/* $NetBSD: subr_log.c,v 1.41 2007/05/17 14:51:41 yamt Exp $ */ /* * Copyright (c) 1982, 1986, 1993 * The 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. 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. * * @(#)subr_log.c 8.3 (Berkeley) 2/14/95 */ /* * Error log buffer for kernel printf's. */ #include __KERNEL_RCSID(0, "$NetBSD: subr_log.c,v 1.41 2007/05/17 14:51:41 yamt Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #define LOG_RDPRI (PZERO + 1) #define LOG_ASYNC 0x04 #define LOG_RDWAIT 0x08 struct logsoftc { int sc_state; /* see above for possibilities */ struct selinfo sc_selp; /* process waiting on select call */ pid_t sc_pgid; /* process/group for async I/O */ } logsoftc; int log_open; /* also used in log() */ int msgbufmapped; /* is the message buffer mapped */ int msgbufenabled; /* is logging to the buffer enabled */ struct kern_msgbuf *msgbufp; /* the mapped buffer, itself. */ void initmsgbuf(void *bf, size_t bufsize) { struct kern_msgbuf *mbp; long new_bufs; /* Sanity-check the given size. */ if (bufsize < sizeof(struct kern_msgbuf)) return; mbp = msgbufp = (struct kern_msgbuf *)bf; new_bufs = bufsize - offsetof(struct kern_msgbuf, msg_bufc); if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) || (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) || (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) { /* * If the buffer magic number is wrong, has changed * size (which shouldn't happen often), or is * internally inconsistent, initialize it. */ memset(bf, 0, bufsize); mbp->msg_magic = MSG_MAGIC; mbp->msg_bufs = new_bufs; } /* mark it as ready for use. */ msgbufmapped = msgbufenabled = 1; } /*ARGSUSED*/ static int logopen(dev_t dev, int flags, int mode, struct lwp *l) { struct kern_msgbuf *mbp = msgbufp; if (log_open) return (EBUSY); log_open = 1; logsoftc.sc_pgid = l->l_proc->p_pid; /* signal process only */ /* * The message buffer is initialized during system configuration. * If it's been clobbered, note that and return an error. (This * allows a user to potentially read the buffer via /dev/kmem, * and try to figure out what clobbered it. */ if (mbp->msg_magic != MSG_MAGIC) { msgbufenabled = 0; return (ENXIO); } return (0); } /*ARGSUSED*/ static int logclose(dev_t dev, int flag, int mode, struct lwp *l) { log_open = 0; logsoftc.sc_state = 0; return (0); } /*ARGSUSED*/ static int logread(dev_t dev, struct uio *uio, int flag) { struct kern_msgbuf *mbp = msgbufp; long l; int s; int error = 0; s = splsched(); while (mbp->msg_bufr == mbp->msg_bufx) { if (flag & IO_NDELAY) { splx(s); return (EWOULDBLOCK); } logsoftc.sc_state |= LOG_RDWAIT; error = tsleep((void *)mbp, LOG_RDPRI | PCATCH, "klog", 0); if (error) { 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 = mbp->msg_bufs - mbp->msg_bufr; l = min(l, uio->uio_resid); if (l == 0) break; error = uiomove((void *)&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio); if (error) break; mbp->msg_bufr += l; if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs) mbp->msg_bufr = 0; } return (error); } /*ARGSUSED*/ static int logpoll(dev_t dev, int events, struct lwp *l) { int revents = 0; int s = splsched(); if (events & (POLLIN | POLLRDNORM)) { if (msgbufp->msg_bufr != msgbufp->msg_bufx) revents |= events & (POLLIN | POLLRDNORM); else selrecord(l, &logsoftc.sc_selp); } splx(s); return (revents); } static void filt_logrdetach(struct knote *kn) { int s; s = splsched(); SLIST_REMOVE(&logsoftc.sc_selp.sel_klist, kn, knote, kn_selnext); splx(s); } static int filt_logread(struct knote *kn, long hint) { if (msgbufp->msg_bufr == msgbufp->msg_bufx) return (0); if (msgbufp->msg_bufr < msgbufp->msg_bufx) kn->kn_data = msgbufp->msg_bufx - msgbufp->msg_bufr; else kn->kn_data = (msgbufp->msg_bufs - msgbufp->msg_bufr) + msgbufp->msg_bufx; return (1); } static const struct filterops logread_filtops = { 1, NULL, filt_logrdetach, filt_logread }; static int logkqfilter(dev_t dev, struct knote *kn) { struct klist *klist; int s; switch (kn->kn_filter) { case EVFILT_READ: klist = &logsoftc.sc_selp.sel_klist; kn->kn_fop = &logread_filtops; break; default: return (1); } kn->kn_hook = NULL; s = splsched(); SLIST_INSERT_HEAD(klist, kn, kn_selnext); splx(s); return (0); } void logwakeup(void) { if (!log_open) return; selnotify(&logsoftc.sc_selp, 0); if (logsoftc.sc_state & LOG_ASYNC) fownsignal(logsoftc.sc_pgid, SIGIO, 0, 0, NULL); if (logsoftc.sc_state & LOG_RDWAIT) { wakeup((void *)msgbufp); logsoftc.sc_state &= ~LOG_RDWAIT; } } /*ARGSUSED*/ static int logioctl(dev_t dev, u_long com, void *data, int flag, struct lwp *lwp) { struct proc *p = lwp->l_proc; long l; int s; switch (com) { /* return number of characters immediately available */ case FIONREAD: s = splsched(); l = msgbufp->msg_bufx - msgbufp->msg_bufr; splx(s); if (l < 0) l += msgbufp->msg_bufs; *(int *)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: case FIOSETOWN: return fsetown(p, &logsoftc.sc_pgid, com, data); case TIOCGPGRP: case FIOGETOWN: return fgetown(p, logsoftc.sc_pgid, com, data); default: return (EPASSTHROUGH); } return (0); } const struct cdevsw log_cdevsw = { logopen, logclose, logread, nowrite, logioctl, nostop, notty, logpoll, nommap, logkqfilter, D_OTHER, };