Date: Sun, 7 Sep 1997 11:04:11 +0200 From: j@uriah.heep.sax.de (J Wunsch) To: freebsd-hackers@FreeBSD.ORG Subject: Re: IOCTL Commands - Where is my mistake? Message-ID: <19970907110411.XU48502@uriah.heep.sax.de> In-Reply-To: <199709030821.RAA00286@word.smith.net.au>; from Mike Smith on Sep 3, 1997 17:51:57 %2B0930 References: <XFMail.970903004053.Shimon@i-Connect.Net> <199709030821.RAA00286@word.smith.net.au>
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As Mike Smith wrote:
> > I want to pass IOCTL commands to a driver. This is what I do:
> >
> > #define DPT_IOCTL_INTERNAL_METRICS _IOW('D', 1, dpt_perf_t)
>
> You want to pass a pointer to the struct, not the struct itself.
He does. The last argument of the _IOR, _IOW, and _IOWR macros always
translates into ``pointer to the given type''. Passing an `int'
directly (as SysV does) is not directly supported in FreeBSD, but can
be emulated using the _IO macro. (The SysV compat syscalls in the
console drivers do need this feature.)
> caddr_t dest;
>
> /* get address in userspace */
> dest = fuword(*(caddr_t *)cmdarg);
> /* copy out to userspace */
> return(copyout(&dpt->performance, dest,
> sizeof(dpt->performance))
In Simon's case, the copyin/copyout would be handled by the upper
ioctl() layers already (unlike SysV). I don't see why he should not
use this feature.
--
cheers, J"org
joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)
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