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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#) Copyright (c) 1991, 1993 The Regents of the University of California. All rights reserved. 34 * @(#)dmesg.c 8.1 (Berkeley) 6/5/93 35 * $FreeBSD: src/sbin/dmesg/dmesg.c,v 1.11.2.3 2001/08/08 22:32:15 obrien Exp $ 36 * $DragonFly: src/sbin/dmesg/dmesg.c,v 1.4 2003/11/01 17:15:58 drhodus Exp $ 37 */ 38 39 #include <sys/types.h> 40 #include <sys/msgbuf.h> 41 #include <sys/sysctl.h> 42 43 #include <err.h> 44 #include <fcntl.h> 45 #include <kvm.h> 46 #include <locale.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <unistd.h> 50 #include <vis.h> 51 #include <sys/syslog.h> 52 53 struct nlist nl[] = { 54 #define X_MSGBUF 0 55 { "_msgbufp" }, 56 { NULL }, 57 }; 58 59 void usage(void); 60 61 #define KREAD(addr, var) \ 62 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 63 64 int 65 main(int argc, char **argv) 66 { 67 int ch, newl, skip; 68 char *p, *ep; 69 struct msgbuf *bufp, cur; 70 char *bp, *memf, *nlistf; 71 kvm_t *kd; 72 char buf[5]; 73 int all = 0; 74 int pri; 75 size_t buflen; 76 int bufpos; 77 78 (void) setlocale(LC_CTYPE, ""); 79 memf = nlistf = NULL; 80 while ((ch = getopt(argc, argv, "aM:N:")) != -1) 81 switch(ch) { 82 case 'a': 83 all++; 84 break; 85 case 'M': 86 memf = optarg; 87 break; 88 case 'N': 89 nlistf = optarg; 90 break; 91 case '?': 92 default: 93 usage(); 94 } 95 argc -= optind; 96 argv += optind; 97 98 if (memf == NULL && nlistf == NULL) { 99 /* Running kernel. Use sysctl. */ 100 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) 101 err(1, "sysctl kern.msgbuf"); 102 if ((bp = malloc(buflen)) == NULL) 103 errx(1, "malloc failed"); 104 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1) 105 err(1, "sysctl kern.msgbuf"); 106 /* We get a dewrapped buffer using sysctl. */ 107 bufpos = 0; 108 } else { 109 /* Read in kernel message buffer, do sanity checks. */ 110 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 111 if (kd == NULL) 112 exit (1); 113 if (kvm_nlist(kd, nl) == -1) 114 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 115 if (nl[X_MSGBUF].n_type == 0) 116 errx(1, "%s: msgbufp not found", 117 nlistf ? nlistf : "namelist"); 118 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 119 errx(1, "kvm_read: %s", kvm_geterr(kd)); 120 if (cur.msg_magic != MSG_MAGIC) 121 errx(1, "kernel message buffer has different magic " 122 "number"); 123 bp = malloc(cur.msg_size); 124 if (!bp) 125 errx(1, "malloc failed"); 126 if (kvm_read(kd, (long)cur.msg_ptr, bp, cur.msg_size) != 127 cur.msg_size) 128 errx(1, "kvm_read: %s", kvm_geterr(kd)); 129 kvm_close(kd); 130 buflen = cur.msg_size; 131 bufpos = cur.msg_bufx; 132 if (bufpos >= buflen) 133 bufpos = 0; 134 } 135 136 /* 137 * The message buffer is circular. If the buffer has wrapped, the 138 * write pointer points to the oldest data. Otherwise, the write 139 * pointer points to \0's following the data. Read the entire 140 * buffer starting at the write pointer and ignore nulls so that 141 * we effectively start at the oldest data. 142 */ 143 p = bp + bufpos; 144 ep = (bufpos == 0 ? bp + buflen : p); 145 newl = skip = 0; 146 do { 147 if (p == bp + buflen) 148 p = bp; 149 ch = *p; 150 /* Skip "\n<.*>" syslog sequences. */ 151 if (skip) { 152 if (ch == '\n') { 153 skip = 0; 154 newl = 1; 155 } if (ch == '>') { 156 if (LOG_FAC(pri) == LOG_KERN || all) 157 newl = skip = 0; 158 } else if (ch >= '0' && ch <= '9') { 159 pri *= 10; 160 pri += ch - '0'; 161 } 162 continue; 163 } 164 if (newl && ch == '<') { 165 pri = 0; 166 skip = 1; 167 continue; 168 } 169 if (ch == '\0') 170 continue; 171 newl = ch == '\n'; 172 (void)vis(buf, ch, 0, 0); 173 if (buf[1] == 0) 174 (void)putchar(buf[0]); 175 else 176 (void)printf("%s", buf); 177 } while (++p != ep); 178 if (!newl) 179 (void)putchar('\n'); 180 exit(0); 181 } 182 183 void 184 usage(void) 185 { 186 (void)fprintf(stderr, "usage: dmesg [-a] [-M core] [-N system]\n"); 187 exit(1); 188 } 189