subr_log.c revision 1549 
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 */
35
36/*
37 * Error log buffer for kernel printf's.
38 */
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/proc.h>
43#include <sys/vnode.h>
44#include <sys/ioctl.h>
45#include <sys/msgbuf.h>
46#include <sys/file.h>
47
48#define LOG_RDPRI	(PZERO + 1)
49
50#define LOG_ASYNC	0x04
51#define LOG_RDWAIT	0x08
52
53struct logsoftc {
54	int	sc_state;		/* see above for possibilities */
55	struct	selinfo sc_selp;	/* process waiting on select call */
56	int	sc_pgid;		/* process/group for async I/O */
57} logsoftc;
58
59int	log_open;			/* also used in log() */
60
61/*ARGSUSED*/
62int
63logopen(dev, flags, mode, p)
64	dev_t dev;
65	int flags, mode;
66	struct proc *p;
67{
68	register struct msgbuf *mbp = msgbufp;
69
70	if (log_open)
71		return (EBUSY);
72	log_open = 1;
73	logsoftc.sc_pgid = p->p_pid;		/* signal process only */
74	/*
75	 * Potential race here with putchar() but since putchar should be
76	 * called by autoconf, msg_magic should be initialized by the time
77	 * we get here.
78	 */
79	if (mbp->msg_magic != MSG_MAGIC) {
80		register int i;
81
82		mbp->msg_magic = MSG_MAGIC;
83		mbp->msg_bufx = mbp->msg_bufr = 0;
84		for (i=0; i < MSG_BSIZE; i++)
85			mbp->msg_bufc[i] = 0;
86	}
87	return (0);
88}
89
90/*ARGSUSED*/
91int
92logclose(dev, flag, mode, p)
93	dev_t dev;
94	int flag, mode;
95	struct proc *p;
96{
97
98	log_open = 0;
99	logsoftc.sc_state = 0;
100	return (0);
101}
102
103/*ARGSUSED*/
104int
105logread(dev, uio, flag)
106	dev_t dev;
107	struct uio *uio;
108	int flag;
109{
110	register struct msgbuf *mbp = msgbufp;
111	register long l;
112	register int s;
113	int error = 0;
114
115	s = splhigh();
116	while (mbp->msg_bufr == mbp->msg_bufx) {
117		if (flag & IO_NDELAY) {
118			splx(s);
119			return (EWOULDBLOCK);
120		}
121		logsoftc.sc_state |= LOG_RDWAIT;
122		if (error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
123		    "klog", 0)) {
124			splx(s);
125			return (error);
126		}
127	}
128	splx(s);
129	logsoftc.sc_state &= ~LOG_RDWAIT;
130
131	while (uio->uio_resid > 0) {
132		l = mbp->msg_bufx - mbp->msg_bufr;
133		if (l < 0)
134			l = MSG_BSIZE - mbp->msg_bufr;
135		l = min(l, uio->uio_resid);
136		if (l == 0)
137			break;
138		error = uiomove((caddr_t)&mbp->msg_bufc[mbp->msg_bufr],
139			(int)l, uio);
140		if (error)
141			break;
142		mbp->msg_bufr += l;
143		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= MSG_BSIZE)
144			mbp->msg_bufr = 0;
145	}
146	return (error);
147}
148
149/*ARGSUSED*/
150int
151logselect(dev, rw, p)
152	dev_t dev;
153	int rw;
154	struct proc *p;
155{
156	int s = splhigh();
157
158	switch (rw) {
159
160	case FREAD:
161		if (msgbufp->msg_bufr != msgbufp->msg_bufx) {
162			splx(s);
163			return (1);
164		}
165		selrecord(p, &logsoftc.sc_selp);
166		break;
167	}
168	splx(s);
169	return (0);
170}
171
172void
173logwakeup()
174{
175	struct proc *p;
176
177	if (!log_open)
178		return;
179	selwakeup(&logsoftc.sc_selp);
180	if (logsoftc.sc_state & LOG_ASYNC) {
181		if (logsoftc.sc_pgid < 0)
182			gsignal(-logsoftc.sc_pgid, SIGIO);
183		else if (p = pfind(logsoftc.sc_pgid))
184			psignal(p, SIGIO);
185	}
186	if (logsoftc.sc_state & LOG_RDWAIT) {
187		wakeup((caddr_t)msgbufp);
188		logsoftc.sc_state &= ~LOG_RDWAIT;
189	}
190}
191
192/*ARGSUSED*/
193int
194logioctl(dev, com, data, flag, p)
195	dev_t dev;
196	int com;
197	caddr_t data;
198	int flag;
199	struct proc *p;
200{
201	long l;
202	int s;
203
204	switch (com) {
205
206	/* return number of characters immediately available */
207	case FIONREAD:
208		s = splhigh();
209		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
210		splx(s);
211		if (l < 0)
212			l += MSG_BSIZE;
213		*(int *)data = l;
214		break;
215
216	case FIONBIO:
217		break;
218
219	case FIOASYNC:
220		if (*(int *)data)
221			logsoftc.sc_state |= LOG_ASYNC;
222		else
223			logsoftc.sc_state &= ~LOG_ASYNC;
224		break;
225
226	case TIOCSPGRP:
227		logsoftc.sc_pgid = *(int *)data;
228		break;
229
230	case TIOCGPGRP:
231		*(int *)data = logsoftc.sc_pgid;
232		break;
233
234	default:
235		return (-1);
236	}
237	return (0);
238}
239