1 /* $NetBSD: subr_log.c,v 1.36 2005/12/11 12:24:30 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)subr_log.c 8.3 (Berkeley) 2/14/95 32 */ 33 34 /* 35 * Error log buffer for kernel printf's. 36 */ 37 38 #include <sys/cdefs.h> 39 __KERNEL_RCSID(0, "$NetBSD: subr_log.c,v 1.36 2005/12/11 12:24:30 christos Exp $"); 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/proc.h> 44 #include <sys/vnode.h> 45 #include <sys/ioctl.h> 46 #include <sys/msgbuf.h> 47 #include <sys/file.h> 48 #include <sys/signalvar.h> 49 #include <sys/syslog.h> 50 #include <sys/conf.h> 51 #include <sys/select.h> 52 #include <sys/poll.h> 53 54 #define LOG_RDPRI (PZERO + 1) 55 56 #define LOG_ASYNC 0x04 57 #define LOG_RDWAIT 0x08 58 59 struct logsoftc { 60 int sc_state; /* see above for possibilities */ 61 struct selinfo sc_selp; /* process waiting on select call */ 62 pid_t sc_pgid; /* process/group for async I/O */ 63 } logsoftc; 64 65 int log_open; /* also used in log() */ 66 int msgbufmapped; /* is the message buffer mapped */ 67 int msgbufenabled; /* is logging to the buffer enabled */ 68 struct kern_msgbuf *msgbufp; /* the mapped buffer, itself. */ 69 70 void 71 initmsgbuf(void *bf, size_t bufsize) 72 { 73 struct kern_msgbuf *mbp; 74 long new_bufs; 75 76 /* Sanity-check the given size. */ 77 if (bufsize < sizeof(struct kern_msgbuf)) 78 return; 79 80 mbp = msgbufp = (struct kern_msgbuf *)bf; 81 82 new_bufs = bufsize - offsetof(struct kern_msgbuf, msg_bufc); 83 if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) || 84 (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) || 85 (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) { 86 /* 87 * If the buffer magic number is wrong, has changed 88 * size (which shouldn't happen often), or is 89 * internally inconsistent, initialize it. 90 */ 91 92 memset(bf, 0, bufsize); 93 mbp->msg_magic = MSG_MAGIC; 94 mbp->msg_bufs = new_bufs; 95 } 96 97 /* mark it as ready for use. */ 98 msgbufmapped = msgbufenabled = 1; 99 } 100 101 /*ARGSUSED*/ 102 static int 103 logopen(dev_t dev, int flags, int mode, struct lwp *l) 104 { 105 struct kern_msgbuf *mbp = msgbufp; 106 107 if (log_open) 108 return (EBUSY); 109 log_open = 1; 110 logsoftc.sc_pgid = l->l_proc->p_pid; /* signal process only */ 111 /* 112 * The message buffer is initialized during system configuration. 113 * If it's been clobbered, note that and return an error. (This 114 * allows a user to potentially read the buffer via /dev/kmem, 115 * and try to figure out what clobbered it. 116 */ 117 if (mbp->msg_magic != MSG_MAGIC) { 118 msgbufenabled = 0; 119 return (ENXIO); 120 } 121 122 return (0); 123 } 124 125 /*ARGSUSED*/ 126 static int 127 logclose(dev_t dev, int flag, int mode, struct lwp *l) 128 { 129 130 log_open = 0; 131 logsoftc.sc_state = 0; 132 return (0); 133 } 134 135 /*ARGSUSED*/ 136 static int 137 logread(dev_t dev, struct uio *uio, int flag) 138 { 139 struct kern_msgbuf *mbp = msgbufp; 140 long l; 141 int s; 142 int error = 0; 143 144 s = splhigh(); 145 while (mbp->msg_bufr == mbp->msg_bufx) { 146 if (flag & IO_NDELAY) { 147 splx(s); 148 return (EWOULDBLOCK); 149 } 150 logsoftc.sc_state |= LOG_RDWAIT; 151 error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH, 152 "klog", 0); 153 if (error) { 154 splx(s); 155 return (error); 156 } 157 } 158 splx(s); 159 logsoftc.sc_state &= ~LOG_RDWAIT; 160 161 while (uio->uio_resid > 0) { 162 l = mbp->msg_bufx - mbp->msg_bufr; 163 if (l < 0) 164 l = mbp->msg_bufs - mbp->msg_bufr; 165 l = min(l, uio->uio_resid); 166 if (l == 0) 167 break; 168 error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr], 169 (int)l, uio); 170 if (error) 171 break; 172 mbp->msg_bufr += l; 173 if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs) 174 mbp->msg_bufr = 0; 175 } 176 return (error); 177 } 178 179 /*ARGSUSED*/ 180 static int 181 logpoll(dev_t dev, int events, struct lwp *l) 182 { 183 int revents = 0; 184 int s = splhigh(); 185 186 if (events & (POLLIN | POLLRDNORM)) { 187 if (msgbufp->msg_bufr != msgbufp->msg_bufx) 188 revents |= events & (POLLIN | POLLRDNORM); 189 else 190 selrecord(l, &logsoftc.sc_selp); 191 } 192 193 splx(s); 194 return (revents); 195 } 196 197 static void 198 filt_logrdetach(struct knote *kn) 199 { 200 int s; 201 202 s = splhigh(); 203 SLIST_REMOVE(&logsoftc.sc_selp.sel_klist, kn, knote, kn_selnext); 204 splx(s); 205 } 206 207 static int 208 filt_logread(struct knote *kn, long hint) 209 { 210 211 if (msgbufp->msg_bufr == msgbufp->msg_bufx) 212 return (0); 213 214 if (msgbufp->msg_bufr < msgbufp->msg_bufx) 215 kn->kn_data = msgbufp->msg_bufx - msgbufp->msg_bufr; 216 else 217 kn->kn_data = (msgbufp->msg_bufs - msgbufp->msg_bufr) + 218 msgbufp->msg_bufx; 219 220 return (1); 221 } 222 223 static const struct filterops logread_filtops = 224 { 1, NULL, filt_logrdetach, filt_logread }; 225 226 static int 227 logkqfilter(dev_t dev, struct knote *kn) 228 { 229 struct klist *klist; 230 int s; 231 232 switch (kn->kn_filter) { 233 case EVFILT_READ: 234 klist = &logsoftc.sc_selp.sel_klist; 235 kn->kn_fop = &logread_filtops; 236 break; 237 238 default: 239 return (1); 240 } 241 242 kn->kn_hook = NULL; 243 244 s = splhigh(); 245 SLIST_INSERT_HEAD(klist, kn, kn_selnext); 246 splx(s); 247 248 return (0); 249 } 250 251 void 252 logwakeup(void) 253 { 254 if (!log_open) 255 return; 256 selnotify(&logsoftc.sc_selp, 0); 257 if (logsoftc.sc_state & LOG_ASYNC) 258 fownsignal(logsoftc.sc_pgid, SIGIO, 0, 0, NULL); 259 if (logsoftc.sc_state & LOG_RDWAIT) { 260 wakeup((caddr_t)msgbufp); 261 logsoftc.sc_state &= ~LOG_RDWAIT; 262 } 263 } 264 265 /*ARGSUSED*/ 266 static int 267 logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct lwp *lwp) 268 { 269 struct proc *p = lwp->l_proc; 270 long l; 271 int s; 272 273 switch (com) { 274 275 /* return number of characters immediately available */ 276 case FIONREAD: 277 s = splhigh(); 278 l = msgbufp->msg_bufx - msgbufp->msg_bufr; 279 splx(s); 280 if (l < 0) 281 l += msgbufp->msg_bufs; 282 *(int *)data = l; 283 break; 284 285 case FIONBIO: 286 break; 287 288 case FIOASYNC: 289 if (*(int *)data) 290 logsoftc.sc_state |= LOG_ASYNC; 291 else 292 logsoftc.sc_state &= ~LOG_ASYNC; 293 break; 294 295 case TIOCSPGRP: 296 case FIOSETOWN: 297 return fsetown(p, &logsoftc.sc_pgid, com, data); 298 299 case TIOCGPGRP: 300 case FIOGETOWN: 301 return fgetown(p, logsoftc.sc_pgid, com, data); 302 303 default: 304 return (EPASSTHROUGH); 305 } 306 return (0); 307 } 308 309 const struct cdevsw log_cdevsw = { 310 logopen, logclose, logread, nowrite, logioctl, 311 nostop, notty, logpoll, nommap, logkqfilter, 312 }; 313