1 /* $OpenBSD: dmesg.c,v 1.21 2008/10/17 18:49:50 deraadt Exp $ */ 2 /* $NetBSD: dmesg.c,v 1.8 1995/03/18 14:54:49 cgd Exp $ */ 3 4 /*- 5 * Copyright (c) 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/param.h> 34 #include <sys/msgbuf.h> 35 #include <sys/sysctl.h> 36 37 #include <err.h> 38 #include <fcntl.h> 39 #include <kvm.h> 40 #include <limits.h> 41 #include <nlist.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <time.h> 46 #include <unistd.h> 47 #include <vis.h> 48 49 struct nlist nl[] = { 50 #define X_MSGBUF 0 51 { "_msgbufp" }, 52 { NULL }, 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, i; 64 char *p; 65 struct msgbuf cur; 66 char *memf, *nlistf, *bufdata = NULL; 67 char buf[5]; 68 69 memf = nlistf = NULL; 70 while ((ch = getopt(argc, argv, "M:N:")) != -1) 71 switch(ch) { 72 case 'M': 73 memf = optarg; 74 break; 75 case 'N': 76 nlistf = optarg; 77 break; 78 case '?': 79 default: 80 usage(); 81 } 82 argc -= optind; 83 argv += optind; 84 85 if (memf == NULL && nlistf == NULL) { 86 int mib[2], msgbufsize; 87 size_t len; 88 89 mib[0] = CTL_KERN; 90 mib[1] = KERN_MSGBUFSIZE; 91 len = sizeof(msgbufsize); 92 if (sysctl(mib, 2, &msgbufsize, &len, NULL, 0)) 93 err(1, "sysctl: KERN_MSGBUFSIZE"); 94 95 msgbufsize += sizeof(struct msgbuf) - 1; 96 bufdata = malloc(msgbufsize); 97 if (bufdata == NULL) 98 errx(1, "couldn't allocate space for buffer data"); 99 100 memset(bufdata, 0, msgbufsize); 101 mib[1] = KERN_MSGBUF; 102 len = msgbufsize; 103 if (sysctl(mib, 2, bufdata, &len, NULL, 0)) 104 err(1, "sysctl: KERN_MSGBUF"); 105 106 memcpy(&cur, bufdata, sizeof(cur)); 107 bufdata = ((struct msgbuf *)bufdata)->msg_bufc; 108 } else { 109 #ifndef NOKVM 110 struct msgbuf *bufp; 111 kvm_t *kd; 112 113 /* Read in kernel message buffer, do sanity checks. */ 114 if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, 115 "dmesg")) == NULL) 116 return (1); 117 118 if (kvm_nlist(kd, nl) == -1) 119 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 120 if (nl[X_MSGBUF].n_type == 0) 121 errx(1, "%s: msgbufp not found", 122 nlistf ? nlistf : "namelist"); 123 if (KREAD(nl[X_MSGBUF].n_value, bufp)) 124 errx(1, "kvm_read: %s: (0x%lx)", kvm_geterr(kd), 125 nl[X_MSGBUF].n_value); 126 if (KREAD((long)bufp, cur)) 127 errx(1, "kvm_read: %s (%0lx)", kvm_geterr(kd), 128 (unsigned long)bufp); 129 if (cur.msg_magic != MSG_MAGIC) 130 errx(1, "magic number incorrect"); 131 bufdata = malloc(cur.msg_bufs); 132 if (bufdata == NULL) 133 errx(1, "couldn't allocate space for buffer data"); 134 if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata, 135 cur.msg_bufs) != cur.msg_bufs) 136 errx(1, "kvm_read: %s", kvm_geterr(kd)); 137 kvm_close(kd); 138 #endif 139 } 140 141 if (cur.msg_bufx >= cur.msg_bufs) 142 cur.msg_bufx = 0; 143 /* 144 * The message buffer is circular; start at the read pointer, and 145 * go to the write pointer - 1. 146 */ 147 for (newl = skip = i = 0, p = bufdata + cur.msg_bufx; 148 i < cur.msg_bufs; i++, p++) { 149 if (p == bufdata + cur.msg_bufs) 150 p = bufdata; 151 ch = *p; 152 /* Skip "\n<.*>" syslog sequences. */ 153 if (skip) { 154 if (ch == '>') 155 newl = skip = 0; 156 continue; 157 } 158 if (newl && ch == '<') { 159 skip = 1; 160 continue; 161 } 162 if (ch == '\0') 163 continue; 164 newl = ch == '\n'; 165 vis(buf, ch, 0, 0); 166 if (buf[1] == 0) 167 putchar(buf[0]); 168 else 169 printf("%s", buf); 170 } 171 if (!newl) 172 putchar('\n'); 173 return (0); 174 } 175 176 void 177 usage(void) 178 { 179 extern char *__progname; 180 181 fprintf(stderr, "usage: %s [-M core] [-N system]\n", __progname); 182 exit(1); 183 } 184