dmesg.c revision 79154 
1/*-
2 * Copyright (c) 1991, 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
34#ifndef lint
35static const char copyright[] =
36"@(#) Copyright (c) 1991, 1993\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static const char sccsid[] = "@(#)dmesg.c	8.1 (Berkeley) 6/5/93";
43#endif
44static const char rcsid[] =
45  "$FreeBSD: head/sbin/dmesg/dmesg.c 79154 2001-07-03 19:49:31Z tmm $";
46#endif /* not lint */
47
48#include <sys/types.h>
49#include <sys/msgbuf.h>
50#include <sys/sysctl.h>
51
52#include <err.h>
53#include <fcntl.h>
54#include <kvm.h>
55#include <locale.h>
56#include <stdio.h>
57#include <stdlib.h>
58#include <unistd.h>
59#include <vis.h>
60#include <sys/syslog.h>
61
62struct nlist nl[] = {
63#define	X_MSGBUF	0
64	{ "_msgbufp" },
65	{ NULL },
66};
67
68void usage __P((void));
69
70#define	KREAD(addr, var) \
71	kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var)
72
73int
74main(argc, argv)
75	int argc;
76	char *argv[];
77{
78	int ch, newl, skip;
79	char *p, *ep;
80	struct msgbuf *bufp, cur;
81	char *bp, *memf, *nlistf;
82	kvm_t *kd;
83	char buf[5];
84	int all = 0;
85	int pri;
86	size_t buflen;
87	int bufpos;
88
89	(void) setlocale(LC_CTYPE, "");
90	memf = nlistf = NULL;
91	while ((ch = getopt(argc, argv, "aM:N:")) != -1)
92		switch(ch) {
93		case 'a':
94			all++;
95			break;
96		case 'M':
97			memf = optarg;
98			break;
99		case 'N':
100			nlistf = optarg;
101			break;
102		case '?':
103		default:
104			usage();
105		}
106	argc -= optind;
107	argv += optind;
108
109	if (memf == NULL && nlistf == NULL) {
110		/* Running kernel. Use sysctl. */
111		if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
112			err(1, "sysctl kern.msgbuf");
113		if ((bp = malloc(buflen)) == NULL)
114			errx(1, "malloc failed");
115		if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)
116			err(1, "sysctl kern.msgbuf");
117		/* We get a dewrapped buffer using sysctl. */
118		bufpos = 0;
119	} else {
120		/* Read in kernel message buffer, do sanity checks. */
121		kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
122		if (kd == NULL)
123			exit (1);
124		if (kvm_nlist(kd, nl) == -1)
125			errx(1, "kvm_nlist: %s", kvm_geterr(kd));
126		if (nl[X_MSGBUF].n_type == 0)
127			errx(1, "%s: msgbufp not found",
128			    nlistf ? nlistf : "namelist");
129		if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur))
130			errx(1, "kvm_read: %s", kvm_geterr(kd));
131		if (cur.msg_magic != MSG_MAGIC)
132			errx(1, "kernel message buffer has different magic "
133			    "number");
134		bp = malloc(cur.msg_size);
135		if (!bp)
136			errx(1, "malloc failed");
137		if (kvm_read(kd, (long)cur.msg_ptr, bp, cur.msg_size) !=
138		    cur.msg_size)
139			errx(1, "kvm_read: %s", kvm_geterr(kd));
140		kvm_close(kd);
141		buflen = cur.msg_size;
142		bufpos = cur.msg_bufx;
143		if (bufpos >= buflen)
144			bufpos = 0;
145	}
146
147	/*
148	 * The message buffer is circular.  If the buffer has wrapped, the
149	 * write pointer points to the oldest data.  Otherwise, the write
150	 * pointer points to \0's following the data.  Read the entire
151	 * buffer starting at the write pointer and ignore nulls so that
152	 * we effectively start at the oldest data.
153	 */
154	p = bp + bufpos;
155	ep = (bufpos == 0 ? bp + buflen : p);
156	newl = skip = 0;
157	do {
158		if (p == bp + buflen)
159			p = bp;
160		ch = *p;
161		/* Skip "\n<.*>" syslog sequences. */
162		if (skip) {
163			if (ch == '\n') {
164				skip = 0;
165				newl = 1;
166			} if (ch == '>') {
167				if (LOG_FAC(pri) == LOG_KERN || all)
168					newl = skip = 0;
169			} else if (ch >= '0' && ch <= '9') {
170				pri *= 10;
171				pri += ch - '0';
172			}
173			continue;
174		}
175		if (newl && ch == '<') {
176			pri = 0;
177			skip = 1;
178			continue;
179		}
180		if (ch == '\0')
181			continue;
182		newl = ch == '\n';
183		(void)vis(buf, ch, 0, 0);
184		if (buf[1] == 0)
185			(void)putchar(buf[0]);
186		else
187			(void)printf("%s", buf);
188	} while (++p != ep);
189	if (!newl)
190		(void)putchar('\n');
191	exit(0);
192}
193
194void
195usage()
196{
197	(void)fprintf(stderr, "usage: dmesg [-M core] [-N system]\n");
198	exit(1);
199}
200