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Annotation of Net2/kern/subr_log.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986 Regents of the University of California.
        !             3:  * 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  7.11 (Berkeley) 3/17/91
        !            34:  */
        !            35: 
        !            36: /*
        !            37:  * Error log buffer for kernel printf's.
        !            38:  */
        !            39: 
        !            40: #include "param.h"
        !            41: #include "proc.h"
        !            42: #include "vnode.h"
        !            43: #include "ioctl.h"
        !            44: #include "msgbuf.h"
        !            45: #include "file.h"
        !            46: 
        !            47: #define LOG_RDPRI      (PZERO + 1)
        !            48: 
        !            49: #define LOG_ASYNC      0x04
        !            50: #define LOG_RDWAIT     0x08
        !            51: 
        !            52: struct logsoftc {
        !            53:        int     sc_state;               /* see above for possibilities */
        !            54:        struct  proc *sc_selp;          /* process waiting on select call */
        !            55:        int     sc_pgid;                /* process/group for async I/O */
        !            56: } logsoftc;
        !            57: 
        !            58: int    log_open;                       /* also used in log() */
        !            59: 
        !            60: /*ARGSUSED*/
        !            61: logopen(dev, flags, mode, p)
        !            62:        dev_t dev;
        !            63:        int flags, mode;
        !            64:        struct proc *p;
        !            65: {
        !            66:        register struct msgbuf *mbp = msgbufp;
        !            67: 
        !            68:        if (log_open)
        !            69:                return (EBUSY);
        !            70:        log_open = 1;
        !            71:        logsoftc.sc_pgid = p->p_pid;            /* signal process only */
        !            72:        /*
        !            73:         * Potential race here with putchar() but since putchar should be
        !            74:         * called by autoconf, msg_magic should be initialized by the time
        !            75:         * we get here.
        !            76:         */
        !            77:        if (mbp->msg_magic != MSG_MAGIC) {
        !            78:                register int i;
        !            79: 
        !            80:                mbp->msg_magic = MSG_MAGIC;
        !            81:                mbp->msg_bufx = mbp->msg_bufr = 0;
        !            82:                for (i=0; i < MSG_BSIZE; i++)
        !            83:                        mbp->msg_bufc[i] = 0;
        !            84:        }
        !            85:        return (0);
        !            86: }
        !            87: 
        !            88: /*ARGSUSED*/
        !            89: logclose(dev, flag)
        !            90:        dev_t dev;
        !            91: {
        !            92:        log_open = 0;
        !            93:        logsoftc.sc_state = 0;
        !            94:        logsoftc.sc_selp = 0;
        !            95: }
        !            96: 
        !            97: /*ARGSUSED*/
        !            98: logread(dev, uio, flag)
        !            99:        dev_t dev;
        !           100:        struct uio *uio;
        !           101:        int flag;
        !           102: {
        !           103:        register struct msgbuf *mbp = msgbufp;
        !           104:        register long l;
        !           105:        register int s;
        !           106:        int error = 0;
        !           107: 
        !           108:        s = splhigh();
        !           109:        while (mbp->msg_bufr == mbp->msg_bufx) {
        !           110:                if (flag & IO_NDELAY) {
        !           111:                        splx(s);
        !           112:                        return (EWOULDBLOCK);
        !           113:                }
        !           114:                logsoftc.sc_state |= LOG_RDWAIT;
        !           115:                if (error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
        !           116:                    "klog", 0)) {
        !           117:                        splx(s);
        !           118:                        return (error);
        !           119:                }
        !           120:        }
        !           121:        splx(s);
        !           122:        logsoftc.sc_state &= ~LOG_RDWAIT;
        !           123: 
        !           124:        while (uio->uio_resid > 0) {
        !           125:                l = mbp->msg_bufx - mbp->msg_bufr;
        !           126:                if (l < 0)
        !           127:                        l = MSG_BSIZE - mbp->msg_bufr;
        !           128:                l = MIN(l, uio->uio_resid);
        !           129:                if (l == 0)
        !           130:                        break;
        !           131:                error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr],
        !           132:                        (int)l, uio);
        !           133:                if (error)
        !           134:                        break;
        !           135:                mbp->msg_bufr += l;
        !           136:                if (mbp->msg_bufr < 0 || mbp->msg_bufr >= MSG_BSIZE)
        !           137:                        mbp->msg_bufr = 0;
        !           138:        }
        !           139:        return (error);
        !           140: }
        !           141: 
        !           142: /*ARGSUSED*/
        !           143: logselect(dev, rw, p)
        !           144:        dev_t dev;
        !           145:        int rw;
        !           146:        struct proc *p;
        !           147: {
        !           148:        int s = splhigh();
        !           149: 
        !           150:        switch (rw) {
        !           151: 
        !           152:        case FREAD:
        !           153:                if (msgbufp->msg_bufr != msgbufp->msg_bufx) {
        !           154:                        splx(s);
        !           155:                        return (1);
        !           156:                }
        !           157:                logsoftc.sc_selp = p;
        !           158:                break;
        !           159:        }
        !           160:        splx(s);
        !           161:        return (0);
        !           162: }
        !           163: 
        !           164: logwakeup()
        !           165: {
        !           166:        struct proc *p;
        !           167: 
        !           168:        if (!log_open)
        !           169:                return;
        !           170:        if (logsoftc.sc_selp) {
        !           171:                selwakeup(logsoftc.sc_selp, 0);
        !           172:                logsoftc.sc_selp = 0;
        !           173:        }
        !           174:        if (logsoftc.sc_state & LOG_ASYNC) {
        !           175:                if (logsoftc.sc_pgid < 0)
        !           176:                        gsignal(-logsoftc.sc_pgid, SIGIO); 
        !           177:                else if (p = pfind(logsoftc.sc_pgid))
        !           178:                        psignal(p, SIGIO);
        !           179:        }
        !           180:        if (logsoftc.sc_state & LOG_RDWAIT) {
        !           181:                wakeup((caddr_t)msgbufp);
        !           182:                logsoftc.sc_state &= ~LOG_RDWAIT;
        !           183:        }
        !           184: }
        !           185: 
        !           186: /*ARGSUSED*/
        !           187: logioctl(dev, com, data, flag)
        !           188:        caddr_t data;
        !           189: {
        !           190:        long l;
        !           191:        int s;
        !           192: 
        !           193:        switch (com) {
        !           194: 
        !           195:        /* return number of characters immediately available */
        !           196:        case FIONREAD:
        !           197:                s = splhigh();
        !           198:                l = msgbufp->msg_bufx - msgbufp->msg_bufr;
        !           199:                splx(s);
        !           200:                if (l < 0)
        !           201:                        l += MSG_BSIZE;
        !           202:                *(off_t *)data = l;
        !           203:                break;
        !           204: 
        !           205:        case FIONBIO:
        !           206:                break;
        !           207: 
        !           208:        case FIOASYNC:
        !           209:                if (*(int *)data)
        !           210:                        logsoftc.sc_state |= LOG_ASYNC;
        !           211:                else
        !           212:                        logsoftc.sc_state &= ~LOG_ASYNC;
        !           213:                break;
        !           214: 
        !           215:        case TIOCSPGRP:
        !           216:                logsoftc.sc_pgid = *(int *)data;
        !           217:                break;
        !           218: 
        !           219:        case TIOCGPGRP:
        !           220:                *(int *)data = logsoftc.sc_pgid;
        !           221:                break;
        !           222: 
        !           223:        default:
        !           224:                return (-1);
        !           225:        }
        !           226:        return (0);
        !           227: }

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