sys/kern/subr_log.c

   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)