FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_log.c
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: releng/5.4/sys/kern/subr_log.c 145335 2005-04-20 19:11:07Z cvs2svn $");
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 #define LOG_RDWAIT 0x08
57
58 static d_open_t logopen;
59 static d_close_t logclose;
60 static d_read_t logread;
61 static d_ioctl_t logioctl;
62 static d_poll_t logpoll;
63
64 static void logtimeout(void *arg);
65
66 #define CDEV_MAJOR 7
67 static struct cdevsw log_cdevsw = {
68 .d_version = D_VERSION,
69 .d_flags = D_NEEDGIANT,
70 .d_open = logopen,
71 .d_close = logclose,
72 .d_read = logread,
73 .d_ioctl = logioctl,
74 .d_poll = logpoll,
75 .d_name = "log",
76 .d_maj = CDEV_MAJOR,
77 };
78
79 static struct logsoftc {
80 int sc_state; /* see above for possibilities */
81 struct selinfo sc_selp; /* process waiting on select call */
82 struct sigio *sc_sigio; /* information for async I/O */
83 struct callout sc_callout; /* callout to wakeup syslog */
84 } logsoftc;
85
86 int log_open; /* also used in log() */
87
88 /* Times per second to check for a pending syslog wakeup. */
89 static int log_wakeups_per_second = 5;
90 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
91 &log_wakeups_per_second, 0, "");
92
93 /*ARGSUSED*/
94 static int
95 logopen(struct cdev *dev, int flags, int mode, struct thread *td)
96 {
97 if (log_open)
98 return (EBUSY);
99 log_open = 1;
100 callout_init(&logsoftc.sc_callout, 0);
101 fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
102 if (log_wakeups_per_second < 1) {
103 printf("syslog wakeup is less than one. Adjusting to 1.\n");
104 log_wakeups_per_second = 1;
105 }
106 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
107 logtimeout, NULL);
108 return (0);
109 }
110
111 /*ARGSUSED*/
112 static int
113 logclose(struct cdev *dev, int flag, int mode, struct thread *td)
114 {
115
116 log_open = 0;
117 callout_stop(&logsoftc.sc_callout);
118 logsoftc.sc_state = 0;
119 funsetown(&logsoftc.sc_sigio);
120 return (0);
121 }
122
123 /*ARGSUSED*/
124 static int
125 logread(struct cdev *dev, struct uio *uio, int flag)
126 {
127 char buf[128];
128 struct msgbuf *mbp = msgbufp;
129 int error = 0, l, s;
130
131 s = splhigh();
132 while (msgbuf_getcount(mbp) == 0) {
133 if (flag & IO_NDELAY) {
134 splx(s);
135 return (EWOULDBLOCK);
136 }
137 logsoftc.sc_state |= LOG_RDWAIT;
138 if ((error = tsleep(mbp, LOG_RDPRI | PCATCH, "klog", 0))) {
139 splx(s);
140 return (error);
141 }
142 }
143 splx(s);
144 logsoftc.sc_state &= ~LOG_RDWAIT;
145
146 while (uio->uio_resid > 0) {
147 l = imin(sizeof(buf), uio->uio_resid);
148 l = msgbuf_getbytes(mbp, buf, l);
149 if (l == 0)
150 break;
151 error = uiomove(buf, l, uio);
152 if (error)
153 break;
154 }
155 return (error);
156 }
157
158 /*ARGSUSED*/
159 static int
160 logpoll(struct cdev *dev, int events, struct thread *td)
161 {
162 int s;
163 int revents = 0;
164
165 s = splhigh();
166
167 if (events & (POLLIN | POLLRDNORM)) {
168 if (msgbuf_getcount(msgbufp) > 0)
169 revents |= events & (POLLIN | POLLRDNORM);
170 else
171 selrecord(td, &logsoftc.sc_selp);
172 }
173 splx(s);
174 return (revents);
175 }
176
177 static void
178 logtimeout(void *arg)
179 {
180
181 if (!log_open)
182 return;
183 if (log_wakeups_per_second < 1) {
184 printf("syslog wakeup is less than one. Adjusting to 1.\n");
185 log_wakeups_per_second = 1;
186 }
187 if (msgbuftrigger == 0) {
188 callout_reset(&logsoftc.sc_callout,
189 hz / log_wakeups_per_second, logtimeout, NULL);
190 return;
191 }
192 msgbuftrigger = 0;
193 selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
194 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
195 pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
196 if (logsoftc.sc_state & LOG_RDWAIT) {
197 wakeup(msgbufp);
198 logsoftc.sc_state &= ~LOG_RDWAIT;
199 }
200 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
201 logtimeout, NULL);
202 }
203
204 /*ARGSUSED*/
205 static int
206 logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td)
207 {
208
209 switch (com) {
210
211 /* return number of characters immediately available */
212 case FIONREAD:
213 *(int *)data = msgbuf_getcount(msgbufp);
214 break;
215
216 case FIONBIO:
217 break;
218
219 case FIOASYNC:
220 if (*(int *)data)
221 logsoftc.sc_state |= LOG_ASYNC;
222 else
223 logsoftc.sc_state &= ~LOG_ASYNC;
224 break;
225
226 case FIOSETOWN:
227 return (fsetown(*(int *)data, &logsoftc.sc_sigio));
228
229 case FIOGETOWN:
230 *(int *)data = fgetown(&logsoftc.sc_sigio);
231 break;
232
233 /* This is deprecated, FIOSETOWN should be used instead. */
234 case TIOCSPGRP:
235 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
236
237 /* This is deprecated, FIOGETOWN should be used instead */
238 case TIOCGPGRP:
239 *(int *)data = -fgetown(&logsoftc.sc_sigio);
240 break;
241
242 default:
243 return (ENOTTY);
244 }
245 return (0);
246 }
247
248 static void
249 log_drvinit(void *unused)
250 {
251
252 make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
253 }
254
255 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)
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