1 /* $OpenBSD: dmesg.c,v 1.22 2010/07/02 22:02:06 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 #ifndef NOKVM 50 struct nlist nl[] = { 51 #define X_MSGBUF 0 52 { "_msgbufp" }, 53 { NULL }, 54 }; 55 #endif 56 57 void usage(void); 58 59 #define KREAD(addr, var) \ 60 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 61 62 int 63 main(int argc, char *argv[]) 64 { 65 int ch, newl, skip, i; 66 char *p; 67 struct msgbuf cur; 68 char *memf, *nlistf, *bufdata = NULL; 69 char buf[5]; 70 71 memf = nlistf = NULL; 72 while ((ch = getopt(argc, argv, "M:N:")) != -1) 73 switch(ch) { 74 case 'M': 75 memf = optarg; 76 break; 77 case 'N': 78 nlistf = optarg; 79 break; 80 case '?': 81 default: 82 usage(); 83 } 84 argc -= optind; 85 argv += optind; 86 87 if (memf == NULL && nlistf == NULL) { 88 int mib[2], msgbufsize; 89 size_t len; 90 91 mib[0] = CTL_KERN; 92 mib[1] = KERN_MSGBUFSIZE; 93 len = sizeof(msgbufsize); 94 if (sysctl(mib, 2, &msgbufsize, &len, NULL, 0)) 95 err(1, "sysctl: KERN_MSGBUFSIZE"); 96 97 msgbufsize += sizeof(struct msgbuf) - 1; 98 bufdata = malloc(msgbufsize); 99 if (bufdata == NULL) 100 errx(1, "couldn't allocate space for buffer data"); 101 102 memset(bufdata, 0, msgbufsize); 103 mib[1] = KERN_MSGBUF; 104 len = msgbufsize; 105 if (sysctl(mib, 2, bufdata, &len, NULL, 0)) 106 err(1, "sysctl: KERN_MSGBUF"); 107 108 memcpy(&cur, bufdata, sizeof(cur)); 109 bufdata = ((struct msgbuf *)bufdata)->msg_bufc; 110 } else { 111 #ifndef NOKVM 112 struct msgbuf *bufp; 113 kvm_t *kd; 114 115 /* Read in kernel message buffer, do sanity checks. */ 116 if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, 117 "dmesg")) == NULL) 118 return (1); 119 120 if (kvm_nlist(kd, nl) == -1) 121 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 122 if (nl[X_MSGBUF].n_type == 0) 123 errx(1, "%s: msgbufp not found", 124 nlistf ? nlistf : "namelist"); 125 if (KREAD(nl[X_MSGBUF].n_value, bufp)) 126 errx(1, "kvm_read: %s: (0x%lx)", kvm_geterr(kd), 127 nl[X_MSGBUF].n_value); 128 if (KREAD((long)bufp, cur)) 129 errx(1, "kvm_read: %s (%0lx)", kvm_geterr(kd), 130 (unsigned long)bufp); 131 if (cur.msg_magic != MSG_MAGIC) 132 errx(1, "magic number incorrect"); 133 bufdata = malloc(cur.msg_bufs); 134 if (bufdata == NULL) 135 errx(1, "couldn't allocate space for buffer data"); 136 if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata, 137 cur.msg_bufs) != cur.msg_bufs) 138 errx(1, "kvm_read: %s", kvm_geterr(kd)); 139 kvm_close(kd); 140 #endif 141 } 142 143 if (cur.msg_bufx >= cur.msg_bufs) 144 cur.msg_bufx = 0; 145 /* 146 * The message buffer is circular; start at the read pointer, and 147 * go to the write pointer - 1. 148 */ 149 for (newl = skip = i = 0, p = bufdata + cur.msg_bufx; 150 i < cur.msg_bufs; i++, p++) { 151 if (p == bufdata + cur.msg_bufs) 152 p = bufdata; 153 ch = *p; 154 /* Skip "\n<.*>" syslog sequences. */ 155 if (skip) { 156 if (ch == '>') 157 newl = skip = 0; 158 continue; 159 } 160 if (newl && ch == '<') { 161 skip = 1; 162 continue; 163 } 164 if (ch == '\0') 165 continue; 166 newl = ch == '\n'; 167 vis(buf, ch, 0, 0); 168 if (buf[1] == 0) 169 putchar(buf[0]); 170 else 171 printf("%s", buf); 172 } 173 if (!newl) 174 putchar('\n'); 175 return (0); 176 } 177 178 void 179 usage(void) 180 { 181 extern char *__progname; 182 183 fprintf(stderr, "usage: %s [-M core] [-N system]\n", __progname); 184 exit(1); 185 } 186