subr_log.c revision 1.18 
1/*	$OpenBSD: subr_log.c,v 1.18 2014/01/21 01:48:44 tedu 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(caddr_t buf, size_t bufsize)
77{
78	struct msgbuf *mbp;
79	long new_bufs;
80
81	/* Sanity-check the given size. */
82	if (bufsize < sizeof(struct msgbuf))
83		return;
84
85	mbp = msgbufp = (struct msgbuf *)buf;
86
87	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
88	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
89	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
90	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
91		/*
92		 * If the buffer magic number is wrong, has changed
93		 * size (which shouldn't happen often), or is
94		 * internally inconsistent, initialize it.
95		 */
96
97		memset(buf, 0, bufsize);
98		mbp->msg_magic = MSG_MAGIC;
99		mbp->msg_bufs = new_bufs;
100	}
101
102	/* Always start new buffer data on a new line. */
103	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
104		msgbuf_putchar('\n');
105
106	/* mark it as ready for use. */
107	msgbufmapped = msgbufenabled = 1;
108}
109
110void
111msgbuf_putchar(const char c)
112{
113	struct msgbuf *mbp = msgbufp;
114
115	if (mbp->msg_magic != MSG_MAGIC)
116		/* Nothing we can do */
117		return;
118
119	mbp->msg_bufc[mbp->msg_bufx++] = c;
120	mbp->msg_bufl = min(mbp->msg_bufl+1, mbp->msg_bufs);
121	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
122		mbp->msg_bufx = 0;
123	/* If the buffer is full, keep the most recent data. */
124	if (mbp->msg_bufr == mbp->msg_bufx) {
125		if (++mbp->msg_bufr >= mbp->msg_bufs)
126			mbp->msg_bufr = 0;
127	}
128}
129
130/*ARGSUSED*/
131int
132logopen(dev_t dev, int flags, int mode, struct proc *p)
133{
134	if (log_open)
135		return (EBUSY);
136	log_open = 1;
137	return (0);
138}
139
140/*ARGSUSED*/
141int
142logclose(dev_t dev, int flag, int mode, struct proc *p)
143{
144
145	log_open = 0;
146	logsoftc.sc_state = 0;
147	return (0);
148}
149
150/*ARGSUSED*/
151int
152logread(dev_t dev, struct uio *uio, int flag)
153{
154	struct msgbuf *mbp = msgbufp;
155	long l;
156	int s;
157	int error = 0;
158
159	s = splhigh();
160	while (mbp->msg_bufr == mbp->msg_bufx) {
161		if (flag & IO_NDELAY) {
162			splx(s);
163			return (EWOULDBLOCK);
164		}
165		logsoftc.sc_state |= LOG_RDWAIT;
166		error = tsleep(mbp, LOG_RDPRI | PCATCH,
167			       "klog", 0);
168		if (error) {
169			splx(s);
170			return (error);
171		}
172	}
173	splx(s);
174	logsoftc.sc_state &= ~LOG_RDWAIT;
175
176	while (uio->uio_resid > 0) {
177		l = mbp->msg_bufx - mbp->msg_bufr;
178		if (l < 0)
179			l = mbp->msg_bufs - mbp->msg_bufr;
180		l = min(l, uio->uio_resid);
181		if (l == 0)
182			break;
183		error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
184		if (error)
185			break;
186		mbp->msg_bufr += l;
187		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
188			mbp->msg_bufr = 0;
189	}
190	return (error);
191}
192
193/*ARGSUSED*/
194int
195logpoll(dev_t dev, int events, struct proc *p)
196{
197	int revents = 0;
198	int s = splhigh();
199
200	if (events & (POLLIN | POLLRDNORM)) {
201		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
202			revents |= events & (POLLIN | POLLRDNORM);
203		else
204			selrecord(p, &logsoftc.sc_selp);
205	}
206	splx(s);
207	return (revents);
208}
209
210int
211logkqfilter(dev_t dev, struct knote *kn)
212{
213	struct klist *klist;
214	int s;
215
216	switch (kn->kn_filter) {
217	case EVFILT_READ:
218		klist = &logsoftc.sc_selp.si_note;
219		kn->kn_fop = &logread_filtops;
220		break;
221	default:
222		return (EINVAL);
223	}
224
225	kn->kn_hook = (void *)msgbufp;
226
227	s = splhigh();
228	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
229	splx(s);
230
231	return (0);
232}
233
234void
235filt_logrdetach(struct knote *kn)
236{
237	int s = splhigh();
238
239	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
240	splx(s);
241}
242
243int
244filt_logread(struct knote *kn, long hint)
245{
246	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
247
248	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
249
250	return (p->msg_bufx != p->msg_bufr);
251}
252
253void
254logwakeup(void)
255{
256	if (!log_open)
257		return;
258	selwakeup(&logsoftc.sc_selp);
259	if (logsoftc.sc_state & LOG_ASYNC)
260		csignal(logsoftc.sc_pgid, SIGIO,
261		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
262	if (logsoftc.sc_state & LOG_RDWAIT) {
263		wakeup(msgbufp);
264		logsoftc.sc_state &= ~LOG_RDWAIT;
265	}
266}
267
268/*ARGSUSED*/
269int
270logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
271{
272	long l;
273	int s;
274
275	switch (com) {
276
277	/* return number of characters immediately available */
278	case FIONREAD:
279		s = splhigh();
280		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
281		splx(s);
282		if (l < 0)
283			l += msgbufp->msg_bufs;
284		*(int *)data = l;
285		break;
286
287	case FIONBIO:
288		break;
289
290	case FIOASYNC:
291		if (*(int *)data)
292			logsoftc.sc_state |= LOG_ASYNC;
293		else
294			logsoftc.sc_state &= ~LOG_ASYNC;
295		break;
296
297	case TIOCSPGRP:
298		logsoftc.sc_pgid = *(int *)data;
299		logsoftc.sc_siguid = p->p_cred->p_ruid;
300		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
301		break;
302
303	case TIOCGPGRP:
304		*(int *)data = logsoftc.sc_pgid;
305		break;
306
307	default:
308		return (ENOTTY);
309	}
310	return (0);
311}
312