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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #ifndef lint 35 static char copyright[] = 36 "@(#) Copyright (c) 1991, 1993\n\ 37 The Regents of the University of California. All rights reserved.\n"; 38 #endif /* not lint */ 39 40 #ifndef lint 41 static char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93"; 42 #endif /* not lint */ 43 44 #include <sys/cdefs.h> 45 #include <sys/msgbuf.h> 46 47 #include <fcntl.h> 48 #include <kvm.h> 49 #include <limits.h> 50 #include <nlist.h> 51 #include <stdio.h> 52 #include <stdlib.h> 53 #include <time.h> 54 #include <unistd.h> 55 #include <vis.h> 56 57 struct nlist nl[] = { 58 #define X_MSGBUF 0 59 { "_msgbufp" }, 60 { NULL }, 61 }; 62 63 void usage __P((void)); 64 65 #define KREAD(addr, var) \ 66 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 67 68 int 69 main(argc, argv) 70 int argc; 71 char *argv[]; 72 { 73 register int ch, newl, skip; 74 register char *p, *ep; 75 struct msgbuf *bufp, cur; 76 char *memf, *nlistf; 77 kvm_t *kd; 78 char buf[5]; 79 80 memf = nlistf = NULL; 81 while ((ch = getopt(argc, argv, "M:N:")) != EOF) 82 switch(ch) { 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 /* 97 * Discard setgid privileges if not the running kernel so that bad 98 * guys can't print interesting stuff from kernel memory. 99 */ 100 if (memf != NULL || nlistf != NULL) 101 setgid(getgid()); 102 103 /* Read in kernel message buffer, do sanity checks. */ 104 if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg")) == NULL) 105 exit (1); 106 if (kvm_nlist(kd, nl) == -1) 107 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 108 if (nl[X_MSGBUF].n_type == 0) 109 errx(1, "%s: msgbufp not found", nlistf ? nlistf : "namelist"); 110 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 111 errx(1, "kvm_read: %s", kvm_geterr(kd)); 112 kvm_close(kd); 113 if (cur.msg_magic != MSG_MAGIC) 114 errx(1, "magic number incorrect"); 115 if (cur.msg_bufx >= MSG_BSIZE) 116 cur.msg_bufx = 0; 117 118 /* 119 * The message buffer is circular; start at the read pointer, and 120 * go to the write pointer - 1. 121 */ 122 p = cur.msg_bufc + cur.msg_bufx; 123 ep = cur.msg_bufc + cur.msg_bufx - 1; 124 for (newl = skip = 0; p != ep; ++p) { 125 if (p == cur.msg_bufc + MSG_BSIZE) 126 p = cur.msg_bufc; 127 ch = *p; 128 /* Skip "\n<.*>" syslog sequences. */ 129 if (skip) { 130 if (ch == '>') 131 newl = skip = 0; 132 continue; 133 } 134 if (newl && ch == '<') { 135 skip = 1; 136 continue; 137 } 138 if (ch == '\0') 139 continue; 140 newl = ch == '\n'; 141 (void)vis(buf, ch, 0, 0); 142 if (buf[1] == 0) 143 (void)putchar(buf[0]); 144 else 145 (void)printf("%s", buf); 146 } 147 if (!newl) 148 (void)putchar('\n'); 149 exit(0); 150 } 151 152 void 153 usage() 154 { 155 (void)fprintf(stderr, "usage: dmesg [-M core] [-N system]\n"); 156 exit(1); 157 } 158