subr_log.c revision 1.13 
1/*	$OpenBSD: subr_log.c,v 1.13 2005/04/20 00:08:50 deraadt 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	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	/* Always start new buffer data on a new line. */
105	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
106		msgbuf_putchar('\n');
107
108	/* mark it as ready for use. */
109	msgbufmapped = msgbufenabled = 1;
110}
111
112void
113msgbuf_putchar(const char c)
114{
115	struct msgbuf *mbp = msgbufp;
116
117	if (mbp->msg_magic != MSG_MAGIC)
118		/* Nothing we can do */
119		return;
120
121	mbp->msg_bufc[mbp->msg_bufx++] = c;
122	mbp->msg_bufl = min(mbp->msg_bufl+1, mbp->msg_bufs);
123	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
124		mbp->msg_bufx = 0;
125	/* If the buffer is full, keep the most recent data. */
126	if (mbp->msg_bufr == mbp->msg_bufx) {
127		if (++mbp->msg_bufr >= mbp->msg_bufs)
128			mbp->msg_bufr = 0;
129	}
130}
131
132/*ARGSUSED*/
133int
134logopen(dev, flags, mode, p)
135	dev_t dev;
136	int flags, mode;
137	struct proc *p;
138{
139	if (log_open)
140		return (EBUSY);
141	log_open = 1;
142	return (0);
143}
144
145/*ARGSUSED*/
146int
147logclose(dev, flag, mode, p)
148	dev_t dev;
149	int flag, mode;
150	struct proc *p;
151{
152
153	log_open = 0;
154	logsoftc.sc_state = 0;
155	return (0);
156}
157
158/*ARGSUSED*/
159int
160logread(dev, uio, flag)
161	dev_t dev;
162	struct uio *uio;
163	int flag;
164{
165	struct msgbuf *mbp = msgbufp;
166	long l;
167	int s;
168	int error = 0;
169
170	s = splhigh();
171	while (mbp->msg_bufr == mbp->msg_bufx) {
172		if (flag & IO_NDELAY) {
173			splx(s);
174			return (EWOULDBLOCK);
175		}
176		logsoftc.sc_state |= LOG_RDWAIT;
177		error = tsleep(mbp, LOG_RDPRI | PCATCH,
178			       "klog", 0);
179		if (error) {
180			splx(s);
181			return (error);
182		}
183	}
184	splx(s);
185	logsoftc.sc_state &= ~LOG_RDWAIT;
186
187	while (uio->uio_resid > 0) {
188		l = mbp->msg_bufx - mbp->msg_bufr;
189		if (l < 0)
190			l = mbp->msg_bufs - mbp->msg_bufr;
191		l = min(l, uio->uio_resid);
192		if (l == 0)
193			break;
194		error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
195		if (error)
196			break;
197		mbp->msg_bufr += l;
198		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
199			mbp->msg_bufr = 0;
200	}
201	return (error);
202}
203
204/*ARGSUSED*/
205int
206logpoll(dev, events, p)
207	dev_t dev;
208	int events;
209	struct proc *p;
210{
211	int revents = 0;
212	int s = splhigh();
213
214	if (events & (POLLIN | POLLRDNORM)) {
215		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
216			revents |= events & (POLLIN | POLLRDNORM);
217		else
218			selrecord(p, &logsoftc.sc_selp);
219	}
220	splx(s);
221	return (revents);
222}
223
224int
225logkqfilter(dev_t dev, struct knote *kn)
226{
227	struct klist *klist;
228	int s;
229
230	switch (kn->kn_filter) {
231	case EVFILT_READ:
232		klist = &logsoftc.sc_selp.si_note;
233		kn->kn_fop = &logread_filtops;
234		break;
235	default:
236		return (1);
237	}
238
239	kn->kn_hook = (void *)msgbufp;
240
241	s = splhigh();
242	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
243	splx(s);
244
245	return (0);
246}
247
248void
249filt_logrdetach(struct knote *kn)
250{
251	int s = splhigh();
252
253	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
254	splx(s);
255}
256
257int
258filt_logread(struct knote *kn, long hint)
259{
260	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
261
262	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
263
264	return (p->msg_bufx != p->msg_bufr);
265}
266
267void
268logwakeup()
269{
270	if (!log_open)
271		return;
272	selwakeup(&logsoftc.sc_selp);
273	if (logsoftc.sc_state & LOG_ASYNC)
274		csignal(logsoftc.sc_pgid, SIGIO,
275		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
276	if (logsoftc.sc_state & LOG_RDWAIT) {
277		wakeup(msgbufp);
278		logsoftc.sc_state &= ~LOG_RDWAIT;
279	}
280	KNOTE(&logsoftc.sc_selp.si_note, 0);
281}
282
283/*ARGSUSED*/
284int
285logioctl(dev, com, data, flag, p)
286	dev_t dev;
287	u_long com;
288	caddr_t data;
289	int flag;
290	struct proc *p;
291{
292	long l;
293	int s;
294
295	switch (com) {
296
297	/* return number of characters immediately available */
298	case FIONREAD:
299		s = splhigh();
300		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
301		splx(s);
302		if (l < 0)
303			l += msgbufp->msg_bufs;
304		*(int *)data = l;
305		break;
306
307	case FIONBIO:
308		break;
309
310	case FIOASYNC:
311		if (*(int *)data)
312			logsoftc.sc_state |= LOG_ASYNC;
313		else
314			logsoftc.sc_state &= ~LOG_ASYNC;
315		break;
316
317	case TIOCSPGRP:
318		logsoftc.sc_pgid = *(int *)data;
319		logsoftc.sc_siguid = p->p_cred->p_ruid;
320		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
321		break;
322
323	case TIOCGPGRP:
324		*(int *)data = logsoftc.sc_pgid;
325		break;
326
327	default:
328		return (-1);
329	}
330	return (0);
331}
332