lint

[unix-history] / usr / src / sys / kern / subr_log.c

/*
* Copyright (c) 1982, 1986 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*
*      @(#)subr_log.c  7.1 (Berkeley) %G%
*/

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

#include "param.h"
#include "dir.h"
#include "user.h"
#include "proc.h"
#include "ioctl.h"
#include "msgbuf.h"
#include "file.h"
#include "errno.h"

#define LOG_RDPRI       (PZERO + 1)

#define LOG_NBIO        0x02
#define LOG_ASYNC       0x04
#define LOG_RDWAIT      0x08

struct logsoftc {
       int     sc_state;               /* see above for possibilities */
       struct  proc *sc_selp;          /* process waiting on select call */
       int     sc_pgrp;                /* process group for async I/O */
} logsoftc;

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

/*ARGSUSED*/
logopen(dev)
       dev_t dev;
{

       if (log_open)
               return (EBUSY);
       log_open = 1;
       logsoftc.sc_selp = 0;
       logsoftc.sc_pgrp = u.u_procp->p_pgrp;
       /*
        * 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 (msgbuf.msg_magic != MSG_MAGIC) {
               register int i;

               msgbuf.msg_magic = MSG_MAGIC;
               msgbuf.msg_bufx = msgbuf.msg_bufr = 0;
               for (i=0; i < MSG_BSIZE; i++)
                       msgbuf.msg_bufc[i] = 0;
       }
       return (0);
}

/*ARGSUSED*/
logclose(dev, flag)
       dev_t dev;
{
       log_open = 0;
       logsoftc.sc_state = 0;
       logsoftc.sc_selp = 0;
       logsoftc.sc_pgrp = 0;
}

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

       s = splhigh();
       while (msgbuf.msg_bufr == msgbuf.msg_bufx) {
               if (logsoftc.sc_state & LOG_NBIO) {
                       splx(s);
                       return (EWOULDBLOCK);
               }
               logsoftc.sc_state |= LOG_RDWAIT;
               sleep((caddr_t)&msgbuf, LOG_RDPRI);
       }
       splx(s);
       logsoftc.sc_state &= ~LOG_RDWAIT;

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

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

       switch (rw) {

       case FREAD:
               if (msgbuf.msg_bufr != msgbuf.msg_bufx) {
                       splx(s);
                       return (1);
               }
               logsoftc.sc_selp = u.u_procp;
               break;
       }
       splx(s);
       return (0);
}

logwakeup()
{

       if (!log_open)
               return;
       if (logsoftc.sc_selp) {
               selwakeup(logsoftc.sc_selp, 0);
               logsoftc.sc_selp = 0;
       }
       if (logsoftc.sc_state & LOG_ASYNC)
               gsignal(logsoftc.sc_pgrp, SIGIO); 
       if (logsoftc.sc_state & LOG_RDWAIT) {
               wakeup((caddr_t)&msgbuf);
               logsoftc.sc_state &= ~LOG_RDWAIT;
       }
}

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

       switch (com) {

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

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

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

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

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

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