dmesg.c revision 136491
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 * 4. 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 30#if 0 31#ifndef lint 32static const char copyright[] = 33"@(#) Copyright (c) 1991, 1993\n\ 34 The Regents of the University of California. All rights reserved.\n"; 35#endif /* not lint */ 36 37#ifndef lint 38static const char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93"; 39#endif /* not lint */ 40#endif 41#include <sys/cdefs.h> 42__FBSDID("$FreeBSD: head/sbin/dmesg/dmesg.c 136491 2004-10-13 20:33:18Z schweikh $"); 43 44#include <sys/types.h> 45#include <sys/msgbuf.h> 46#include <sys/sysctl.h> 47 48#include <err.h> 49#include <errno.h> 50#include <fcntl.h> 51#include <kvm.h> 52#include <limits.h> 53#include <locale.h> 54#include <nlist.h> 55#include <stdio.h> 56#include <stdlib.h> 57#include <string.h> 58#include <unistd.h> 59#include <vis.h> 60#include <sys/syslog.h> 61 62struct nlist nl[] = { 63#define X_MSGBUF 0 64 { "_msgbufp" }, 65 { NULL }, 66}; 67 68void usage(void) __dead2; 69 70#define KREAD(addr, var) \ 71 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 72 73int 74main(int argc, char *argv[]) 75{ 76 struct msgbuf *bufp, cur; 77 char *bp, *ep, *memf, *nextp, *nlistf, *p, *q, *visbp; 78 kvm_t *kd; 79 size_t buflen, bufpos; 80 long pri; 81 int all, ch; 82 83 all = 0; 84 (void) setlocale(LC_CTYPE, ""); 85 memf = nlistf = NULL; 86 while ((ch = getopt(argc, argv, "aM:N:")) != -1) 87 switch(ch) { 88 case 'a': 89 all++; 90 break; 91 case 'M': 92 memf = optarg; 93 break; 94 case 'N': 95 nlistf = optarg; 96 break; 97 case '?': 98 default: 99 usage(); 100 } 101 argc -= optind; 102 if (argc != 0) 103 usage(); 104 105 if (memf == NULL) { 106 /* 107 * Running kernel. Use sysctl. This gives an unwrapped 108 * buffer as a side effect. 109 */ 110 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) 111 err(1, "sysctl kern.msgbuf"); 112 if ((bp = malloc(buflen + 2)) == NULL) 113 errx(1, "malloc failed"); 114 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1) 115 err(1, "sysctl kern.msgbuf"); 116 } else { 117 /* Read in kernel message buffer and do sanity checks. */ 118 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 119 if (kd == NULL) 120 exit (1); 121 if (kvm_nlist(kd, nl) == -1) 122 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 123 if (nl[X_MSGBUF].n_type == 0) 124 errx(1, "%s: msgbufp not found", 125 nlistf ? nlistf : "namelist"); 126 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 127 errx(1, "kvm_read: %s", kvm_geterr(kd)); 128 if (cur.msg_magic != MSG_MAGIC) 129 errx(1, "kernel message buffer has different magic " 130 "number"); 131 if ((bp = malloc(cur.msg_size + 2)) == NULL) 132 errx(1, "malloc failed"); 133 134 /* Unwrap the circular buffer to start from the oldest data. */ 135 bufpos = MSGBUF_SEQ_TO_POS(&cur, cur.msg_wseq); 136 if (kvm_read(kd, (long)&cur.msg_ptr[bufpos], bp, 137 cur.msg_size - bufpos) != cur.msg_size - bufpos) 138 errx(1, "kvm_read: %s", kvm_geterr(kd)); 139 if (bufpos != 0 && kvm_read(kd, (long)cur.msg_ptr, 140 &bp[cur.msg_size - bufpos], bufpos) != bufpos) 141 errx(1, "kvm_read: %s", kvm_geterr(kd)); 142 kvm_close(kd); 143 buflen = cur.msg_size; 144 } 145 146 /* 147 * Ensure that the buffer ends with a newline and a \0 to avoid 148 * complications below. We left space above. 149 */ 150 if (buflen == 0 || bp[buflen - 1] != '\n') 151 bp[buflen++] = '\n'; 152 bp[buflen] = '\0'; 153 154 if ((visbp = malloc(4 * buflen + 1)) == NULL) 155 errx(1, "malloc failed"); 156 157 /* 158 * The message buffer is circular, but has been unwrapped so that 159 * the oldest data comes first. The data will be preceded by \0's 160 * if the message buffer was not full. 161 */ 162 p = bp; 163 ep = &bp[buflen]; 164 if (*p == '\0') { 165 /* Strip leading \0's */ 166 while (*p == '\0') 167 p++; 168 } else if (!all) { 169 /* Skip the first line, since it is probably incomplete. */ 170 p = memchr(p, '\n', ep - p); 171 p++; 172 } 173 for (; p < ep; p = nextp) { 174 nextp = memchr(p, '\n', ep - p); 175 nextp++; 176 177 /* Skip ^<[0-9]+> syslog sequences. */ 178 if (*p == '<') { 179 errno = 0; 180 pri = strtol(p + 1, &q, 10); 181 if (*q == '>' && pri >= 0 && pri < INT_MAX && 182 errno == 0) { 183 if (LOG_FAC(pri) != LOG_KERN && !all) 184 continue; 185 p = q + 1; 186 } 187 } 188 189 (void)strvisx(visbp, p, nextp - p, 0); 190 (void)printf("%s", visbp); 191 } 192 exit(0); 193} 194 195void 196usage(void) 197{ 198 (void)fprintf(stderr, "usage: dmesg [-a] [-M core [-N system]]\n"); 199 exit(1); 200} 201