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. 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.
16 *
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
27 * SUCH DAMAGE.
28 *
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 $
32 */
33
34 #include <sys/types.h>
35 #include <sys/msgbuf.h>
36 #include <sys/sysctl.h>
37 #include <sys/stat.h>
38
39 #include <err.h>
40 #include <fcntl.h>
41 #include <kvm.h>
42 #include <locale.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <unistd.h>
46 #include <vis.h>
47 #include <sys/syslog.h>
48
49 static struct nlist nl[] = {
50 #define X_MSGBUF 0
51 { "_msgbufp", 0, 0, 0, 0 },
52 { NULL, 0, 0, 0, 0 },
53 };
54
55 static void dumpbuf(char *bp, size_t bufpos, size_t buflen,
56 int *newl, int *skip, int *pri);
57 static void usage(void) __dead2;
58
59 #define KREAD(addr, var) \
60 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var)
61
62 #define INCRBUFSIZE 65536
63
64 static int all_opt;
65
66 int
main(int argc,char ** argv)67 main(int argc, char **argv)
68 {
69 int newl, skip;
70 struct msgbuf *bufp, cur;
71 char *bp, *memf, *nlistf;
72 kvm_t *kd;
73 int ch;
74 int clear = 0;
75 int pri = 0;
76 int tailmode = 0;
77 int kno;
78 size_t buflen, bufpos;
79 struct stat st;
80
81 setlocale(LC_CTYPE, "");
82 memf = nlistf = NULL;
83 while ((ch = getopt(argc, argv, "acfM:N:n:")) != -1) {
84 switch(ch) {
85 case 'a':
86 all_opt++;
87 break;
88 case 'c':
89 clear = 1;
90 break;
91 case 'f':
92 ++tailmode;
93 break;
94 case 'M':
95 memf = optarg;
96 break;
97 case 'N':
98 nlistf = optarg;
99 break;
100 case 'n':
101 kno = strtol(optarg, NULL, 0);
102 asprintf(&memf, "vmcore.%d", kno);
103 asprintf(&nlistf, "kern.%d", kno);
104 if (stat(memf, &st) || stat(nlistf, &st)) {
105 free(memf);
106 free(nlistf);
107 asprintf(&memf, "/var/crash/vmcore.%d", kno);
108 asprintf(&nlistf, "/var/crash/kern.%d", kno);
109 }
110 break;
111 case '?':
112 default:
113 usage();
114 }
115 }
116 argc -= optind;
117 argv += optind;
118
119 newl = 1;
120 skip = 0;
121 pri = 0;
122
123 if (memf == NULL && nlistf == NULL && tailmode == 0) {
124 /* Running kernel. Use sysctl. */
125 buflen = 0;
126 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1)
127 err(1, "sysctl kern.msgbuf");
128 if (buflen == 0) /* can happen if msgbuf was cleared */
129 buflen = 1;
130
131 if ((bp = malloc(buflen)) == NULL)
132 errx(1, "malloc failed");
133 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1)
134 err(1, "sysctl kern.msgbuf");
135 /* We get a dewrapped buffer using sysctl. */
136 bufpos = 0;
137 dumpbuf(bp, bufpos, buflen, &newl, &skip, &pri);
138 } else {
139 u_int rindex;
140 u_int xindex;
141 u_int ri;
142 u_int xi;
143 u_int n;
144
145 /* Read in kernel message buffer, do sanity checks. */
146 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg");
147 if (kd == NULL)
148 exit (1);
149 if (kvm_nlist(kd, nl) == -1)
150 errx(1, "kvm_nlist: %s", kvm_geterr(kd));
151 if (nl[X_MSGBUF].n_type == 0)
152 errx(1, "%s: msgbufp not found",
153 nlistf ? nlistf : "namelist");
154 bp = malloc(INCRBUFSIZE);
155 if (!bp)
156 errx(1, "malloc failed");
157 if (KREAD(nl[X_MSGBUF].n_value, bufp))
158 errx(1, "kvm_read: %s", kvm_geterr(kd));
159 if (KREAD((long)bufp, cur))
160 errx(1, "kvm_read: %s", kvm_geterr(kd));
161 if (cur.msg_magic != MSG_MAGIC && cur.msg_magic != MSG_OMAGIC)
162 errx(1, "kernel message buffer has different magic "
163 "number");
164
165 /*
166 * NOTE: current algorithm is compatible with both old and
167 * new msgbuf structures. The new structure doesn't
168 * modulo the indexes (so we do), and adds a separate
169 * log index which we don't access here.
170 */
171
172 rindex = cur.msg_bufr;
173
174 for (;;) {
175 /*
176 * Calculate index for dump and do sanity clipping.
177 */
178 xindex = cur.msg_bufx;
179 n = xindex - rindex;
180 if (n > cur.msg_size - 1024) {
181 rindex = xindex - cur.msg_size + 2048;
182 n = xindex - rindex;
183 }
184 ri = rindex % cur.msg_size;
185 xi = xindex % cur.msg_size;
186
187 if (ri < xi)
188 buflen = xi - ri;
189 else
190 buflen = cur.msg_size - ri;
191 if (buflen > n)
192 buflen = n;
193 if (buflen > INCRBUFSIZE)
194 buflen = INCRBUFSIZE;
195
196 if (kvm_read(kd, (long)cur.msg_ptr + ri,
197 bp, buflen) != (ssize_t)buflen) {
198 errx(1, "kvm_read: %s", kvm_geterr(kd));
199 }
200 if (buflen)
201 dumpbuf(bp, 0, buflen, &newl, &skip, &pri);
202 ri = (ri + buflen) % cur.msg_size;
203 n = n - buflen;
204 rindex += buflen;
205 if ((int)n <= 0) {
206 if (tailmode == 0)
207 break;
208 fflush(stdout);
209 if (tailmode == 1)
210 sleep(1);
211 }
212 if (KREAD((long)bufp, cur))
213 errx(1, "kvm_read: %s", kvm_geterr(kd));
214 }
215 kvm_close(kd);
216 }
217 if (!newl)
218 putchar('\n');
219 if (clear) {
220 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL,
221 &clear, sizeof(int)) != 0) {
222 err(1, "sysctl kern.msgbuf_clear");
223 }
224 }
225 return(0);
226 }
227
228 static
229 void
dumpbuf(char * bp,size_t bufpos,size_t buflen,int * newl,int * skip,int * pri)230 dumpbuf(char *bp, size_t bufpos, size_t buflen,
231 int *newl, int *skip, int *pri)
232 {
233 int ch;
234 char *p, *ep;
235 char buf[5];
236
237 /*
238 * The message buffer is circular. If the buffer has wrapped, the
239 * write pointer points to the oldest data. Otherwise, the write
240 * pointer points to \0's following the data. Read the entire
241 * buffer starting at the write pointer and ignore nulls so that
242 * we effectively start at the oldest data.
243 */
244 p = bp + bufpos;
245 ep = (bufpos == 0 ? bp + buflen : p);
246 do {
247 if (p == bp + buflen)
248 p = bp;
249 ch = *p;
250 /* Skip "\n<.*>" syslog sequences. */
251 if (*skip) {
252 if (ch == '\n') {
253 *skip = 0;
254 *newl = 1;
255 } if (ch == '>') {
256 if (LOG_FAC(*pri) == LOG_KERN)
257 *newl = *skip = 0;
258 } else if (ch >= '0' && ch <= '9') {
259 *pri *= 10;
260 *pri += ch - '0';
261 }
262 continue;
263 }
264 if (*newl && ch == '<' && all_opt == 0) {
265 *pri = 0;
266 *skip = 1;
267 continue;
268 }
269 if (ch == '\0')
270 continue;
271 *newl = (ch == '\n');
272 vis(buf, ch, VIS_NOSLASH, 0);
273 if (buf[1] == 0)
274 putchar(buf[0]);
275 else
276 printf("%s", buf);
277 } while (++p != ep);
278 }
279
280 static void
usage(void)281 usage(void)
282 {
283 fprintf(stderr, "usage: dmesg [-ac] [-M core] [-N system]\n");
284 exit(1);
285 }
286