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 1.10 2006/07/28 02:17:40 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/device.h> 46 #include <sys/proc.h> 47 #include <sys/vnode.h> 48 #include <sys/filio.h> 49 #include <sys/ttycom.h> 50 #include <sys/msgbuf.h> 51 #include <sys/signalvar.h> 52 #include <sys/kernel.h> 53 #include <sys/event.h> 54 #include <sys/filedesc.h> 55 #include <sys/sysctl.h> 56 #include <sys/thread2.h> 57 58 #define LOG_ASYNC 0x04 59 #define LOG_RDWAIT 0x08 60 61 static d_open_t logopen; 62 static d_close_t logclose; 63 static d_read_t logread; 64 static d_ioctl_t logioctl; 65 static d_kqfilter_t logkqfilter; 66 67 static void logtimeout(void *arg); 68 static void logfiltdetach(struct knote *kn); 69 static int logfiltread(struct knote *kn, long hint); 70 71 #define CDEV_MAJOR 7 72 static struct dev_ops log_ops = { 73 { "log", CDEV_MAJOR, D_KQFILTER }, 74 .d_open = logopen, 75 .d_close = logclose, 76 .d_read = logread, 77 .d_ioctl = logioctl, 78 .d_kqfilter = logkqfilter 79 }; 80 81 static struct logsoftc { 82 int sc_state; /* see above for possibilities */ 83 struct selinfo sc_selp; /* process waiting on select call */ 84 struct sigio *sc_sigio; /* information for async I/O */ 85 struct callout sc_callout; /* callout to wakeup syslog */ 86 } logsoftc; 87 88 int log_open; /* also used in log() */ 89 90 /* Times per second to check for a pending syslog wakeup. */ 91 static int log_wakeups_per_second = 5; 92 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW, 93 &log_wakeups_per_second, 0, ""); 94 95 /*ARGSUSED*/ 96 static int 97 logopen(struct dev_open_args *ap) 98 { 99 struct proc *p = curproc; 100 101 KKASSERT(p != NULL); 102 if (log_open) 103 return (EBUSY); 104 log_open = 1; 105 callout_init(&logsoftc.sc_callout); 106 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */ 107 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second, 108 logtimeout, NULL); 109 return (0); 110 } 111 112 /*ARGSUSED*/ 113 static int 114 logclose(struct dev_close_args *ap) 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 dev_read_args *ap) 126 { 127 struct uio *uio = ap->a_uio; 128 struct msgbuf *mbp = msgbufp; 129 long l; 130 int error = 0; 131 132 crit_enter(); 133 while (mbp->msg_bufr == mbp->msg_bufx) { 134 if (ap->a_ioflag & IO_NDELAY) { 135 crit_exit(); 136 return (EWOULDBLOCK); 137 } 138 logsoftc.sc_state |= LOG_RDWAIT; 139 if ((error = tsleep((caddr_t)mbp, PCATCH, "klog", 0))) { 140 crit_exit(); 141 return (error); 142 } 143 } 144 crit_exit(); 145 logsoftc.sc_state &= ~LOG_RDWAIT; 146 147 while (uio->uio_resid > 0) { 148 l = (long)mbp->msg_bufx - (long)mbp->msg_bufr; 149 if (l < 0) 150 l = mbp->msg_size - mbp->msg_bufr; 151 l = (long)szmin(l, uio->uio_resid); 152 if (l == 0) 153 break; 154 error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr, 155 (size_t)l, uio); 156 if (error) 157 break; 158 mbp->msg_bufr += l; 159 if (mbp->msg_bufr >= mbp->msg_size) 160 mbp->msg_bufr = 0; 161 } 162 return (error); 163 } 164 165 static struct filterops logread_filtops = 166 { 1, NULL, logfiltdetach, logfiltread }; 167 168 static int 169 logkqfilter(struct dev_kqfilter_args *ap) 170 { 171 struct knote *kn = ap->a_kn; 172 struct klist *klist = &logsoftc.sc_selp.si_note; 173 174 ap->a_result = 0; 175 switch (kn->kn_filter) { 176 case EVFILT_READ: 177 kn->kn_fop = &logread_filtops; 178 break; 179 default: 180 ap->a_result = EOPNOTSUPP; 181 return (0); 182 } 183 184 crit_enter(); 185 SLIST_INSERT_HEAD(klist, kn, kn_selnext); 186 crit_exit(); 187 188 return (0); 189 } 190 191 static void 192 logfiltdetach(struct knote *kn) 193 { 194 struct klist *klist = &logsoftc.sc_selp.si_note; 195 196 crit_enter(); 197 SLIST_REMOVE(klist, kn, knote, kn_selnext); 198 crit_exit(); 199 } 200 201 static int 202 logfiltread(struct knote *kn, long hint) 203 { 204 int ret = 0; 205 206 crit_enter(); 207 if (msgbufp->msg_bufr != msgbufp->msg_bufx) 208 ret = 1; 209 crit_exit(); 210 211 return (ret); 212 } 213 214 static void 215 logtimeout(void *arg) 216 { 217 218 if (!log_open) 219 return; 220 if (msgbuftrigger == 0) { 221 callout_reset(&logsoftc.sc_callout, 222 hz / log_wakeups_per_second, logtimeout, NULL); 223 return; 224 } 225 msgbuftrigger = 0; 226 selwakeup(&logsoftc.sc_selp); 227 KNOTE(&logsoftc.sc_selp.si_note, 0); 228 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL) 229 pgsigio(logsoftc.sc_sigio, SIGIO, 0); 230 if (logsoftc.sc_state & LOG_RDWAIT) { 231 wakeup((caddr_t)msgbufp); 232 logsoftc.sc_state &= ~LOG_RDWAIT; 233 } 234 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second, 235 logtimeout, NULL); 236 } 237 238 /*ARGSUSED*/ 239 static int 240 logioctl(struct dev_ioctl_args *ap) 241 { 242 long l; 243 244 switch (ap->a_cmd) { 245 case FIONREAD: 246 /* return number of characters immediately available */ 247 crit_enter(); 248 l = msgbufp->msg_bufx - msgbufp->msg_bufr; 249 crit_exit(); 250 if (l < 0) 251 l += msgbufp->msg_size; 252 *(int *)ap->a_data = l; 253 break; 254 255 case FIOASYNC: 256 if (*(int *)ap->a_data) 257 logsoftc.sc_state |= LOG_ASYNC; 258 else 259 logsoftc.sc_state &= ~LOG_ASYNC; 260 break; 261 262 case FIOSETOWN: 263 return (fsetown(*(int *)ap->a_data, &logsoftc.sc_sigio)); 264 265 case FIOGETOWN: 266 *(int *)ap->a_data = fgetown(logsoftc.sc_sigio); 267 break; 268 269 /* This is deprecated, FIOSETOWN should be used instead. */ 270 case TIOCSPGRP: 271 return (fsetown(-(*(int *)ap->a_data), &logsoftc.sc_sigio)); 272 273 /* This is deprecated, FIOGETOWN should be used instead */ 274 case TIOCGPGRP: 275 *(int *)ap->a_data = -fgetown(logsoftc.sc_sigio); 276 break; 277 278 default: 279 return (ENOTTY); 280 } 281 return (0); 282 } 283 284 static void 285 log_drvinit(void *unused) 286 { 287 make_dev(&log_ops, 0, UID_ROOT, GID_WHEEL, 0600, "klog"); 288 } 289 290 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL) 291