subr_log.c revision 69741 
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 69741 2000-12-08 06:57:39Z phk $
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
54#define LOG_RDPRI	(PZERO + 1)
55
56#define LOG_ASYNC	0x04
57#define LOG_RDWAIT	0x08
58
59static	d_open_t	logopen;
60static	d_close_t	logclose;
61static	d_read_t	logread;
62static	d_ioctl_t	logioctl;
63static	d_poll_t	logpoll;
64
65#define CDEV_MAJOR 7
66static struct cdevsw log_cdevsw = {
67	/* open */	logopen,
68	/* close */	logclose,
69	/* read */	logread,
70	/* write */	nowrite,
71	/* ioctl */	logioctl,
72	/* poll */	logpoll,
73	/* mmap */	nommap,
74	/* strategy */	nostrategy,
75	/* name */	"log",
76	/* maj */	CDEV_MAJOR,
77	/* dump */	nodump,
78	/* psize */	nopsize,
79	/* flags */	0,
80	/* bmaj */	-1
81};
82
83static struct logsoftc {
84	int	sc_state;		/* see above for possibilities */
85	struct	selinfo sc_selp;	/* process waiting on select call */
86	struct  sigio *sc_sigio;	/* information for async I/O */
87} logsoftc;
88
89int	log_open;			/* also used in log() */
90
91/*ARGSUSED*/
92static	int
93logopen(dev_t dev, int flags, int mode, struct proc *p)
94{
95	if (log_open)
96		return (EBUSY);
97	log_open = 1;
98	fsetown(p->p_pid, &logsoftc.sc_sigio);	/* signal process only */
99	return (0);
100}
101
102/*ARGSUSED*/
103static	int
104logclose(dev_t dev, int flag, int mode, struct proc *p)
105{
106
107	log_open = 0;
108	logsoftc.sc_state = 0;
109	funsetown(logsoftc.sc_sigio);
110	return (0);
111}
112
113/*ARGSUSED*/
114static	int
115logread(dev_t dev, struct uio *uio, int flag)
116{
117	struct msgbuf *mbp = msgbufp;
118	long l;
119	int s;
120	int error = 0;
121
122	s = splhigh();
123	while (mbp->msg_bufr == mbp->msg_bufx) {
124		if (flag & IO_NDELAY) {
125			splx(s);
126			return (EWOULDBLOCK);
127		}
128		logsoftc.sc_state |= LOG_RDWAIT;
129		if ((error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
130		    "klog", 0))) {
131			splx(s);
132			return (error);
133		}
134	}
135	splx(s);
136	logsoftc.sc_state &= ~LOG_RDWAIT;
137
138	while (uio->uio_resid > 0) {
139		l = mbp->msg_bufx - mbp->msg_bufr;
140		if (l < 0)
141			l = mbp->msg_size - mbp->msg_bufr;
142		l = min(l, uio->uio_resid);
143		if (l == 0)
144			break;
145		error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr,
146		    (int)l, uio);
147		if (error)
148			break;
149		mbp->msg_bufr += l;
150		if (mbp->msg_bufr >= mbp->msg_size)
151			mbp->msg_bufr = 0;
152	}
153	return (error);
154}
155
156/*ARGSUSED*/
157static	int
158logpoll(dev_t dev, int events, struct proc *p)
159{
160	int s;
161	int revents = 0;
162
163	s = splhigh();
164
165	if (events & (POLLIN | POLLRDNORM)) {
166		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
167			revents |= events & (POLLIN | POLLRDNORM);
168		else
169			selrecord(p, &logsoftc.sc_selp);
170	}
171	splx(s);
172	return (revents);
173}
174
175void
176logwakeup(void)
177{
178	if (!log_open)
179		return;
180	selwakeup(&logsoftc.sc_selp);
181	if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
182		pgsigio(logsoftc.sc_sigio, SIGIO, 0);
183	if (logsoftc.sc_state & LOG_RDWAIT) {
184		wakeup((caddr_t)msgbufp);
185		logsoftc.sc_state &= ~LOG_RDWAIT;
186	}
187}
188
189/*ARGSUSED*/
190static	int
191logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
192{
193	long l;
194	int s;
195
196	switch (com) {
197
198	/* return number of characters immediately available */
199	case FIONREAD:
200		s = splhigh();
201		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
202		splx(s);
203		if (l < 0)
204			l += msgbufp->msg_size;
205		*(int *)data = l;
206		break;
207
208	case FIONBIO:
209		break;
210
211	case FIOASYNC:
212		if (*(int *)data)
213			logsoftc.sc_state |= LOG_ASYNC;
214		else
215			logsoftc.sc_state &= ~LOG_ASYNC;
216		break;
217
218	case FIOSETOWN:
219		return (fsetown(*(int *)data, &logsoftc.sc_sigio));
220
221	case FIOGETOWN:
222		*(int *)data = fgetown(logsoftc.sc_sigio);
223		break;
224
225	/* This is deprecated, FIOSETOWN should be used instead. */
226	case TIOCSPGRP:
227		return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
228
229	/* This is deprecated, FIOGETOWN should be used instead */
230	case TIOCGPGRP:
231		*(int *)data = -fgetown(logsoftc.sc_sigio);
232		break;
233
234	default:
235		return (ENOTTY);
236	}
237	return (0);
238}
239
240static void
241log_drvinit(void *unused)
242{
243
244	make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
245}
246
247SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)
248