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 * @(#) 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 * $DragonFly: src/sbin/dmesg/dmesg.c,v 1.7 2005/01/14 06:38:41 cpressey Exp $ 33 */ 34 35 #include <sys/types.h> 36 #include <sys/msgbuf.h> 37 #include <sys/sysctl.h> 38 39 #include <err.h> 40 #include <fcntl.h> 41 #include <kvm.h> 42 #include <locale.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <unistd.h> 46 #include <vis.h> 47 #include <sys/syslog.h> 48 49 struct nlist nl[] = { 50 #define X_MSGBUF 0 51 { "_msgbufp", 0, 0, 0, 0 }, 52 { NULL, 0, 0, 0, 0 }, 53 }; 54 55 void usage(void); 56 57 #define KREAD(addr, var) \ 58 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 59 60 int 61 main(int argc, char **argv) 62 { 63 int ch, newl, skip; 64 char *p, *ep; 65 struct msgbuf *bufp, cur; 66 char *bp, *memf, *nlistf; 67 kvm_t *kd; 68 char buf[5]; 69 int all = 0; 70 int pri = 0; 71 size_t buflen, bufpos; 72 73 setlocale(LC_CTYPE, ""); 74 memf = nlistf = NULL; 75 while ((ch = getopt(argc, argv, "aM:N:")) != -1) 76 switch(ch) { 77 case 'a': 78 all++; 79 break; 80 case 'M': 81 memf = optarg; 82 break; 83 case 'N': 84 nlistf = optarg; 85 break; 86 case '?': 87 default: 88 usage(); 89 } 90 argc -= optind; 91 argv += optind; 92 93 if (memf == NULL && nlistf == NULL) { 94 /* Running kernel. Use sysctl. */ 95 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) 96 err(1, "sysctl kern.msgbuf"); 97 buflen += 4096; /* add some slop */ 98 if ((bp = malloc(buflen)) == NULL) 99 errx(1, "malloc failed"); 100 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1) 101 err(1, "sysctl kern.msgbuf"); 102 /* We get a dewrapped buffer using sysctl. */ 103 bufpos = 0; 104 } else { 105 /* Read in kernel message buffer, do sanity checks. */ 106 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 107 if (kd == NULL) 108 exit (1); 109 if (kvm_nlist(kd, nl) == -1) 110 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 111 if (nl[X_MSGBUF].n_type == 0) 112 errx(1, "%s: msgbufp not found", 113 nlistf ? nlistf : "namelist"); 114 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 115 errx(1, "kvm_read: %s", kvm_geterr(kd)); 116 if (cur.msg_magic != MSG_MAGIC) 117 errx(1, "kernel message buffer has different magic " 118 "number"); 119 bp = malloc(cur.msg_size); 120 if (!bp) 121 errx(1, "malloc failed"); 122 if (kvm_read(kd, (long)cur.msg_ptr, bp, cur.msg_size) != 123 (ssize_t)cur.msg_size) 124 errx(1, "kvm_read: %s", kvm_geterr(kd)); 125 kvm_close(kd); 126 buflen = cur.msg_size; 127 bufpos = cur.msg_bufx; 128 if (bufpos >= buflen) 129 bufpos = 0; 130 } 131 132 /* 133 * The message buffer is circular. If the buffer has wrapped, the 134 * write pointer points to the oldest data. Otherwise, the write 135 * pointer points to \0's following the data. Read the entire 136 * buffer starting at the write pointer and ignore nulls so that 137 * we effectively start at the oldest data. 138 */ 139 p = bp + bufpos; 140 ep = (bufpos == 0 ? bp + buflen : p); 141 newl = skip = 0; 142 do { 143 if (p == bp + buflen) 144 p = bp; 145 ch = *p; 146 /* Skip "\n<.*>" syslog sequences. */ 147 if (skip) { 148 if (ch == '\n') { 149 skip = 0; 150 newl = 1; 151 } if (ch == '>') { 152 if (LOG_FAC(pri) == LOG_KERN || all) 153 newl = skip = 0; 154 } else if (ch >= '0' && ch <= '9') { 155 pri *= 10; 156 pri += ch - '0'; 157 } 158 continue; 159 } 160 if (newl && ch == '<') { 161 pri = 0; 162 skip = 1; 163 continue; 164 } 165 if (ch == '\0') 166 continue; 167 newl = ch == '\n'; 168 vis(buf, ch, 0, 0); 169 if (buf[1] == 0) 170 putchar(buf[0]); 171 else 172 printf("%s", buf); 173 } while (++p != ep); 174 if (!newl) 175 putchar('\n'); 176 exit(0); 177 } 178 179 void 180 usage(void) 181 { 182 fprintf(stderr, "usage: dmesg [-a] [-M core] [-N system]\n"); 183 exit(1); 184 } 185