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https://github.com/freebsd/freebsd-src
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e649887b1e
be done internally. Ensure that no one can fsetown() to a dying process/pgrp. We need to check the process for P_WEXIT to see if it's exiting. Process groups are already safe because there is no such thing as a pgrp zombie, therefore the proctree lock completely protects the pgrp from having sigio structures associated with it after it runs funsetownlst. Add sigio lock to witness list under proctree and allproc, but over proc and pgrp. Seigo Tanimura helped with this.
269 lines
6.6 KiB
C
269 lines
6.6 KiB
C
/*
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* Copyright (c) 1982, 1986, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)subr_log.c 8.1 (Berkeley) 6/10/93
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* $FreeBSD$
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*/
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/*
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* Error log buffer for kernel printf's.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/filio.h>
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#include <sys/ttycom.h>
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#include <sys/msgbuf.h>
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#include <sys/signalvar.h>
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#include <sys/kernel.h>
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#include <sys/poll.h>
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#include <sys/filedesc.h>
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#include <sys/sysctl.h>
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#define LOG_RDPRI (PZERO + 1)
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#define LOG_ASYNC 0x04
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#define LOG_RDWAIT 0x08
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static d_open_t logopen;
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static d_close_t logclose;
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static d_read_t logread;
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static d_ioctl_t logioctl;
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static d_poll_t logpoll;
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static void logtimeout(void *arg);
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#define CDEV_MAJOR 7
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static struct cdevsw log_cdevsw = {
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/* open */ logopen,
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/* close */ logclose,
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/* read */ logread,
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/* write */ nowrite,
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/* ioctl */ logioctl,
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/* poll */ logpoll,
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/* mmap */ nommap,
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/* strategy */ nostrategy,
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/* name */ "log",
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/* maj */ CDEV_MAJOR,
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/* dump */ nodump,
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/* psize */ nopsize,
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/* flags */ 0,
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};
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static struct logsoftc {
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int sc_state; /* see above for possibilities */
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struct selinfo sc_selp; /* process waiting on select call */
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struct sigio *sc_sigio; /* information for async I/O */
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struct callout sc_callout; /* callout to wakeup syslog */
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} logsoftc;
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int log_open; /* also used in log() */
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/* Times per second to check for a pending syslog wakeup. */
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static int log_wakeups_per_second = 5;
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SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
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&log_wakeups_per_second, 0, "");
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/*ARGSUSED*/
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static int
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logopen(dev_t dev, int flags, int mode, struct thread *td)
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{
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if (log_open)
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return (EBUSY);
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log_open = 1;
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callout_init(&logsoftc.sc_callout, 0);
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fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
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callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
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logtimeout, NULL);
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return (0);
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}
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/*ARGSUSED*/
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static int
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logclose(dev_t dev, int flag, int mode, struct thread *td)
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{
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log_open = 0;
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callout_stop(&logsoftc.sc_callout);
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logsoftc.sc_state = 0;
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funsetown(&logsoftc.sc_sigio);
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return (0);
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}
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/*ARGSUSED*/
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static int
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logread(dev_t dev, struct uio *uio, int flag)
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{
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struct msgbuf *mbp = msgbufp;
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long l;
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int s;
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int error = 0;
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s = splhigh();
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while (mbp->msg_bufr == mbp->msg_bufx) {
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if (flag & IO_NDELAY) {
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splx(s);
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return (EWOULDBLOCK);
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}
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logsoftc.sc_state |= LOG_RDWAIT;
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if ((error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
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"klog", 0))) {
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splx(s);
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return (error);
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}
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}
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splx(s);
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logsoftc.sc_state &= ~LOG_RDWAIT;
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while (uio->uio_resid > 0) {
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l = mbp->msg_bufx - mbp->msg_bufr;
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if (l < 0)
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l = mbp->msg_size - mbp->msg_bufr;
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l = min(l, uio->uio_resid);
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if (l == 0)
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break;
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error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr,
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(int)l, uio);
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if (error)
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break;
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mbp->msg_bufr += l;
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if (mbp->msg_bufr >= mbp->msg_size)
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mbp->msg_bufr = 0;
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}
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return (error);
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}
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/*ARGSUSED*/
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static int
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logpoll(dev_t dev, int events, struct thread *td)
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{
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int s;
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int revents = 0;
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s = splhigh();
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if (events & (POLLIN | POLLRDNORM)) {
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if (msgbufp->msg_bufr != msgbufp->msg_bufx)
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revents |= events & (POLLIN | POLLRDNORM);
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else
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selrecord(td, &logsoftc.sc_selp);
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}
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splx(s);
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return (revents);
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}
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static void
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logtimeout(void *arg)
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{
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if (!log_open)
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return;
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if (msgbuftrigger == 0) {
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callout_reset(&logsoftc.sc_callout,
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hz / log_wakeups_per_second, logtimeout, NULL);
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return;
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}
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msgbuftrigger = 0;
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selwakeup(&logsoftc.sc_selp);
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if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
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pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
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if (logsoftc.sc_state & LOG_RDWAIT) {
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wakeup((caddr_t)msgbufp);
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logsoftc.sc_state &= ~LOG_RDWAIT;
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}
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callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
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logtimeout, NULL);
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}
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/*ARGSUSED*/
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static int
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logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct thread *td)
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{
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long l;
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int s;
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switch (com) {
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/* return number of characters immediately available */
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case FIONREAD:
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s = splhigh();
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l = msgbufp->msg_bufx - msgbufp->msg_bufr;
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splx(s);
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if (l < 0)
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l += msgbufp->msg_size;
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*(int *)data = l;
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break;
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case FIONBIO:
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break;
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case FIOASYNC:
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if (*(int *)data)
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logsoftc.sc_state |= LOG_ASYNC;
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else
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logsoftc.sc_state &= ~LOG_ASYNC;
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break;
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case FIOSETOWN:
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return (fsetown(*(int *)data, &logsoftc.sc_sigio));
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case FIOGETOWN:
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*(int *)data = fgetown(logsoftc.sc_sigio);
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break;
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/* This is deprecated, FIOSETOWN should be used instead. */
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case TIOCSPGRP:
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return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
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/* This is deprecated, FIOGETOWN should be used instead */
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case TIOCGPGRP:
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*(int *)data = -fgetown(logsoftc.sc_sigio);
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break;
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default:
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return (ENOTTY);
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}
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return (0);
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}
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static void
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log_drvinit(void *unused)
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{
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make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
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}
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SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)
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