1 /* $NetBSD: dmesg.c,v 1.10 1997/05/03 17:18:05 mjacob Exp $ */ 2 /*- 3 * Copyright (c) 1991, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by the University of 17 * California, Berkeley and its contributors. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #ifndef lint 36 static char copyright[] = 37 "@(#) Copyright (c) 1991, 1993\n\ 38 The Regents of the University of California. All rights reserved.\n"; 39 #endif /* not lint */ 40 41 #ifndef lint 42 #if 0 43 static char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93"; 44 #else 45 static char rcsid[] = "$NetBSD: dmesg.c,v 1.10 1997/05/03 17:18:05 mjacob Exp $"; 46 #endif 47 #endif /* not lint */ 48 49 #include <sys/cdefs.h> 50 #include <sys/msgbuf.h> 51 52 #include <err.h> 53 #include <fcntl.h> 54 #include <kvm.h> 55 #include <limits.h> 56 #include <nlist.h> 57 #include <stdio.h> 58 #include <stdlib.h> 59 #include <time.h> 60 #include <unistd.h> 61 #include <vis.h> 62 63 struct nlist nl[] = { 64 #define X_MSGBUF 0 65 { "_msgbufp" }, 66 { NULL }, 67 }; 68 69 void usage __P((void)); 70 71 #define KREAD(addr, var) \ 72 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 73 74 int 75 main(argc, argv) 76 int argc; 77 char *argv[]; 78 { 79 register int ch, newl, skip; 80 register char *p, *ep; 81 struct msgbuf *bufp, cur; 82 char *memf, *nlistf; 83 kvm_t *kd; 84 char buf[5]; 85 86 memf = nlistf = NULL; 87 while ((ch = getopt(argc, argv, "M:N:")) != EOF) 88 switch(ch) { 89 case 'M': 90 memf = optarg; 91 break; 92 case 'N': 93 nlistf = optarg; 94 break; 95 case '?': 96 default: 97 usage(); 98 } 99 argc -= optind; 100 argv += optind; 101 102 /* 103 * Discard setgid privileges if not the running kernel so that bad 104 * guys can't print interesting stuff from kernel memory. 105 */ 106 if (memf != NULL || nlistf != NULL) 107 setgid(getgid()); 108 109 /* Read in kernel message buffer, do sanity checks. */ 110 if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg")) == 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", nlistf ? nlistf : "namelist"); 116 if (KREAD(nl[X_MSGBUF].n_value, bufp)) 117 errx(1, "kvm_read: %s (%lx)", kvm_geterr(kd), 118 nl[X_MSGBUF].n_value); 119 if (KREAD((long)bufp, cur)) 120 errx(1, "kvm_read: %s (%lx)", kvm_geterr(kd), bufp); 121 kvm_close(kd); 122 if (cur.msg_magic != MSG_MAGIC) 123 errx(1, "magic number incorrect"); 124 if (cur.msg_bufx >= MSG_BSIZE) 125 cur.msg_bufx = 0; 126 127 /* 128 * The message buffer is circular; start at the read pointer, and 129 * go to the write pointer - 1. 130 */ 131 p = ep = cur.msg_bufc + (cur.msg_bufx - 1 + MSG_BSIZE) % MSG_BSIZE; 132 newl = skip = 0; 133 do { 134 if (++p == cur.msg_bufc + MSG_BSIZE) 135 p = cur.msg_bufc; 136 ch = *p; 137 /* Skip "\n<.*>" syslog sequences. */ 138 if (skip) { 139 if (ch == '>') 140 newl = skip = 0; 141 continue; 142 } 143 if (newl && ch == '<') { 144 skip = 1; 145 continue; 146 } 147 if (ch == '\0') 148 continue; 149 newl = ch == '\n'; 150 (void)vis(buf, ch, 0, 0); 151 if (buf[1] == 0) 152 (void)putchar(buf[0]); 153 else 154 (void)printf("%s", buf); 155 } while (p != ep); 156 if (!newl) 157 (void)putchar('\n'); 158 exit(0); 159 } 160 161 void 162 usage() 163 { 164 (void)fprintf(stderr, "usage: dmesg [-M core] [-N system]\n"); 165 exit(1); 166 } 167