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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)subr_log.c 8.1 (Berkeley) 6/10/93 34 * $FreeBSD: src/sys/kern/subr_log.c,v 1.39.2.2 2001/06/02 08:11:25 phk Exp $ 35 * $DragonFly: src/sys/kern/subr_log.c,v 1.7 2004/05/19 22:52:58 dillon Exp $ 36 */ 37 38 /* 39 * Error log buffer for kernel printf's. 40 */ 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/conf.h> 45 #include <sys/proc.h> 46 #include <sys/vnode.h> 47 #include <sys/filio.h> 48 #include <sys/ttycom.h> 49 #include <sys/msgbuf.h> 50 #include <sys/signalvar.h> 51 #include <sys/kernel.h> 52 #include <sys/poll.h> 53 #include <sys/filedesc.h> 54 #include <sys/sysctl.h> 55 56 #define LOG_ASYNC 0x04 57 #define LOG_RDWAIT 0x08 58 59 static d_open_t logopen; 60 static d_close_t logclose; 61 static d_read_t logread; 62 static d_ioctl_t logioctl; 63 static d_poll_t logpoll; 64 65 static void logtimeout(void *arg); 66 67 #define CDEV_MAJOR 7 68 static struct cdevsw log_cdevsw = { 69 /* name */ "log", 70 /* maj */ CDEV_MAJOR, 71 /* flags */ 0, 72 /* port */ NULL, 73 /* clone */ NULL, 74 75 /* open */ logopen, 76 /* close */ logclose, 77 /* read */ logread, 78 /* write */ nowrite, 79 /* ioctl */ logioctl, 80 /* poll */ logpoll, 81 /* mmap */ nommap, 82 /* strategy */ nostrategy, 83 /* dump */ nodump, 84 /* psize */ nopsize 85 }; 86 87 static 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 94 int log_open; /* also used in log() */ 95 96 /* Times per second to check for a pending syslog wakeup. */ 97 static int log_wakeups_per_second = 5; 98 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW, 99 &log_wakeups_per_second, 0, ""); 100 101 /*ARGSUSED*/ 102 static int 103 logopen(dev_t dev, int flags, int mode, struct thread *td) 104 { 105 struct proc *p = td->td_proc; 106 107 KKASSERT(p != NULL); 108 if (log_open) 109 return (EBUSY); 110 log_open = 1; 111 callout_init(&logsoftc.sc_callout); 112 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */ 113 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second, 114 logtimeout, NULL); 115 return (0); 116 } 117 118 /*ARGSUSED*/ 119 static int 120 logclose(dev_t dev, int flag, int mode, struct thread *td) 121 { 122 123 log_open = 0; 124 callout_stop(&logsoftc.sc_callout); 125 logsoftc.sc_state = 0; 126 funsetown(logsoftc.sc_sigio); 127 return (0); 128 } 129 130 /*ARGSUSED*/ 131 static int 132 logread(dev_t dev, struct uio *uio, int flag) 133 { 134 struct msgbuf *mbp = msgbufp; 135 long l; 136 int s; 137 int error = 0; 138 139 s = splhigh(); 140 while (mbp->msg_bufr == mbp->msg_bufx) { 141 if (flag & IO_NDELAY) { 142 splx(s); 143 return (EWOULDBLOCK); 144 } 145 logsoftc.sc_state |= LOG_RDWAIT; 146 if ((error = tsleep((caddr_t)mbp, PCATCH, "klog", 0))) { 147 splx(s); 148 return (error); 149 } 150 } 151 splx(s); 152 logsoftc.sc_state &= ~LOG_RDWAIT; 153 154 while (uio->uio_resid > 0) { 155 l = mbp->msg_bufx - mbp->msg_bufr; 156 if (l < 0) 157 l = mbp->msg_size - mbp->msg_bufr; 158 l = min(l, uio->uio_resid); 159 if (l == 0) 160 break; 161 error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr, 162 (int)l, uio); 163 if (error) 164 break; 165 mbp->msg_bufr += l; 166 if (mbp->msg_bufr >= mbp->msg_size) 167 mbp->msg_bufr = 0; 168 } 169 return (error); 170 } 171 172 /*ARGSUSED*/ 173 static int 174 logpoll(dev_t dev, int events, struct thread *td) 175 { 176 int s; 177 int revents = 0; 178 179 s = splhigh(); 180 181 if (events & (POLLIN | POLLRDNORM)) { 182 if (msgbufp->msg_bufr != msgbufp->msg_bufx) 183 revents |= events & (POLLIN | POLLRDNORM); 184 else 185 selrecord(td, &logsoftc.sc_selp); 186 } 187 splx(s); 188 return (revents); 189 } 190 191 static void 192 logtimeout(void *arg) 193 { 194 195 if (!log_open) 196 return; 197 if (msgbuftrigger == 0) { 198 callout_reset(&logsoftc.sc_callout, 199 hz / log_wakeups_per_second, logtimeout, NULL); 200 return; 201 } 202 msgbuftrigger = 0; 203 selwakeup(&logsoftc.sc_selp); 204 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL) 205 pgsigio(logsoftc.sc_sigio, SIGIO, 0); 206 if (logsoftc.sc_state & LOG_RDWAIT) { 207 wakeup((caddr_t)msgbufp); 208 logsoftc.sc_state &= ~LOG_RDWAIT; 209 } 210 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second, 211 logtimeout, NULL); 212 } 213 214 /*ARGSUSED*/ 215 static int 216 logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct thread *td) 217 { 218 long l; 219 int s; 220 221 switch (com) { 222 223 /* return number of characters immediately available */ 224 case FIONREAD: 225 s = splhigh(); 226 l = msgbufp->msg_bufx - msgbufp->msg_bufr; 227 splx(s); 228 if (l < 0) 229 l += msgbufp->msg_size; 230 *(int *)data = l; 231 break; 232 233 case FIONBIO: 234 break; 235 236 case FIOASYNC: 237 if (*(int *)data) 238 logsoftc.sc_state |= LOG_ASYNC; 239 else 240 logsoftc.sc_state &= ~LOG_ASYNC; 241 break; 242 243 case FIOSETOWN: 244 return (fsetown(*(int *)data, &logsoftc.sc_sigio)); 245 246 case FIOGETOWN: 247 *(int *)data = fgetown(logsoftc.sc_sigio); 248 break; 249 250 /* This is deprecated, FIOSETOWN should be used instead. */ 251 case TIOCSPGRP: 252 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio)); 253 254 /* This is deprecated, FIOGETOWN should be used instead */ 255 case TIOCGPGRP: 256 *(int *)data = -fgetown(logsoftc.sc_sigio); 257 break; 258 259 default: 260 return (ENOTTY); 261 } 262 return (0); 263 } 264 265 static void 266 log_drvinit(void *unused) 267 { 268 cdevsw_add(&log_cdevsw, 0, 0); 269 make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog"); 270 } 271 272 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL) 273