2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 static const char copyright[] =
35 "@(#) Copyright (c) 1991, 1993\n\
36 The Regents of the University of California. All rights reserved.\n";
40 static const char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93";
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
46 #include <sys/types.h>
47 #include <sys/msgbuf.h>
48 #include <sys/sysctl.h>
64 #include <sys/syslog.h>
66 static struct nlist nl[] = {
68 { "_msgbufp", 0, 0, 0, 0 },
72 void usage(void) __dead2;
74 #define KREAD(addr, var) \
75 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var)
78 main(int argc, char *argv[])
80 struct msgbuf *bufp, cur;
81 char *bp, *ep, *memf, *nextp, *nlistf, *p, *q, *visbp;
83 size_t buflen, bufpos;
90 (void) setlocale(LC_CTYPE, "");
92 while ((ch = getopt(argc, argv, "acM:N:")) != -1)
116 * Running kernel. Use sysctl. This gives an unwrapped buffer
117 * as a side effect. Remove nulterm (if present) so the value
118 * returned by sysctl is formatted as the rest of the code
119 * expects (the same as the value read from a core file below).
121 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
122 err(1, "sysctl kern.msgbuf");
123 /* Allocate extra room for growth between the sysctl calls. */
125 /* Allocate more than sysctl sees, for room to append \n\0. */
126 if ((bp = malloc(buflen + 2)) == NULL)
127 errx(1, "malloc failed");
128 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)
129 err(1, "sysctl kern.msgbuf");
130 if (buflen > 0 && bp[buflen - 1] == '\0')
133 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, &clear, sizeof(int)))
134 err(1, "sysctl kern.msgbuf_clear");
136 /* Read in kernel message buffer and do sanity checks. */
137 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
140 if (kvm_nlist(kd, nl) == -1)
141 errx(1, "kvm_nlist: %s", kvm_geterr(kd));
142 if (nl[X_MSGBUF].n_type == 0)
143 errx(1, "%s: msgbufp not found",
144 nlistf ? nlistf : "namelist");
145 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur))
146 errx(1, "kvm_read: %s", kvm_geterr(kd));
147 if (cur.msg_magic != MSG_MAGIC)
148 errx(1, "kernel message buffer has different magic "
150 if ((bp = malloc(cur.msg_size + 2)) == NULL)
151 errx(1, "malloc failed");
153 /* Unwrap the circular buffer to start from the oldest data. */
154 bufpos = MSGBUF_SEQ_TO_POS(&cur, cur.msg_wseq);
155 if (kvm_read(kd, (long)&cur.msg_ptr[bufpos], bp,
156 cur.msg_size - bufpos) != (ssize_t)(cur.msg_size - bufpos))
157 errx(1, "kvm_read: %s", kvm_geterr(kd));
158 if (bufpos != 0 && kvm_read(kd, (long)cur.msg_ptr,
159 &bp[cur.msg_size - bufpos], bufpos) != (ssize_t)bufpos)
160 errx(1, "kvm_read: %s", kvm_geterr(kd));
162 buflen = cur.msg_size;
166 * Ensure that the buffer ends with a newline and a \0 to avoid
167 * complications below. We left space above.
169 if (buflen == 0 || bp[buflen - 1] != '\n')
173 if ((visbp = malloc(4 * buflen + 1)) == NULL)
174 errx(1, "malloc failed");
177 * The message buffer is circular, but has been unwrapped so that
178 * the oldest data comes first. The data will be preceded by \0's
179 * if the message buffer was not full.
184 /* Strip leading \0's */
188 for (; p < ep; p = nextp) {
189 nextp = memchr(p, '\n', ep - p);
192 /* Skip ^<[0-9]+> syslog sequences. */
193 if (*p == '<' && isdigit(*(p+1))) {
195 pri = strtol(p + 1, &q, 10);
196 if (*q == '>' && pri >= 0 && pri < INT_MAX &&
198 if (LOG_FAC(pri) != LOG_KERN && !all)
204 (void)strvisx(visbp, p, nextp - p, 0);
205 (void)printf("%s", visbp);
213 fprintf(stderr, "usage: dmesg [-ac] [-M core [-N system]]\n");