus, a va_list is a *pointer* to what
warn() expects, and it is exactly this pointer that vwarn() needs.
G'luck,
Peter
--
I am jealous of the first word in this sentence.
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20010718205134.D635>