Date: Tue, 27 Jun 2006 13:12:06 +0400 From: Yar Tikhiy <yar@comp.chem.msu.su> To: mal content <artifact.one@googlemail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Real time privileges for non-root users Message-ID: <20060627091206.GB36941@comp.chem.msu.su> In-Reply-To: <8e96a0b90606220747vf80e805k650518981bde754@mail.gmail.com> References: <8e96a0b90606220747vf80e805k650518981bde754@mail.gmail.com>
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On Thu, Jun 22, 2006 at 03:47:44PM +0100, mal content wrote:
> Hello.
>
> Is it possible to grant real-time privileges to ordinary
> users (not root) under FreeBSD? I'm doing some audio
> work and I'd like to give real time privileges to my user id.
While I can't think of an existing user-friendly solution, you can
use available tools and interfaces to satisfy your needs.
The easiest, but not the smartest, way is to use rtprio(1).
>From rtprio(2):
Realtime and idle priority is inherited through fork() and exec().
That is, you can start a shell with higher real-time priority, and
it will hand its priority down to its children:
$ su
# rtprio 1 su yourself
A smarter way is to use login.conf(5). Idle or real-time priority
can be set for a login class, but the feature doesn't seem to be
documented anywhere except in the code itself. The respective block
from src/lib/libutil/login_class.c is as follows:
/* Set the process priority */
if (flags & LOGIN_SETPRIORITY) {
p = login_getcapnum(lc, "priority", LOGIN_DEFPRI, LOGIN_DEFPRI);
if(p > PRIO_MAX) {
rtp.type = RTP_PRIO_IDLE;
rtp.prio = p - PRIO_MAX - 1;
p = (rtp.prio > RTP_PRIO_MAX) ? 31 : p;
if(rtprio(RTP_SET, 0, &rtp))
syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
pwd->pw_name, lc ? lc->lc_class : LOGIN_DEFCLASS);
} else if(p < PRIO_MIN) {
rtp.type = RTP_PRIO_REALTIME;
rtp.prio = abs(p - PRIO_MIN + RTP_PRIO_MAX);
p = (rtp.prio > RTP_PRIO_MAX) ? 1 : p;
if(rtprio(RTP_SET, 0, &rtp))
syslog(LOG_WARNING, "rtprio '%s' (%s): %m",
pwd->pw_name, lc ? lc->lc_class : LOGIN_DEFCLASS);
} else {
if (setpriority(PRIO_PROCESS, 0, (int)p) != 0)
syslog(LOG_WARNING, "setpriority '%s' (%s): %m",
pwd->pw_name, lc ? lc->lc_class : LOGIN_DEFCLASS);
}
}
Can you grok it? ;-)
--
Yar
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