subr_log.c revision 106917 
1/*
2 * Copyright (c) 1982, 1986, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 *	@(#)subr_log.c	8.1 (Berkeley) 6/10/93
34 * $FreeBSD: head/sys/kern/subr_log.c 106917 2002-11-14 16:11:12Z tmm $
35 */
36
37/*
38 * Error log buffer for kernel printf's.
39 */
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/conf.h>
44#include <sys/proc.h>
45#include <sys/vnode.h>
46#include <sys/filio.h>
47#include <sys/ttycom.h>
48#include <sys/msgbuf.h>
49#include <sys/signalvar.h>
50#include <sys/kernel.h>
51#include <sys/poll.h>
52#include <sys/filedesc.h>
53#include <sys/sysctl.h>
54
55#define LOG_RDPRI	(PZERO + 1)
56
57#define LOG_ASYNC	0x04
58#define LOG_RDWAIT	0x08
59
60static	d_open_t	logopen;
61static	d_close_t	logclose;
62static	d_read_t	logread;
63static	d_ioctl_t	logioctl;
64static	d_poll_t	logpoll;
65
66static	void logtimeout(void *arg);
67
68#define CDEV_MAJOR 7
69static struct cdevsw log_cdevsw = {
70	/* open */	logopen,
71	/* close */	logclose,
72	/* read */	logread,
73	/* write */	nowrite,
74	/* ioctl */	logioctl,
75	/* poll */	logpoll,
76	/* mmap */	nommap,
77	/* strategy */	nostrategy,
78	/* name */	"log",
79	/* maj */	CDEV_MAJOR,
80	/* dump */	nodump,
81	/* psize */	nopsize,
82	/* flags */	0,
83};
84
85static struct logsoftc {
86	int	sc_state;		/* see above for possibilities */
87	struct	selinfo sc_selp;	/* process waiting on select call */
88	struct  sigio *sc_sigio;	/* information for async I/O */
89	struct	callout sc_callout;	/* callout to wakeup syslog  */
90} logsoftc;
91
92int	log_open;			/* also used in log() */
93
94/* Times per second to check for a pending syslog wakeup. */
95static int	log_wakeups_per_second = 5;
96SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
97    &log_wakeups_per_second, 0, "");
98
99/*ARGSUSED*/
100static	int
101logopen(dev_t dev, int flags, int mode, struct thread *td)
102{
103	if (log_open)
104		return (EBUSY);
105	log_open = 1;
106	callout_init(&logsoftc.sc_callout, 0);
107	fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio);	/* signal process only */
108	callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
109	    logtimeout, NULL);
110	return (0);
111}
112
113/*ARGSUSED*/
114static	int
115logclose(dev_t dev, int flag, int mode, struct thread *td)
116{
117
118	log_open = 0;
119	callout_stop(&logsoftc.sc_callout);
120	logsoftc.sc_state = 0;
121	funsetown(&logsoftc.sc_sigio);
122	return (0);
123}
124
125/*ARGSUSED*/
126static	int
127logread(dev_t dev, struct uio *uio, int flag)
128{
129	struct msgbuf *mbp = msgbufp;
130	int error = 0, l, s;
131
132	s = splhigh();
133	while (mbp->msg_bufr == mbp->msg_bufx) {
134		if (flag & IO_NDELAY) {
135			splx(s);
136			return (EWOULDBLOCK);
137		}
138		logsoftc.sc_state |= LOG_RDWAIT;
139		if ((error = tsleep(mbp, LOG_RDPRI | PCATCH, "klog", 0))) {
140			splx(s);
141			return (error);
142		}
143	}
144	splx(s);
145	logsoftc.sc_state &= ~LOG_RDWAIT;
146
147	while (uio->uio_resid > 0) {
148		l = mbp->msg_bufx - mbp->msg_bufr;
149		if (l < 0)
150			l = mbp->msg_size - mbp->msg_bufr;
151		l = imin(l, uio->uio_resid);
152		if (l == 0)
153			break;
154		error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr,
155		    l, uio);
156		if (error)
157			break;
158		mbp->msg_bufr += l;
159		if (mbp->msg_bufr >= mbp->msg_size)
160			mbp->msg_bufr = 0;
161	}
162	return (error);
163}
164
165/*ARGSUSED*/
166static	int
167logpoll(dev_t dev, int events, struct thread *td)
168{
169	int s;
170	int revents = 0;
171
172	s = splhigh();
173
174	if (events & (POLLIN | POLLRDNORM)) {
175		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
176			revents |= events & (POLLIN | POLLRDNORM);
177		else
178			selrecord(td, &logsoftc.sc_selp);
179	}
180	splx(s);
181	return (revents);
182}
183
184static void
185logtimeout(void *arg)
186{
187
188	if (!log_open)
189		return;
190	if (msgbuftrigger == 0) {
191		callout_reset(&logsoftc.sc_callout,
192		    hz / log_wakeups_per_second, logtimeout, NULL);
193		return;
194	}
195	msgbuftrigger = 0;
196	selwakeup(&logsoftc.sc_selp);
197	if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
198		pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
199	if (logsoftc.sc_state & LOG_RDWAIT) {
200		wakeup((caddr_t)msgbufp);
201		logsoftc.sc_state &= ~LOG_RDWAIT;
202	}
203	callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
204	    logtimeout, NULL);
205}
206
207/*ARGSUSED*/
208static	int
209logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct thread *td)
210{
211	int l, s;
212
213	switch (com) {
214
215	/* return number of characters immediately available */
216	case FIONREAD:
217		s = splhigh();
218		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
219		splx(s);
220		if (l < 0)
221			l += msgbufp->msg_size;
222		*(int *)data = l;
223		break;
224
225	case FIONBIO:
226		break;
227
228	case FIOASYNC:
229		if (*(int *)data)
230			logsoftc.sc_state |= LOG_ASYNC;
231		else
232			logsoftc.sc_state &= ~LOG_ASYNC;
233		break;
234
235	case FIOSETOWN:
236		return (fsetown(*(int *)data, &logsoftc.sc_sigio));
237
238	case FIOGETOWN:
239		*(int *)data = fgetown(&logsoftc.sc_sigio);
240		break;
241
242	/* This is deprecated, FIOSETOWN should be used instead. */
243	case TIOCSPGRP:
244		return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
245
246	/* This is deprecated, FIOGETOWN should be used instead */
247	case TIOCGPGRP:
248		*(int *)data = -fgetown(&logsoftc.sc_sigio);
249		break;
250
251	default:
252		return (ENOTTY);
253	}
254	return (0);
255}
256
257static void
258log_drvinit(void *unused)
259{
260
261	make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
262}
263
264SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)
265