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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #if 0 31 #ifndef lint 32 static const char copyright[] = 33 "@(#) 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 static const char sccsid[] = "@(#)dmesg.c 8.1 (Berkeley) 6/5/93"; 39 #endif /* not lint */ 40 #endif 41 #include <sys/cdefs.h> 42 __FBSDID("$FreeBSD$"); 43 44 #include <sys/types.h> 45 #include <sys/msgbuf.h> 46 #include <sys/sysctl.h> 47 48 #include <ctype.h> 49 #include <err.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <kvm.h> 53 #include <limits.h> 54 #include <locale.h> 55 #include <nlist.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <unistd.h> 60 #include <vis.h> 61 #include <sys/syslog.h> 62 63 char s_msgbufp[] = "_msgbufp"; 64 65 struct nlist nl[] = { 66 #define X_MSGBUF 0 67 { s_msgbufp, 0, 0, 0, 0 }, 68 { NULL, 0, 0, 0, 0 }, 69 }; 70 71 void usage(void) __dead2; 72 73 #define KREAD(addr, var) \ 74 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 75 76 int 77 main(int argc, char *argv[]) 78 { 79 struct msgbuf *bufp, cur; 80 char *bp, *ep, *memf, *nextp, *nlistf, *p, *q, *visbp; 81 kvm_t *kd; 82 size_t buflen, bufpos; 83 long pri; 84 int all, ch; 85 86 all = 0; 87 (void) setlocale(LC_CTYPE, ""); 88 memf = nlistf = NULL; 89 while ((ch = getopt(argc, argv, "aM:N:")) != -1) 90 switch(ch) { 91 case 'a': 92 all++; 93 break; 94 case 'M': 95 memf = optarg; 96 break; 97 case 'N': 98 nlistf = optarg; 99 break; 100 case '?': 101 default: 102 usage(); 103 } 104 argc -= optind; 105 if (argc != 0) 106 usage(); 107 108 if (memf == NULL) { 109 /* 110 * Running kernel. Use sysctl. This gives an unwrapped 111 * buffer as a side effect. 112 */ 113 if (sysctlbyname("kern.msgbuf", NULL, &buflen, NULL, 0) == -1) 114 err(1, "sysctl kern.msgbuf"); 115 if ((bp = malloc(buflen + 2)) == NULL) 116 errx(1, "malloc failed"); 117 if (sysctlbyname("kern.msgbuf", bp, &buflen, NULL, 0) == -1) 118 err(1, "sysctl kern.msgbuf"); 119 } else { 120 /* Read in kernel message buffer and do sanity checks. */ 121 kd = kvm_open(nlistf, memf, NULL, O_RDONLY, "dmesg"); 122 if (kd == NULL) 123 exit (1); 124 if (kvm_nlist(kd, nl) == -1) 125 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 126 if (nl[X_MSGBUF].n_type == 0) 127 errx(1, "%s: msgbufp not found", 128 nlistf ? nlistf : "namelist"); 129 if (KREAD(nl[X_MSGBUF].n_value, bufp) || KREAD((long)bufp, cur)) 130 errx(1, "kvm_read: %s", kvm_geterr(kd)); 131 if (cur.msg_magic != MSG_MAGIC) 132 errx(1, "kernel message buffer has different magic " 133 "number"); 134 if ((bp = malloc(cur.msg_size + 2)) == NULL) 135 errx(1, "malloc failed"); 136 137 /* Unwrap the circular buffer to start from the oldest data. */ 138 bufpos = MSGBUF_SEQ_TO_POS(&cur, cur.msg_wseq); 139 if (kvm_read(kd, (long)&cur.msg_ptr[bufpos], bp, 140 cur.msg_size - bufpos) != (ssize_t)(cur.msg_size - bufpos)) 141 errx(1, "kvm_read: %s", kvm_geterr(kd)); 142 if (bufpos != 0 && kvm_read(kd, (long)cur.msg_ptr, 143 &bp[cur.msg_size - bufpos], bufpos) != (ssize_t)bufpos) 144 errx(1, "kvm_read: %s", kvm_geterr(kd)); 145 kvm_close(kd); 146 buflen = cur.msg_size; 147 } 148 149 /* 150 * Ensure that the buffer ends with a newline and a \0 to avoid 151 * complications below. We left space above. 152 */ 153 if (buflen == 0 || bp[buflen - 1] != '\n') 154 bp[buflen++] = '\n'; 155 bp[buflen] = '\0'; 156 157 if ((visbp = malloc(4 * buflen + 1)) == NULL) 158 errx(1, "malloc failed"); 159 160 /* 161 * The message buffer is circular, but has been unwrapped so that 162 * the oldest data comes first. The data will be preceded by \0's 163 * if the message buffer was not full. 164 */ 165 p = bp; 166 ep = &bp[buflen]; 167 if (*p == '\0') { 168 /* Strip leading \0's */ 169 while (*p == '\0') 170 p++; 171 } else if (!all) { 172 /* Skip the first line, since it is probably incomplete. */ 173 p = memchr(p, '\n', ep - p); 174 p++; 175 } 176 for (; p < ep; p = nextp) { 177 nextp = memchr(p, '\n', ep - p); 178 nextp++; 179 180 /* Skip ^<[0-9]+> syslog sequences. */ 181 if (*p == '<' && isdigit(*(p+1))) { 182 errno = 0; 183 pri = strtol(p + 1, &q, 10); 184 if (*q == '>' && pri >= 0 && pri < INT_MAX && 185 errno == 0) { 186 if (LOG_FAC(pri) != LOG_KERN && !all) 187 continue; 188 p = q + 1; 189 } 190 } 191 192 (void)strvisx(visbp, p, nextp - p, 0); 193 (void)printf("%s", visbp); 194 } 195 exit(0); 196 } 197 198 void 199 usage(void) 200 { 201 (void)fprintf(stderr, "usage: dmesg [-a] [-M core [-N system]]\n"); 202 exit(1); 203 } 204