subr_log.c revision 1.11 
1/*	$OpenBSD: subr_log.c,v 1.11 2003/09/23 16:51:12 millert Exp $	*/
2/*	$NetBSD: subr_log.c,v 1.11 1996/03/30 22:24:44 christos Exp $	*/
3
4/*
5 * Copyright (c) 1982, 1986, 1993
6 *	The Regents of the University of California.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 *	@(#)subr_log.c	8.1 (Berkeley) 6/10/93
33 */
34
35/*
36 * Error log buffer for kernel printf's.
37 */
38
39#include <sys/param.h>
40#include <sys/systm.h>
41#include <sys/proc.h>
42#include <sys/vnode.h>
43#include <sys/ioctl.h>
44#include <sys/msgbuf.h>
45#include <sys/file.h>
46#include <sys/signalvar.h>
47#include <sys/syslog.h>
48#include <sys/conf.h>
49#include <sys/poll.h>
50
51#define LOG_RDPRI	(PZERO + 1)
52
53#define LOG_ASYNC	0x04
54#define LOG_RDWAIT	0x08
55
56struct logsoftc {
57	int	sc_state;		/* see above for possibilities */
58	struct	selinfo sc_selp;	/* process waiting on select call */
59	int	sc_pgid;		/* process/group for async I/O */
60	uid_t	sc_siguid;		/* uid for process that set sc_pgid */
61	uid_t	sc_sigeuid;		/* euid for process that set sc_pgid */
62} logsoftc;
63
64int	log_open;			/* also used in log() */
65int	msgbufmapped;			/* is the message buffer mapped */
66int	msgbufenabled;			/* is logging to the buffer enabled */
67struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
68
69void filt_logrdetach(struct knote *kn);
70int filt_logread(struct knote *kn, long hint);
71
72struct filterops logread_filtops =
73	{ 1, NULL, filt_logrdetach, filt_logread};
74
75void
76initmsgbuf(buf, bufsize)
77	caddr_t buf;
78	size_t bufsize;
79{
80	register struct msgbuf *mbp;
81	long new_bufs;
82
83	/* Sanity-check the given size. */
84	if (bufsize < sizeof(struct msgbuf))
85		return;
86
87	mbp = msgbufp = (struct msgbuf *)buf;
88
89	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
90	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
91	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
92	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
93		/*
94		 * If the buffer magic number is wrong, has changed
95		 * size (which shouldn't happen often), or is
96		 * internally inconsistent, initialize it.
97		 */
98
99		bzero(buf, bufsize);
100		mbp->msg_magic = MSG_MAGIC;
101		mbp->msg_bufs = new_bufs;
102	}
103
104	/* mark it as ready for use. */
105	msgbufmapped = msgbufenabled = 1;
106}
107
108/*ARGSUSED*/
109int
110logopen(dev, flags, mode, p)
111	dev_t dev;
112	int flags, mode;
113	struct proc *p;
114{
115	if (log_open)
116		return (EBUSY);
117	log_open = 1;
118	return (0);
119}
120
121/*ARGSUSED*/
122int
123logclose(dev, flag, mode, p)
124	dev_t dev;
125	int flag, mode;
126	struct proc *p;
127{
128
129	log_open = 0;
130	logsoftc.sc_state = 0;
131	return (0);
132}
133
134/*ARGSUSED*/
135int
136logread(dev, uio, flag)
137	dev_t dev;
138	struct uio *uio;
139	int flag;
140{
141	register struct msgbuf *mbp = msgbufp;
142	register long l;
143	register int s;
144	int error = 0;
145
146	s = splhigh();
147	while (mbp->msg_bufr == mbp->msg_bufx) {
148		if (flag & IO_NDELAY) {
149			splx(s);
150			return (EWOULDBLOCK);
151		}
152		logsoftc.sc_state |= LOG_RDWAIT;
153		error = tsleep(mbp, LOG_RDPRI | PCATCH,
154			       "klog", 0);
155		if (error) {
156			splx(s);
157			return (error);
158		}
159	}
160	splx(s);
161	logsoftc.sc_state &= ~LOG_RDWAIT;
162
163	while (uio->uio_resid > 0) {
164		l = mbp->msg_bufx - mbp->msg_bufr;
165		if (l < 0)
166			l = mbp->msg_bufs - mbp->msg_bufr;
167		l = min(l, uio->uio_resid);
168		if (l == 0)
169			break;
170		error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
171		if (error)
172			break;
173		mbp->msg_bufr += l;
174		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
175			mbp->msg_bufr = 0;
176	}
177	return (error);
178}
179
180/*ARGSUSED*/
181int
182logpoll(dev, events, p)
183	dev_t dev;
184	int events;
185	struct proc *p;
186{
187	int revents = 0;
188	int s = splhigh();
189
190	if (events & (POLLIN | POLLRDNORM)) {
191		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
192			revents |= events & (POLLIN | POLLRDNORM);
193		else
194			selrecord(p, &logsoftc.sc_selp);
195	}
196	splx(s);
197	return (revents);
198}
199
200int
201logkqfilter(dev_t dev, struct knote *kn)
202{
203	struct klist *klist;
204	int s;
205
206	switch (kn->kn_filter) {
207	case EVFILT_READ:
208		klist = &logsoftc.sc_selp.si_note;
209		kn->kn_fop = &logread_filtops;
210		break;
211	default:
212		return (1);
213	}
214
215	kn->kn_hook = (void *)msgbufp;
216
217	s = splhigh();
218	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
219	splx(s);
220
221	return (0);
222}
223
224void
225filt_logrdetach(struct knote *kn)
226{
227	int s = splhigh();
228
229	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
230	splx(s);
231}
232
233int
234filt_logread(struct knote *kn, long hint)
235{
236	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
237
238	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
239
240	return (p->msg_bufx != p->msg_bufr);
241}
242
243void
244logwakeup()
245{
246	if (!log_open)
247		return;
248	selwakeup(&logsoftc.sc_selp);
249	if (logsoftc.sc_state & LOG_ASYNC)
250		csignal(logsoftc.sc_pgid, SIGIO,
251		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
252	if (logsoftc.sc_state & LOG_RDWAIT) {
253		wakeup(msgbufp);
254		logsoftc.sc_state &= ~LOG_RDWAIT;
255	}
256	KNOTE(&logsoftc.sc_selp.si_note, 0);
257}
258
259/*ARGSUSED*/
260int
261logioctl(dev, com, data, flag, p)
262	dev_t dev;
263	u_long com;
264	caddr_t data;
265	int flag;
266	struct proc *p;
267{
268	long l;
269	int s;
270
271	switch (com) {
272
273	/* return number of characters immediately available */
274	case FIONREAD:
275		s = splhigh();
276		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
277		splx(s);
278		if (l < 0)
279			l += msgbufp->msg_bufs;
280		*(int *)data = l;
281		break;
282
283	case FIONBIO:
284		break;
285
286	case FIOASYNC:
287		if (*(int *)data)
288			logsoftc.sc_state |= LOG_ASYNC;
289		else
290			logsoftc.sc_state &= ~LOG_ASYNC;
291		break;
292
293	case TIOCSPGRP:
294		logsoftc.sc_pgid = *(int *)data;
295		logsoftc.sc_siguid = p->p_cred->p_ruid;
296		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
297		break;
298
299	case TIOCGPGRP:
300		*(int *)data = logsoftc.sc_pgid;
301		break;
302
303	default:
304		return (-1);
305	}
306	return (0);
307}
308