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: head/sys/kern/subr_log.c 216952 2011-01-04 10:59:38Z kib $");
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;
62
63static void logtimeout(void *arg);
64
65static struct cdevsw log_cdevsw = {
66 .d_version = D_VERSION,
67 .d_open = logopen,
68 .d_close = logclose,
69 .d_read = logread,
70 .d_ioctl = logioctl,
71 .d_poll = logpoll,
72 .d_name = "log",
73};
74
75static struct logsoftc {
76 int sc_state; /* see above for possibilities */
77 struct selinfo sc_selp; /* process waiting on select call */
78 struct sigio *sc_sigio; /* information for async I/O */
79 struct callout sc_callout; /* callout to wakeup syslog */
80} logsoftc;
81
82int log_open; /* also used in log() */
83static struct cv log_wakeup;
84struct mtx msgbuf_lock;
85MTX_SYSINIT(msgbuf_lock, &msgbuf_lock, "msgbuf lock", MTX_DEF);
86
87/* Times per second to check for a pending syslog wakeup. */
88static int log_wakeups_per_second = 5;
89SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
90 &log_wakeups_per_second, 0, "");
91
92/*ARGSUSED*/
93static int
94logopen(struct cdev *dev, int flags, int mode, struct thread *td)
95{
96
97 if (log_wakeups_per_second < 1) {
98 printf("syslog wakeup is less than one. Adjusting to 1.\n");
99 log_wakeups_per_second = 1;
100 }
101
102 mtx_lock(&msgbuf_lock);
103 if (log_open) {
104 mtx_unlock(&msgbuf_lock);
105 return (EBUSY);
106 }
107 log_open = 1;
108 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
109 logtimeout, NULL);
110 mtx_unlock(&msgbuf_lock);
111
112 fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
113 return (0);
114}
115
116/*ARGSUSED*/
117static int
118logclose(struct cdev *dev, int flag, int mode, struct thread *td)
119{
120
121 funsetown(&logsoftc.sc_sigio);
122
123 mtx_lock(&msgbuf_lock);
124 callout_stop(&logsoftc.sc_callout);
125 logsoftc.sc_state = 0;
126 log_open = 0;
127 mtx_unlock(&msgbuf_lock);
128
129 return (0);
130}
131
132/*ARGSUSED*/
133static int
134logread(struct cdev *dev, struct uio *uio, int flag)
135{
136 char buf[128];
137 struct msgbuf *mbp = msgbufp;
138 int error = 0, l;
139
140 mtx_lock(&msgbuf_lock);
141 while (msgbuf_getcount(mbp) == 0) {
142 if (flag & IO_NDELAY) {
143 mtx_unlock(&msgbuf_lock);
144 return (EWOULDBLOCK);
145 }
146 if ((error = cv_wait_sig(&log_wakeup, &msgbuf_lock)) != 0) {
147 mtx_unlock(&msgbuf_lock);
148 return (error);
149 }
150 }
151
152 while (uio->uio_resid > 0) {
153 l = imin(sizeof(buf), uio->uio_resid);
154 l = msgbuf_getbytes(mbp, buf, l);
155 if (l == 0)
156 break;
157 mtx_unlock(&msgbuf_lock);
158 error = uiomove(buf, l, uio);
159 if (error || uio->uio_resid == 0)
160 return (error);
161 mtx_lock(&msgbuf_lock);
162 }
163 mtx_unlock(&msgbuf_lock);
164 return (error);
165}
166
167/*ARGSUSED*/
168static int
169logpoll(struct cdev *dev, int events, struct thread *td)
170{
171 int revents = 0;
172
173 if (events & (POLLIN | POLLRDNORM)) {
174 mtx_lock(&msgbuf_lock);
175 if (msgbuf_getcount(msgbufp) > 0)
176 revents |= events & (POLLIN | POLLRDNORM);
177 else
178 selrecord(td, &logsoftc.sc_selp);
179 mtx_unlock(&msgbuf_lock);
180 }
181 return (revents);
182}
183
184static void
185logtimeout(void *arg)
186{
187
188 if (!log_open)
189 return;
190 if (log_wakeups_per_second < 1) {
191 printf("syslog wakeup is less than one. Adjusting to 1.\n");
192 log_wakeups_per_second = 1;
193 }
194 if (msgbuftrigger == 0) {
195 callout_schedule(&logsoftc.sc_callout,
196 hz / log_wakeups_per_second);
197 return;
198 }
199 msgbuftrigger = 0;
200 selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
201 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
202 pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
203 cv_broadcastpri(&log_wakeup, LOG_RDPRI);
204 callout_schedule(&logsoftc.sc_callout, hz / log_wakeups_per_second);
205}
206
207/*ARGSUSED*/
208static int
209logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td)
210{
211
212 switch (com) {
213
214 /* return number of characters immediately available */
215 case FIONREAD:
216 *(int *)data = msgbuf_getcount(msgbufp);
217 break;
218
219 case FIONBIO:
220 break;
221
222 case FIOASYNC:
223 mtx_lock(&msgbuf_lock);
224 if (*(int *)data)
225 logsoftc.sc_state |= LOG_ASYNC;
226 else
227 logsoftc.sc_state &= ~LOG_ASYNC;
228 mtx_unlock(&msgbuf_lock);
229 break;
230
231 case FIOSETOWN:
232 return (fsetown(*(int *)data, &logsoftc.sc_sigio));
233
234 case FIOGETOWN:
235 *(int *)data = fgetown(&logsoftc.sc_sigio);
236 break;
237
238 /* This is deprecated, FIOSETOWN should be used instead. */
239 case TIOCSPGRP:
240 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
241
242 /* This is deprecated, FIOGETOWN should be used instead */
243 case TIOCGPGRP:
244 *(int *)data = -fgetown(&logsoftc.sc_sigio);
245 break;
246
247 default:
248 return (ENOTTY);
249 }
250 return (0);
251}
252
253static void
254log_drvinit(void *unused)
255{
256
257 cv_init(&log_wakeup, "klog");
258 callout_init_mtx(&logsoftc.sc_callout, &msgbuf_lock, 0);
259 make_dev_credf(MAKEDEV_ETERNAL, &log_cdevsw, 0, NULL, UID_ROOT,
260 GID_WHEEL, 0600, "klog");
261}
262
263SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,log_drvinit,NULL);