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. 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 */ 33 34 #include <sys/types.h> 35 #include <sys/msgbuf.h> 36 #include <sys/sysctl.h> 37 38 #include <err.h> 39 #include <fcntl.h> 40 #include <kvm.h> 41 #include <locale.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <unistd.h> 45 #include <vis.h> 46 #include <sys/syslog.h> 47 48 struct nlist nl[] = { 49 #define X_MSGBUF 0 50 { "_msgbufp", 0, 0, 0, 0 }, 51 { NULL, 0, 0, 0, 0 }, 52 }; 53 54 void usage(void); 55 56 #define KREAD(addr, var) \ 57 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 58 59 int 60 main(int argc, char **argv) 61 { 62 int ch, newl, skip; 63 char *p, *ep; 64 struct msgbuf *bufp, cur; 65 char *bp, *memf, *nlistf; 66 kvm_t *kd; 67 char buf[5]; 68 int all = 0; 69 int clear = 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, "acM:N:")) != -1) 76 switch(ch) { 77 case 'a': 78 all++; 79 break; 80 case 'c': 81 clear = 1; 82 break; 83 case 'M': 84 memf = optarg; 85 break; 86 case 'N': 87 nlistf = optarg; 88 break; 89 case '?': 90 default: 91 usage(); 92 } 93 argc -= optind; 94 argv += optind; 95 96 if (memf == NULL && nlistf == NULL) { 97 /* Running kernel. Use sysctl. */ 98 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) 99 err(1, "sysctl kern.msgbuf"); 100 buflen += 4096; /* add some slop */ 101 if ((bp = malloc(buflen)) == NULL) 102 errx(1, "malloc failed"); 103 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1) 104 err(1, "sysctl kern.msgbuf"); 105 /* We get a dewrapped buffer using sysctl. */ 106 bufpos = 0; 107 } else { 108 /* Read in kernel message buffer, do sanity checks. */ 109 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 110 if (kd == NULL) 111 exit (1); 112 if (kvm_nlist(kd, nl) == -1) 113 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 114 if (nl[X_MSGBUF].n_type == 0) 115 errx(1, "%s: msgbufp not found", 116 nlistf ? nlistf : "namelist"); 117 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 118 errx(1, "kvm_read: %s", kvm_geterr(kd)); 119 if (cur.msg_magic != MSG_MAGIC) 120 errx(1, "kernel message buffer has different magic " 121 "number"); 122 bp = malloc(cur.msg_size); 123 if (!bp) 124 errx(1, "malloc failed"); 125 if (kvm_read(kd, (long)cur.msg_ptr, bp, cur.msg_size) != 126 (ssize_t)cur.msg_size) 127 errx(1, "kvm_read: %s", kvm_geterr(kd)); 128 kvm_close(kd); 129 buflen = cur.msg_size; 130 bufpos = cur.msg_bufx; 131 if (bufpos >= buflen) 132 bufpos = 0; 133 } 134 135 /* 136 * The message buffer is circular. If the buffer has wrapped, the 137 * write pointer points to the oldest data. Otherwise, the write 138 * pointer points to \0's following the data. Read the entire 139 * buffer starting at the write pointer and ignore nulls so that 140 * we effectively start at the oldest data. 141 */ 142 p = bp + bufpos; 143 ep = (bufpos == 0 ? bp + buflen : p); 144 newl = skip = 0; 145 do { 146 if (p == bp + buflen) 147 p = bp; 148 ch = *p; 149 /* Skip "\n<.*>" syslog sequences. */ 150 if (skip) { 151 if (ch == '\n') { 152 skip = 0; 153 newl = 1; 154 } if (ch == '>') { 155 if (LOG_FAC(pri) == LOG_KERN || all) 156 newl = skip = 0; 157 } else if (ch >= '0' && ch <= '9') { 158 pri *= 10; 159 pri += ch - '0'; 160 } 161 continue; 162 } 163 if (newl && ch == '<') { 164 pri = 0; 165 skip = 1; 166 continue; 167 } 168 if (ch == '\0') 169 continue; 170 newl = ch == '\n'; 171 vis(buf, ch, 0, 0); 172 if (buf[1] == 0) 173 putchar(buf[0]); 174 else 175 printf("%s", buf); 176 } while (++p != ep); 177 if (!newl) 178 putchar('\n'); 179 if (clear) 180 if (sysctlbyname("kern.msgbuf_clear", NULL, NULL, &clear, sizeof(int)) != 0) 181 err(1, "sysctl kern.msgbuf_clear"); 182 exit(0); 183 } 184 185 void 186 usage(void) 187 { 188 fprintf(stderr, "usage: dmesg [-ac] [-M core] [-N system]\n"); 189 exit(1); 190 } 191