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  * $FreeBSD$
   35  */
   36 
   37 /*
   38  * Error log buffer for kernel printf's.
   39  */
   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 #define LOG_RDWAIT      0x08
   59 
   60 static  d_open_t        logopen;
   61 static  d_close_t       logclose;
   62 static  d_read_t        logread;
   63 static  d_ioctl_t       logioctl;
   64 static  d_poll_t        logpoll;
   65 
   66 static  void logtimeout(void *arg);
   67 
   68 #define CDEV_MAJOR 7
   69 static struct cdevsw log_cdevsw = {
   70         /* open */      logopen,
   71         /* close */     logclose,
   72         /* read */      logread,
   73         /* write */     nowrite,
   74         /* ioctl */     logioctl,
   75         /* poll */      logpoll,
   76         /* mmap */      nommap,
   77         /* strategy */  nostrategy,
   78         /* name */      "log",
   79         /* maj */       CDEV_MAJOR,
   80         /* dump */      nodump,
   81         /* psize */     nopsize,
   82         /* flags */     0,
   83         /* bmaj */      -1
   84 };
   85 
   86 static struct logsoftc {
   87         int     sc_state;               /* see above for possibilities */
   88         struct  selinfo sc_selp;        /* process waiting on select call */
   89         struct  sigio *sc_sigio;        /* information for async I/O */
   90         struct  callout sc_callout;     /* callout to wakeup syslog  */
   91 } logsoftc;
   92 
   93 int     log_open;                       /* also used in log() */
   94 
   95 /* Times per second to check for a pending syslog wakeup. */
   96 static int      log_wakeups_per_second = 5;
   97 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
   98     &log_wakeups_per_second, 0, "");
   99 
  100 /*ARGSUSED*/
  101 static  int
  102 logopen(dev_t dev, int flags, int mode, struct proc *p)
  103 {
  104         if (log_open)
  105                 return (EBUSY);
  106         log_open = 1;
  107         callout_init(&logsoftc.sc_callout);
  108         fsetown(p->p_pid, &logsoftc.sc_sigio);  /* signal process only */
  109         callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
  110             logtimeout, NULL);
  111         return (0);
  112 }
  113 
  114 /*ARGSUSED*/
  115 static  int
  116 logclose(dev_t dev, int flag, int mode, struct proc *p)
  117 {
  118 
  119         log_open = 0;
  120         callout_stop(&logsoftc.sc_callout);
  121         logsoftc.sc_state = 0;
  122         funsetown(logsoftc.sc_sigio);
  123         return (0);
  124 }
  125 
  126 /*ARGSUSED*/
  127 static  int
  128 logread(dev_t dev, struct uio *uio, int flag)
  129 {
  130         struct msgbuf *mbp = msgbufp;
  131         long l;
  132         int s;
  133         int error = 0;
  134 
  135         s = splhigh();
  136         while (mbp->msg_bufr == mbp->msg_bufx) {
  137                 if (flag & IO_NDELAY) {
  138                         splx(s);
  139                         return (EWOULDBLOCK);
  140                 }
  141                 logsoftc.sc_state |= LOG_RDWAIT;
  142                 if ((error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
  143                     "klog", 0))) {
  144                         splx(s);
  145                         return (error);
  146                 }
  147         }
  148         splx(s);
  149         logsoftc.sc_state &= ~LOG_RDWAIT;
  150 
  151         while (uio->uio_resid > 0) {
  152                 l = mbp->msg_bufx - mbp->msg_bufr;
  153                 if (l < 0)
  154                         l = mbp->msg_size - mbp->msg_bufr;
  155                 l = min(l, uio->uio_resid);
  156                 if (l == 0)
  157                         break;
  158                 error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr,
  159                     (int)l, uio);
  160                 if (error)
  161                         break;
  162                 mbp->msg_bufr += l;
  163                 if (mbp->msg_bufr >= mbp->msg_size)
  164                         mbp->msg_bufr = 0;
  165         }
  166         return (error);
  167 }
  168 
  169 /*ARGSUSED*/
  170 static  int
  171 logpoll(dev_t dev, int events, struct proc *p)
  172 {
  173         int s;
  174         int revents = 0;
  175 
  176         s = splhigh();
  177 
  178         if (events & (POLLIN | POLLRDNORM)) {
  179                 if (msgbufp->msg_bufr != msgbufp->msg_bufx)
  180                         revents |= events & (POLLIN | POLLRDNORM);
  181                 else
  182                         selrecord(p, &logsoftc.sc_selp);
  183         }
  184         splx(s);
  185         return (revents);
  186 }
  187 
  188 static void
  189 logtimeout(void *arg)
  190 {
  191 
  192         if (!log_open)
  193                 return;
  194         if (msgbuftrigger == 0) {
  195                 callout_reset(&logsoftc.sc_callout,
  196                     hz / log_wakeups_per_second, logtimeout, NULL);
  197                 return;
  198         }
  199         msgbuftrigger = 0;
  200         selwakeup(&logsoftc.sc_selp);
  201         if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
  202                 pgsigio(logsoftc.sc_sigio, SIGIO, 0);
  203         if (logsoftc.sc_state & LOG_RDWAIT) {
  204                 wakeup((caddr_t)msgbufp);
  205                 logsoftc.sc_state &= ~LOG_RDWAIT;
  206         }
  207         callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
  208             logtimeout, NULL);
  209 }
  210 
  211 /*ARGSUSED*/
  212 static  int
  213 logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
  214 {
  215         long l;
  216         int s;
  217 
  218         switch (com) {
  219 
  220         /* return number of characters immediately available */
  221         case FIONREAD:
  222                 s = splhigh();
  223                 l = msgbufp->msg_bufx - msgbufp->msg_bufr;
  224                 splx(s);
  225                 if (l < 0)
  226                         l += msgbufp->msg_size;
  227                 *(int *)data = l;
  228                 break;
  229 
  230         case FIONBIO:
  231                 break;
  232 
  233         case FIOASYNC:
  234                 if (*(int *)data)
  235                         logsoftc.sc_state |= LOG_ASYNC;
  236                 else
  237                         logsoftc.sc_state &= ~LOG_ASYNC;
  238                 break;
  239 
  240         case FIOSETOWN:
  241                 return (fsetown(*(int *)data, &logsoftc.sc_sigio));
  242 
  243         case FIOGETOWN:
  244                 *(int *)data = fgetown(logsoftc.sc_sigio);
  245                 break;
  246 
  247         /* This is deprecated, FIOSETOWN should be used instead. */
  248         case TIOCSPGRP:
  249                 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
  250 
  251         /* This is deprecated, FIOGETOWN should be used instead */
  252         case TIOCGPGRP:
  253                 *(int *)data = -fgetown(logsoftc.sc_sigio);
  254                 break;
  255 
  256         default:
  257                 return (ENOTTY);
  258         }
  259         return (0);
  260 }
  261 
  262 static void
  263 log_drvinit(void *unused)
  264 {
  265 
  266         make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
  267 }
  268 
  269 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