1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #if 0 33 #ifndef lint 34 static const char copyright[] = 35 "@(#) Copyright (c) 1991, 1993\n\ 36 The Regents of the University of California. All rights reserved.\n"; 37 #endif /* not lint */ 38 39 #ifndef lint 40 static const char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93"; 41 #endif /* not lint */ 42 #endif 43 #include <sys/cdefs.h> 44 __FBSDID("$FreeBSD$"); 45 46 #include <sys/types.h> 47 #include <sys/msgbuf.h> 48 #include <sys/sysctl.h> 49 50 #include <ctype.h> 51 #include <err.h> 52 #include <errno.h> 53 #include <fcntl.h> 54 #include <kvm.h> 55 #include <limits.h> 56 #include <locale.h> 57 #include <nlist.h> 58 #include <stdio.h> 59 #include <stdbool.h> 60 #include <stdlib.h> 61 #include <string.h> 62 #include <unistd.h> 63 #include <vis.h> 64 #include <sys/syslog.h> 65 66 static struct nlist nl[] = { 67 #define X_MSGBUF 0 68 { "_msgbufp", 0, 0, 0, 0 }, 69 { NULL, 0, 0, 0, 0 }, 70 }; 71 72 void usage(void) __dead2; 73 74 #define KREAD(addr, var) \ 75 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 76 77 int 78 main(int argc, char *argv[]) 79 { 80 struct msgbuf *bufp, cur; 81 char *bp, *ep, *memf, *nextp, *nlistf, *p, *q, *visbp; 82 kvm_t *kd; 83 size_t buflen, bufpos; 84 long pri; 85 int ch, clear; 86 bool all; 87 88 all = false; 89 clear = false; 90 (void) setlocale(LC_CTYPE, ""); 91 memf = nlistf = NULL; 92 while ((ch = getopt(argc, argv, "acM:N:")) != -1) 93 switch(ch) { 94 case 'a': 95 all = true; 96 break; 97 case 'c': 98 clear = true; 99 break; 100 case 'M': 101 memf = optarg; 102 break; 103 case 'N': 104 nlistf = optarg; 105 break; 106 case '?': 107 default: 108 usage(); 109 } 110 argc -= optind; 111 if (argc != 0) 112 usage(); 113 114 if (memf == NULL) { 115 /* 116 * Running kernel. Use sysctl. This gives an unwrapped buffer 117 * as a side effect. Remove nulterm (if present) so the value 118 * returned by sysctl is formatted as the rest of the code 119 * expects (the same as the value read from a core file below). 120 */ 121 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) 122 err(1, "sysctl kern.msgbuf"); 123 /* Allocate extra room for growth between the sysctl calls. */ 124 buflen += buflen/8; 125 /* Allocate more than sysctl sees, for room to append \n\0. */ 126 if ((bp = malloc(buflen + 2)) == NULL) 127 errx(1, "malloc failed"); 128 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1) 129 err(1, "sysctl kern.msgbuf"); 130 if (buflen > 0 && bp[buflen - 1] == '\0') 131 buflen--; 132 if (clear) 133 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, &clear, sizeof(int))) 134 err(1, "sysctl kern.msgbuf_clear"); 135 } else { 136 /* Read in kernel message buffer and do sanity checks. */ 137 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 138 if (kd == NULL) 139 exit (1); 140 if (kvm_nlist(kd, nl) == -1) 141 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 142 if (nl[X_MSGBUF].n_type == 0) 143 errx(1, "%s: msgbufp not found", 144 nlistf ? nlistf : "namelist"); 145 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 146 errx(1, "kvm_read: %s", kvm_geterr(kd)); 147 if (cur.msg_magic != MSG_MAGIC) 148 errx(1, "kernel message buffer has different magic " 149 "number"); 150 if ((bp = malloc(cur.msg_size + 2)) == NULL) 151 errx(1, "malloc failed"); 152 153 /* Unwrap the circular buffer to start from the oldest data. */ 154 bufpos = MSGBUF_SEQ_TO_POS(&cur, cur.msg_wseq); 155 if (kvm_read(kd, (long)&cur.msg_ptr[bufpos], bp, 156 cur.msg_size - bufpos) != (ssize_t)(cur.msg_size - bufpos)) 157 errx(1, "kvm_read: %s", kvm_geterr(kd)); 158 if (bufpos != 0 && kvm_read(kd, (long)cur.msg_ptr, 159 &bp[cur.msg_size - bufpos], bufpos) != (ssize_t)bufpos) 160 errx(1, "kvm_read: %s", kvm_geterr(kd)); 161 kvm_close(kd); 162 buflen = cur.msg_size; 163 } 164 165 /* 166 * Ensure that the buffer ends with a newline and a \0 to avoid 167 * complications below. We left space above. 168 */ 169 if (buflen == 0 || bp[buflen - 1] != '\n') 170 bp[buflen++] = '\n'; 171 bp[buflen] = '\0'; 172 173 if ((visbp = malloc(4 * buflen + 1)) == NULL) 174 errx(1, "malloc failed"); 175 176 /* 177 * The message buffer is circular, but has been unwrapped so that 178 * the oldest data comes first. The data will be preceded by \0's 179 * if the message buffer was not full. 180 */ 181 p = bp; 182 ep = &bp[buflen]; 183 if (*p == '\0') { 184 /* Strip leading \0's */ 185 while (*p == '\0') 186 p++; 187 } else if (!all) { 188 /* Skip the first line, since it is probably incomplete. */ 189 p = memchr(p, '\n', ep - p); 190 p++; 191 } 192 for (; p < ep; p = nextp) { 193 nextp = memchr(p, '\n', ep - p); 194 nextp++; 195 196 /* Skip ^<[0-9]+> syslog sequences. */ 197 if (*p == '<' && isdigit(*(p+1))) { 198 errno = 0; 199 pri = strtol(p + 1, &q, 10); 200 if (*q == '>' && pri >= 0 && pri < INT_MAX && 201 errno == 0) { 202 if (LOG_FAC(pri) != LOG_KERN && !all) 203 continue; 204 p = q + 1; 205 } 206 } 207 208 (void)strvisx(visbp, p, nextp - p, 0); 209 (void)printf("%s", visbp); 210 } 211 exit(0); 212 } 213 214 void 215 usage(void) 216 { 217 fprintf(stderr, "usage: dmesg [-ac] [-M core [-N system]]\n"); 218 exit(1); 219 } 220