/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1982, 1986, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)subr_log.c 8.1 (Berkeley) 6/10/93
*/
/*
* Error log buffer for kernel printf's.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/filio.h>
#include <sys/ttycom.h>
#include <sys/msgbuf.h>
#include <sys/signalvar.h>
#include <sys/kernel.h>
#include <sys/poll.h>
#include <sys/filedesc.h>
#include <sys/sysctl.h>
#define LOG_RDPRI (PZERO + 1)
#define LOG_ASYNC 0x04
static d_open_t logopen;
static d_close_t logclose;
static d_read_t logread;
static d_ioctl_t logioctl;
static d_poll_t logpoll;
static d_kqfilter_t logkqfilter;
static void logtimeout(void *arg);
static struct cdevsw log_cdevsw = {
.d_version = D_VERSION,
.d_open = logopen,
.d_close = logclose,
.d_read = logread,
.d_ioctl = logioctl,
.d_poll = logpoll,
.d_kqfilter = logkqfilter,
.d_name = "log",
};
static int logkqread(struct knote *note, long hint);
static void logkqdetach(struct knote *note);
static struct filterops log_read_filterops = {
.f_isfd = 1,
.f_attach = NULL,
.f_detach = logkqdetach,
.f_event = logkqread,
};
static struct logsoftc {
int sc_state; /* see above for possibilities */
struct selinfo sc_selp; /* process waiting on select call */
struct sigio *sc_sigio; /* information for async I/O */
struct callout sc_callout; /* callout to wakeup syslog */
} logsoftc;
int log_open; /* also used in log() */
static struct cv log_wakeup;
struct mtx msgbuf_lock;
MTX_SYSINIT(msgbuf_lock, &msgbuf_lock, "msgbuf lock", MTX_DEF);
static int log_wakeups_per_second = 5;
SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
&log_wakeups_per_second, 0,
"How often (times per second) to check for /dev/log waiters.");
/*ARGSUSED*/
static int
logopen(struct cdev *dev, int flags, int mode, struct thread *td)
{
if (log_wakeups_per_second < 1) {
printf("syslog wakeup is less than one. Adjusting to 1.\n");
log_wakeups_per_second = 1;
}
mtx_lock(&msgbuf_lock);
if (log_open) {
mtx_unlock(&msgbuf_lock);
return (EBUSY);
}
log_open = 1;
callout_reset_sbt(&logsoftc.sc_callout,
SBT_1S / log_wakeups_per_second, 0, logtimeout, NULL, C_PREL(1));
mtx_unlock(&msgbuf_lock);
fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
return (0);
}
/*ARGSUSED*/
static int
logclose(struct cdev *dev, int flag, int mode, struct thread *td)
{
funsetown(&logsoftc.sc_sigio);
mtx_lock(&msgbuf_lock);
callout_stop(&logsoftc.sc_callout);
logsoftc.sc_state = 0;
log_open = 0;
mtx_unlock(&msgbuf_lock);
return (0);
}
/*ARGSUSED*/
static int
logread(struct cdev *dev, struct uio *uio, int flag)
{
char buf[128];
struct msgbuf *mbp = msgbufp;
int error = 0, l;
mtx_lock(&msgbuf_lock);
while (msgbuf_getcount(mbp) == 0) {
if (flag & IO_NDELAY) {
mtx_unlock(&msgbuf_lock);
return (EWOULDBLOCK);
}
if ((error = cv_wait_sig(&log_wakeup, &msgbuf_lock)) != 0) {
mtx_unlock(&msgbuf_lock);
return (error);
}
}
while (uio->uio_resid > 0) {
l = imin(sizeof(buf), uio->uio_resid);
l = msgbuf_getbytes(mbp, buf, l);
if (l == 0)
break;
mtx_unlock(&msgbuf_lock);
error = uiomove(buf, l, uio);
if (error || uio->uio_resid == 0)
return (error);
mtx_lock(&msgbuf_lock);
}
mtx_unlock(&msgbuf_lock);
return (error);
}
/*ARGSUSED*/
static int
logpoll(struct cdev *dev, int events, struct thread *td)
{
int revents = 0;
if (events & (POLLIN | POLLRDNORM)) {
mtx_lock(&msgbuf_lock);
if (msgbuf_getcount(msgbufp) > 0)
revents |= events & (POLLIN | POLLRDNORM);
else
selrecord(td, &logsoftc.sc_selp);
mtx_unlock(&msgbuf_lock);
}
return (revents);
}
static int
logkqfilter(struct cdev *dev, struct knote *kn)
{
if (kn->kn_filter != EVFILT_READ)
return (EINVAL);
kn->kn_fop = &log_read_filterops;
kn->kn_hook = NULL;
mtx_lock(&msgbuf_lock);
knlist_add(&logsoftc.sc_selp.si_note, kn, 1);
mtx_unlock(&msgbuf_lock);
return (0);
}
static int
logkqread(struct knote *kn, long hint)
{
mtx_assert(&msgbuf_lock, MA_OWNED);
kn->kn_data = msgbuf_getcount(msgbufp);
return (kn->kn_data != 0);
}
static void
logkqdetach(struct knote *kn)
{
mtx_lock(&msgbuf_lock);
knlist_remove(&logsoftc.sc_selp.si_note, kn, 1);
mtx_unlock(&msgbuf_lock);
}
static void
logtimeout(void *arg)
{
if (!log_open)
return;
if (msgbuftrigger == 0)
goto done;
msgbuftrigger = 0;
selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
KNOTE_LOCKED(&logsoftc.sc_selp.si_note, 0);
if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
cv_broadcastpri(&log_wakeup, LOG_RDPRI);
done:
if (log_wakeups_per_second < 1) {
printf("syslog wakeup is less than one. Adjusting to 1.\n");
log_wakeups_per_second = 1;
}
callout_reset_sbt(&logsoftc.sc_callout,
SBT_1S / log_wakeups_per_second, 0, logtimeout, NULL, C_PREL(1));
}
/*ARGSUSED*/
static int
logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td)
{
switch (com) {
/* return number of characters immediately available */
case FIONREAD:
*(int *)data = msgbuf_getcount(msgbufp);
break;
case FIONBIO:
break;
case FIOASYNC:
mtx_lock(&msgbuf_lock);
if (*(int *)data)
logsoftc.sc_state |= LOG_ASYNC;
else
logsoftc.sc_state &= ~LOG_ASYNC;
mtx_unlock(&msgbuf_lock);
break;
case FIOSETOWN:
return (fsetown(*(int *)data, &logsoftc.sc_sigio));
case FIOGETOWN:
*(int *)data = fgetown(&logsoftc.sc_sigio);
break;
/* This is deprecated, FIOSETOWN should be used instead. */
case TIOCSPGRP:
return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
/* This is deprecated, FIOGETOWN should be used instead */
case TIOCGPGRP:
*(int *)data = -fgetown(&logsoftc.sc_sigio);
break;
default:
return (ENOTTY);
}
return (0);
}
static void
log_drvinit(void *unused)
{
cv_init(&log_wakeup, "klog");
callout_init_mtx(&logsoftc.sc_callout, &msgbuf_lock, 0);
knlist_init_mtx(&logsoftc.sc_selp.si_note, &msgbuf_lock);
make_dev_credf(MAKEDEV_ETERNAL, &log_cdevsw, 0, NULL, UID_ROOT,
GID_WHEEL, 0600, "klog");
}
SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,log_drvinit,NULL);
