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 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 *	@(#)subr_log.c	8.1 (Berkeley) 6/10/93
30 */
31
32/*
33 * Error log buffer for kernel printf's.
34 */
35
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD$");
38
39#include <sys/param.h>
40#include <sys/systm.h>
41#include <sys/conf.h>
42#include <sys/proc.h>
43#include <sys/vnode.h>
44#include <sys/filio.h>
45#include <sys/ttycom.h>
46#include <sys/msgbuf.h>
47#include <sys/signalvar.h>
48#include <sys/kernel.h>
49#include <sys/poll.h>
50#include <sys/filedesc.h>
51#include <sys/sysctl.h>
52
53#define LOG_RDPRI	(PZERO + 1)
54
55#define LOG_ASYNC	0x04
56
57static	d_open_t	logopen;
58static	d_close_t	logclose;
59static	d_read_t	logread;
60static	d_ioctl_t	logioctl;
61static	d_poll_t	logpoll;
62static	d_kqfilter_t	logkqfilter;
63
64static	void logtimeout(void *arg);
65
66static struct cdevsw log_cdevsw = {
67	.d_version =	D_VERSION,
68	.d_open =	logopen,
69	.d_close =	logclose,
70	.d_read =	logread,
71	.d_ioctl =	logioctl,
72	.d_poll =	logpoll,
73	.d_kqfilter =	logkqfilter,
74	.d_name =	"log",
75};
76
77static int	logkqread(struct knote *note, long hint);
78static void	logkqdetach(struct knote *note);
79
80static struct filterops log_read_filterops = {
81	.f_isfd =	1,
82	.f_attach =	NULL,
83	.f_detach =	logkqdetach,
84	.f_event =	logkqread,
85};
86
87static struct logsoftc {
88	int	sc_state;		/* see above for possibilities */
89	struct	selinfo sc_selp;	/* process waiting on select call */
90	struct  sigio *sc_sigio;	/* information for async I/O */
91	struct	callout sc_callout;	/* callout to wakeup syslog  */
92} logsoftc;
93
94int			log_open;	/* also used in log() */
95static struct cv	log_wakeup;
96struct mtx		msgbuf_lock;
97MTX_SYSINIT(msgbuf_lock, &msgbuf_lock, "msgbuf lock", MTX_DEF);
98
99/* Times per second to check for a pending syslog wakeup. */
100static int	log_wakeups_per_second = 5;
101SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
102    &log_wakeups_per_second, 0, "");
103
104/*ARGSUSED*/
105static	int
106logopen(struct cdev *dev, int flags, int mode, struct thread *td)
107{
108
109	if (log_wakeups_per_second < 1) {
110		printf("syslog wakeup is less than one.  Adjusting to 1.\n");
111		log_wakeups_per_second = 1;
112	}
113
114	mtx_lock(&msgbuf_lock);
115	if (log_open) {
116		mtx_unlock(&msgbuf_lock);
117		return (EBUSY);
118	}
119	log_open = 1;
120	callout_reset_sbt(&logsoftc.sc_callout,
121	    SBT_1S / log_wakeups_per_second, 0, logtimeout, NULL, C_PREL(1));
122	mtx_unlock(&msgbuf_lock);
123
124	fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio);	/* signal process only */
125	return (0);
126}
127
128/*ARGSUSED*/
129static	int
130logclose(struct cdev *dev, int flag, int mode, struct thread *td)
131{
132
133	funsetown(&logsoftc.sc_sigio);
134
135	mtx_lock(&msgbuf_lock);
136	callout_stop(&logsoftc.sc_callout);
137	logsoftc.sc_state = 0;
138	log_open = 0;
139	mtx_unlock(&msgbuf_lock);
140
141	return (0);
142}
143
144/*ARGSUSED*/
145static	int
146logread(struct cdev *dev, struct uio *uio, int flag)
147{
148	char buf[128];
149	struct msgbuf *mbp = msgbufp;
150	int error = 0, l;
151
152	mtx_lock(&msgbuf_lock);
153	while (msgbuf_getcount(mbp) == 0) {
154		if (flag & IO_NDELAY) {
155			mtx_unlock(&msgbuf_lock);
156			return (EWOULDBLOCK);
157		}
158		if ((error = cv_wait_sig(&log_wakeup, &msgbuf_lock)) != 0) {
159			mtx_unlock(&msgbuf_lock);
160			return (error);
161		}
162	}
163
164	while (uio->uio_resid > 0) {
165		l = imin(sizeof(buf), uio->uio_resid);
166		l = msgbuf_getbytes(mbp, buf, l);
167		if (l == 0)
168			break;
169		mtx_unlock(&msgbuf_lock);
170		error = uiomove(buf, l, uio);
171		if (error || uio->uio_resid == 0)
172			return (error);
173		mtx_lock(&msgbuf_lock);
174	}
175	mtx_unlock(&msgbuf_lock);
176	return (error);
177}
178
179/*ARGSUSED*/
180static	int
181logpoll(struct cdev *dev, int events, struct thread *td)
182{
183	int revents = 0;
184
185	if (events & (POLLIN | POLLRDNORM)) {
186		mtx_lock(&msgbuf_lock);
187		if (msgbuf_getcount(msgbufp) > 0)
188			revents |= events & (POLLIN | POLLRDNORM);
189		else
190			selrecord(td, &logsoftc.sc_selp);
191		mtx_unlock(&msgbuf_lock);
192	}
193	return (revents);
194}
195
196static int
197logkqfilter(struct cdev *dev, struct knote *kn)
198{
199
200	if (kn->kn_filter != EVFILT_READ)
201		return (EINVAL);
202
203	kn->kn_fop = &log_read_filterops;
204	kn->kn_hook = NULL;
205
206	mtx_lock(&msgbuf_lock);
207	knlist_add(&logsoftc.sc_selp.si_note, kn, 1);
208	mtx_unlock(&msgbuf_lock);
209	return (0);
210}
211
212static int
213logkqread(struct knote *kn, long hint)
214{
215
216	mtx_assert(&msgbuf_lock, MA_OWNED);
217	kn->kn_data = msgbuf_getcount(msgbufp);
218	return (kn->kn_data != 0);
219}
220
221static void
222logkqdetach(struct knote *kn)
223{
224
225	mtx_lock(&msgbuf_lock);
226	knlist_remove(&logsoftc.sc_selp.si_note, kn, 1);
227	mtx_unlock(&msgbuf_lock);
228}
229
230static void
231logtimeout(void *arg)
232{
233
234	if (!log_open)
235		return;
236	if (msgbuftrigger == 0)
237		goto done;
238	msgbuftrigger = 0;
239	selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
240	KNOTE_LOCKED(&logsoftc.sc_selp.si_note, 0);
241	if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
242		pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
243	cv_broadcastpri(&log_wakeup, LOG_RDPRI);
244done:
245	if (log_wakeups_per_second < 1) {
246		printf("syslog wakeup is less than one.  Adjusting to 1.\n");
247		log_wakeups_per_second = 1;
248	}
249	callout_reset_sbt(&logsoftc.sc_callout,
250	    SBT_1S / log_wakeups_per_second, 0, logtimeout, NULL, C_PREL(1));
251}
252
253/*ARGSUSED*/
254static	int
255logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td)
256{
257
258	switch (com) {
259
260	/* return number of characters immediately available */
261	case FIONREAD:
262		*(int *)data = msgbuf_getcount(msgbufp);
263		break;
264
265	case FIONBIO:
266		break;
267
268	case FIOASYNC:
269		mtx_lock(&msgbuf_lock);
270		if (*(int *)data)
271			logsoftc.sc_state |= LOG_ASYNC;
272		else
273			logsoftc.sc_state &= ~LOG_ASYNC;
274		mtx_unlock(&msgbuf_lock);
275		break;
276
277	case FIOSETOWN:
278		return (fsetown(*(int *)data, &logsoftc.sc_sigio));
279
280	case FIOGETOWN:
281		*(int *)data = fgetown(&logsoftc.sc_sigio);
282		break;
283
284	/* This is deprecated, FIOSETOWN should be used instead. */
285	case TIOCSPGRP:
286		return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
287
288	/* This is deprecated, FIOGETOWN should be used instead */
289	case TIOCGPGRP:
290		*(int *)data = -fgetown(&logsoftc.sc_sigio);
291		break;
292
293	default:
294		return (ENOTTY);
295	}
296	return (0);
297}
298
299static void
300log_drvinit(void *unused)
301{
302
303	cv_init(&log_wakeup, "klog");
304	callout_init_mtx(&logsoftc.sc_callout, &msgbuf_lock, 0);
305	knlist_init_mtx(&logsoftc.sc_selp.si_note, &msgbuf_lock);
306	make_dev_credf(MAKEDEV_ETERNAL, &log_cdevsw, 0, NULL, UID_ROOT,
307	    GID_WHEEL, 0600, "klog");
308}
309
310SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,log_drvinit,NULL);
311