1 /* $NetBSD: dmesg.c,v 1.23 2005/01/20 15:55:01 xtraeme 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. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 #ifndef lint 33 __COPYRIGHT("@(#) Copyright (c) 1991, 1993\n\ 34 The Regents of the University of California. All rights reserved.\n"); 35 #endif /* not lint */ 36 37 #ifndef lint 38 #if 0 39 static char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93"; 40 #else 41 __RCSID("$NetBSD: dmesg.c,v 1.23 2005/01/20 15:55:01 xtraeme Exp $"); 42 #endif 43 #endif /* not lint */ 44 45 #include <sys/param.h> 46 #include <sys/msgbuf.h> 47 #include <sys/sysctl.h> 48 49 #include <err.h> 50 #include <fcntl.h> 51 #include <kvm.h> 52 #include <nlist.h> 53 #include <stdio.h> 54 #include <stddef.h> 55 #include <stdlib.h> 56 #include <unistd.h> 57 #include <vis.h> 58 59 #ifndef SMALL 60 struct nlist nl[] = { 61 #define X_MSGBUF 0 62 { "_msgbufp" }, 63 { NULL }, 64 }; 65 #endif 66 67 void usage(void); 68 69 #define KREAD(addr, var) \ 70 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 71 72 int 73 main(int argc, char *argv[]) 74 { 75 struct kern_msgbuf cur; 76 int ch, newl, skip, i; 77 char *p, *bufdata; 78 #ifndef SMALL 79 char *memf, *nlistf; 80 #endif 81 char buf[5]; 82 83 #ifndef SMALL 84 memf = nlistf = NULL; 85 while ((ch = getopt(argc, argv, "M:N:")) != -1) 86 switch(ch) { 87 case 'M': 88 memf = optarg; 89 break; 90 case 'N': 91 nlistf = optarg; 92 break; 93 case '?': 94 default: 95 usage(); 96 } 97 argc -= optind; 98 argv += optind; 99 100 if (memf == NULL) { 101 #endif 102 size_t size; 103 int mib[2]; 104 105 mib[0] = CTL_KERN; 106 mib[1] = KERN_MSGBUF; 107 108 if (sysctl(mib, 2, NULL, &size, NULL, 0) == -1) 109 errx(1, "can't get size of msgbuf"); 110 111 if ((bufdata = malloc(size)) == NULL) 112 err(1, "couldn't allocate space for buffer data"); 113 114 if (sysctl(mib, 2, bufdata, &size, NULL, 0) == -1) 115 err(1, "can't get msgbuf"); 116 117 /* make a dummy struct msgbuf for the display logic */ 118 cur.msg_bufx = cur.msg_bufs = size; 119 #ifndef SMALL 120 } else { 121 kvm_t *kd; 122 struct kern_msgbuf *bufp; 123 124 /* 125 * Read in message buffer header and data, and do sanity 126 * checks. 127 */ 128 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 129 if (kd == NULL) 130 exit (1); 131 if (kvm_nlist(kd, nl) == -1) 132 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 133 if (nl[X_MSGBUF].n_type == 0) 134 errx(1, "%s: msgbufp not found", nlistf ? nlistf : 135 "namelist"); 136 if (KREAD(nl[X_MSGBUF].n_value, bufp)) 137 errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd), 138 nl[X_MSGBUF].n_value); 139 if (kvm_read(kd, (long)bufp, &cur, 140 offsetof(struct kern_msgbuf, msg_bufc)) != 141 offsetof(struct kern_msgbuf, msg_bufc)) 142 errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd), 143 (unsigned long)bufp); 144 if (cur.msg_magic != MSG_MAGIC) 145 errx(1, "magic number incorrect"); 146 bufdata = malloc(cur.msg_bufs); 147 if (bufdata == NULL) 148 errx(1, "couldn't allocate space for buffer data"); 149 if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata, 150 cur.msg_bufs) != cur.msg_bufs) 151 errx(1, "kvm_read: %s", kvm_geterr(kd)); 152 kvm_close(kd); 153 if (cur.msg_bufx >= cur.msg_bufs) 154 cur.msg_bufx = 0; 155 } 156 #endif 157 158 /* 159 * The message buffer is circular; start at the write pointer 160 * (which points the oldest character), and go to the write 161 * pointer - 1 (which points the newest character). I.e, loop 162 * over cur.msg_bufs times. Unused area is skipped since it 163 * contains nul. 164 */ 165 for (newl = skip = i = 0, p = bufdata + cur.msg_bufx; 166 i < cur.msg_bufs; i++, p++) { 167 if (p == bufdata + cur.msg_bufs) 168 p = bufdata; 169 ch = *p; 170 /* Skip "\n<.*>" syslog sequences. */ 171 if (skip) { 172 if (ch == '>') 173 newl = skip = 0; 174 continue; 175 } 176 if (newl && ch == '<') { 177 skip = 1; 178 continue; 179 } 180 if (ch == '\0') 181 continue; 182 newl = ch == '\n'; 183 (void)vis(buf, ch, VIS_NOSLASH, 0); 184 if (buf[1] == 0) 185 (void)putchar(buf[0]); 186 else 187 (void)printf("%s", buf); 188 } 189 if (!newl) 190 (void)putchar('\n'); 191 exit(0); 192 } 193 194 void 195 usage(void) 196 { 197 198 #ifdef SMALL 199 (void)fprintf(stderr, "usage: dmesg\n"); 200 #else 201 (void)fprintf(stderr, "usage: dmesg [-M core] [-N system]\n"); 202 #endif 203 exit(1); 204 } 205