/*	$OpenBSD: subr_log.c,v 1.60 2019/12/24 12:56:07 bluhm Exp $	*/
/*	$NetBSD: subr_log.c,v 1.11 1996/03/30 22:24:44 christos 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	8.1 (Berkeley) 6/10/93
 */

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/ioctl.h>
#include <sys/msgbuf.h>
#include <sys/file.h>
#include <sys/tty.h>
#include <sys/signalvar.h>
#include <sys/syslog.h>
#include <sys/poll.h>
#include <sys/malloc.h>
#include <sys/filedesc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/fcntl.h>
#include <sys/timeout.h>

#ifdef KTRACE
#include <sys/ktrace.h>
#endif

#include <sys/mount.h>
#include <sys/syscallargs.h>

#include <dev/cons.h>

#define LOG_RDPRI	(PZERO + 1)
#define LOG_TICK	50		/* log tick interval in msec */

#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 */
	int	sc_pgid;		/* process/group for async I/O */
	uid_t	sc_siguid;		/* uid for process that set sc_pgid */
	uid_t	sc_sigeuid;		/* euid for process that set sc_pgid */
	int	sc_need_wakeup;		/* if set, wake up waiters */
	struct timeout sc_tick;		/* wakeup poll timeout */
} logsoftc;

int	log_open;			/* also used in log() */
int	msgbufmapped;			/* is the message buffer mapped */
struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
struct	msgbuf *consbufp;		/* console message buffer. */
struct	file *syslogf;

void filt_logrdetach(struct knote *kn);
int filt_logread(struct knote *kn, long hint);

struct filterops logread_filtops =
	{ 1, NULL, filt_logrdetach, filt_logread};

int dosendsyslog(struct proc *, const char *, size_t, int, enum uio_seg);
void logtick(void *);

void
initmsgbuf(caddr_t buf, size_t bufsize)
{
	struct msgbuf *mbp;
	long new_bufs;

	/* Sanity-check the given size. */
	if (bufsize < sizeof(struct msgbuf))
		return;

	mbp = msgbufp = (struct msgbuf *)buf;

	new_bufs = bufsize - offsetof(struct 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(buf, 0, bufsize);
		mbp->msg_magic = MSG_MAGIC;
		mbp->msg_bufs = new_bufs;
	}

	/* Always start new buffer data on a new line. */
	if (mbp->msg_bufx > 0 && mbp->msg_bufc[mbp->msg_bufx - 1] != '\n')
		msgbuf_putchar(msgbufp, '\n');

	/* mark it as ready for use. */
	msgbufmapped = 1;
}

void
initconsbuf(void)
{
	/* Set up a buffer to collect /dev/console output */
	consbufp = malloc(CONSBUFSIZE, M_TTYS, M_WAITOK | M_ZERO);
	consbufp->msg_magic = MSG_MAGIC;
	consbufp->msg_bufs = CONSBUFSIZE - offsetof(struct msgbuf, msg_bufc);
}

void
msgbuf_putchar(struct msgbuf *mbp, const char c)
{
	int s;

	if (mbp->msg_magic != MSG_MAGIC)
		/* Nothing we can do */
		return;

	s = splhigh();
	mbp->msg_bufc[mbp->msg_bufx++] = c;
	mbp->msg_bufl = lmin(mbp->msg_bufl+1, mbp->msg_bufs);
	if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
		mbp->msg_bufx = 0;
	/* If the buffer is full, keep the most recent data. */
	if (mbp->msg_bufr == mbp->msg_bufx) {
		if (++mbp->msg_bufr >= mbp->msg_bufs)
			mbp->msg_bufr = 0;
		mbp->msg_bufd++;
	}
	splx(s);
}

int
logopen(dev_t dev, int flags, int mode, struct proc *p)
{
	if (log_open)
		return (EBUSY);
	log_open = 1;
	timeout_set(&logsoftc.sc_tick, logtick, NULL);
	timeout_add_msec(&logsoftc.sc_tick, LOG_TICK);
	return (0);
}

int
logclose(dev_t dev, int flag, int mode, struct proc *p)
{
	struct file *fp;

	fp = syslogf;
	syslogf = NULL;
	if (fp)
		FRELE(fp, p);
	log_open = 0;
	timeout_del(&logsoftc.sc_tick);
	logsoftc.sc_state = 0;
	return (0);
}

int
logread(dev_t dev, struct uio *uio, int flag)
{
	struct msgbuf *mbp = msgbufp;
	size_t l;
	int s, error = 0;

	s = splhigh();
	while (mbp->msg_bufr == mbp->msg_bufx) {
		if (flag & IO_NDELAY) {
			error = EWOULDBLOCK;
			goto out;
		}
		logsoftc.sc_state |= LOG_RDWAIT;
		error = tsleep(mbp, LOG_RDPRI | PCATCH,
			       "klog", 0);
		if (error)
			goto out;
	}
	logsoftc.sc_state &= ~LOG_RDWAIT;

	if (mbp->msg_bufd > 0) {
		char buf[64];

		l = snprintf(buf, sizeof(buf),
		    "<%d>klog: dropped %ld byte%s, message buffer full\n",
		    LOG_KERN|LOG_WARNING, mbp->msg_bufd,
                    mbp->msg_bufd == 1 ? "" : "s");
		error = uiomove(buf, ulmin(l, sizeof(buf) - 1), uio);
		if (error)
			goto out;
		mbp->msg_bufd = 0;
	}

	while (uio->uio_resid > 0) {
		if (mbp->msg_bufx >= mbp->msg_bufr)
			l = mbp->msg_bufx - mbp->msg_bufr;
		else
			l = mbp->msg_bufs - mbp->msg_bufr;
		l = ulmin(l, uio->uio_resid);
		if (l == 0)
			break;
		error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], l, uio);
		if (error)
			break;
		mbp->msg_bufr += l;
		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
			mbp->msg_bufr = 0;
	}
 out:
	splx(s);
	return (error);
}

int
logpoll(dev_t dev, int events, struct proc *p)
{
	int s, revents = 0;

	s = splhigh();
	if (events & (POLLIN | POLLRDNORM)) {
		if (msgbufp->msg_bufr != msgbufp->msg_bufx)
			revents |= events & (POLLIN | POLLRDNORM);
		else
			selrecord(p, &logsoftc.sc_selp);
	}
	splx(s);
	return (revents);
}

int
logkqfilter(dev_t dev, struct knote *kn)
{
	struct klist *klist;
	int s;

	switch (kn->kn_filter) {
	case EVFILT_READ:
		klist = &logsoftc.sc_selp.si_note;
		kn->kn_fop = &logread_filtops;
		break;
	default:
		return (EINVAL);
	}

	kn->kn_hook = (void *)msgbufp;

	s = splhigh();
	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
	splx(s);

	return (0);
}

void
filt_logrdetach(struct knote *kn)
{
	int s;

	s = splhigh();
	SLIST_REMOVE(&logsoftc.sc_selp.si_note, kn, knote, kn_selnext);
	splx(s);
}

int
filt_logread(struct knote *kn, long hint)
{
	struct  msgbuf *p = (struct  msgbuf *)kn->kn_hook;
	int s, event = 0;

	s = splhigh();
	kn->kn_data = (int)(p->msg_bufx - p->msg_bufr);
	event = (p->msg_bufx != p->msg_bufr);
	splx(s);
	return (event);
}

void
logwakeup(void)
{
	/*
	 * The actual wakeup has to be deferred because logwakeup() can be
	 * called in very varied contexts.
	 * Keep the print routines usable in as many situations as possible
	 * by not using locking here.
	 */

	/*
	 * Ensure that preceding stores become visible to other CPUs
	 * before the flag.
	 */
	membar_producer();

	logsoftc.sc_need_wakeup = 1;
}

void
logtick(void *arg)
{
	if (!log_open)
		return;

	if (!logsoftc.sc_need_wakeup)
		goto out;
	logsoftc.sc_need_wakeup = 0;

	/*
	 * sc_need_wakeup has to be cleared before handling the wakeup.
	 * This ensures that no wakeup is lost.
	 */
	membar_enter();

	selwakeup(&logsoftc.sc_selp);
	if (logsoftc.sc_state & LOG_ASYNC)
		csignal(logsoftc.sc_pgid, SIGIO,
		    logsoftc.sc_siguid, logsoftc.sc_sigeuid);
	if (logsoftc.sc_state & LOG_RDWAIT) {
		wakeup(msgbufp);
		logsoftc.sc_state &= ~LOG_RDWAIT;
	}
out:
	timeout_add_msec(&logsoftc.sc_tick, LOG_TICK);
}

int
logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
{
	struct file *fp;
	long l;
	int error, s;

	switch (com) {

	/* return number of characters immediately available */
	case FIONREAD:
		s = splhigh();
		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:
		logsoftc.sc_pgid = *(int *)data;
		logsoftc.sc_siguid = p->p_ucred->cr_ruid;
		logsoftc.sc_sigeuid = p->p_ucred->cr_uid;
		break;

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

	case LIOCSFD:
		if ((error = suser(p)) != 0)
			return (error);
		fp = syslogf;
		if ((error = getsock(p, *(int *)data, &syslogf)) != 0)
			return (error);
		if (fp)
			FRELE(fp, p);
		break;

	default:
		return (ENOTTY);
	}
	return (0);
}

int
sys_sendsyslog(struct proc *p, void *v, register_t *retval)
{
	struct sys_sendsyslog_args /* {
		syscallarg(const char *) buf;
		syscallarg(size_t) nbyte;
		syscallarg(int) flags;
	} */ *uap = v;
	int error;
	static int dropped_count, orig_error, orig_pid;

	if (dropped_count) {
		size_t l;
		char buf[80];

		l = snprintf(buf, sizeof(buf),
		    "<%d>sendsyslog: dropped %d message%s, error %d, pid %d",
		    LOG_KERN|LOG_WARNING, dropped_count,
		    dropped_count == 1 ? "" : "s", orig_error, orig_pid);
		error = dosendsyslog(p, buf, ulmin(l, sizeof(buf) - 1),
		    0, UIO_SYSSPACE);
		if (error == 0) {
			dropped_count = 0;
			orig_error = 0;
			orig_pid = 0;
		}
	}
	error = dosendsyslog(p, SCARG(uap, buf), SCARG(uap, nbyte),
	    SCARG(uap, flags), UIO_USERSPACE);
	if (error) {
		dropped_count++;
		orig_error = error;
		orig_pid = p->p_p->ps_pid;
	}
	return (error);
}

int
dosendsyslog(struct proc *p, const char *buf, size_t nbyte, int flags,
    enum uio_seg sflg)
{
#ifdef KTRACE
	struct iovec ktriov;
#endif
	struct file *fp;
	char pri[6], *kbuf;
	struct iovec aiov;
	struct uio auio;
	size_t i, len;
	int error;

	if (nbyte > LOG_MAXLINE)
		nbyte = LOG_MAXLINE;

	/* Global variable syslogf may change during sleep, use local copy. */
	fp = syslogf;
	if (fp)
		FREF(fp);
	else if (!ISSET(flags, LOG_CONS))
		return (ENOTCONN);
	else {
		/*
		 * Strip off syslog priority when logging to console.
		 * LOG_PRIMASK | LOG_FACMASK is 0x03ff, so at most 4
		 * decimal digits may appear in priority as <1023>.
		 */
		len = MIN(nbyte, sizeof(pri));
		if (sflg == UIO_USERSPACE) {
			if ((error = copyin(buf, pri, len)))
				return (error);
		} else
			memcpy(pri, buf, len);
		if (0 < len && pri[0] == '<') {
			for (i = 1; i < len; i++) {
				if (pri[i] < '0' || pri[i] > '9')
					break;
			}
			if (i < len && pri[i] == '>') {
				i++;
				/* There must be at least one digit <0>. */
				if (i >= 3) {
					buf += i;
					nbyte -= i;
				}
			}
		}
	}

	aiov.iov_base = (char *)buf;
	aiov.iov_len = nbyte;
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_segflg = sflg;
	auio.uio_rw = UIO_WRITE;
	auio.uio_procp = p;
	auio.uio_offset = 0;
	auio.uio_resid = aiov.iov_len;
#ifdef KTRACE
	if (sflg == UIO_USERSPACE && KTRPOINT(p, KTR_GENIO))
		ktriov = aiov;
	else
		ktriov.iov_len = 0;
#endif

	len = auio.uio_resid;
	if (fp) {
		int flags = (fp->f_flag & FNONBLOCK) ? MSG_DONTWAIT : 0;
		error = sosend(fp->f_data, NULL, &auio, NULL, NULL, flags);
		if (error == 0)
			len -= auio.uio_resid;
	} else if (constty || cn_devvp) {
		error = cnwrite(0, &auio, 0);
		if (error == 0)
			len -= auio.uio_resid;
		aiov.iov_base = "\r\n";
		aiov.iov_len = 2;
		auio.uio_iov = &aiov;
		auio.uio_iovcnt = 1;
		auio.uio_segflg = UIO_SYSSPACE;
		auio.uio_rw = UIO_WRITE;
		auio.uio_procp = p;
		auio.uio_offset = 0;
		auio.uio_resid = aiov.iov_len;
		cnwrite(0, &auio, 0);
	} else {
		/* XXX console redirection breaks down... */
		if (sflg == UIO_USERSPACE) {
			kbuf = malloc(len, M_TEMP, M_WAITOK);
			error = copyin(aiov.iov_base, kbuf, len);
		} else {
			kbuf = aiov.iov_base;
			error = 0;
		}
		if (error == 0)
			for (i = 0; i < len; i++) {
				if (kbuf[i] == '\0')
					break;
				cnputc(kbuf[i]);
				auio.uio_resid--;
			}
		if (sflg == UIO_USERSPACE)
			free(kbuf, M_TEMP, len);
		if (error == 0)
			len -= auio.uio_resid;
		cnputc('\n');
	}

#ifdef KTRACE
	if (error == 0 && ktriov.iov_len != 0)
		ktrgenio(p, -1, UIO_WRITE, &ktriov, len);
#endif
	if (fp)
		FRELE(fp, p);
	else
		error = ENOTCONN;
	return (error);
}