FreeBSD-5.3/sys/kern/subr_log.c
/*
* 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.
* 4. 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: src/sys/kern/subr_log.c,v 1.62 2004/06/16 09:47:12 phk Exp $");
#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
#define LOG_RDWAIT 0x08
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 void logtimeout(void *arg);
#define CDEV_MAJOR 7
static struct cdevsw log_cdevsw = {
.d_version = D_VERSION,
.d_flags = D_NEEDGIANT,
.d_open = logopen,
.d_close = logclose,
.d_read = logread,
.d_ioctl = logioctl,
.d_poll = logpoll,
.d_name = "log",
.d_maj = CDEV_MAJOR,
};
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() */
/* Times per second to check for a pending syslog wakeup. */
static int log_wakeups_per_second = 5;
SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
&log_wakeups_per_second, 0, "");
/*ARGSUSED*/
static int
logopen(struct cdev *dev, int flags, int mode, struct thread *td)
{
if (log_open)
return (EBUSY);
log_open = 1;
callout_init(&logsoftc.sc_callout, 0);
fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
if (log_wakeups_per_second < 1) {
printf("syslog wakeup is less than one. Adjusting to 1.\n");
log_wakeups_per_second = 1;
}
callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
logtimeout, NULL);
return (0);
}
/*ARGSUSED*/
static int
logclose(struct cdev *dev, int flag, int mode, struct thread *td)
{
log_open = 0;
callout_stop(&logsoftc.sc_callout);
logsoftc.sc_state = 0;
funsetown(&logsoftc.sc_sigio);
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, s;
s = splhigh();
while (msgbuf_getcount(mbp) == 0) {
if (flag & IO_NDELAY) {
splx(s);
return (EWOULDBLOCK);
}
logsoftc.sc_state |= LOG_RDWAIT;
if ((error = tsleep(mbp, LOG_RDPRI | PCATCH, "klog", 0))) {
splx(s);
return (error);
}
}
splx(s);
logsoftc.sc_state &= ~LOG_RDWAIT;
while (uio->uio_resid > 0) {
l = imin(sizeof(buf), uio->uio_resid);
l = msgbuf_getbytes(mbp, buf, l);
if (l == 0)
break;
error = uiomove(buf, l, uio);
if (error)
break;
}
return (error);
}
/*ARGSUSED*/
static int
logpoll(struct cdev *dev, int events, struct thread *td)
{
int s;
int revents = 0;
s = splhigh();
if (events & (POLLIN | POLLRDNORM)) {
if (msgbuf_getcount(msgbufp) > 0)
revents |= events & (POLLIN | POLLRDNORM);
else
selrecord(td, &logsoftc.sc_selp);
}
splx(s);
return (revents);
}
static void
logtimeout(void *arg)
{
if (!log_open)
return;
if (log_wakeups_per_second < 1) {
printf("syslog wakeup is less than one. Adjusting to 1.\n");
log_wakeups_per_second = 1;
}
if (msgbuftrigger == 0) {
callout_reset(&logsoftc.sc_callout,
hz / log_wakeups_per_second, logtimeout, NULL);
return;
}
msgbuftrigger = 0;
selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
if (logsoftc.sc_state & LOG_RDWAIT) {
wakeup(msgbufp);
logsoftc.sc_state &= ~LOG_RDWAIT;
}
callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
logtimeout, NULL);
}
/*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:
if (*(int *)data)
logsoftc.sc_state |= LOG_ASYNC;
else
logsoftc.sc_state &= ~LOG_ASYNC;
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)
{
make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
}
SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)