1 /* $NetBSD: dmesg.c,v 1.8 1995/03/18 14:54:49 cgd Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #ifndef lint 37 static char copyright[] = 38 "@(#) Copyright (c) 1991, 1993\n\ 39 The Regents of the University of California. All rights reserved.\n"; 40 #endif /* not lint */ 41 42 #ifndef lint 43 #if 0 44 static char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93"; 45 #else 46 static char rcsid[] = "$NetBSD: dmesg.c,v 1.8 1995/03/18 14:54:49 cgd Exp $"; 47 #endif 48 #endif /* not lint */ 49 50 #include <sys/cdefs.h> 51 #include <sys/msgbuf.h> 52 53 #include <err.h> 54 #include <fcntl.h> 55 #include <kvm.h> 56 #include <limits.h> 57 #include <nlist.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <time.h> 61 #include <unistd.h> 62 #include <vis.h> 63 64 struct nlist nl[] = { 65 #define X_MSGBUF 0 66 { "_msgbufp" }, 67 { NULL }, 68 }; 69 70 void usage __P((void)); 71 72 #define KREAD(addr, var) \ 73 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 74 75 int 76 main(argc, argv) 77 int argc; 78 char *argv[]; 79 { 80 register int ch, newl, skip; 81 register char *p, *ep; 82 struct msgbuf *bufp, cur; 83 char *memf, *nlistf; 84 kvm_t *kd; 85 char buf[5]; 86 87 memf = nlistf = NULL; 88 while ((ch = getopt(argc, argv, "M:N:")) != EOF) 89 switch(ch) { 90 case 'M': 91 memf = optarg; 92 break; 93 case 'N': 94 nlistf = optarg; 95 break; 96 case '?': 97 default: 98 usage(); 99 } 100 argc -= optind; 101 argv += optind; 102 103 /* 104 * Discard setgid privileges if not the running kernel so that bad 105 * guys can't print interesting stuff from kernel memory. 106 */ 107 if (memf != NULL || nlistf != NULL) 108 setgid(getgid()); 109 110 /* Read in kernel message buffer, do sanity checks. */ 111 if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg")) == 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", 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 kvm_close(kd); 120 if (cur.msg_magic != MSG_MAGIC) 121 errx(1, "magic number incorrect"); 122 if (cur.msg_bufx >= MSG_BSIZE) 123 cur.msg_bufx = 0; 124 125 /* 126 * The message buffer is circular; start at the read pointer, and 127 * go to the write pointer - 1. 128 */ 129 p = cur.msg_bufc + cur.msg_bufx; 130 ep = cur.msg_bufc + cur.msg_bufx - 1; 131 for (newl = skip = 0; p != ep; ++p) { 132 if (p == cur.msg_bufc + MSG_BSIZE) 133 p = cur.msg_bufc; 134 ch = *p; 135 /* Skip "\n<.*>" syslog sequences. */ 136 if (skip) { 137 if (ch == '>') 138 newl = skip = 0; 139 continue; 140 } 141 if (newl && ch == '<') { 142 skip = 1; 143 continue; 144 } 145 if (ch == '\0') 146 continue; 147 newl = ch == '\n'; 148 (void)vis(buf, ch, 0, 0); 149 if (buf[1] == 0) 150 (void)putchar(buf[0]); 151 else 152 (void)printf("%s", buf); 153 } 154 if (!newl) 155 (void)putchar('\n'); 156 exit(0); 157 } 158 159 void 160 usage() 161 { 162 (void)fprintf(stderr, "usage: dmesg [-M core] [-N system]\n"); 163 exit(1); 164 } 165