subr_log.c revision 9979 
1/*
2 * Copyright (c) 1982, 1986, 1993
3 *	The Regents of the University of California.  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	8.1 (Berkeley) 6/10/93
34 * $Id: subr_log.c,v 1.8 1995/05/30 08:05:52 rgrimes Exp $
35 */
36
37/*
38 * Error log buffer for kernel printf's.
39 */
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/proc.h>
44#include <sys/vnode.h>
45#include <sys/ioctl.h>
46#include <sys/msgbuf.h>
47#include <sys/file.h>
48#include <sys/signalvar.h>
49
50#define LOG_RDPRI	(PZERO + 1)
51
52#define LOG_ASYNC	0x04
53#define LOG_RDWAIT	0x08
54
55struct logsoftc {
56	int	sc_state;		/* see above for possibilities */
57	struct	selinfo sc_selp;	/* process waiting on select call */
58	int	sc_pgid;		/* process/group for async I/O */
59} logsoftc;
60
61int	log_open;			/* also used in log() */
62
63/*ARGSUSED*/
64int
65logopen(dev, flags, mode, p)
66	dev_t dev;
67	int flags, mode;
68	struct proc *p;
69{
70	register struct msgbuf *mbp = msgbufp;
71
72	if (log_open)
73		return (EBUSY);
74	log_open = 1;
75	logsoftc.sc_pgid = p->p_pid;		/* signal process only */
76	return (0);
77}
78
79/*ARGSUSED*/
80int
81logclose(dev, flag, mode, p)
82	dev_t dev;
83	int flag, mode;
84	struct proc *p;
85{
86
87	log_open = 0;
88	logsoftc.sc_state = 0;
89	return (0);
90}
91
92/*ARGSUSED*/
93int
94logread(dev, uio, flag)
95	dev_t dev;
96	struct uio *uio;
97	int flag;
98{
99	register struct msgbuf *mbp = msgbufp;
100	register long l;
101	register int s;
102	int error = 0;
103
104	s = splhigh();
105	while (mbp->msg_bufr == mbp->msg_bufx) {
106		if (flag & IO_NDELAY) {
107			splx(s);
108			return (EWOULDBLOCK);
109		}
110		logsoftc.sc_state |= LOG_RDWAIT;
111		if ((error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
112		    "klog", 0))) {
113			splx(s);
114			return (error);
115		}
116	}
117	splx(s);
118	logsoftc.sc_state &= ~LOG_RDWAIT;
119
120	while (uio->uio_resid > 0) {
121		l = mbp->msg_bufx - mbp->msg_bufr;
122		if (l < 0)
123			l = MSG_BSIZE - mbp->msg_bufr;
124		l = min(l, uio->uio_resid);
125		if (l == 0)
126			break;
127		error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr],
128			(int)l, uio);
129		if (error)
130			break;
131		mbp->msg_bufr += l;
132		if (mbp->msg_bufr >= MSG_BSIZE)
133			mbp->msg_bufr = 0;
134	}
135	return (error);
136}
137
138/*ARGSUSED*/
139int
140logselect(dev, rw, p)
141	dev_t dev;
142	int rw;
143	struct proc *p;
144{
145	int s = splhigh();
146
147	switch (rw) {
148
149	case FREAD:
150		if (msgbufp->msg_bufr != msgbufp->msg_bufx) {
151			splx(s);
152			return (1);
153		}
154		selrecord(p, &logsoftc.sc_selp);
155		break;
156	}
157	splx(s);
158	return (0);
159}
160
161void
162logwakeup()
163{
164	struct proc *p;
165
166	if (!log_open)
167		return;
168	selwakeup(&logsoftc.sc_selp);
169	if (logsoftc.sc_state & LOG_ASYNC) {
170		if (logsoftc.sc_pgid < 0)
171			gsignal(-logsoftc.sc_pgid, SIGIO);
172		else if ((p = pfind(logsoftc.sc_pgid)))
173			psignal(p, SIGIO);
174	}
175	if (logsoftc.sc_state & LOG_RDWAIT) {
176		wakeup((caddr_t)msgbufp);
177		logsoftc.sc_state &= ~LOG_RDWAIT;
178	}
179}
180
181/*ARGSUSED*/
182int
183logioctl(dev, com, data, flag, p)
184	dev_t dev;
185	int com;
186	caddr_t data;
187	int flag;
188	struct proc *p;
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		*(int *)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 (ENOTTY);
225	}
226	return (0);
227}
228