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 38 #include <err.h> 39 #include <fcntl.h> 40 #include <kvm.h> 41 #include <locale.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <unistd.h> 45 #include <vis.h> 46 #include <sys/syslog.h> 47 48 struct nlist nl[] = { 49 #define X_MSGBUF 0 50 { "_msgbufp", 0, 0, 0, 0 }, 51 { NULL, 0, 0, 0, 0 }, 52 }; 53 54 static void dumpbuf(char *bp, size_t bufpos, size_t buflen, 55 int *newl, int *skip, int *pri); 56 void usage(void); 57 58 #define KREAD(addr, var) \ 59 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 60 61 #define INCRBUFSIZE 65536 62 63 int all_opt; 64 65 int 66 main(int argc, char **argv) 67 { 68 int newl, skip; 69 struct msgbuf *bufp, cur; 70 char *bp, *memf, *nlistf; 71 kvm_t *kd; 72 int ch; 73 int clear = 0; 74 int pri = 0; 75 int tailmode = 0; 76 int kno; 77 size_t buflen, bufpos; 78 79 setlocale(LC_CTYPE, ""); 80 memf = nlistf = NULL; 81 while ((ch = getopt(argc, argv, "acfM:N:n:")) != -1) { 82 switch(ch) { 83 case 'a': 84 all_opt++; 85 break; 86 case 'c': 87 clear = 1; 88 break; 89 case 'f': 90 ++tailmode; 91 break; 92 case 'M': 93 memf = optarg; 94 break; 95 case 'N': 96 nlistf = optarg; 97 break; 98 case 'n': 99 kno = strtol(optarg, NULL, 0); 100 asprintf(&memf, "/var/crash/vmcore.%d", kno); 101 asprintf(&nlistf, "/var/crash/kern.%d", kno); 102 break; 103 case '?': 104 default: 105 usage(); 106 } 107 } 108 argc -= optind; 109 argv += optind; 110 111 newl = 1; 112 skip = 0; 113 pri = 0; 114 115 if (memf == NULL && nlistf == NULL && tailmode == 0) { 116 /* Running kernel. Use sysctl. */ 117 buflen = 0; 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 */ 121 buflen = 1; 122 123 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. */ 128 bufpos = 0; 129 dumpbuf(bp, bufpos, buflen, &newl, &skip, &pri); 130 } else { 131 u_int rindex; 132 u_int xindex; 133 u_int ri; 134 u_int xi; 135 u_int n; 136 137 /* Read in kernel message buffer, do sanity checks. */ 138 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 139 if (kd == NULL) 140 exit (1); 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); 147 if (!bp) 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 " 155 "number"); 156 157 /* 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. 162 */ 163 164 rindex = cur.msg_bufr; 165 166 for (;;) { 167 /* 168 * Calculate index for dump and do sanity clipping. 169 */ 170 xindex = cur.msg_bufx; 171 n = xindex - rindex; 172 if (n > cur.msg_size - 1024) { 173 rindex = xindex - cur.msg_size + 2048; 174 n = xindex - rindex; 175 } 176 ri = rindex % cur.msg_size; 177 xi = xindex % cur.msg_size; 178 179 if (ri < xi) 180 buflen = xi - ri; 181 else 182 buflen = cur.msg_size - ri; 183 if (buflen > n) 184 buflen = n; 185 if (buflen > INCRBUFSIZE) 186 buflen = INCRBUFSIZE; 187 188 if (kvm_read(kd, (long)cur.msg_ptr + ri, 189 bp, buflen) != (ssize_t)buflen) { 190 errx(1, "kvm_read: %s", kvm_geterr(kd)); 191 } 192 if (buflen) 193 dumpbuf(bp, 0, buflen, &newl, &skip, &pri); 194 ri = (ri + buflen) % cur.msg_size; 195 n = n - buflen; 196 rindex += buflen; 197 if ((int)n <= 0) { 198 if (tailmode == 0) 199 break; 200 fflush(stdout); 201 if (tailmode == 1) 202 sleep(1); 203 } 204 if (KREAD((long)bufp, cur)) 205 errx(1, "kvm_read: %s", kvm_geterr(kd)); 206 } 207 kvm_close(kd); 208 } 209 if (!newl) 210 putchar('\n'); 211 if (clear) { 212 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, 213 &clear, sizeof(int)) != 0) { 214 err(1, "sysctl kern.msgbuf_clear"); 215 } 216 } 217 return(0); 218 } 219 220 static 221 void 222 dumpbuf(char *bp, size_t bufpos, size_t buflen, 223 int *newl, int *skip, int *pri) 224 { 225 int ch; 226 char *p, *ep; 227 char buf[5]; 228 229 /* 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. 235 */ 236 p = bp + bufpos; 237 ep = (bufpos == 0 ? bp + buflen : p); 238 do { 239 if (p == bp + buflen) 240 p = bp; 241 ch = *p; 242 /* Skip "\n<.*>" syslog sequences. */ 243 if (*skip) { 244 if (ch == '\n') { 245 *skip = 0; 246 *newl = 1; 247 } if (ch == '>') { 248 if (LOG_FAC(*pri) == LOG_KERN) 249 *newl = *skip = 0; 250 } else if (ch >= '0' && ch <= '9') { 251 *pri *= 10; 252 *pri += ch - '0'; 253 } 254 continue; 255 } 256 if (*newl && ch == '<' && all_opt == 0) { 257 *pri = 0; 258 *skip = 1; 259 continue; 260 } 261 if (ch == '\0') 262 continue; 263 *newl = (ch == '\n'); 264 vis(buf, ch, 0, 0); 265 if (buf[1] == 0) 266 putchar(buf[0]); 267 else 268 printf("%s", buf); 269 } while (++p != ep); 270 } 271 272 void 273 usage(void) 274 { 275 fprintf(stderr, "usage: dmesg [-ac] [-M core] [-N system]\n"); 276 exit(1); 277 } 278