1 /* $NetBSD: dmesg.c,v 1.26 2008/07/20 01:20:22 lukem 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\ 34 The Regents of the University of California. All rights reserved."); 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 1.26 2008/07/20 01:20:22 lukem 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 { .n_name = "_msgbufp" }, 63 { .n_name = NULL }, 64 }; 65 66 void usage(void); 67 68 #define KREAD(addr, var) \ 69 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 70 #endif 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 (bufdata = malloc(size)) == NULL || 110 sysctl(mib, 2, bufdata, &size, NULL, 0) == -1) 111 err(1, "can't get msgbuf"); 112 113 /* make a dummy struct msgbuf for the display logic */ 114 cur.msg_bufx = 0; 115 cur.msg_bufs = size; 116 #ifndef SMALL 117 } else { 118 kvm_t *kd; 119 struct kern_msgbuf *bufp; 120 121 /* 122 * Read in message buffer header and data, and do sanity 123 * checks. 124 */ 125 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 126 if (kd == NULL) 127 exit (1); 128 if (kvm_nlist(kd, nl) == -1) 129 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 130 if (nl[X_MSGBUF].n_type == 0) 131 errx(1, "%s: msgbufp not found", nlistf ? nlistf : 132 "namelist"); 133 if (KREAD(nl[X_MSGBUF].n_value, bufp)) 134 errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd), 135 nl[X_MSGBUF].n_value); 136 if (kvm_read(kd, (long)bufp, &cur, 137 offsetof(struct kern_msgbuf, msg_bufc)) != 138 offsetof(struct kern_msgbuf, msg_bufc)) 139 errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd), 140 (unsigned long)bufp); 141 if (cur.msg_magic != MSG_MAGIC) 142 errx(1, "magic number incorrect"); 143 bufdata = malloc(cur.msg_bufs); 144 if (bufdata == NULL) 145 errx(1, "couldn't allocate space for buffer data"); 146 if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata, 147 cur.msg_bufs) != cur.msg_bufs) 148 errx(1, "kvm_read: %s", kvm_geterr(kd)); 149 kvm_close(kd); 150 if (cur.msg_bufx >= cur.msg_bufs) 151 cur.msg_bufx = 0; 152 } 153 #endif 154 155 /* 156 * The message buffer is circular; start at the write pointer 157 * (which points the oldest character), and go to the write 158 * pointer - 1 (which points the newest character). I.e, loop 159 * over cur.msg_bufs times. Unused area is skipped since it 160 * contains nul. 161 */ 162 for (newl = skip = i = 0, p = bufdata + cur.msg_bufx; 163 i < cur.msg_bufs; i++, p++) { 164 #ifndef SMALL 165 if (p == bufdata + cur.msg_bufs) 166 p = bufdata; 167 #endif 168 ch = *p; 169 /* Skip "\n<.*>" syslog sequences. */ 170 if (skip) { 171 if (ch == '>') 172 newl = skip = 0; 173 continue; 174 } 175 if (newl && ch == '<') { 176 skip = 1; 177 continue; 178 } 179 if (ch == '\0') 180 continue; 181 newl = ch == '\n'; 182 (void)vis(buf, ch, VIS_NOSLASH, 0); 183 #ifndef SMALL 184 if (buf[1] == 0) 185 (void)putchar(buf[0]); 186 else 187 #endif 188 (void)printf("%s", buf); 189 } 190 if (!newl) 191 (void)putchar('\n'); 192 exit(0); 193 } 194 195 #ifndef SMALL 196 void 197 usage(void) 198 { 199 200 (void)fprintf(stderr, "usage: dmesg [-M core] [-N system]\n"); 201 exit(1); 202 } 203 #endif 204