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/poll.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_poll_t logpoll; 66 67 static void logtimeout(void *arg); 68 69 #define CDEV_MAJOR 7 70 static struct dev_ops log_ops = { 71 { "log", CDEV_MAJOR, 0 }, 72 .d_open = logopen, 73 .d_close = logclose, 74 .d_read = logread, 75 .d_ioctl = logioctl, 76 .d_poll = logpoll, 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 dev_open_args *ap) 96 { 97 struct proc *p = curproc; 98 99 KKASSERT(p != NULL); 100 if (log_open) 101 return (EBUSY); 102 log_open = 1; 103 callout_init(&logsoftc.sc_callout); 104 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */ 105 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second, 106 logtimeout, NULL); 107 return (0); 108 } 109 110 /*ARGSUSED*/ 111 static int 112 logclose(struct dev_close_args *ap) 113 { 114 log_open = 0; 115 callout_stop(&logsoftc.sc_callout); 116 logsoftc.sc_state = 0; 117 funsetown(logsoftc.sc_sigio); 118 return (0); 119 } 120 121 /*ARGSUSED*/ 122 static int 123 logread(struct dev_read_args *ap) 124 { 125 struct uio *uio = ap->a_uio; 126 struct msgbuf *mbp = msgbufp; 127 long l; 128 int error = 0; 129 130 crit_enter(); 131 while (mbp->msg_bufr == mbp->msg_bufx) { 132 if (ap->a_ioflag & IO_NDELAY) { 133 crit_exit(); 134 return (EWOULDBLOCK); 135 } 136 logsoftc.sc_state |= LOG_RDWAIT; 137 if ((error = tsleep((caddr_t)mbp, PCATCH, "klog", 0))) { 138 crit_exit(); 139 return (error); 140 } 141 } 142 crit_exit(); 143 logsoftc.sc_state &= ~LOG_RDWAIT; 144 145 while (uio->uio_resid > 0) { 146 l = mbp->msg_bufx - mbp->msg_bufr; 147 if (l < 0) 148 l = mbp->msg_size - mbp->msg_bufr; 149 l = (long)szmin(l, uio->uio_resid); 150 if (l == 0) 151 break; 152 error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr, 153 (size_t)l, uio); 154 if (error) 155 break; 156 mbp->msg_bufr += l; 157 if (mbp->msg_bufr >= mbp->msg_size) 158 mbp->msg_bufr = 0; 159 } 160 return (error); 161 } 162 163 /*ARGSUSED*/ 164 static int 165 logpoll(struct dev_poll_args *ap) 166 { 167 int revents = 0; 168 169 crit_enter(); 170 if (ap->a_events & (POLLIN | POLLRDNORM)) { 171 if (msgbufp->msg_bufr != msgbufp->msg_bufx) 172 revents |= ap->a_events & (POLLIN | POLLRDNORM); 173 else 174 selrecord(curthread, &logsoftc.sc_selp); 175 } 176 crit_exit(); 177 ap->a_events = revents; 178 return (0); 179 } 180 181 static void 182 logtimeout(void *arg) 183 { 184 185 if (!log_open) 186 return; 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 selwakeup(&logsoftc.sc_selp); 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((caddr_t)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 dev_ioctl_args *ap) 207 { 208 long l; 209 210 switch (ap->a_cmd) { 211 case FIONREAD: 212 /* return number of characters immediately available */ 213 crit_enter(); 214 l = msgbufp->msg_bufx - msgbufp->msg_bufr; 215 crit_exit(); 216 if (l < 0) 217 l += msgbufp->msg_size; 218 *(int *)ap->a_data = l; 219 break; 220 221 case FIOASYNC: 222 if (*(int *)ap->a_data) 223 logsoftc.sc_state |= LOG_ASYNC; 224 else 225 logsoftc.sc_state &= ~LOG_ASYNC; 226 break; 227 228 case FIOSETOWN: 229 return (fsetown(*(int *)ap->a_data, &logsoftc.sc_sigio)); 230 231 case FIOGETOWN: 232 *(int *)ap->a_data = fgetown(logsoftc.sc_sigio); 233 break; 234 235 /* This is deprecated, FIOSETOWN should be used instead. */ 236 case TIOCSPGRP: 237 return (fsetown(-(*(int *)ap->a_data), &logsoftc.sc_sigio)); 238 239 /* This is deprecated, FIOGETOWN should be used instead */ 240 case TIOCGPGRP: 241 *(int *)ap->a_data = -fgetown(logsoftc.sc_sigio); 242 break; 243 244 default: 245 return (ENOTTY); 246 } 247 return (0); 248 } 249 250 static void 251 log_drvinit(void *unused) 252 { 253 make_dev(&log_ops, 0, UID_ROOT, GID_WHEEL, 0600, "klog"); 254 } 255 256 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL) 257