1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 8.1 (Berkeley) 6/10/93 32 */ 33 34 /* 35 * Error log buffer for kernel printf's. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/conf.h> 44 #include <sys/proc.h> 45 #include <sys/vnode.h> 46 #include <sys/filio.h> 47 #include <sys/ttycom.h> 48 #include <sys/msgbuf.h> 49 #include <sys/signalvar.h> 50 #include <sys/kernel.h> 51 #include <sys/poll.h> 52 #include <sys/filedesc.h> 53 #include <sys/sysctl.h> 54 55 #define LOG_RDPRI (PZERO + 1) 56 57 #define LOG_ASYNC 0x04 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 static d_kqfilter_t logkqfilter; 65 66 static void logtimeout(void *arg); 67 68 static struct cdevsw log_cdevsw = { 69 .d_version = D_VERSION, 70 .d_open = logopen, 71 .d_close = logclose, 72 .d_read = logread, 73 .d_ioctl = logioctl, 74 .d_poll = logpoll, 75 .d_kqfilter = logkqfilter, 76 .d_name = "log", 77 }; 78 79 static int logkqread(struct knote *note, long hint); 80 static void logkqdetach(struct knote *note); 81 82 static struct filterops log_read_filterops = { 83 .f_isfd = 1, 84 .f_attach = NULL, 85 .f_detach = logkqdetach, 86 .f_event = logkqread, 87 }; 88 89 static struct logsoftc { 90 int sc_state; /* see above for possibilities */ 91 struct selinfo sc_selp; /* process waiting on select call */ 92 struct sigio *sc_sigio; /* information for async I/O */ 93 struct callout sc_callout; /* callout to wakeup syslog */ 94 } logsoftc; 95 96 int log_open; /* also used in log() */ 97 static struct cv log_wakeup; 98 struct mtx msgbuf_lock; 99 MTX_SYSINIT(msgbuf_lock, &msgbuf_lock, "msgbuf lock", MTX_DEF); 100 101 static int log_wakeups_per_second = 5; 102 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW, 103 &log_wakeups_per_second, 0, 104 "How often (times per second) to check for /dev/log waiters."); 105 106 /*ARGSUSED*/ 107 static int 108 logopen(struct cdev *dev, int flags, int mode, struct thread *td) 109 { 110 111 if (log_wakeups_per_second < 1) { 112 printf("syslog wakeup is less than one. Adjusting to 1.\n"); 113 log_wakeups_per_second = 1; 114 } 115 116 mtx_lock(&msgbuf_lock); 117 if (log_open) { 118 mtx_unlock(&msgbuf_lock); 119 return (EBUSY); 120 } 121 log_open = 1; 122 callout_reset_sbt(&logsoftc.sc_callout, 123 SBT_1S / log_wakeups_per_second, 0, logtimeout, NULL, C_PREL(1)); 124 mtx_unlock(&msgbuf_lock); 125 126 fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */ 127 return (0); 128 } 129 130 /*ARGSUSED*/ 131 static int 132 logclose(struct cdev *dev, int flag, int mode, struct thread *td) 133 { 134 135 funsetown(&logsoftc.sc_sigio); 136 137 mtx_lock(&msgbuf_lock); 138 callout_stop(&logsoftc.sc_callout); 139 logsoftc.sc_state = 0; 140 log_open = 0; 141 mtx_unlock(&msgbuf_lock); 142 143 return (0); 144 } 145 146 /*ARGSUSED*/ 147 static int 148 logread(struct cdev *dev, struct uio *uio, int flag) 149 { 150 char buf[128]; 151 struct msgbuf *mbp = msgbufp; 152 int error = 0, l; 153 154 mtx_lock(&msgbuf_lock); 155 while (msgbuf_getcount(mbp) == 0) { 156 if (flag & IO_NDELAY) { 157 mtx_unlock(&msgbuf_lock); 158 return (EWOULDBLOCK); 159 } 160 if ((error = cv_wait_sig(&log_wakeup, &msgbuf_lock)) != 0) { 161 mtx_unlock(&msgbuf_lock); 162 return (error); 163 } 164 } 165 166 while (uio->uio_resid > 0) { 167 l = imin(sizeof(buf), uio->uio_resid); 168 l = msgbuf_getbytes(mbp, buf, l); 169 if (l == 0) 170 break; 171 mtx_unlock(&msgbuf_lock); 172 error = uiomove(buf, l, uio); 173 if (error || uio->uio_resid == 0) 174 return (error); 175 mtx_lock(&msgbuf_lock); 176 } 177 mtx_unlock(&msgbuf_lock); 178 return (error); 179 } 180 181 /*ARGSUSED*/ 182 static int 183 logpoll(struct cdev *dev, int events, struct thread *td) 184 { 185 int revents = 0; 186 187 if (events & (POLLIN | POLLRDNORM)) { 188 mtx_lock(&msgbuf_lock); 189 if (msgbuf_getcount(msgbufp) > 0) 190 revents |= events & (POLLIN | POLLRDNORM); 191 else 192 selrecord(td, &logsoftc.sc_selp); 193 mtx_unlock(&msgbuf_lock); 194 } 195 return (revents); 196 } 197 198 static int 199 logkqfilter(struct cdev *dev, struct knote *kn) 200 { 201 202 if (kn->kn_filter != EVFILT_READ) 203 return (EINVAL); 204 205 kn->kn_fop = &log_read_filterops; 206 kn->kn_hook = NULL; 207 208 mtx_lock(&msgbuf_lock); 209 knlist_add(&logsoftc.sc_selp.si_note, kn, 1); 210 mtx_unlock(&msgbuf_lock); 211 return (0); 212 } 213 214 static int 215 logkqread(struct knote *kn, long hint) 216 { 217 218 mtx_assert(&msgbuf_lock, MA_OWNED); 219 kn->kn_data = msgbuf_getcount(msgbufp); 220 return (kn->kn_data != 0); 221 } 222 223 static void 224 logkqdetach(struct knote *kn) 225 { 226 227 mtx_lock(&msgbuf_lock); 228 knlist_remove(&logsoftc.sc_selp.si_note, kn, 1); 229 mtx_unlock(&msgbuf_lock); 230 } 231 232 static void 233 logtimeout(void *arg) 234 { 235 236 if (!log_open) 237 return; 238 if (msgbuftrigger == 0) 239 goto done; 240 msgbuftrigger = 0; 241 selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI); 242 KNOTE_LOCKED(&logsoftc.sc_selp.si_note, 0); 243 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL) 244 pgsigio(&logsoftc.sc_sigio, SIGIO, 0); 245 cv_broadcastpri(&log_wakeup, LOG_RDPRI); 246 done: 247 if (log_wakeups_per_second < 1) { 248 printf("syslog wakeup is less than one. Adjusting to 1.\n"); 249 log_wakeups_per_second = 1; 250 } 251 callout_reset_sbt(&logsoftc.sc_callout, 252 SBT_1S / log_wakeups_per_second, 0, logtimeout, NULL, C_PREL(1)); 253 } 254 255 /*ARGSUSED*/ 256 static int 257 logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td) 258 { 259 260 switch (com) { 261 /* return number of characters immediately available */ 262 case FIONREAD: 263 *(int *)data = msgbuf_getcount(msgbufp); 264 break; 265 266 case FIONBIO: 267 break; 268 269 case FIOASYNC: 270 mtx_lock(&msgbuf_lock); 271 if (*(int *)data) 272 logsoftc.sc_state |= LOG_ASYNC; 273 else 274 logsoftc.sc_state &= ~LOG_ASYNC; 275 mtx_unlock(&msgbuf_lock); 276 break; 277 278 case FIOSETOWN: 279 return (fsetown(*(int *)data, &logsoftc.sc_sigio)); 280 281 case FIOGETOWN: 282 *(int *)data = fgetown(&logsoftc.sc_sigio); 283 break; 284 285 /* This is deprecated, FIOSETOWN should be used instead. */ 286 case TIOCSPGRP: 287 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio)); 288 289 /* This is deprecated, FIOGETOWN should be used instead */ 290 case TIOCGPGRP: 291 *(int *)data = -fgetown(&logsoftc.sc_sigio); 292 break; 293 294 default: 295 return (ENOTTY); 296 } 297 return (0); 298 } 299 300 static void 301 log_drvinit(void *unused) 302 { 303 304 cv_init(&log_wakeup, "klog"); 305 callout_init_mtx(&logsoftc.sc_callout, &msgbuf_lock, 0); 306 knlist_init_mtx(&logsoftc.sc_selp.si_note, &msgbuf_lock); 307 make_dev_credf(MAKEDEV_ETERNAL, &log_cdevsw, 0, NULL, UID_ROOT, 308 GID_WHEEL, 0600, "klog"); 309 } 310 311 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,log_drvinit,NULL); 312