404 lines
10 KiB
C
404 lines
10 KiB
C
/* $NetBSD: subr_log.c,v 1.50 2008/04/28 20:24:04 martin Exp $ */
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/*-
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* Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Andrew Doran.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Copyright (c) 1982, 1986, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)subr_log.c 8.3 (Berkeley) 2/14/95
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*/
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/*
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* Error log buffer for kernel printf's.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: subr_log.c,v 1.50 2008/04/28 20:24:04 martin Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/ioctl.h>
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#include <sys/msgbuf.h>
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#include <sys/file.h>
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#include <sys/syslog.h>
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#include <sys/conf.h>
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#include <sys/select.h>
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#include <sys/poll.h>
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#include <sys/intr.h>
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static void logsoftintr(void *);
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static bool log_async;
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static struct selinfo log_selp; /* process waiting on select call */
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static pid_t log_pgid; /* process/group for async I/O */
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static kcondvar_t log_cv;
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static void *log_sih;
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kmutex_t log_lock;
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int log_open; /* also used in log() */
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int msgbufmapped; /* is the message buffer mapped */
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int msgbufenabled; /* is logging to the buffer enabled */
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struct kern_msgbuf *msgbufp; /* the mapped buffer, itself. */
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void
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initmsgbuf(void *bf, size_t bufsize)
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{
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struct kern_msgbuf *mbp;
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long new_bufs;
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/* Sanity-check the given size. */
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if (bufsize < sizeof(struct kern_msgbuf))
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return;
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mbp = msgbufp = (struct kern_msgbuf *)bf;
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new_bufs = bufsize - offsetof(struct kern_msgbuf, msg_bufc);
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if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
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(mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
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(mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
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/*
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* If the buffer magic number is wrong, has changed
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* size (which shouldn't happen often), or is
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* internally inconsistent, initialize it.
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*/
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memset(bf, 0, bufsize);
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mbp->msg_magic = MSG_MAGIC;
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mbp->msg_bufs = new_bufs;
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}
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/* mark it as ready for use. */
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msgbufmapped = msgbufenabled = 1;
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}
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void
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loginit(void)
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{
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mutex_init(&log_lock, MUTEX_DEFAULT, IPL_VM);
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selinit(&log_selp);
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cv_init(&log_cv, "klog");
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log_sih = softint_establish(SOFTINT_CLOCK | SOFTINT_MPSAFE,
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logsoftintr, NULL);
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}
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/*ARGSUSED*/
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static int
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logopen(dev_t dev, int flags, int mode, struct lwp *l)
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{
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struct kern_msgbuf *mbp = msgbufp;
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int error = 0;
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mutex_spin_enter(&log_lock);
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if (log_open) {
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error = EBUSY;
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} else {
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log_open = 1;
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log_pgid = l->l_proc->p_pid; /* signal process only */
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/*
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* The message buffer is initialized during system
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* configuration. If it's been clobbered, note that
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* and return an error. (This allows a user to read
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* the buffer via /dev/kmem, and try to figure out
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* what clobbered it.
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*/
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if (mbp->msg_magic != MSG_MAGIC) {
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msgbufenabled = 0;
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error = ENXIO;
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}
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}
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mutex_spin_exit(&log_lock);
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return error;
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}
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/*ARGSUSED*/
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static int
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logclose(dev_t dev, int flag, int mode, struct lwp *l)
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{
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mutex_spin_enter(&log_lock);
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log_pgid = 0;
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log_open = 0;
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log_async = 0;
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mutex_spin_exit(&log_lock);
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return 0;
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}
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/*ARGSUSED*/
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static int
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logread(dev_t dev, struct uio *uio, int flag)
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{
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struct kern_msgbuf *mbp = msgbufp;
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long l;
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int error = 0;
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mutex_spin_enter(&log_lock);
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while (mbp->msg_bufr == mbp->msg_bufx) {
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if (flag & IO_NDELAY) {
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mutex_spin_exit(&log_lock);
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return EWOULDBLOCK;
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}
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error = cv_wait_sig(&log_cv, &log_lock);
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if (error) {
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mutex_spin_exit(&log_lock);
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return error;
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}
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}
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while (uio->uio_resid > 0) {
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l = mbp->msg_bufx - mbp->msg_bufr;
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if (l < 0)
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l = mbp->msg_bufs - mbp->msg_bufr;
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l = min(l, uio->uio_resid);
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if (l == 0)
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break;
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mutex_spin_exit(&log_lock);
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error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
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mutex_spin_enter(&log_lock);
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if (error)
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break;
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mbp->msg_bufr += l;
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if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
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mbp->msg_bufr = 0;
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}
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mutex_spin_exit(&log_lock);
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return error;
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}
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/*ARGSUSED*/
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static int
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logpoll(dev_t dev, int events, struct lwp *l)
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{
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int revents = 0;
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if (events & (POLLIN | POLLRDNORM)) {
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mutex_spin_enter(&log_lock);
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if (msgbufp->msg_bufr != msgbufp->msg_bufx)
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revents |= events & (POLLIN | POLLRDNORM);
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else
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selrecord(l, &log_selp);
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mutex_spin_exit(&log_lock);
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}
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return revents;
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}
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static void
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filt_logrdetach(struct knote *kn)
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{
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mutex_spin_enter(&log_lock);
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SLIST_REMOVE(&log_selp.sel_klist, kn, knote, kn_selnext);
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mutex_spin_exit(&log_lock);
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}
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static int
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filt_logread(struct knote *kn, long hint)
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{
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int rv;
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if ((hint & NOTE_SUBMIT) == 0)
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mutex_spin_enter(&log_lock);
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if (msgbufp->msg_bufr == msgbufp->msg_bufx) {
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rv = 0;
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} else if (msgbufp->msg_bufr < msgbufp->msg_bufx) {
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kn->kn_data = msgbufp->msg_bufx - msgbufp->msg_bufr;
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rv = 1;
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} else {
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kn->kn_data = (msgbufp->msg_bufs - msgbufp->msg_bufr) +
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msgbufp->msg_bufx;
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rv = 1;
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}
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if ((hint & NOTE_SUBMIT) == 0)
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mutex_spin_exit(&log_lock);
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return rv;
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}
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static const struct filterops logread_filtops =
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{ 1, NULL, filt_logrdetach, filt_logread };
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static int
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logkqfilter(dev_t dev, struct knote *kn)
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{
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struct klist *klist;
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switch (kn->kn_filter) {
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case EVFILT_READ:
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klist = &log_selp.sel_klist;
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kn->kn_fop = &logread_filtops;
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break;
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default:
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return (EINVAL);
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}
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mutex_spin_enter(&log_lock);
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kn->kn_hook = NULL;
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SLIST_INSERT_HEAD(klist, kn, kn_selnext);
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mutex_spin_exit(&log_lock);
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return (0);
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}
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void
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logwakeup(void)
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{
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if (!cold && log_open) {
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mutex_spin_enter(&log_lock);
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selnotify(&log_selp, 0, NOTE_SUBMIT);
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if (log_async)
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softint_schedule(log_sih);
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cv_broadcast(&log_cv);
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mutex_spin_exit(&log_lock);
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}
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}
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static void
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logsoftintr(void *cookie)
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{
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pid_t pid;
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if ((pid = log_pgid) != 0)
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fownsignal(pid, SIGIO, 0, 0, NULL);
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}
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/*ARGSUSED*/
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static int
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logioctl(dev_t dev, u_long com, void *data, int flag, struct lwp *lwp)
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{
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long l;
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switch (com) {
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/* return number of characters immediately available */
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case FIONREAD:
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mutex_spin_enter(&log_lock);
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l = msgbufp->msg_bufx - msgbufp->msg_bufr;
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if (l < 0)
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l += msgbufp->msg_bufs;
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mutex_spin_exit(&log_lock);
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*(int *)data = l;
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break;
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case FIONBIO:
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break;
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case FIOASYNC:
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/* No locking needed, 'thread private'. */
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log_async = (*((int *)data) != 0);
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break;
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case TIOCSPGRP:
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case FIOSETOWN:
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return fsetown(&log_pgid, com, data);
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case TIOCGPGRP:
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case FIOGETOWN:
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return fgetown(log_pgid, com, data);
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default:
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return (EPASSTHROUGH);
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}
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return (0);
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}
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void
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logputchar(int c)
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{
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struct kern_msgbuf *mbp;
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if (!cold)
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mutex_spin_enter(&log_lock);
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if (msgbufenabled) {
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mbp = msgbufp;
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if (mbp->msg_magic != MSG_MAGIC) {
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/*
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* Arguably should panic or somehow notify the
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* user... but how? Panic may be too drastic,
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* and would obliterate the message being kicked
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* out (maybe a panic itself), and printf
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* would invoke us recursively. Silently punt
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* for now. If syslog is running, it should
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* notice.
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*/
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msgbufenabled = 0;
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} else {
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mbp->msg_bufc[mbp->msg_bufx++] = c;
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if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
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mbp->msg_bufx = 0;
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/* If the buffer is full, keep the most recent data. */
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if (mbp->msg_bufr == mbp->msg_bufx) {
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if (++mbp->msg_bufr >= mbp->msg_bufs)
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mbp->msg_bufr = 0;
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}
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}
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}
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if (!cold)
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mutex_spin_exit(&log_lock);
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}
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const struct cdevsw log_cdevsw = {
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logopen, logclose, logread, nowrite, logioctl,
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nostop, notty, logpoll, nommap, logkqfilter,
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D_OTHER | D_MPSAFE
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};
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