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 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 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 281 usage(void) 282 { 283 fprintf(stderr, "usage: dmesg [-ac] [-M core] [-N system]\n"); 284 exit(1); 285 } 286