subr_log.c

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    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  */
   35 
   36 /*
   37  * Error log buffer for kernel printf's.
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD: releng/5.2/sys/kern/subr_log.c 122352 2003-11-09 09:17:26Z tanimura $");
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/conf.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 
   57 #define LOG_RDPRI       (PZERO + 1)
   58 
   59 #define LOG_ASYNC       0x04
   60 #define LOG_RDWAIT      0x08
   61 
   62 static  d_open_t        logopen;
   63 static  d_close_t       logclose;
   64 static  d_read_t        logread;
   65 static  d_ioctl_t       logioctl;
   66 static  d_poll_t        logpoll;
   67 
   68 static  void logtimeout(void *arg);
   69 
   70 #define CDEV_MAJOR 7
   71 static struct cdevsw log_cdevsw = {
   72         .d_open =       logopen,
   73         .d_close =      logclose,
   74         .d_read =       logread,
   75         .d_ioctl =      logioctl,
   76         .d_poll =       logpoll,
   77         .d_name =       "log",
   78         .d_maj =        CDEV_MAJOR,
   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(dev_t dev, int flags, int mode, struct thread *td)
   98 {
   99         if (log_open)
  100                 return (EBUSY);
  101         log_open = 1;
  102         callout_init(&logsoftc.sc_callout, 0);
  103         fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio);        /* signal process only */
  104         if (log_wakeups_per_second < 1) {
  105                 printf("syslog wakeup is less than one.  Adjusting to 1.\n");
  106                 log_wakeups_per_second = 1;
  107         }
  108         callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
  109             logtimeout, NULL);
  110         return (0);
  111 }
  112 
  113 /*ARGSUSED*/
  114 static  int
  115 logclose(dev_t dev, int flag, int mode, struct thread *td)
  116 {
  117 
  118         log_open = 0;
  119         callout_stop(&logsoftc.sc_callout);
  120         logsoftc.sc_state = 0;
  121         funsetown(&logsoftc.sc_sigio);
  122         return (0);
  123 }
  124 
  125 /*ARGSUSED*/
  126 static  int
  127 logread(dev_t dev, struct uio *uio, int flag)
  128 {
  129         char buf[128];
  130         struct msgbuf *mbp = msgbufp;
  131         int error = 0, l, s;
  132 
  133         s = splhigh();
  134         while (msgbuf_getcount(mbp) == 0) {
  135                 if (flag & IO_NDELAY) {
  136                         splx(s);
  137                         return (EWOULDBLOCK);
  138                 }
  139                 logsoftc.sc_state |= LOG_RDWAIT;
  140                 if ((error = tsleep(mbp, LOG_RDPRI | PCATCH, "klog", 0))) {
  141                         splx(s);
  142                         return (error);
  143                 }
  144         }
  145         splx(s);
  146         logsoftc.sc_state &= ~LOG_RDWAIT;
  147 
  148         while (uio->uio_resid > 0) {
  149                 l = imin(sizeof(buf), uio->uio_resid);
  150                 l = msgbuf_getbytes(mbp, buf, l);
  151                 if (l == 0)
  152                         break;
  153                 error = uiomove(buf, l, uio);
  154                 if (error)
  155                         break;
  156         }
  157         return (error);
  158 }
  159 
  160 /*ARGSUSED*/
  161 static  int
  162 logpoll(dev_t dev, int events, struct thread *td)
  163 {
  164         int s;
  165         int revents = 0;
  166 
  167         s = splhigh();
  168 
  169         if (events & (POLLIN | POLLRDNORM)) {
  170                 if (msgbuf_getcount(msgbufp) > 0)
  171                         revents |= events & (POLLIN | POLLRDNORM);
  172                 else
  173                         selrecord(td, &logsoftc.sc_selp);
  174         }
  175         splx(s);
  176         return (revents);
  177 }
  178 
  179 static void
  180 logtimeout(void *arg)
  181 {
  182 
  183         if (!log_open)
  184                 return;
  185         if (log_wakeups_per_second < 1) {
  186                 printf("syslog wakeup is less than one.  Adjusting to 1.\n");
  187                 log_wakeups_per_second = 1;
  188         }
  189         if (msgbuftrigger == 0) {
  190                 callout_reset(&logsoftc.sc_callout,
  191                     hz / log_wakeups_per_second, logtimeout, NULL);
  192                 return;
  193         }
  194         msgbuftrigger = 0;
  195         selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
  196         if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
  197                 pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
  198         if (logsoftc.sc_state & LOG_RDWAIT) {
  199                 wakeup(msgbufp);
  200                 logsoftc.sc_state &= ~LOG_RDWAIT;
  201         }
  202         callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
  203             logtimeout, NULL);
  204 }
  205 
  206 /*ARGSUSED*/
  207 static  int
  208 logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct thread *td)
  209 {
  210 
  211         switch (com) {
  212 
  213         /* return number of characters immediately available */
  214         case FIONREAD:
  215                 *(int *)data = msgbuf_getcount(msgbufp);
  216                 break;
  217 
  218         case FIONBIO:
  219                 break;
  220 
  221         case FIOASYNC:
  222                 if (*(int *)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 *)data, &logsoftc.sc_sigio));
  230 
  231         case FIOGETOWN:
  232                 *(int *)data = fgetown(&logsoftc.sc_sigio);
  233                 break;
  234 
  235         /* This is deprecated, FIOSETOWN should be used instead. */
  236         case TIOCSPGRP:
  237                 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
  238 
  239         /* This is deprecated, FIOGETOWN should be used instead */
  240         case TIOCGPGRP:
  241                 *(int *)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 
  254         make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
  255 }
  256 
  257 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)

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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_log.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_log.c