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Annotation of kernel/bsd/kern/subr_log.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
        !            26: /*
        !            27:  * Copyright (c) 1982, 1986, 1993
        !            28:  *     The Regents of the University of California.  All rights reserved.
        !            29:  *
        !            30:  * Redistribution and use in source and binary forms, with or without
        !            31:  * modification, are permitted provided that the following conditions
        !            32:  * are met:
        !            33:  * 1. Redistributions of source code must retain the above copyright
        !            34:  *    notice, this list of conditions and the following disclaimer.
        !            35:  * 2. Redistributions in binary form must reproduce the above copyright
        !            36:  *    notice, this list of conditions and the following disclaimer in the
        !            37:  *    documentation and/or other materials provided with the distribution.
        !            38:  * 3. All advertising materials mentioning features or use of this software
        !            39:  *    must display the following acknowledgement:
        !            40:  *     This product includes software developed by the University of
        !            41:  *     California, Berkeley and its contributors.
        !            42:  * 4. Neither the name of the University nor the names of its contributors
        !            43:  *    may be used to endorse or promote products derived from this software
        !            44:  *    without specific prior written permission.
        !            45:  *
        !            46:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            47:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            48:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            49:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            50:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            51:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            52:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            53:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            54:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            55:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            56:  * SUCH DAMAGE.
        !            57:  *
        !            58:  *     @(#)subr_log.c  8.3 (Berkeley) 2/14/95
        !            59:  */
        !            60: 
        !            61: /*
        !            62:  * Error log buffer for kernel printf's.
        !            63:  */
        !            64: 
        !            65: #include <sys/param.h>
        !            66: #include <sys/systm.h>
        !            67: #include <sys/proc.h>
        !            68: #include <sys/vnode.h>
        !            69: #include <sys/ioctl.h>
        !            70: #include <sys/msgbuf.h>
        !            71: #include <sys/file.h>
        !            72: #include <sys/errno.h>
        !            73: #include <sys/select.h>
        !            74: #include <kern/thread.h>
        !            75: #include <kern/sched_prim.h>
        !            76: #include <kern/parallel.h>
        !            77: 
        !            78: #define LOG_RDPRI      (PZERO + 1)
        !            79: 
        !            80: #define LOG_NBIO       0x02
        !            81: #define LOG_ASYNC      0x04
        !            82: #define LOG_RDWAIT     0x08
        !            83: 
        !            84: struct logsoftc {
        !            85:        int     sc_state;               /* see above for possibilities */
        !            86:        struct  selinfo sc_selp;        /* thread waiting for select */
        !            87:        int     sc_pgid;                /* process/group for async I/O */
        !            88: } logsoftc;
        !            89: 
        !            90: int    log_open;                       /* also used in log() */
        !            91: struct msgbuf *msgbufp;
        !            92: 
        !            93: /*
        !            94:  * Serialize log access.  Note that the log can be written at interrupt level,
        !            95:  * so any log manipulations that can be done from, or affect, another processor
        !            96:  * at interrupt level must be guarded with a spin lock.
        !            97:  */
        !            98: decl_simple_lock_data(,log_lock);      /* stop races dead in their tracks */
        !            99: #define        LOG_LOCK()      simple_lock(&log_lock)
        !           100: #define        LOG_UNLOCK()    simple_unlock(&log_lock)
        !           101: #define        LOG_LOCK_INIT() simple_lock_init(&log_lock)
        !           102: 
        !           103: /*ARGSUSED*/
        !           104: logopen(dev, flags, mode, p)
        !           105:        dev_t dev;
        !           106:        int flags, mode;
        !           107:        struct proc *p;
        !           108: {
        !           109:        unix_master();                  /* for pg_id, sigh */
        !           110:        LOG_LOCK();
        !           111:        if (log_open) {
        !           112:                LOG_UNLOCK();
        !           113:                return (EBUSY);
        !           114:        }
        !           115:        log_open = 1;
        !           116:        logsoftc.sc_pgid = p->p_pid;            /* signal process only */
        !           117:        /*
        !           118:         * Potential race here with putchar() but since putchar should be
        !           119:         * called by autoconf, msg_magic should be initialized by the time
        !           120:         * we get here.
        !           121:         */
        !           122:        if (msgbufp->msg_magic != MSG_MAGIC) {
        !           123:                register int i;
        !           124: 
        !           125:                msgbufp->msg_magic = MSG_MAGIC;
        !           126:                msgbufp->msg_bufx = msgbufp->msg_bufr = 0;
        !           127:                for (i=0; i < MSG_BSIZE; i++)
        !           128:                        msgbufp->msg_bufc[i] = 0;
        !           129:        }
        !           130:        LOG_UNLOCK();
        !           131:        unix_release();
        !           132:        return (0);
        !           133: }
        !           134: 
        !           135: /*ARGSUSED*/
        !           136: int
        !           137: logclose(dev, flag)
        !           138:        dev_t dev;
        !           139: {
        !           140:        int oldpri;
        !           141:        LOG_LOCK();
        !           142:        log_open = 0;
        !           143:        selwakeup(&logsoftc.sc_selp);
        !           144:        oldpri = splhigh();
        !           145:        selthreadclear(&logsoftc.sc_selp);
        !           146:        splx(oldpri);
        !           147:        LOG_UNLOCK();
        !           148:        return (0);
        !           149: }
        !           150: 
        !           151: /*ARGSUSED*/
        !           152: int
        !           153: logread(dev, uio, flag)
        !           154:        dev_t dev;
        !           155:        struct uio *uio;
        !           156:        int flag;
        !           157: {
        !           158:        register long l;
        !           159:        register int s;
        !           160:        int error = 0;
        !           161: 
        !           162:        s = splhigh();
        !           163:        while (msgbufp->msg_bufr == msgbufp->msg_bufx) {
        !           164:                if (flag & IO_NDELAY) {
        !           165:                        splx(s);
        !           166:                        return (EWOULDBLOCK);
        !           167:                }
        !           168:                if (logsoftc.sc_state & LOG_NBIO) {
        !           169:                        splx(s);
        !           170:                        return (EWOULDBLOCK);
        !           171:                }
        !           172:                logsoftc.sc_state |= LOG_RDWAIT;
        !           173:                if (error = tsleep((caddr_t)msgbufp, LOG_RDPRI | PCATCH,
        !           174:                                "klog", 0)) {
        !           175:                        splx(s);
        !           176:                        return (error);
        !           177:                }
        !           178:        }
        !           179:        splx(s);
        !           180:        logsoftc.sc_state &= ~LOG_RDWAIT;
        !           181: 
        !           182:        while (uio->uio_resid > 0) {
        !           183:                l = msgbufp->msg_bufx - msgbufp->msg_bufr;
        !           184:                if (l < 0)
        !           185:                        l = MSG_BSIZE - msgbufp->msg_bufr;
        !           186:                l = min(l, uio->uio_resid);
        !           187:                if (l == 0)
        !           188:                        break;
        !           189:                error = uiomove((caddr_t)&msgbufp->msg_bufc[msgbufp->msg_bufr],
        !           190:                        (int)l, uio);
        !           191:                if (error)
        !           192:                        break;
        !           193:                msgbufp->msg_bufr += l;
        !           194:                if (msgbufp->msg_bufr < 0 || msgbufp->msg_bufr >= MSG_BSIZE)
        !           195:                        msgbufp->msg_bufr = 0;
        !           196:        }
        !           197:        return (error);
        !           198: }
        !           199: 
        !           200: /*ARGSUSED*/
        !           201: int
        !           202: logselect(dev, rw, p)
        !           203:        dev_t dev;
        !           204:        int rw;
        !           205:        struct proc *p;
        !           206: {
        !           207:        int s = splhigh();
        !           208: 
        !           209:        switch (rw) {
        !           210: 
        !           211:        case FREAD:
        !           212:                if (msgbufp->msg_bufr != msgbufp->msg_bufx) {
        !           213:                        splx(s);
        !           214:                        return (1);
        !           215:                }
        !           216:                selrecord(p, &logsoftc.sc_selp);
        !           217:                break;
        !           218:        }
        !           219:        splx(s);
        !           220:        return (0);
        !           221: }
        !           222: 
        !           223: void
        !           224: logwakeup()
        !           225: {
        !           226:        struct proc *p;
        !           227:        int pgid;
        !           228: 
        !           229:        if (!log_open)
        !           230:                return;
        !           231:        selwakeup(&logsoftc.sc_selp);
        !           232:        if (logsoftc.sc_state & LOG_ASYNC) {
        !           233:                unix_master();
        !           234:                LOG_LOCK();
        !           235:                pgid = logsoftc.sc_pgid;
        !           236:                LOG_UNLOCK();
        !           237:                if (pgid < 0)
        !           238:                        gsignal(-pgid, SIGIO); 
        !           239:                else if (p = pfind(pgid))
        !           240:                        psignal(p, SIGIO);
        !           241:                unix_release();
        !           242:        }
        !           243:        if (logsoftc.sc_state & LOG_RDWAIT) {
        !           244:                wakeup((caddr_t)msgbufp);
        !           245:                logsoftc.sc_state &= ~LOG_RDWAIT;
        !           246:        }
        !           247: }
        !           248: 
        !           249: /*ARGSUSED*/
        !           250: int
        !           251: logioctl(com, data, flag)
        !           252:        caddr_t data;
        !           253: {
        !           254:        long l;
        !           255:        int s;
        !           256: 
        !           257:        switch (com) {
        !           258: 
        !           259:        /* return number of characters immediately available */
        !           260:        case FIONREAD:
        !           261:                s = splhigh();
        !           262:                l = msgbufp->msg_bufx - msgbufp->msg_bufr;
        !           263:                splx(s);
        !           264:                if (l < 0)
        !           265:                        l += MSG_BSIZE;
        !           266:                *(off_t *)data = l;
        !           267:                break;
        !           268: 
        !           269:        case FIONBIO:
        !           270:                if (*(int *)data)
        !           271:                        logsoftc.sc_state |= LOG_NBIO;
        !           272:                else
        !           273:                        logsoftc.sc_state &= ~LOG_NBIO;
        !           274:                break;
        !           275: 
        !           276:        case FIOASYNC:
        !           277:                if (*(int *)data)
        !           278:                        logsoftc.sc_state |= LOG_ASYNC;
        !           279:                else
        !           280:                        logsoftc.sc_state &= ~LOG_ASYNC;
        !           281:                break;
        !           282: 
        !           283:        case TIOCSPGRP:
        !           284:                LOG_LOCK();
        !           285:                logsoftc.sc_pgid = *(int *)data;
        !           286:                LOG_UNLOCK();
        !           287:                break;
        !           288: 
        !           289:        case TIOCGPGRP:
        !           290:                LOG_LOCK();
        !           291:                *(int *)data = logsoftc.sc_pgid;
        !           292:                LOG_UNLOCK();
        !           293:                break;
        !           294: 
        !           295:        default:
        !           296:                return (-1);
        !           297:        }
        !           298:        return (0);
        !           299: }
        !           300: 
        !           301: void
        !           302: log_init()
        !           303: {
        !           304:        LOG_LOCK_INIT();
        !           305: }

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