subr_log.c revision 50477 
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 50477 1999-08-28 01:08:13Z peter $
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	/* stop */	nostop,
73	/* reset */	noreset,
74	/* devtotty */	nodevtotty,
75	/* poll */	logpoll,
76	/* mmap */	nommap,
77	/* strategy */	nostrategy,
78	/* name */	"log",
79	/* parms */	noparms,
80	/* maj */	CDEV_MAJOR,
81	/* dump */	nodump,
82	/* psize */	nopsize,
83	/* flags */	0,
84	/* maxio */	0,
85	/* bmaj */	-1
86};
87
88static struct logsoftc {
89	int	sc_state;		/* see above for possibilities */
90	struct	selinfo sc_selp;	/* process waiting on select call */
91	struct  sigio *sc_sigio;	/* information for async I/O */
92} logsoftc;
93
94int	log_open;			/* also used in log() */
95
96/*ARGSUSED*/
97static	int
98logopen(dev, flags, mode, p)
99	dev_t dev;
100	int flags, mode;
101	struct proc *p;
102{
103	if (log_open)
104		return (EBUSY);
105	log_open = 1;
106	fsetown(p->p_pid, &logsoftc.sc_sigio);	/* signal process only */
107	return (0);
108}
109
110/*ARGSUSED*/
111static	int
112logclose(dev, flag, mode, p)
113	dev_t dev;
114	int flag, mode;
115	struct proc *p;
116{
117
118	log_open = 0;
119	logsoftc.sc_state = 0;
120	funsetown(logsoftc.sc_sigio);
121	return (0);
122}
123
124/*ARGSUSED*/
125static	int
126logread(dev, uio, flag)
127	dev_t dev;
128	struct uio *uio;
129	int flag;
130{
131	register struct msgbuf *mbp = msgbufp;
132	register long l;
133	register int s;
134	int error = 0;
135
136	s = splhigh();
137	while (mbp->msg_bufr == mbp->msg_bufx) {
138		if (flag & IO_NDELAY) {
139			splx(s);
140			return (EWOULDBLOCK);
141		}
142		logsoftc.sc_state |= LOG_RDWAIT;
143		if ((error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
144		    "klog", 0))) {
145			splx(s);
146			return (error);
147		}
148	}
149	splx(s);
150	logsoftc.sc_state &= ~LOG_RDWAIT;
151
152	while (uio->uio_resid > 0) {
153		l = mbp->msg_bufx - mbp->msg_bufr;
154		if (l < 0)
155			l = mbp->msg_size - mbp->msg_bufr;
156		l = min(l, uio->uio_resid);
157		if (l == 0)
158			break;
159		error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr,
160		    (int)l, uio);
161		if (error)
162			break;
163		mbp->msg_bufr += l;
164		if (mbp->msg_bufr >= mbp->msg_size)
165			mbp->msg_bufr = 0;
166	}
167	return (error);
168}
169
170/*ARGSUSED*/
171static	int
172logpoll(dev, events, p)
173	dev_t dev;
174	int events;
175	struct proc *p;
176{
177	int s;
178	int revents = 0;
179
180	s = splhigh();
181
182	if (events & (POLLIN | POLLRDNORM)) {
183		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
184			revents |= events & (POLLIN | POLLRDNORM);
185		else
186			selrecord(p, &logsoftc.sc_selp);
187	}
188	splx(s);
189	return (revents);
190}
191
192void
193logwakeup()
194{
195	if (!log_open)
196		return;
197	selwakeup(&logsoftc.sc_selp);
198	if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
199		pgsigio(logsoftc.sc_sigio, SIGIO, 0);
200	if (logsoftc.sc_state & LOG_RDWAIT) {
201		wakeup((caddr_t)msgbufp);
202		logsoftc.sc_state &= ~LOG_RDWAIT;
203	}
204}
205
206/*ARGSUSED*/
207static	int
208logioctl(dev, com, data, flag, p)
209	dev_t dev;
210	u_long com;
211	caddr_t data;
212	int flag;
213	struct proc *p;
214{
215	long l;
216	int s;
217
218	switch (com) {
219
220	/* return number of characters immediately available */
221	case FIONREAD:
222		s = splhigh();
223		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
224		splx(s);
225		if (l < 0)
226			l += msgbufp->msg_size;
227		*(int *)data = l;
228		break;
229
230	case FIONBIO:
231		break;
232
233	case FIOASYNC:
234		if (*(int *)data)
235			logsoftc.sc_state |= LOG_ASYNC;
236		else
237			logsoftc.sc_state &= ~LOG_ASYNC;
238		break;
239
240	case FIOSETOWN:
241		return (fsetown(*(int *)data, &logsoftc.sc_sigio));
242
243	case FIOGETOWN:
244		*(int *)data = fgetown(logsoftc.sc_sigio);
245		break;
246
247	/* This is deprecated, FIOSETOWN should be used instead. */
248	case TIOCSPGRP:
249		return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
250
251	/* This is deprecated, FIOGETOWN should be used instead */
252	case TIOCGPGRP:
253		*(int *)data = -fgetown(logsoftc.sc_sigio);
254		break;
255
256	default:
257		return (ENOTTY);
258	}
259	return (0);
260}
261
262
263static void log_drvinit __P((void *unused));
264
265static void
266log_drvinit(unused)
267	void *unused;
268{
269	make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
270}
271
272SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)
273