1169695Skan/*- 2169695Skan * SPDX-License-Identifier: BSD-3-Clause 3169695Skan * 4169695Skan * Copyright (c) 1991, 1993 5169695Skan * The Regents of the University of California. All rights reserved. 6169695Skan * 7169695Skan * Redistribution and use in source and binary forms, with or without 8169695Skan * modification, are permitted provided that the following conditions 9169695Skan * are met: 10169695Skan * 1. Redistributions of source code must retain the above copyright 11169695Skan * notice, this list of conditions and the following disclaimer. 12169695Skan * 2. Redistributions in binary form must reproduce the above copyright 13169695Skan * notice, this list of conditions and the following disclaimer in the 14169695Skan * documentation and/or other materials provided with the distribution. 15169695Skan * 3. Neither the name of the University nor the names of its contributors 16169695Skan * may be used to endorse or promote products derived from this software 17169695Skan * without specific prior written permission. 18169695Skan * 19169695Skan * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20169695Skan * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21169695Skan * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22169695Skan * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23169695Skan * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24169695Skan * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25169695Skan * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26169695Skan * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27169695Skan * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28169695Skan * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29169695Skan * SUCH DAMAGE. 30169695Skan */ 31169695Skan 32169695Skan#include <sys/types.h> 33169695Skan#include <sys/msgbuf.h> 34169695Skan#include <sys/sysctl.h> 35169695Skan 36169695Skan#include <ctype.h> 37169695Skan#include <err.h> 38169695Skan#include <errno.h> 39169695Skan#include <fcntl.h> 40169695Skan#include <kvm.h> 41169695Skan#include <limits.h> 42169695Skan#include <locale.h> 43169695Skan#include <nlist.h> 44169695Skan#include <stdio.h> 45169695Skan#include <stdbool.h> 46169695Skan#include <stdlib.h> 47169695Skan#include <string.h> 48169695Skan#include <unistd.h> 49169695Skan#include <vis.h> 50169695Skan#include <sys/syslog.h> 51169695Skan 52169695Skanstatic struct nlist nl[] = { 53169695Skan#define X_MSGBUF 0 54169695Skan { "_msgbufp", 0, 0, 0, 0 }, 55169695Skan { NULL, 0, 0, 0, 0 }, 56169695Skan}; 57169695Skan 58169695Skanvoid usage(void) __dead2; 59169695Skan 60169695Skan#define KREAD(addr, var) \ 61169695Skan kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 62169695Skan 63169695Skanint 64169695Skanmain(int argc, char *argv[]) 65169695Skan{ 66169695Skan struct msgbuf *bufp, cur; 67169695Skan char *bp, *ep, *memf, *nextp, *nlistf, *p, *q, *visbp; 68169695Skan kvm_t *kd; 69169695Skan size_t buflen, bufpos; 70169695Skan long pri; 71169695Skan int ch, clear; 72169695Skan bool all; 73169695Skan 74169695Skan all = false; 75169695Skan clear = false; 76169695Skan (void) setlocale(LC_CTYPE, ""); 77169695Skan memf = nlistf = NULL; 78169695Skan while ((ch = getopt(argc, argv, "acM:N:")) != -1) 79169695Skan switch(ch) { 80169695Skan case 'a': 81169695Skan all = true; 82169695Skan break; 83169695Skan case 'c': 84169695Skan clear = true; 85169695Skan break; 86169695Skan case 'M': 87169695Skan memf = optarg; 88169695Skan break; 89169695Skan case 'N': 90169695Skan nlistf = optarg; 91169695Skan break; 92169695Skan case '?': 93169695Skan default: 94169695Skan usage(); 95169695Skan } 96169695Skan argc -= optind; 97169695Skan if (argc != 0) 98169695Skan usage(); 99169695Skan 100169695Skan if (memf == NULL) { 101169695Skan /* 102169695Skan * Running kernel. Use sysctl. This gives an unwrapped buffer 103169695Skan * as a side effect. Remove nulterm (if present) so the value 104169695Skan * returned by sysctl is formatted as the rest of the code 105169695Skan * expects (the same as the value read from a core file below). 106169695Skan */ 107169695Skan if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) 108169695Skan err(1, "sysctl kern.msgbuf"); 109169695Skan /* Allocate extra room for growth between the sysctl calls. */ 110169695Skan buflen += buflen/8; 111169695Skan /* Allocate more than sysctl sees, for room to append \n\0. */ 112169695Skan 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 if (buflen > 0 && bp[buflen - 1] == '\0') 117 buflen--; 118 if (clear) 119 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, &clear, sizeof(int))) 120 err(1, "sysctl kern.msgbuf_clear"); 121 } else { 122 /* Read in kernel message buffer and do sanity checks. */ 123 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 124 if (kd == NULL) 125 exit (1); 126 if (kvm_nlist(kd, nl) == -1) 127 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 128 if (nl[X_MSGBUF].n_type == 0) 129 errx(1, "%s: msgbufp not found", 130 nlistf ? nlistf : "namelist"); 131 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 132 errx(1, "kvm_read: %s", kvm_geterr(kd)); 133 if (cur.msg_magic != MSG_MAGIC) 134 errx(1, "kernel message buffer has different magic " 135 "number"); 136 if ((bp = malloc(cur.msg_size + 2)) == NULL) 137 errx(1, "malloc failed"); 138 139 /* Unwrap the circular buffer to start from the oldest data. */ 140 bufpos = MSGBUF_SEQ_TO_POS(&cur, cur.msg_wseq); 141 if (kvm_read(kd, (long)&cur.msg_ptr[bufpos], bp, 142 cur.msg_size - bufpos) != (ssize_t)(cur.msg_size - bufpos)) 143 errx(1, "kvm_read: %s", kvm_geterr(kd)); 144 if (bufpos != 0 && kvm_read(kd, (long)cur.msg_ptr, 145 &bp[cur.msg_size - bufpos], bufpos) != (ssize_t)bufpos) 146 errx(1, "kvm_read: %s", kvm_geterr(kd)); 147 kvm_close(kd); 148 buflen = cur.msg_size; 149 } 150 151 /* 152 * Ensure that the buffer ends with a newline and a \0 to avoid 153 * complications below. We left space above. 154 */ 155 if (buflen == 0 || bp[buflen - 1] != '\n') 156 bp[buflen++] = '\n'; 157 bp[buflen] = '\0'; 158 159 if ((visbp = malloc(4 * buflen + 1)) == NULL) 160 errx(1, "malloc failed"); 161 162 /* 163 * The message buffer is circular, but has been unwrapped so that 164 * the oldest data comes first. The data will be preceded by \0's 165 * if the message buffer was not full. 166 */ 167 p = bp; 168 ep = &bp[buflen]; 169 if (*p == '\0') { 170 /* Strip leading \0's */ 171 while (*p == '\0') 172 p++; 173 } 174 for (; p < ep; p = nextp) { 175 nextp = memchr(p, '\n', ep - p); 176 nextp++; 177 178 /* Skip ^<[0-9]+> syslog sequences. */ 179 if (*p == '<' && isdigit(*(p+1))) { 180 errno = 0; 181 pri = strtol(p + 1, &q, 10); 182 if (*q == '>' && pri >= 0 && pri < INT_MAX && 183 errno == 0) { 184 if (LOG_FAC(pri) != LOG_KERN && !all) 185 continue; 186 p = q + 1; 187 } 188 } 189 190 (void)strvisx(visbp, p, nextp - p, 0); 191 (void)printf("%s", visbp); 192 } 193 exit(0); 194} 195 196void 197usage(void) 198{ 199 fprintf(stderr, "usage: dmesg [-ac] [-M core [-N system]]\n"); 200 exit(1); 201} 202