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 unsigned int rindex; 77 size_t buflen, bufpos; 78 79 setlocale(LC_CTYPE, ""); 80 memf = nlistf = NULL; 81 while ((ch = getopt(argc, argv, "acfM: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 '?': 99 default: 100 usage(); 101 } 102 } 103 argc -= optind; 104 argv += optind; 105 106 newl = 0; 107 skip = 0; 108 pri = 0; 109 110 if (memf == NULL && nlistf == NULL && tailmode == 0) { 111 /* Running kernel. Use sysctl. */ 112 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) 113 err(1, "sysctl kern.msgbuf"); 114 buflen += 4096; /* add some slop */ 115 if ((bp = malloc(buflen)) == NULL) 116 errx(1, "malloc failed"); 117 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1) 118 err(1, "sysctl kern.msgbuf"); 119 /* We get a dewrapped buffer using sysctl. */ 120 bufpos = 0; 121 dumpbuf(bp, bufpos, buflen, &newl, &skip, &pri); 122 } else { 123 /* Read in kernel message buffer, do sanity checks. */ 124 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 125 if (kd == NULL) 126 exit (1); 127 if (kvm_nlist(kd, nl) == -1) 128 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 129 if (nl[X_MSGBUF].n_type == 0) 130 errx(1, "%s: msgbufp not found", 131 nlistf ? nlistf : "namelist"); 132 bp = malloc(INCRBUFSIZE); 133 if (!bp) 134 errx(1, "malloc failed"); 135 if (KREAD(nl[X_MSGBUF].n_value, bufp)) 136 errx(1, "kvm_read: %s", kvm_geterr(kd)); 137 if (KREAD((long)bufp, cur)) 138 errx(1, "kvm_read: %s", kvm_geterr(kd)); 139 if (cur.msg_magic != MSG_MAGIC) 140 errx(1, "kernel message buffer has different magic " 141 "number"); 142 143 /* 144 * Start point. Use rindex == bufx as our end-of-buffer 145 * indication but for the initial rindex from the kernel 146 * this means the buffer has cycled and is 100% full. 147 */ 148 rindex = cur.msg_bufr; 149 if (rindex == cur.msg_bufx) { 150 if (++rindex >= cur.msg_size) 151 rindex = 0; 152 } 153 154 for (;;) { 155 if (cur.msg_bufx >= rindex) 156 buflen = cur.msg_bufx - rindex; 157 else 158 buflen = cur.msg_size - rindex; 159 if (buflen > INCRBUFSIZE) 160 buflen = INCRBUFSIZE; 161 if (kvm_read(kd, (long)cur.msg_ptr + rindex, 162 bp, buflen) != (ssize_t)buflen) { 163 errx(1, "kvm_read: %s", kvm_geterr(kd)); 164 } 165 if (buflen) 166 dumpbuf(bp, 0, buflen, &newl, &skip, &pri); 167 rindex += buflen; 168 if (rindex >= cur.msg_size) 169 rindex = 0; 170 if (rindex == cur.msg_bufx) { 171 if (tailmode == 0) 172 break; 173 fflush(stdout); 174 if (tailmode == 1) 175 sleep(1); 176 } 177 if (KREAD((long)bufp, cur)) 178 errx(1, "kvm_read: %s", kvm_geterr(kd)); 179 } 180 kvm_close(kd); 181 } 182 if (!newl) 183 putchar('\n'); 184 if (clear) { 185 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, 186 &clear, sizeof(int)) != 0) { 187 err(1, "sysctl kern.msgbuf_clear"); 188 } 189 } 190 return(0); 191 } 192 193 static 194 void 195 dumpbuf(char *bp, size_t bufpos, size_t buflen, 196 int *newl, int *skip, int *pri) 197 { 198 int ch; 199 char *p, *ep; 200 char buf[5]; 201 202 /* 203 * The message buffer is circular. If the buffer has wrapped, the 204 * write pointer points to the oldest data. Otherwise, the write 205 * pointer points to \0's following the data. Read the entire 206 * buffer starting at the write pointer and ignore nulls so that 207 * we effectively start at the oldest data. 208 */ 209 p = bp + bufpos; 210 ep = (bufpos == 0 ? bp + buflen : p); 211 do { 212 if (p == bp + buflen) 213 p = bp; 214 ch = *p; 215 /* Skip "\n<.*>" syslog sequences. */ 216 if (*skip) { 217 if (ch == '\n') { 218 *skip = 0; 219 *newl = 1; 220 } if (ch == '>') { 221 if (LOG_FAC(*pri) == LOG_KERN || all_opt) 222 *newl = *skip = 0; 223 } else if (ch >= '0' && ch <= '9') { 224 *pri *= 10; 225 *pri += ch - '0'; 226 } 227 continue; 228 } 229 if (*newl && ch == '<') { 230 *pri = 0; 231 *skip = 1; 232 continue; 233 } 234 if (ch == '\0') 235 continue; 236 *newl = ch == '\n'; 237 vis(buf, ch, 0, 0); 238 if (buf[1] == 0) 239 putchar(buf[0]); 240 else 241 printf("%s", buf); 242 } while (++p != ep); 243 } 244 245 void 246 usage(void) 247 { 248 fprintf(stderr, "usage: dmesg [-ac] [-M core] [-N system]\n"); 249 exit(1); 250 } 251