subr_log.c revision 32726 
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 * $Id: subr_log.c,v 1.25 1997/10/28 15:58:21 bde Exp $
35 */
36
37/*
38 * Error log buffer for kernel printf's.
39 */
40
41#include "opt_devfs.h"
42
43#include <sys/param.h>
44#include <sys/systm.h>
45#include <sys/conf.h>
46#include <sys/proc.h>
47#include <sys/vnode.h>
48#include <sys/filio.h>
49#include <sys/ttycom.h>
50#include <sys/msgbuf.h>
51#include <sys/signalvar.h>
52#include <sys/kernel.h>
53#include <sys/poll.h>
54#ifdef DEVFS
55#include <sys/devfsext.h>
56#endif /*DEVFS*/
57
58#define LOG_RDPRI	(PZERO + 1)
59
60#define LOG_ASYNC	0x04
61#define LOG_RDWAIT	0x08
62
63static	d_open_t	logopen;
64static	d_close_t	logclose;
65static	d_read_t	logread;
66static	d_ioctl_t	logioctl;
67static	d_poll_t	logpoll;
68
69#define CDEV_MAJOR 7
70static struct cdevsw log_cdevsw =
71	{ logopen,	logclose,	logread,	nowrite,	/*7*/
72	  logioctl,	nostop,		nullreset,	nodevtotty,/* klog */
73	  logpoll,	nommap,		NULL,	"log",	NULL,	-1 };
74
75static struct logsoftc {
76	int	sc_state;		/* see above for possibilities */
77	struct	selinfo sc_selp;	/* process waiting on select call */
78	int	sc_pgid;		/* process/group for async I/O */
79} logsoftc;
80
81int	log_open;			/* also used in log() */
82
83/*ARGSUSED*/
84static	int
85logopen(dev, flags, mode, p)
86	dev_t dev;
87	int flags, mode;
88	struct proc *p;
89{
90	if (log_open)
91		return (EBUSY);
92	log_open = 1;
93	logsoftc.sc_pgid = p->p_pid;		/* signal process only */
94	return (0);
95}
96
97/*ARGSUSED*/
98static	int
99logclose(dev, flag, mode, p)
100	dev_t dev;
101	int flag, mode;
102	struct proc *p;
103{
104
105	log_open = 0;
106	logsoftc.sc_state = 0;
107	return (0);
108}
109
110/*ARGSUSED*/
111static	int
112logread(dev, uio, flag)
113	dev_t dev;
114	struct uio *uio;
115	int flag;
116{
117	register struct msgbuf *mbp = msgbufp;
118	register long l;
119	register 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 = MSG_BSIZE - mbp->msg_bufr;
142		l = min(l, uio->uio_resid);
143		if (l == 0)
144			break;
145		error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr],
146			(int)l, uio);
147		if (error)
148			break;
149		mbp->msg_bufr += l;
150		if (mbp->msg_bufr >= MSG_BSIZE)
151			mbp->msg_bufr = 0;
152	}
153	return (error);
154}
155
156/*ARGSUSED*/
157static	int
158logpoll(dev, events, p)
159	dev_t dev;
160	int events;
161	struct proc *p;
162{
163	int s;
164	int revents = 0;
165
166	s = splhigh();
167
168	if (events & (POLLIN | POLLRDNORM))
169		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
170			revents |= events & (POLLIN | POLLRDNORM);
171		else
172			selrecord(p, &logsoftc.sc_selp);
173
174	splx(s);
175	return (revents);
176}
177
178void
179logwakeup()
180{
181	struct proc *p;
182
183	if (!log_open)
184		return;
185	selwakeup(&logsoftc.sc_selp);
186	if (logsoftc.sc_state & LOG_ASYNC) {
187		if (logsoftc.sc_pgid < 0)
188			gsignal(-logsoftc.sc_pgid, SIGIO);
189		else if ((p = pfind(logsoftc.sc_pgid)))
190			psignal(p, SIGIO);
191	}
192	if (logsoftc.sc_state & LOG_RDWAIT) {
193		wakeup((caddr_t)msgbufp);
194		logsoftc.sc_state &= ~LOG_RDWAIT;
195	}
196}
197
198/*ARGSUSED*/
199static	int
200logioctl(dev, com, data, flag, p)
201	dev_t dev;
202	int com;
203	caddr_t data;
204	int flag;
205	struct proc *p;
206{
207	long l;
208	int s;
209
210	switch (com) {
211
212	/* return number of characters immediately available */
213	case FIONREAD:
214		s = splhigh();
215		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
216		splx(s);
217		if (l < 0)
218			l += MSG_BSIZE;
219		*(int *)data = l;
220		break;
221
222	case FIONBIO:
223		break;
224
225	case FIOASYNC:
226		if (*(int *)data)
227			logsoftc.sc_state |= LOG_ASYNC;
228		else
229			logsoftc.sc_state &= ~LOG_ASYNC;
230		break;
231
232	case TIOCSPGRP:
233		logsoftc.sc_pgid = *(int *)data;
234		break;
235
236	case TIOCGPGRP:
237		*(int *)data = logsoftc.sc_pgid;
238		break;
239
240	default:
241		return (ENOTTY);
242	}
243	return (0);
244}
245
246static log_devsw_installed = 0;
247#ifdef DEVFS
248static	void	*log_devfs_token;
249#endif
250
251static void log_drvinit __P((void *unused));
252static void
253log_drvinit(unused)
254	void *unused;
255{
256	dev_t dev;
257
258	if( ! log_devsw_installed ) {
259		dev = makedev(CDEV_MAJOR,0);
260		cdevsw_add(&dev,&log_cdevsw,NULL);
261		log_devsw_installed = 1;
262#ifdef DEVFS
263		log_devfs_token = devfs_add_devswf(&log_cdevsw, 0, DV_CHR,
264						   UID_ROOT, GID_WHEEL, 0600,
265						   "klog");
266#endif
267    	}
268}
269
270SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)
271
272
273