sys/kern/subr_log.c

/*
 * Copyright (c) 1982, 1986 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      from: @(#)subr_log.c    7.11 (Berkeley) 3/17/91
 *      $Id$
 */

/*
 * Error log buffer for kernel printf's.
 */

#include "param.h"
#include "systm.h"
#include "proc.h"
#include "vnode.h"
#include "ioctl.h"
#include "msgbuf.h"
#include "file.h"

#define LOG_RDPRI       (PZERO + 1)

#define LOG_ASYNC       0x04
#define LOG_RDWAIT      0x08

struct logsoftc {
        int     sc_state;               /* see above for possibilities */
        pid_t   sc_sel;         /* pid of process waiting on select call 16 Jun 93 */
        int     sc_pgid;                /* process/group for async I/O */
} logsoftc;

int     log_open;                       /* also used in log() */

/*ARGSUSED*/
logopen(dev, flags, mode, p)
        dev_t dev;
        int flags, mode;
        struct proc *p;
{
        register struct msgbuf *mbp = msgbufp;

        if (log_open)
                return (EBUSY);
        log_open = 1;
        logsoftc.sc_pgid = p->p_pid;            /* signal process only */
        /*
         * Potential race here with putchar() but since putchar should be
         * called by autoconf, msg_magic should be initialized by the time
         * we get here.
         */
        if (mbp->msg_magic != MSG_MAGIC) {
                register int i;

                mbp->msg_magic = MSG_MAGIC;
                mbp->msg_bufx = mbp->msg_bufr = 0;
                for (i=0; i < MSG_BSIZE; i++)
                        mbp->msg_bufc[i] = 0;
        }
        return (0);
}

/*ARGSUSED*/
logclose(dev, flag)
        dev_t dev;
{
        log_open = 0;
        logsoftc.sc_state = 0;
        logsoftc.sc_sel = 0; /* 16 Jun 93 */
}

/*ARGSUSED*/
logread(dev, uio, flag)
        dev_t dev;
        struct uio *uio;
        int flag;
{
        register struct msgbuf *mbp = msgbufp;
        register long l;
        register int s;
        int error = 0;

        s = splhigh();
        while (mbp->msg_bufr == mbp->msg_bufx) {
                if (flag & IO_NDELAY) {
                        splx(s);
                        return (EWOULDBLOCK);
                }
                logsoftc.sc_state |= LOG_RDWAIT;
                if (error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
                    "klog", 0)) {
                        splx(s);
                        return (error);
                }
        }
        splx(s);
        logsoftc.sc_state &= ~LOG_RDWAIT;

        while (uio->uio_resid > 0) {
                l = mbp->msg_bufx - mbp->msg_bufr;
                if (l < 0)
                        l = MSG_BSIZE - mbp->msg_bufr;
                l = MIN(l, uio->uio_resid);
                if (l == 0)
                        break;
                error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr],
                        (int)l, uio);
                if (error)
                        break;
                mbp->msg_bufr += l;
                if (mbp->msg_bufr < 0 || mbp->msg_bufr >= MSG_BSIZE)
                        mbp->msg_bufr = 0;
        }
        return (error);
}

/*ARGSUSED*/
logselect(dev, rw, p)
        dev_t dev;
        int rw;
        struct proc *p;
{
        int s = splhigh();

        switch (rw) {

        case FREAD:
                if (msgbufp->msg_bufr != msgbufp->msg_bufx) {
                        splx(s);
                        return (1);
                }
                logsoftc.sc_sel = p->p_pid; /* 16 Jun 93 */
                break;
        }
        splx(s);
        return (0);
}

logwakeup()
{
        struct proc *p;

        if (!log_open)
                return;
        if (logsoftc.sc_sel) {                  /* 16 Jun 93 */
                selwakeup(logsoftc.sc_sel, 0);
                logsoftc.sc_sel = 0;
        }
        if (logsoftc.sc_state & LOG_ASYNC) {
                if (logsoftc.sc_pgid < 0)
                        gsignal(-logsoftc.sc_pgid, SIGIO);
                else if (p = pfind(logsoftc.sc_pgid))
                        psignal(p, SIGIO);
        }
        if (logsoftc.sc_state & LOG_RDWAIT) {
                wakeup((caddr_t)msgbufp);
                logsoftc.sc_state &= ~LOG_RDWAIT;
        }
}

/*ARGSUSED*/
logioctl(dev, com, data, flag)
        caddr_t data;
{
        long l;
        int s;

        switch (com) {

        /* return number of characters immediately available */
        case FIONREAD:
                s = splhigh();
                l = msgbufp->msg_bufx - msgbufp->msg_bufr;
                splx(s);
                if (l < 0)
                        l += MSG_BSIZE;
                *(off_t *)data = l;
                break;

        case FIONBIO:
                break;

        case FIOASYNC:
                if (*(int *)data)
                        logsoftc.sc_state |= LOG_ASYNC;
                else
                        logsoftc.sc_state &= ~LOG_ASYNC;
                break;

        case TIOCSPGRP:
                logsoftc.sc_pgid = *(int *)data;
                break;

        case TIOCGPGRP:
                *(int *)data = logsoftc.sc_pgid;
                break;

        default:
                return (-1);
        }
        return (0);
}