1 /* $OpenBSD: dmesg.c,v 1.33 2022/12/04 23:50:46 cheloha Exp $ */ 2 /* $NetBSD: dmesg.c,v 1.8 1995/03/18 14:54:49 cgd Exp $ */ 3 4 /*- 5 * Copyright (c) 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/msgbuf.h> 35 #include <sys/sysctl.h> 36 37 #include <err.h> 38 #include <fcntl.h> 39 #include <kvm.h> 40 #include <limits.h> 41 #include <nlist.h> 42 #include <stddef.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 #include <vis.h> 48 49 #ifndef NOKVM 50 struct nlist nl[] = { 51 #define X_MSGBUF 0 52 { "_msgbufp" }, 53 { NULL }, 54 }; 55 #endif 56 57 void usage(void); 58 59 #define KREAD(addr, var) \ 60 kvm_read(kd, addr, &var, sizeof(var)) != sizeof(var) 61 62 int 63 main(int argc, char *argv[]) 64 { 65 int ch, newl, skip, i; 66 char *p; 67 struct msgbuf cur; 68 char *memf, *nlistf, *bufdata = NULL; 69 char *allocated = NULL; 70 int startupmsgs = 0; 71 char buf[5]; 72 73 memf = nlistf = NULL; 74 while ((ch = getopt(argc, argv, "sM:N:")) != -1) 75 switch(ch) { 76 case 's': 77 startupmsgs = 1; 78 break; 79 case 'M': 80 memf = optarg; 81 break; 82 case 'N': 83 nlistf = optarg; 84 break; 85 default: 86 usage(); 87 } 88 argc -= optind; 89 argv += optind; 90 91 if (argc != 0) 92 usage(); 93 94 if (memf == NULL && nlistf == NULL) { 95 int mib[2], msgbufsize; 96 size_t len; 97 98 mib[0] = CTL_KERN; 99 mib[1] = startupmsgs ? KERN_CONSBUFSIZE : KERN_MSGBUFSIZE; 100 len = sizeof(msgbufsize); 101 if (sysctl(mib, 2, &msgbufsize, &len, NULL, 0)) 102 err(1, "sysctl: %s", startupmsgs ? "KERN_CONSBUFSIZE" : 103 "KERN_MSGBUFSIZE"); 104 105 msgbufsize += offsetof(struct msgbuf, msg_bufc); 106 allocated = bufdata = calloc(1, msgbufsize); 107 if (bufdata == NULL) 108 errx(1, "couldn't allocate space for buffer data"); 109 110 mib[1] = startupmsgs ? KERN_CONSBUF : KERN_MSGBUF; 111 len = msgbufsize; 112 if (sysctl(mib, 2, bufdata, &len, NULL, 0)) 113 err(1, "sysctl: %s", 114 startupmsgs ? "KERN_CONSBUF" : "KERN_MSGBUF"); 115 116 if (pledge("stdio", NULL) == -1) 117 err(1, "pledge"); 118 119 memcpy(&cur, bufdata, sizeof(cur)); 120 bufdata = ((struct msgbuf *)bufdata)->msg_bufc; 121 } else { 122 #ifndef NOKVM 123 struct msgbuf *bufp; 124 kvm_t *kd; 125 126 /* Read in kernel message buffer, do sanity checks. */ 127 if ((kd = kvm_open(nlistf, memf, NULL, O_RDONLY, 128 "dmesg")) == NULL) 129 return (1); 130 131 if (pledge("stdio", NULL) == -1) 132 err(1, "pledge"); 133 134 if (kvm_nlist(kd, nl) == -1) 135 errx(1, "kvm_nlist: %s", kvm_geterr(kd)); 136 if (nl[X_MSGBUF].n_type == 0) 137 errx(1, "%s: msgbufp not found", 138 nlistf ? nlistf : "namelist"); 139 if (KREAD(nl[X_MSGBUF].n_value, bufp)) 140 errx(1, "kvm_read: %s: (0x%lx)", kvm_geterr(kd), 141 nl[X_MSGBUF].n_value); 142 if (KREAD((long)bufp, cur)) 143 errx(1, "kvm_read: %s (%0lx)", kvm_geterr(kd), 144 (unsigned long)bufp); 145 if (cur.msg_magic != MSG_MAGIC) 146 errx(1, "magic number incorrect"); 147 allocated = bufdata = malloc(cur.msg_bufs); 148 if (bufdata == NULL) 149 errx(1, "couldn't allocate space for buffer data"); 150 if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata, 151 cur.msg_bufs) != cur.msg_bufs) 152 errx(1, "kvm_read: %s", kvm_geterr(kd)); 153 kvm_close(kd); 154 #endif 155 } 156 157 if (cur.msg_bufx >= cur.msg_bufs) 158 cur.msg_bufx = 0; 159 /* 160 * The message buffer is circular; start at the read pointer, and 161 * go to the write pointer - 1. 162 */ 163 for (newl = skip = i = 0, p = bufdata + cur.msg_bufx; 164 i < cur.msg_bufs; i++, p++) { 165 if (p == bufdata + cur.msg_bufs) 166 p = bufdata; 167 ch = *p; 168 /* Skip "\n<.*>" syslog sequences. */ 169 if (skip) { 170 if (ch == '>') 171 newl = skip = 0; 172 continue; 173 } 174 if (newl && ch == '<') { 175 skip = 1; 176 continue; 177 } 178 if (ch == '\0') 179 continue; 180 newl = ch == '\n'; 181 vis(buf, ch, 0, 0); 182 if (buf[1] == 0) 183 putchar(buf[0]); 184 else 185 printf("%s", buf); 186 } 187 if (!newl) 188 putchar('\n'); 189 free(allocated); 190 return (0); 191 } 192 193 void 194 usage(void) 195 { 196 extern char *__progname; 197 198 fprintf(stderr, "usage: %s [-s] [-M core] [-N system]\n", __progname); 199 exit(1); 200 } 201