2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#) Copyright (c) 1991, 1993 The Regents of the University of California. All rights reserved.
30 * @(#)dmesg.c 8.1 (Berkeley) 6/5/93
31 * $FreeBSD: src/sbin/dmesg/dmesg.c,v 1.11.2.3 2001/08/08 22:32:15 obrien Exp $
34 #include <sys/types.h>
35 #include <sys/msgbuf.h>
36 #include <sys/sysctl.h>
46 #include <sys/syslog.h>
50 { "_msgbufp", 0, 0, 0, 0 },
54 static void dumpbuf(char *bp, size_t bufpos, size_t buflen,
55 int *newl, int *skip, int *pri);
58 #define KREAD(addr, var) \
59 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var)
61 #define INCRBUFSIZE 65536
66 main(int argc, char **argv)
69 struct msgbuf *bufp, cur;
70 char *bp, *memf, *nlistf;
77 size_t buflen, bufpos;
79 setlocale(LC_CTYPE, "");
81 while ((ch = getopt(argc, argv, "acfM:N:n:")) != -1) {
99 kno = strtol(optarg, NULL, 0);
100 asprintf(&memf, "/var/crash/vmcore.%d", kno);
101 asprintf(&nlistf, "/var/crash/kern.%d", kno);
115 if (memf == NULL && nlistf == NULL && tailmode == 0) {
116 /* Running kernel. Use sysctl. */
118 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
119 err(1, "sysctl kern.msgbuf");
120 if (buflen == 0) /* can happen if msgbuf was cleared */
123 if ((bp = malloc(buflen)) == NULL)
124 errx(1, "malloc failed");
125 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)
126 err(1, "sysctl kern.msgbuf");
127 /* We get a dewrapped buffer using sysctl. */
129 dumpbuf(bp, bufpos, buflen, &newl, &skip, &pri);
137 /* Read in kernel message buffer, do sanity checks. */
138 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
141 if (kvm_nlist(kd, nl) == -1)
142 errx(1, "kvm_nlist: %s", kvm_geterr(kd));
143 if (nl[X_MSGBUF].n_type == 0)
144 errx(1, "%s: msgbufp not found",
145 nlistf ? nlistf : "namelist");
146 bp = malloc(INCRBUFSIZE);
148 errx(1, "malloc failed");
149 if (KREAD(nl[X_MSGBUF].n_value, bufp))
150 errx(1, "kvm_read: %s", kvm_geterr(kd));
151 if (KREAD((long)bufp, cur))
152 errx(1, "kvm_read: %s", kvm_geterr(kd));
153 if (cur.msg_magic != MSG_MAGIC && cur.msg_magic != MSG_OMAGIC)
154 errx(1, "kernel message buffer has different magic "
158 * NOTE: current algorithm is compatible with both old and
159 * new msgbuf structures. The new structure doesn't
160 * modulo the indexes (so we do), and adds a separate
161 * log index which we don't access here.
164 rindex = cur.msg_bufr;
168 * Calculate index for dump and do sanity clipping.
170 xindex = cur.msg_bufx;
172 if (n > cur.msg_size - 1024) {
173 rindex = xindex - cur.msg_size + 2048;
176 ri = rindex % cur.msg_size;
177 xi = xindex % cur.msg_size;
182 buflen = cur.msg_size - ri;
185 if (buflen > INCRBUFSIZE)
186 buflen = INCRBUFSIZE;
188 if (kvm_read(kd, (long)cur.msg_ptr + ri,
189 bp, buflen) != (ssize_t)buflen) {
190 errx(1, "kvm_read: %s", kvm_geterr(kd));
193 dumpbuf(bp, 0, buflen, &newl, &skip, &pri);
194 ri = (ri + buflen) % cur.msg_size;
204 if (KREAD((long)bufp, cur))
205 errx(1, "kvm_read: %s", kvm_geterr(kd));
212 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL,
213 &clear, sizeof(int)) != 0) {
214 err(1, "sysctl kern.msgbuf_clear");
222 dumpbuf(char *bp, size_t bufpos, size_t buflen,
223 int *newl, int *skip, int *pri)
230 * The message buffer is circular. If the buffer has wrapped, the
231 * write pointer points to the oldest data. Otherwise, the write
232 * pointer points to \0's following the data. Read the entire
233 * buffer starting at the write pointer and ignore nulls so that
234 * we effectively start at the oldest data.
237 ep = (bufpos == 0 ? bp + buflen : p);
239 if (p == bp + buflen)
242 /* Skip "\n<.*>" syslog sequences. */
248 if (LOG_FAC(*pri) == LOG_KERN)
250 } else if (ch >= '0' && ch <= '9') {
256 if (*newl && ch == '<' && all_opt == 0) {
263 *newl = (ch == '\n');
275 fprintf(stderr, "usage: dmesg [-ac] [-M core] [-N system]\n");