1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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.
18 *
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
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/types.h>
33 #include <sys/msgbuf.h>
34 #include <sys/sysctl.h>
35 #include <sys/syslog.h>
36 #include <sys/time.h>
37
38 #include <ctype.h>
39 #include <err.h>
40 #include <errno.h>
41 #include <fcntl.h>
42 #include <kvm.h>
43 #include <limits.h>
44 #include <locale.h>
45 #include <nlist.h>
46 #include <stdio.h>
47 #include <stdbool.h>
48 #include <stdlib.h>
49 #include <string.h>
50 #include <unistd.h>
51 #include <vis.h>
52
53 static struct nlist nl[] = {
54 #define X_MSGBUF 0
55 { "_msgbufp", 0, 0, 0, 0 },
56 { NULL, 0, 0, 0, 0 },
57 };
58
59 void usage(void) __dead2;
60
61 #define KREAD(addr, var) \
62 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var)
63
64 int
main(int argc,char * argv[])65 main(int argc, char *argv[])
66 {
67 struct msgbuf *bufp, cur;
68 struct timeval boottime, reltime, abstime;
69 char timebuf[1024];
70 char *bp, *ep, *memf, *nextp, *nlistf, *p, *q, *visbp;
71 const char *timefmt = "%d %b %T";
72 kvm_t *kd;
73 size_t buflen, bufpos;
74 long pri;
75 int ch, clear;
76 bool all, timeconv;
77
78 all = false;
79 clear = false;
80 timeconv = false;
81 (void) setlocale(LC_CTYPE, "");
82 memf = nlistf = NULL;
83 while ((ch = getopt(argc, argv, "actM:N:f:")) != -1)
84 switch(ch) {
85 case 'a':
86 all = true;
87 break;
88 case 'c':
89 clear = true;
90 break;
91 case 't':
92 timeconv = true;
93 break;
94 case 'M':
95 memf = optarg;
96 break;
97 case 'N':
98 nlistf = optarg;
99 break;
100 case 'f':
101 timefmt = optarg;
102 break;
103 case '?':
104 default:
105 usage();
106 }
107 argc -= optind;
108 if (argc != 0)
109 usage();
110
111 if (timeconv) {
112 int mib[2] = {CTL_KERN, KERN_BOOTTIME};
113
114 size_t l = sizeof(boottime);
115 if (sysctl(mib, 2, &boottime, &l, 0, 0) < 0)
116 err(1, "sysctl kern.boottime");
117 }
118
119 if (memf == NULL) {
120 /*
121 * Running kernel. Use sysctl. This gives an unwrapped buffer
122 * as a side effect. Remove nulterm (if present) so the value
123 * returned by sysctl is formatted as the rest of the code
124 * expects (the same as the value read from a core file below).
125 */
126 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
127 err(1, "sysctl kern.msgbuf");
128 /* Allocate extra room for growth between the sysctl calls. */
129 buflen += buflen/8;
130 /* Allocate more than sysctl sees, for room to append \n\0. */
131 if ((bp = malloc(buflen + 2)) == NULL)
132 errx(1, "malloc failed");
133 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)
134 err(1, "sysctl kern.msgbuf");
135 if (buflen > 0 && bp[buflen - 1] == '\0')
136 buflen--;
137 if (clear)
138 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, &clear, sizeof(int)))
139 err(1, "sysctl kern.msgbuf_clear");
140 } else {
141 /* Read in kernel message buffer and do sanity checks. */
142 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
143 if (kd == NULL)
144 exit (1);
145 if (kvm_nlist(kd, nl) == -1)
146 errx(1, "kvm_nlist: %s", kvm_geterr(kd));
147 if (nl[X_MSGBUF].n_type == 0)
148 errx(1, "%s: msgbufp not found",
149 nlistf ? nlistf : "namelist");
150 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur))
151 errx(1, "kvm_read: %s", kvm_geterr(kd));
152 if (cur.msg_magic != MSG_MAGIC)
153 errx(1, "kernel message buffer has different magic "
154 "number");
155 if ((bp = malloc(cur.msg_size + 2)) == NULL)
156 errx(1, "malloc failed");
157
158 /* Unwrap the circular buffer to start from the oldest data. */
159 bufpos = MSGBUF_SEQ_TO_POS(&cur, cur.msg_wseq);
160 if (kvm_read(kd, (long)&cur.msg_ptr[bufpos], bp,
161 cur.msg_size - bufpos) != (ssize_t)(cur.msg_size - bufpos))
162 errx(1, "kvm_read: %s", kvm_geterr(kd));
163 if (bufpos != 0 && kvm_read(kd, (long)cur.msg_ptr,
164 &bp[cur.msg_size - bufpos], bufpos) != (ssize_t)bufpos)
165 errx(1, "kvm_read: %s", kvm_geterr(kd));
166 kvm_close(kd);
167 buflen = cur.msg_size;
168 }
169
170 /*
171 * Ensure that the buffer ends with a newline and a \0 to avoid
172 * complications below. We left space above.
173 */
174 if (buflen == 0 || bp[buflen - 1] != '\n')
175 bp[buflen++] = '\n';
176 bp[buflen] = '\0';
177
178 if ((visbp = malloc(4 * buflen + 1)) == NULL)
179 errx(1, "malloc failed");
180
181 /*
182 * The message buffer is circular, but has been unwrapped so that
183 * the oldest data comes first. The data will be preceded by \0's
184 * if the message buffer was not full.
185 */
186 p = bp;
187 ep = &bp[buflen];
188 if (*p == '\0') {
189 /* Strip leading \0's */
190 while (*p == '\0')
191 p++;
192 }
193 for (; p < ep; p = nextp) {
194 nextp = memchr(p, '\n', ep - p);
195 nextp++;
196
197 /* Skip ^<[0-9]+> syslog sequences. */
198 if (*p == '<' && isdigit(*(p+1))) {
199 errno = 0;
200 pri = strtol(p + 1, &q, 10);
201 if (*q == '>' && pri >= 0 && pri < INT_MAX &&
202 errno == 0) {
203 if (LOG_FAC(pri) != LOG_KERN && !all)
204 continue;
205 p = q + 1;
206 }
207 }
208
209 (void)strvisx(visbp, p, nextp - p, 0);
210 if (!timeconv) {
211 printf("%s", visbp);
212 continue;
213 }
214
215 if (visbp[0] != '[') {
216 printf("%s", visbp);
217 continue;
218 }
219
220 reltime.tv_usec = 0;
221 errno = 0;
222 reltime.tv_sec = strtoul(visbp + 1, &q, 10);
223 if (errno != 0) {
224 printf("%s", visbp);
225 continue;
226 }
227
228 if (*q == '.') {
229 errno = 0;
230 reltime.tv_usec = strtof(q, &q) * 1000000.0;
231 if (errno != 0) {
232 printf("%s", visbp);
233 continue;
234 }
235 }
236
237 if (*q != ']' || q[1] != ' ') {
238 printf("%s", visbp);
239 continue;
240 }
241 q++;
242
243 timeradd(&boottime, &reltime, &abstime);
244
245 if (strftime(timebuf, sizeof timebuf, timefmt,
246 localtime(&abstime.tv_sec)) != 0) {
247 printf("[%s]%s", timebuf, q);
248 } else {
249 printf("%s", visbp);
250 continue;
251 }
252 }
253 exit(0);
254 }
255
256 void
usage(void)257 usage(void)
258 {
259 fprintf(stderr, "usage: dmesg [-ac] [-t [-f output_fmt]] [-M core [-N system]]\n");
260 exit(1);
261 }
262