NetBSD/sys/kern/subr_log.c

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/* $NetBSD: subr_log.c,v 1.33 2003/09/22 12:59:57 christos Exp $ */
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/*
* Copyright (c) 1982, 1986, 1993
* The Regents of the University of California. All rights reserved.
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*
* 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
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* 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.
*
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* @(#)subr_log.c 8.3 (Berkeley) 2/14/95
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*/
/*
* Error log buffer for kernel printf's.
*/
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#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_log.c,v 1.33 2003/09/22 12:59:57 christos Exp $");
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#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/ioctl.h>
#include <sys/msgbuf.h>
#include <sys/file.h>
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#include <sys/signalvar.h>
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#include <sys/syslog.h>
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#include <sys/conf.h>
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#include <sys/select.h>
#include <sys/poll.h>
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#define LOG_RDPRI (PZERO + 1)
#define LOG_ASYNC 0x04
#define LOG_RDWAIT 0x08
struct logsoftc {
int sc_state; /* see above for possibilities */
struct selinfo sc_selp; /* process waiting on select call */
pid_t sc_pgid; /* process/group for async I/O */
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} logsoftc;
int log_open; /* also used in log() */
int msgbufmapped; /* is the message buffer mapped */
int msgbufenabled; /* is logging to the buffer enabled */
struct kern_msgbuf *msgbufp; /* the mapped buffer, itself. */
dev_type_open(logopen);
dev_type_close(logclose);
dev_type_read(logread);
dev_type_ioctl(logioctl);
dev_type_poll(logpoll);
dev_type_kqfilter(logkqfilter);
const struct cdevsw log_cdevsw = {
logopen, logclose, logread, nowrite, logioctl,
nostop, notty, logpoll, nommap, logkqfilter,
};
void
initmsgbuf(buf, bufsize)
caddr_t buf;
size_t bufsize;
{
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struct kern_msgbuf *mbp;
long new_bufs;
/* Sanity-check the given size. */
if (bufsize < sizeof(struct kern_msgbuf))
return;
mbp = msgbufp = (struct kern_msgbuf *)buf;
new_bufs = bufsize - offsetof(struct kern_msgbuf, msg_bufc);
if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
(mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
(mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
/*
* If the buffer magic number is wrong, has changed
* size (which shouldn't happen often), or is
* internally inconsistent, initialize it.
*/
memset(buf, 0, bufsize);
mbp->msg_magic = MSG_MAGIC;
mbp->msg_bufs = new_bufs;
}
/* mark it as ready for use. */
msgbufmapped = msgbufenabled = 1;
}
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/*ARGSUSED*/
int
logopen(dev, flags, mode, p)
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dev_t dev;
int flags, mode;
struct proc *p;
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{
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struct kern_msgbuf *mbp = msgbufp;
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if (log_open)
return (EBUSY);
log_open = 1;
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logsoftc.sc_pgid = p->p_pid; /* signal process only */
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/*
* The message buffer is initialized during system configuration.
* If it's been clobbered, note that and return an error. (This
* allows a user to potentially read the buffer via /dev/kmem,
* and try to figure out what clobbered it.
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*/
if (mbp->msg_magic != MSG_MAGIC) {
msgbufenabled = 0;
return (ENXIO);
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}
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return (0);
}
/*ARGSUSED*/
int
logclose(dev, flag, mode, p)
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dev_t dev;
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int flag, mode;
struct proc *p;
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{
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log_open = 0;
logsoftc.sc_state = 0;
return (0);
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}
/*ARGSUSED*/
int
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logread(dev, uio, flag)
dev_t dev;
struct uio *uio;
int flag;
{
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struct kern_msgbuf *mbp = msgbufp;
long l;
int s;
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int error = 0;
s = splhigh();
while (mbp->msg_bufr == mbp->msg_bufx) {
if (flag & IO_NDELAY) {
splx(s);
return (EWOULDBLOCK);
}
logsoftc.sc_state |= LOG_RDWAIT;
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error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
"klog", 0);
if (error) {
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splx(s);
return (error);
}
}
splx(s);
logsoftc.sc_state &= ~LOG_RDWAIT;
while (uio->uio_resid > 0) {
l = mbp->msg_bufx - mbp->msg_bufr;
if (l < 0)
l = mbp->msg_bufs - mbp->msg_bufr;
l = min(l, uio->uio_resid);
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if (l == 0)
break;
error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr],
(int)l, uio);
if (error)
break;
mbp->msg_bufr += l;
if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
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mbp->msg_bufr = 0;
}
return (error);
}
/*ARGSUSED*/
int
logpoll(dev, events, p)
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dev_t dev;
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int events;
struct proc *p;
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{
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int revents = 0;
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int s = splhigh();
if (events & (POLLIN | POLLRDNORM)) {
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if (msgbufp->msg_bufr != msgbufp->msg_bufx)
revents |= events & (POLLIN | POLLRDNORM);
else
selrecord(p, &logsoftc.sc_selp);
}
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splx(s);
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return (revents);
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}
static void
filt_logrdetach(struct knote *kn)
{
int s;
s = splhigh();
SLIST_REMOVE(&logsoftc.sc_selp.sel_klist, kn, knote, kn_selnext);
splx(s);
}
static int
filt_logread(struct knote *kn, long hint)
{
if (msgbufp->msg_bufr == msgbufp->msg_bufx)
return (0);
if (msgbufp->msg_bufr < msgbufp->msg_bufx)
kn->kn_data = msgbufp->msg_bufx - msgbufp->msg_bufr;
else
kn->kn_data = (msgbufp->msg_bufs - msgbufp->msg_bufr) +
msgbufp->msg_bufx;
return (1);
}
static const struct filterops logread_filtops =
{ 1, NULL, filt_logrdetach, filt_logread };
int
logkqfilter(dev_t dev, struct knote *kn)
{
struct klist *klist;
int s;
switch (kn->kn_filter) {
case EVFILT_READ:
klist = &logsoftc.sc_selp.sel_klist;
kn->kn_fop = &logread_filtops;
break;
default:
return (1);
}
kn->kn_hook = NULL;
s = splhigh();
SLIST_INSERT_HEAD(klist, kn, kn_selnext);
splx(s);
return (0);
}
void
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logwakeup()
{
if (!log_open)
return;
selnotify(&logsoftc.sc_selp, 0);
if (logsoftc.sc_state & LOG_ASYNC)
fownsignal(logsoftc.sc_pgid, SIGIO, 0, 0, NULL);
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if (logsoftc.sc_state & LOG_RDWAIT) {
wakeup((caddr_t)msgbufp);
logsoftc.sc_state &= ~LOG_RDWAIT;
}
}
/*ARGSUSED*/
int
logioctl(dev, com, data, flag, p)
dev_t dev;
u_long com;
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caddr_t data;
int flag;
struct proc *p;
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{
long l;
int s;
switch (com) {
/* return number of characters immediately available */
case FIONREAD:
s = splhigh();
l = msgbufp->msg_bufx - msgbufp->msg_bufr;
splx(s);
if (l < 0)
l += msgbufp->msg_bufs;
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*(int *)data = l;
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break;
case FIONBIO:
break;
case FIOASYNC:
if (*(int *)data)
logsoftc.sc_state |= LOG_ASYNC;
else
logsoftc.sc_state &= ~LOG_ASYNC;
break;
case TIOCSPGRP:
case FIOSETOWN:
return fsetown(p, &logsoftc.sc_pgid, com, data);
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case TIOCGPGRP:
case FIOGETOWN:
return fgetown(p, logsoftc.sc_pgid, com, data);
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default:
return (EPASSTHROUGH);
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}
return (0);
}