dmesg.c revision 1.29
1 /* $NetBSD: dmesg.c,v 1.29 2018/04/01 19:36:13 christos 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 1.29 2018/04/01 19:36:13 christos 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 <time.h> 52 #include <kvm.h> 53 #include <nlist.h> 54 #include <stdio.h> 55 #include <stddef.h> 56 #include <stdlib.h> 57 #include <unistd.h> 58 #include <vis.h> 59 60 #ifndef SMALL 61 static struct nlist nl[] = { 62 #define X_MSGBUF 0 63 { .n_name = "_msgbufp" }, 64 { .n_name = NULL }, 65 }; 66 67 __dead static void usage(void); 68 69 #define KREAD(addr, var) \ 70 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 71 #endif 72 73 int 74 main(int argc, char *argv[]) 75 { 76 struct kern_msgbuf cur; 77 int ch, newl, log, i; 78 size_t tstamp, size; 79 char *p, *bufdata; 80 char buf[5]; 81 #ifndef SMALL 82 char tbuf[64]; 83 char *memf, *nlistf; 84 struct timeval boottime; 85 int ptime = 0; 86 87 static const int bmib[] = { CTL_KERN, KERN_BOOTTIME }; 88 size = sizeof(boottime); 89 90 boottime.tv_sec = 0; 91 boottime.tv_usec = 0; 92 ptime = 0; 93 94 (void)sysctl(bmib, 2, &boottime, &size, NULL, 0); 95 96 memf = nlistf = NULL; 97 while ((ch = getopt(argc, argv, "M:N:qt")) != -1) 98 switch(ch) { 99 case 'M': 100 memf = optarg; 101 break; 102 case 'N': 103 nlistf = optarg; 104 break; 105 case 'q': 106 ptime = -1; 107 break; 108 case 't': 109 ptime = 1; 110 break; 111 case '?': 112 default: 113 usage(); 114 } 115 argc -= optind; 116 argv += optind; 117 118 if (memf == NULL) { 119 #endif 120 static const int mmib[2] = { CTL_KERN, KERN_MSGBUF }; 121 122 if (sysctl(mmib, 2, NULL, &size, NULL, 0) == -1 || 123 (bufdata = malloc(size)) == NULL || 124 sysctl(mmib, 2, bufdata, &size, NULL, 0) == -1) 125 err(1, "can't get msgbuf"); 126 127 /* make a dummy struct msgbuf for the display logic */ 128 cur.msg_bufx = 0; 129 cur.msg_bufs = size; 130 #ifndef SMALL 131 } else { 132 kvm_t *kd; 133 struct kern_msgbuf *bufp; 134 135 /* 136 * Read in message buffer header and data, and do sanity 137 * checks. 138 */ 139 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 140 if (kd == NULL) 141 exit (1); 142 if (kvm_nlist(kd, nl) == -1) 143 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 144 if (nl[X_MSGBUF].n_type == 0) 145 errx(1, "%s: msgbufp not found", nlistf ? nlistf : 146 "namelist"); 147 if (KREAD(nl[X_MSGBUF].n_value, bufp)) 148 errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd), 149 nl[X_MSGBUF].n_value); 150 if (kvm_read(kd, (long)bufp, &cur, 151 offsetof(struct kern_msgbuf, msg_bufc)) != 152 offsetof(struct kern_msgbuf, msg_bufc)) 153 errx(1, "kvm_read: %s (0x%lx)", kvm_geterr(kd), 154 (unsigned long)bufp); 155 if (cur.msg_magic != MSG_MAGIC) 156 errx(1, "magic number incorrect"); 157 bufdata = malloc(cur.msg_bufs); 158 if (bufdata == NULL) 159 errx(1, "couldn't allocate space for buffer data"); 160 if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata, 161 cur.msg_bufs) != cur.msg_bufs) 162 errx(1, "kvm_read: %s", kvm_geterr(kd)); 163 kvm_close(kd); 164 if (cur.msg_bufx >= cur.msg_bufs) 165 cur.msg_bufx = 0; 166 } 167 #endif 168 169 /* 170 * The message buffer is circular; start at the write pointer 171 * (which points the oldest character), and go to the write 172 * pointer - 1 (which points the newest character). I.e, loop 173 * over cur.msg_bufs times. Unused area is skipped since it 174 * contains nul. 175 */ 176 for (tstamp = 0, newl = 1, log = i = 0, p = bufdata + cur.msg_bufx; 177 i < cur.msg_bufs; i++, p++) { 178 #ifndef SMALL 179 if (p == bufdata + cur.msg_bufs) 180 p = bufdata; 181 #define ADDC(c) \ 182 do \ 183 if (tstamp < sizeof(tbuf) - 1) \ 184 tbuf[tstamp++] = (c); \ 185 while (/*CONSTCOND*/0) 186 #else 187 #define ADDC(c) 188 #endif 189 ch = *p; 190 /* Skip "\n<.*>" syslog sequences. */ 191 /* Gather timestamp sequences */ 192 if (newl) { 193 switch (ch) { 194 case '[': 195 ADDC(ch); 196 continue; 197 case '<': 198 log = 1; 199 continue; 200 case '>': 201 log = 0; 202 continue; 203 case ']': 204 ADDC(ch); 205 ADDC('\0'); 206 tstamp = 0; 207 #ifndef SMALL 208 if (ptime == 1) { 209 intmax_t sec; 210 time_t t; 211 long nsec; 212 struct tm tm; 213 214 sscanf(tbuf, "[%jd.%ld]", &sec, &nsec); 215 t = boottime.tv_sec + sec; 216 if (localtime_r(&t, &tm) != NULL) { 217 strftime(tbuf, sizeof(tbuf), 218 "[%a %b %e %H:%M:%S %Z %Y]", 219 &tm); 220 printf("%s ", tbuf); 221 } 222 continue; 223 } else if (ptime != -1) 224 printf("%s ", tbuf); 225 #endif 226 continue; 227 case ' ': 228 if (!tstamp) 229 continue; 230 /*FALLTHROUGH*/ 231 default: 232 if (tstamp) { 233 ADDC(ch); 234 continue; 235 } 236 if (log) 237 continue; 238 break; 239 } 240 newl = 0; 241 } 242 if (ch == '\0') 243 continue; 244 newl = ch == '\n'; 245 (void)vis(buf, ch, VIS_NOSLASH, 0); 246 #ifndef SMALL 247 if (buf[1] == 0) 248 (void)putchar(buf[0]); 249 else 250 #endif 251 (void)printf("%s", buf); 252 } 253 if (!newl) 254 (void)putchar('\n'); 255 return EXIT_SUCCESS; 256 } 257 258 #ifndef SMALL 259 static void 260 usage(void) 261 { 262 263 (void)fprintf(stderr, "Usage: %s [-qt] [-M core] [-N system]\n", 264 getprogname()); 265 exit(EXIT_FAILURE); 266 } 267 #endif 268
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